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-t.--
)i~
&$Sl!..fo'
Strategies for Today’s
-nJ.Y'
Environmental
Pavtnersbip
Environmental Partnership
API
API ENVIRONMENTAL,
ENVIRONMENTAL,HEALTH
HEALTHAND
ANDSAFETY
SAFETYMISSION
MISSION
.
AND
AND GUIDING
GUIDING PRINCIPLES
PRINCIPLES
The members
Petroleum
members of
ofthe
theAmerican
American
Petroleum Institute
Institute are
are dedicated
dedicated to continuous
continuous efforts
efforts to
improve
of our operations
improve the compatibility
compatibility of
operations with the environment
environment while
while economically
economically
developing
developing energy
energyresources
resources and supplying
supplying high quality
quality products
products and
andservices
services to consumconsumers.
others
ers. We recognize
recognize our responsibility
responsibilityto work with
withthe public,
public, the
the government,
government,and
and
others to
develop
develop and to use natural
natural resources
resources in an
anenvironmentally
environmentallysound
sound manner while
while protecting
protecting
the health
these responsibilities,
responsibilities,API
health and safety
safety of our employees
employees and
andthe public.
public. To meet these
members
pledge
to
manage
our
businesses
according
to
the
following
members pledge manage
businesses according the following principles
principles using
sound
science
to
prioritize
risks
and
to
implement
cost-effective
management
sound science prioritize risks
implement cost-effective management practices:
practices:
•e To recognize
recognize and to respond
respond to community
community concerns
concerns about our raw materials,
materials, products and
and operations.
operations.
•e To operate
operate our plants and
andfacilities,
facilities, and totohandle
handle our raw materials
materials and products
products in aa
manner that protects
protects the environment,
environment, and the safety
safety and health
health of our employees
employees
and the public.
public.
•e To
To make
make safety,
safety, health
health and
andenvironmental
environmentalconsiderations
considerations a priority
priority in our planning,
planning,
and our development
products and processes.
processes.
development of new products
•e To advise
the public
advise promptly,
promptly, appropriate
appropriate officials,
officials, employees,
employees, customers
customers and the
public of
information
information on
onsignificant
significantindustry-related
industry-related safety,
safety, health and environmental
environmentalhazards,
hazards,
and to recommend
recommend protective
protectivemeasures.
measures.
•e To counsel
counsel customers,
customers, transporters
transporters and others
others in the safe
safe use,
use, transpQrtation
transpqrtation and disposal of our raw materials,
materials, products
products and waste
waste materials.
materials.
economically develop
develop and produce
produce natural resources
resources and to conserve
conserve those
•e To economically
resources
resources by using
usingenergy
energyefficiently.
efficiently.
•e To extend
extend knowledge
knowledge by conducting
conducting or supporting
supportingresearch
research on the safety,
safety, health
health and
environmental
materials, products,
products, processes
processes and waste
wastematerials.
materials.
environmental effects
effects of our raw materials.
•e To
To commit to
to reduce
reduce overall
overall emissions
emissions and waste
wastegeneration.
generation.
•e To work with
with others
others to resolve problems created
created by handling
handlingand
anddisposal
disposal of hazardhazardous substances
substances from
from our operations.
operations.
•e To
To participate
participate with government
government and
and others
others in creating
creating responsible
responsible laws,
laws, regulations
regulations
and standards
standards to safeguard
safeguard the community,
community, workplace
workplaceand
andenvironment.
environment.
•e To promote
promote these
these principles
principles and practices
practices by sharing
sharing experiences
experiences and
andoffering
offering assisassistance to others
others who produce;
produce, handle,
handle, use, transport
transport or dispose
dispose of similar
similar raw materimaterials,
als, petroleum
petroleum products
products and
andwastes.
wastes.
~~
~~
~
STD-API/PETRO RP
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Ob15533
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I073i?;390
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Electrical
Electrical Installations
Installationsinin
Petroleum
Petroleum Processing
ProcessingPlants·
Plants
Downstream
DownstreamSegment
Segment
API
API RECOMMENDED
RECOMMENDED PRACTICE
PRACTICE540
540
FOURTH
FOURTH EDITION,
EDITION,APRIL
APRIL1999
1999
American
American
Petroleum
Petroleum
Institute
Institute
Helping
HelpingYou
You
Clet
Get The
The Job
Job
Done
Right.l'M
Done R¡ght.SM
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SPECIAL
SPECIAL NOTES
NOTES
A
PI publications
address
problems
of
API
publicationsnecessarily
necessarily
address
problems
of aa general
generalnature.
nature.With
With respect
respectto
to particparticular
circumstances,
local,
state,
and
federal
laws
and
regulations
should
be
reviewed.
ular circumstances,local, state, and federal laws and regulations should be reviewed.
API
duties of
API is
is not
not undertaking
undertaking to
to meet
meet the duties
of employers,
employers, manufacturers,
manufacturers,or
or suppliers
suppliers to
to
warn
and
properly
train
and
equip
their
employees,
and
others
exposed,
concerning
warn and properly train and equip their employees, and others exposed, concerninghealth
health
and
obligations
under
local,
state,state,
or
and safety
safety risks
lisks and
and precautions,
precautions,nor
norundertaking
undertakingtheir
their
obligations
under
local,
or fedfederallaws.
eral laws.
Information
andand
health
precautions
withwith
respect
to
Informationconcerning
concerningsafety
safety
healthrisks
risks and
andproper
proper
precautions
respect
to parparticular
be
the manufacturer
manufactureror
or
ticular materials
materialsand
andconditions
conditionsshould
should
be obtained
obtained from
fromthe
theemployer,
employer,the
supplier
supplierof
of that
thatmaterial,
material,or
or the
thematerial
material safety
safetydata
datasheet.
sheet.
Nothing
any API
Nothing contained
contained in
in any
API publication
publication isis to
to be
be construed
construed as
as granting
granting any
any right,
right, by
by
implication
or
implicationororotherwise,
otherwise,for
forthe
themanufacture,
manufacture,sale,
sale,
oruse
useof
of any
anymethod,
method,apparatus,
apparatus,or
orprodproduct
be be
conuct covered
covered by
by letters
letters patent
patent.Neither
Neithershould
shouldanything
anythingcontained
containedininthethepublication
publication
construed
liability
for
struedas
asinsuring
insuringanyone
anyoneagainst
against
liability
forinfringement
infringementof
of letters
letterspatent.
patent.
Generally.
are are
reviewed
and revised,
reaffirmed,
or
every
Generally,API
APIstandards
standards
reviewed
and revised,
reaffirmed,
or withdrawn
withdrawnatatleast
least
every
five
fiveyears.
years. Sometimes
Sometimesa aone-time
one-timeextension
extensionof
of up
up to
to two
two years
years will
willbe
beadded
addedtotothis
thisreview
review
cycle.
five
five years
years after
afterits
its publication
publicationdate
dateas
as an
an
cycle.This
This publication
publication will
willno
nolonger
longerbebeinineffect
effect
operative
been
granted,
upon
republication.
Status
operativeAPI
API standard
standard or,
or,where
whereananextension
extensionhashas
been
granted,
upon
republication.
Status
of
(202)
of the
the publication
publicationcan
canbe
be ascertained
ascertainedfrom
fromthe
the API
API Downstream
DownstreamSegment
Segment[telephone
[telephone(202)
682-8000].
andand
materials
is
682-8000].AAcatalog
catalogofofAPI
APIpublications
publications
materials
is published
published annually
annuallyand
andupdated
updated
quarterly
quarterlyby
by API,
API, 1220
1220LL Street,
Street,N.W.,
N.W.,Washington,
Washington,D.C.
D.C. 20005.
20005.
This
document
was
produced
under
API
standardization
procedures
that that
ensure
appropriThis document was produced under API standardization
procedures
ensure
appropriate
notification
and
participation
in
the
developmental
process
and
is
designated
as
ate notification and participation inthe developmental process andis designated asan
an API
API
standard.
this standard
standard or
or comcomstandard. QuestionsQuestionsconcerning
concerning the
the interpretation
interpretation of
of the
the content of
of this
ments
questions concerning
concerningthe
theprocedures
proceduresunder
under
which
standard
developed
ments and questions
which
thisthis
standard
waswas
developed
should
be
directed
in
writing
to
the
director
of
the
Downstream
Segment,
American
Petroshould be directed in writing tothe director of the Downstream Segment, American
Petroleum
Institute,
1220
L
Street,
N.W.,
Washington,
D.C.
20005.
Requests
for
permission
to
leum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permission to
reproduce
all or
thematerial
material
published
herein
reproduce or
or translate
translateall
or any
any part
part of
ofthe
published
herein
shouldshould also
also be
be
addressed
addressedto
to the
the director.
director.
API
of proven,
sound
engineerAPI standards
standardsare
arepublished
publishedto
to facilitate
facilitatethe
thebroad
broadavailability
availability
of proven,
sound
engineering
These
standards
are
applyarenot
not intended
intendedto
to obviate
obviatethe
theneed
needforfor
applying and
andoperating
operatingpractices.
practices.
These
standards
ing
andwhere
where
these
standards
should be
ing sound
sound engineering
engineering judgment
judgment regarding
regarding when
whenand
these
standards
should
be
utilized.
utilized. The
The formulation
formulation and
and publication
publication of
of API
A P I standards
standards isis not
not intended
intended in any
any way to
to
inhibit
practices.
inhibitanyone
anyonefrom
fromusing
usingany
anyother
other
practices.
Any
equipment or
conformancewith
withthethe
marking
Any manufacturer
manufacturer marking
marking equipment
or materials
materials in conformance
marking
requirements
of an
anAPI
API standard
standardisis solely
solely responsible
responsiblefor
for complying
complyingwith
withallallthe
the applicable
applicable
requirementsof
requirements
suchprodprodrequirementsof
of that
that standard.
standard.API
API does
doesnot
not represent,
represent,warrant,
warrant,or
or guarantee
guaranteethat
that such
ucts
doin
in fact
fact conform to
tothe
the applicable
applicableAPI
APIstandard.
standard.
.
uctsdo
All
All rights
rights reserved.
reserved.No
No part
part of
of this
this work
workmay
may be
be reproduced,
reproduced,stored
storedin
in aaretrieval
retrieval system,
system,or
or
transmitted
transmitted by
byany
anymeans,
means, electronic,
electronic, meclulnical,
mechanical,photocopying,
photocopying,recording,
recording,or
orothelWise,
otherwise,
without
withoutprior
prior written
written pennission
permissionfrom
jìom the
thepublisher.
publishel:Contact
Contactthe
the Publisher,
Publisher
API
1220LL Street,
Street, N.
N.tv.,
W ,Washington,
Washington, D.C.
D.C.20005.
20005.
API Publishing
Publishing Services,
Services,1220
Copyright
Copyright©
O1999
1999American
AmericanPetroleum
PetroleumInstitute
Institute
!L
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FOREWORD
FOREWORD
This
onon
electrical
installations
in
This recommended
recommended practice
practiceprovides
providesinfolIDation
information
electrical
installations
in petroleum
petroleum
facilities.
concerned
with
the the
safe safe
design,
facilities.ItIt isis intended
intendedfor
forall
all individuals
individualsand
andorganizations
organizations
concerned
with
design,
installation,
of
.
of electrical
electricalsystems
systemsin
in petroleum
petroleumfacilities.
facilities.
installation,and
andoperation
operation
This
by
This recommended
recommended practice
practicehas
hasbeen
beendeveloped
developed
by individuals
individuals with
withmany
many years'
years’ experiexperience
in
the
petroleum
industry.
Although
of
interest
to
anyone
seeking
information
on
elecence in the petroleum industry. Although of interestanyone
to
seeking informationon electrical
systems
in
petroleum
facilities,
it
is
primarily
intended
used by
trical systems in petroleum facilities, it
is primarilyintended to
to be
beused
by individuals
individuals
knowledgeable
knowledgeablein
in engineering
engineering fundamentals
fundamentalswho
who require
require specific
specific guidance
guidanceconcerning
concerningcurcurrently
accepted
practices
in
the
petroleum
indusu),.
rently accepted practicesin the petroleum industry.
API
do
been
so. Every
Everyeffort
efforthashas
been made
made by
by
API publications
publications may
may be
be used
usedby
by anyone
anyonedesiring
desiringto to
do so.
the
of
the Institute
Institute to
to assure
assure the
the accuracy
accuracyand
andreliability
reliability
of the
the data
data contained
containedin
in them;
them; however,
however, the
the
with
this
Institute
this publication
publication
Institutemakes
makesno
no representation,
representation,warranty,
warranty,or
or guarantee
guaranteeinincOlmection
connection
with
and
disclaims any
any liability
liability or
and hereby expressly disclaims
or responsibility
responsibility for
for loss
loss or
or damage
damage resulting
resulting
any
which
this this
from
from its
its use
use or
or for
for the
the violation
violationofof
any federal,
federal, state,
state,or
or municipal
municipalregulation
regulationwith
with
which
publication
publication may
may conflict
conflict.
to
Suggested
Suggestedrevisions
revisionsare
are invited
invited and
and should
shouldbebesubmitted
submitted
to the
the director
directorof
of the
the Downstream
Downstream
Segment,American
Institute,
1220
1220LL Street,
Street,N.W.,
N.W., Washington,
Washington,D.C.
D.C. 20005.
20005.
Segment, AmericanPetroleum
Petroleum
Institute,
iiiiii
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IMPORTANT
IMPORTANT INFORMATION
INFORMATIONCONCERNING
CONCERNINGUSE
USE OF ASBESTOS
OR ALTERNATIVE
ALTERNATIVE MATERIALS
MATERIALS
Asbestos is specified
certain
components
of the
specified ororreferenced
referencedforfor
certain
components
the equipment
equipmentdescribed
describedinin
some
It has
in minimizing
fire hazards
associated
some API
APIstandards.
standards.
has been
beenofofexu'eme
extremeusefulness
usefulness
in minimizing
fire hazards
associated
been aauniversal
universalsealing
sealing
material,
compatible
with petroleum
petroleum processing.
processing. It has also been
material,
compatible
withwith
most refining
refiningfluid
fluidservices.
services.
Certain serious
adverse
with asbestos,
serious adverse health effects
effects are associated
associated with
asbestos, among
among them the
of
lung
cancer,
asbestosis,
and
mesothelioma
serious
and
often
fatal
diseases
serious and often fatal diseases
cancèr, asbestosis, and mesothelioma(a(acancer of
the chest and abdominal
linings).
The
degree
to asbestos
abdominal linings).
degreeofofexposure
exposure
asbestos varies
varieswith
withthe product and the work
workpractices
practices involved.
involved.
and Health
HealthAdministration
Administration
Consult the most
most recent
recentedition
edition of the
the Occupational Safety and
(OSHA),
Safety
and and
Health
Standard
for
(OSHA), U.S.
U.S. Department
Department of
ofLabor,
Labor,Occupational
Occupational
Safety
Health
Standard
for Asbestos,
Asbestos,
Tremolite,
Anthophyllite, and
Tremolite,Anthophyllite,
and Actinolite,
Actinolite, 29 Code
Code of
of Federal
Federal Regulations
Regulations Section
1910.1001;
the U.S.
ProtectionAgency,
Agency,
National
Emission
Standard for
U.S. Environmental
EnvironmentalProtection
National
Emission
Standard
for
1910.1001;the
61.156; and
and the U.S.
Asbestos,40
Asbestos, 40 Code
Code of Federal
Federal Regulations Sections
Sections 61.140 through 61.156;
Environmental
requirements
andand
phased
banning
Environmental Protection
ProtectionAgency
Agency(EPA)
(EPA)rule
ruleononlabeling
labeling
requirements
phased
banning
of asbestos
asbestosproducts
products(Sections
(Sections763.160-179).
763.160-179).
There
in use
use and under development
development a number of substitute
substitute materials to
There are currently in
replace
areare
encouraged
to develop
replace asbestos
asbestos in
in certain
certainapplications.
applications.Manufacturers
Manufacturersand
andusers
users
encouraged
develop
and use
useeffective
effectivesubstitute
substitute
materials
can the
meet
the specifications
materials
thatthat
can meet
specifications
for, and for, and operating
operating
requirements
requirements of,
of,the equipment
equipment to which they
they would
would apply.
apply.
SAFETY
INFORMATION WITH
HEALTHINFORMATION
WITH RESPECT
RESPECT TO PARTICULAR
SAFETY AND HEALTH
PRODUCTS
FROM THE EMPLOYER,
PRODUCTS OR MATERIALS
MATERTALS CAN BE OBTAINED
OBTAINED FROM
EMPLOYER, THE
MANUFACTURER
SUPPLIER OF
PRODUCTOR
ORMATERIAL,,
MATERIAL, OR THE
MANUFACTURER OR SUPPLIER
OF THAT PRODUCT
MATERIAL
MATERIAL SAFETY
SAFETY DATA
DATA SHEET.
SHEET.
iv
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CONTENTS
CONTENTS
Page
1
INTRODUCTION.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
INTRODUCTION ......................................................
1.1
Purpose...........................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
1.1Purpose
1.2
1.2 Scope
Scope ...........................................................
...........................................................
1.3 References.
References .......................................................
1.3
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
2
CLASSIFIED
OR ELECTRICAL
CLASSIFED LOCATIONSOR
ELECTRICAL EQUIPMENT
EQUIPMENT..................
................ 5
2.1
Purpose...........................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5
2.1Purpose
2.2Scope
Scope ............................................................
5
............................................................
2.3 Classification
Classification of Flammable and Combustible
Combustible Liquids
Liquidsand
andGases
Gases ............
. . . . . . . . .. 5
2.4 Classification
......................................... 5
Classification of Locations
Locations ...........................................
2.5 Electrical
Electrical
Equipment
for Classified
Locations............................
. . . . . . . . . . . . . . . . . . . . . . . . .. 6
Equipment
for Classified
Locations
Alternative Design
Design in Classified
2.6 Alternative
ClassifiedLocations
Locations...............................
............................. 6
3
9
ELECTRICAL
EFFICIENCY ....................................
....................................
ELECTRICALENERGYEFFICIENCY
3.1
Purpose
..........................................................
9
3.1Purpose ..........................................................
3.2 Scope ...........................................................
........................................................... 9
3.3
Efficiency .....................
,............... 9
3.3 The Role of Electrical Efficiency
.....................................
3.4 Definition of Efficiency .............................................
............................................. 9
Considerations
.........................................
3.5Specification
Specification
Considerations .........................................
9
3.6Economic
Economic
Evaluation ...............................................
9
...............................................
Evaluation
3.7Cogeneration
Cogeneration
and Energy
Recovery ..................................
10
..................................
10
andEnergy
Recovery
3.8Design
Design
Considerations .............................................
Considerations
............................................. 12
12
to Power
Factor
........................................ 15
15
3.9 Relationship
Relationship
to Power
Factor........................................
3.10 Definitions
Definitions and Conversion
Conversion Factors
Factors...................................
................................... 15
15
4
FACILITY
..........................................
FACILITY POWER SYSTEMS
SYSTEMS..........................................
4.1
~ .......................................
4.1 Purpose .................
.........................................................
4.2 Scope.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Scope ..........................................................
4.3Power
Power
Sources ..........
'.' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
....................................................
Sources
4.4System
System
Voltages...................................................
.................................................
Voltagès
4.5 Power
Power
System
Arrangements.........................................
.......................................
System
Arrangements
Power
System Studies.
............................................
4.6Power
System
Studies .............................................
System
Protection ................................................
4.7System
Protection
................................................
...........................................................
4.8 Fuses ...........................................................
4.9 Circuit Breakers.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
Breakers ..................................................
4.10Switchgear
Switchgear ......................................................
......................................................
4.11
Transformers.....................................................
....................................................
4.11Transformers
4.12 Overhead
OverheadElectric
ElectricPower
Power Distribution
Distribution .................................
.................................
17
17
17
17
17
17
17
17
22
23
23
26
27
28
28
29
33
33
5
GROUNDING
GROUNDING AND LIGHTNING
LIGHTNINGPROTECTION ..........................
..........................
5.1 Purpose .........................................................
.........................................................
5.2 Scope
..........................................................
Scope ..........................................................
5.3 Static
Electricity
andStray
StrayCurrents
Currents ..................................
Static
and
..................................
5.4 System
Grounding
................................................
SystemGrounding................................................
5.5Eiquipment
Equipment
Grounding .............................................
.............................................
Grounding
5.6Connections
Connectipns
..............................................
to to Earth ..............................................
5.7Lightning
Lightning
Protection ..............................................
Protection
..............................................
35
35
35
35
35
36
38
38
6
41
MOTORS
CONTROLLERS........................................
........................................
41
MOTORS AND CONTROLLERS
6.1
Purpose .........................................................
......................................................... 41
41
6.1Purpose
vV
1
11
1
1
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Page
Page
6.2
Scope ..............•...............
-..................... '........ 41
6.2Scope
............................................................
41
........................................ 41
41
6.3 Motor
MotorRatingand
6.3
andEfficiency
Efficiency ........................................
6.4
. . . . . . . . . . . . . . . . . . . . . . . .. 41
of Motors
Motors and Controllers ...........................
41
6.4 Relative
RelativeLocations
Locationsof
6.5
Frequencies ......
" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41
6.5
Frequencies
......................................................
41
6.6
Standard
Voltage for
. . . . . . . .. . . . . . . . . . . . . . .. . . . . . . .. . . .. . .. 41
41
6.6Standard
Voltage
forMotors
Motors .........................................
6.7
Motor
Voltage
Selection.............................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 41
41
6.7 Motor
Voltage
Selection
6.8
6.8 Temperature
Temperature and
and Altitude
Altitude Considerations
Considerations in Motor Applications ...........
. . . . . . . . . . . 42
42
6.9
Other
Conditions
Affecting
Design
and
Application .....................
..................... 42
42
6.9 Other
Conditions
Affecting
Design
and
Application
6.10
Types
of
Motor
Construction
........................................
42
42
6.10 Types of Motor Construction........................................
6.11
Installation......................................................
6.11Installation
...................................................... 45
45
6.12
Constnlction of
6.12 Construction
of Totally
Totally Enclosed
EnclosedMotors
Motors..............................
.............................. 45
45
, . , . . . . . . . . . . . . . . . . . . . . .. 46
6,13
Motors for
Locations...............
........................................
46
6.13 Motors
for Class
Class II Locations
6.14
Motors for
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 47
II Locations
Locations ........................................
47
6.14 Motors
for Class
Class II
6.15
MotorService
ServiceFactor
Factor ..............................................
6.15 Motor
.............................................. 48
48
6.16
Frequency of
. . . .. . .. . .. . . . . . . .. . .. . . . .. .. . . . . . .. .. .. . . . .. 48
of Starting.
Starting..............................................
48
6.16 Frequency
6.17
Temperature,Vibration,
Vibration, and
and Current
Cmrent Indicators
Indicators .........................
6.17 Temperature.
......................... 48
48
6.18
Conduit or
. . .. . .. .. .. . . . . . . . . . . . . . . . . . . . . .. . . . .. .. 48
6.18 -Conduit
or Terminal
Terminal Box
Box...
...........................................
48
6.19
SpaceHeaters
Heaters .....................
6.19 Space
..................... , ..........................
.............................., ... 48
48
6.20
Bearingsand
andLubrication
Lubrication ...........................................
6.20 Bearings
........................................... 49
49
.. .. . . . . . . . . .. . .. . . .. . . . . . . . . . . .. . . . . . . . . . .. 50
6.21
TorqueRequirements
Requirements..
..............................................
50
6.21 Torque
' ......' ..................... , 52
6.22
Method of
of Starting
Starting....................
................................................
52
6.22 Method
6.23
MotorControllers
Controllers..................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
6.23 Motor
55
6.24
Application of
, . . . . . . . .. . . . . . . . . . .. . .. 60
of Motor
Motor Control
Control ................
.......................................
60
6.24 Application
6.25
Means of
'. . .. 61
6.25 Means
of Disconnection
Disconnection .......................................
...........................................
61
6.26
Coordination of
or or
Circuit
Breakers
On On
of Controller
Controller Applications
ApplicationsWith
WithFuses
Fuses
Circuit
Breakers
6.26 Coordination
, ... , .. ,. ' .•........ .- ............... 61
Low-Voltage
Low-VoltageSystems
Systems ..........
.............................................
61
6.27
OverloadProtection:
Protection:Special
SpecialApplications
Applications..............................
. . . . . . . . . . .. . . . . . . . . . . . . . . .. 62
62
6.27 Overload
6.28
VoltageLimitations
Limitations ................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... 62
62
6.28Voltage
6.29
Application of
.... . . . . . . .. .. . . . . . . . . . .. 62
.............................
62
6.29 Application
of Outdoor
Outdoor and
andIndoor
IndoorTypes
Types....
6.30
PushbuttonStations
Stations ................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 62
62
6.30Pushbutton
6.31
Additional
References
..........
,
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
63
6.3 1 Additional
............................................. 63
L
77
LIGHTING
" .........................................
LIGHTING ...............
..........................................................
7.1
Purpose..........................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
7.1Purpose
~ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
7.2
Scope ....
..........................................................
7.2Scope
7.3
Definition of
of Terms
Terms .............................................
............................................... "
7.3Definition
7.4
Lighting
Facilities ...............
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
7.4Lighting
Facilities
................................................
7.5
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
7.5 Luminaires..
Luminaires ......................................................
7.6
; ................
7.6 LightQuality
LightQuality ...................................
....................................................
7.7
7.7 llluminance
nluminance......................................................
......................................................
7.8
Installation
Initial
Values ..........
, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
...........................................
7.8Installation
Initial
Values
7.9
Supply ......................................
7.9 Lighting
LightingSystem
System Power Supply
.......................................
7.10
EmergencyLighting
Lighting...............................................
...............................................
7.10 Emergency
7.11
; . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
DesignConsiderations
Considerations...
.............................................
7.1 1 Design
7.12
EstimatingElectric
ElectricPower
PowerRequirements
Requirements ................................
. . . . . . . . . . . . . . . . .. . . . . . . . . . ..
7.12 Estimating
7.13
llluminanceMeters
7.13Illuminance
Meters ...............................................
...............................................
65
65
65
65
65
65
65
65
65
65
70
70
71
71
71
71
72
72
72
72
72
72
73
73
73
73
74
74
88
WIRING
WIRING.............................................................
.............................................................
8.1
Purpose ....
, ....................................................
8.1Purpose
..........................................................
8.2
Scope ............................
, . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
..........................................................
8.2Scope
8.3
General-.........................................................
..........................................................
8.3General
8.4
Conduit
Systems ..................
" ..............................
.................................................
8.4Conduit
Systems
8.5
Electrical
Metallic
Tubing..
. .. . .. . .. . . . . . . . . . .... . .. .. .. .. .. . .. ....
..........................................
8.5Electrical
Metallic
Tubing
75
75
75
75
75
75
75
75
75
75
79
79
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8.6Busways
Busways .........................................................
........................................................
.......................................................
8.7 Wireways
Wireways .......................................................
8.8 CableTrays
.....................................................
8.8
Trays ......................................................
8.9
Manholes
and
Above
Grade
Pull
Points ...............................
8.9 Manholes
and
Above
Grade
Pull
Points
...............................
8.10 Wire and Cable
Cable...................................................
...................................................
8.10
8.11Fireproofing
.....................................................
8.11
Fireproofing.....................................................
79
79
80
80
81
81
85
85
9 POWER
POWER
SYSTEMS
INSTRUMENTATION
PROCESS
CONTROL ..
. . 87
SYSTEMS
FORFOR
INSTRUMENTATION
ANDAND
PROCESS
CONTROL
9.1Purpose
..................... ;: .........................
...................................
9.1
Purpose .....................
'.' ........ 87
9.2Scope
Scope ..........................................................
.......................................................... 87
9.3 BasicDesign
.............................................. 87
9.3
DesignCriteria
Criteria ..............................................
87
9.4
9
A DesignConsiderations
Considerations..............................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 87
............................................
9.5Electric
Electric
Power
Systems ............................................
89
Power
Systems
............................................... 90
9.6 DistributionSystem
System ...............................................
Methods
9.7Wiring
Wiring
Methods...................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
9.8 System
System
Equipment
Grounding ...................................
92
...................................
andand
Equipment
Grounding
9.9 Considerations
............................... 92
Considerations for Classified
ClassifiedLocations ...............................
................................................ 93
93
10 SPECIAL
SPECIALEQUIPMENT
10
EQUIPMENT ................................................
10.1
Purpose ........................................................
93
........................................................
93
10.1Purpose
10.2Scope
.........................................................
93
10.2
Scope .................
'.' ...................................... 93
10.3
General ........................................................
93
........................................................
93
10.3General
lOA
Communication
Systems ..........................................
10.4Communication
Systems
.......................................... 93
93
. . . . . . . . . . 93
93
10.5 Supervisory
Control
andand
Data
Acquisition
Equipment
(SCADA)
10.5
Supervisory
Control
Data
Acquisition
Equipment
(SCADA) ..........
10.6
Closed-Circuit
Television
(CCTV) ..................................
94
..................................
10.6Closed-Circuit
Television
(CCTV)
10.7Obstruction
andand
Warning
Lighting
...................................
10.7
Obstruction
Warning
Lighting ....
".............................. 94
10.8
Navigation
Lighting ..............................................
.............................................. 94
10.8Navigation
Lighting
10.9
10.9FireFire Alarm Systems
Systems ..............................................
.............................................. 94
10.10
ElectricHeat
HeatTracing
Tracing..............................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
10.10 Electric
....................................... 94
10.1 1 Cathodic Protection
Protection Systems
Systems.......................................
10.11
10.12
Desaltersand
andPrecipitators
Precipitators ....................
~ ................... 94
........................................
10.12 Desalters
10.13
Portable Equipment.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
Equipment ..............................................
95
1O.13 Portable
11 INHERENT
INHERENT ELECTRICAL SAFETY
SAFETY.....................................
.....................................
11
11.1
GeneraL........................................................
.........................................................
11.1General
11.2
References......................................................
11.2References
......................................................
.........................................................
11.3
Specifics.........................................................
11.3Specifics
97
97
97
97
................................
APPENDIX
A INFORMATIVE ANNEX A ................................
APPENDIXA
99
Figures
1Brayton
Brayton
Cogeneration
.......................................... 11
11
Cogeneration
Cycle Cycle ..........................................
2Carnot
Carnot
Topping
Cycle.
.
.
.
.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 11
Topping
Cycle ...............................................
11
3System
System
Energy
Losses:
Adjustable Speed
Versus Throttling
. . . . . . . . . . . . . . . . .14
14
Energy
Losses:
Adjustable
Speedversus
Throttling .................
4PowerRelationship
Power Relationship..................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15
15
SingleMain
Arrangement ........................................
18
5
Single
Main Bus Arrangement.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 18
6
UnitConstruction
Construction Bus Arrangement ...................................
................................... 18
18
7Synchronizing
Synchronizing Bus Arrangement ....
.... : .................................
................................. 19
19
8
PurchasedPower:
Power:Divided
DividedFeeder
Feeder
Operation .............................
Operation
............................. 20
9
PurchasedPower:
Power:Parallel
Parallel
Feeder
Operation ..............................
. . . . . . . . . . . . . . . . . . . . . . . . . . .. 20
Feeder
Operation
10
System................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
. . . . . . . . . . . . .. 24
10 Simple
Simple Radial System
;...............
vi
vii
..
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Copyrighted material licensed to IDOM.
RP 540
ENGL
J977or distribution
.0732290
Ob&5540 Obd I
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Primary-Selective
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 24
Primary-SelectiveRadial
RadialSystem.
System......................................
24
Secondary-Selective
Secondary-SelectiveRadial
RadialSystem
System....................................
.................................... 25
25
Secondary-Selective
: ....... 25
Secondary-SelectiveParallel
ParallelSystem
System...........................
...................................
25
Combined
. . . . . . . . . . . . . . . . . . . . . . .. 51
Combined Motor
Motorand
andLoad
LoadSpeed-Torque
Speed-TorqueCurve
Curve..........................
51
TYpical
......................... 53
53
TypicalWiring
WiringDiagram
Diagramfor
forFull-Voltage
Full-VoltageStarting
Starting..........................
Typical
WIring
Diagram
for
Autotransformer
Method
of
ReducedTypical Wiring Diagramfor Autotransformer Method of ReducedVoltage
Starting.....................................................
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
54
Voltagestarting
17
Typical
Wiring
Diagram
for Wound-RotOr
Wound-RotorMotor
MotorControl
Control..................
..................55
55
17 Typical Wiring.Diagramfor
18
Supply
Considerations.
. . . . . . . . . . . . . . . . . . . . . . . . .. 72
LightingSystem
SystemPower
Power
Supply
Considerations
...........................
72
18 Lighting
19
Standby
Generator
Not Not
Required
TypicalInstrument
InstrumentPower
PowerSupplies:
Supplies:
Standby
Generator
Required
19 Typical
for
................................................ 90
90
forInstrumentPower
Instrument Power................................................
Supply:
Standby
Generator
Required
for
20
TypicalInstrument
InstrumentPower
Power
Supply:
Standby
Generator
Required
for
20 Typical
Instrument
. . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 90
InstrumentPower
Power ...................................................
90
21
TypicalInstrument
InstrumentPower
PowerSupply
Supplywith
withSupply
SupplySwitching
Switching..................
..................91
91
21 Typical
11
11
12
12
13
13
14
14
15
15
16
16
Tables
Tables
11 Conditions
: ..........
AffectingMotor
MotorDesign
Design .........................
ConditionsAffecting
....................................
Characteristic
Torques ...............................................
22Characteristic
Torques
...............................................
NEMA
Types for
Controllers.........................
. . . . . . . . . . . . . . . . . . . . . ..
33
NEMA EnclosureTypes
forAC
ACMotor Controllers
Illuminances
Recommended for
Chemical,and
and
44
IlluminancesCurrently
CurrentlyRecommended
forPetroleum,
Petroleum.Chemical.
Petrochemical
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..
PetrochemicalPlants.
Plants ................................................
Temperature
Identification
Numbers ............................
55
TemperatureMarkingIdentification
Numbers
............................
66
Constants
EstimatingLighting
LightingLoads
Loads.................................
. . . . . . . . . . . . . . . . . .. . . . . . . . . . . ..
Constantsfor Estimating
viii
viii
43
43
50
50
58
58
67
67
71
71
73
73
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STD.API/PETRO RP
0732290
TT4 E
Electrical Installations
InstallationsininPetroleum
PetroleumProcessing
ProcessingPlants
Plants
Electrical
SECTION 1-INTRODUCTION
1-INTRODUCTION
1.1
PURPOSE
1.1
PURPOSE
Std 610
information on
This recommended practice
practice provides
provides information
electrical
electrical installations
installations in petroleum
petroleum facilities.
facilities. Petroleum
processing
processing requires
requires specialized
specialized equipment that continually
processes,
processes, often at high rates
rates and elevated temperatures
temperatures and
pressures,
undergo
both
chemical
pressures, liquids,
liquids, and
andgases
gasesthat
that
undergo
both
chemical and
physical changes.
changes. Consequently,
Consequently, it is necessary
necessary that electrielectrical installations
equipmentinin
petroleum facilities
installations and equipment
petroleum
facilities be
accidentalignition of flammable
flammable liquids
liquids
designed to prevent accidental
and gases.
gases.
To maintain
maintain safety
safety and
and operating
operatingcontinuity,
continuity,requirements
requirements
for the
theelectrical
electrical
systems in petroleumfacilities
facilitiesareare more
systems
stringent
manufacturing facilities.
facilities.
stringent than those for most
most other manufacturing
This recommended practice addresses specific
specific requirements
for
fos those electrical
electricalsystems.
systems.
Centrifugal
Pumps for Petroleum,
Petroleum, .Heavy
Centrifugal Pumps
Industry Service
Duty Chemical and
andGas Industry
Service
Lubrication, Shaft-Sealing,
Lubrication,
Shaft-Sealing,and Control-Oil
Control-Oil
Petroleum,
Systems and Auxiliaries for Petroleum,
Chemical
Chemical and Gas
Gas Industry Service
Service
Cathodic
Cathodic Protection of
of Aboveground StorStorage Tanks
Tanks
Refineries
Fire Protection in Rejìneries
Protection Against Ignitions Arising
Arisingout
outof
of
Static, Lightning,
and Stray
StrayCurrents
Currents
Static,
Lightning, and
Std 614
614
RP651
RP 651
RP 2001
2001
RP2003
RP 2003
AEICl
CSI
CS 1
Specification for Impregnated Paper-InsuPaper-lnsuSpecijìcation
lated,
luted, Lead-Covered
Lead-CoveredCable,
Cable,Solid Type
Type
Specifications
Specifications for Thermoplastic
Thermoplastic
and and
Crosslinked Polyethylene
PolyethyleneInsulated
InsulatedShielded
Shielded
Power Cables
Cables Rated
Rated5 Through
Through 46 kV
Specifications for Ethylene Propylene
Propylene RubSpecifications
Rubber Insulated
Shielded Power Cables
Shielded
Cables
Through 69 kV
Rated 5 Through
CS5
CS5
1.2 SCOPE
CS6
CS6
This
This recommended practice
practiceis limited to electrical
electrical installainstallations
facilities.It provides aa basis
basisfor specificaspecifications in petroleum
petroleum facilities.
tionsincluded
engineering and construction
constructioncontracts.
tions
included in engineering
contracts.
Electrical
equipmenttest
test
standards are excluded
fromthe
the
Electricalequipment
standards
excludedfrom
recommended practice.
scope
scope of this recommended
practice. Operation
Operation and
and maintemaintenance
affect electrical
electrical syssysnance are addressed
addressed only
only insofar
insofaras they affect
electrical equipment
equipmentselection.
selection.The subject
subject of
tem design and electrical
energy.
energy conservation
conservationis isreviewed.
reviewed.
AGMA2
AG MA^
6019-E
6019-E
Gearmotors
HerringGearmotors Using
Using Spur,
Spul; Helical,
Helical, Herringbone,
Bevel, or Spiral Bevel
BevelGears
Gears
bone, Straight
StraightBevel,
ANSI3
ANSP
C80.1
C80.1
REFERENCES
1.3
REFERENCES
C80.5
C84.1
C84.1
1.3.1 The following
standards,
codes,
and specifications
followingstandards,
codes,
andspecifications
recommended practice:
practice:
are cited in this recommended
!
AAPI
PI
RP14F
RP 14F
KF'
500
RP500
RP505
RP 505
Std 541
Std541
Std 546
RP 552
RP552
.
ASTM4
ASTM4
D877
Installation of
SysDesign and Installation
of ElectricalSystems for Offshore
Platforms
Offshore Production
ProductionPlagoms
Recommended Practice for Classification
Classification
of Locations for Electrical Installations
of
Installations at
Petroleum Facilities
Classified as Class
I,
Petroleum
Facilities Clussijìed
Class I,
Division 1I and Division 2
Recommended Practice for Classification
Classification
of
Installations at
of Locations for Electrical Installations
Petroleum Facilities
Classified as
I,
Petroleum
Facilities Classijìed
as Class
Class I,
Zone 0,
0, Zone 1,
I , and Zone
Zone2
Squirrel-Cage
Induction
Form-Wound Squirrel-Cage
Induction
Motors-250 Horsepower and Larger
Motors-250
Machines-500
Brushless Synchronous
Machines-500
kVA
kVA and
undLarger
Larger
Practice for Transmission
Recommended
Practice
Transmission
Systems
~~
~
Standard Test Method
for Dielectric BreakBreakMethodfor
down Voltage
Voltage of
of Insulating
down
Insulating Liquids Using
Using
Disk Electrodes
Electrodes
CSA5
CSAS
Canadian
Canadian Electrical Code
Code
lAssociation
'Association of Edison llluminating
Rluminating Companies,
Companies, P.O.
P.O. Box 2641,
2641,
Binningham,
Birmingham, Alabama 35291.
35291.
2American
2AmericanGear Manufacturers
Manufacturers Association, 1500
1500King Street,
Street, Suite
Suite
201, Alexandria, Virginia 22314.
22314.
33American
American National Standards
Standards fustitute,
Institute, 1430
1430 Broadway, New
NewYork,
New York 10018.
10018.
4American Society of Testing and Materials, 1
()() Barr Harbor Drive,
4American
100
West Conshohocken, Pennsylvania 19428-2959.
19428-2959.
5Canadian
Association, 178
5CanadianStandards Association,
178 Rexdale Boulevard, Rexdale,
Ontario
Ontario M9W lR3,
1R3,Canada.
Canada.
1
~~~
Specification for Rigid Steel
Steel Conduit,
Conduit, Zinc
Coated
Specification
Specificationfor Rigid Aluminum Conduit
Conduit
Electric Power Systems and Equipment
(60 Hz)
VoltugeRatings (60
Voltage
Hz)
Copyrighted material licensed to IDOM.
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2
API RECOMMENDED PRACTICE 540
EPA6
EPA~
40CFR
40
CFR
Part 761
Part
761
IEEE7
Std 32
32
Std 80
Std 100
100
Std 141
‘I
Std
142142
Std 242
Std 399
Std422
Std 422
Std446
Std 446
Std493
Std 493
Std
Std 515
5 15
Std
Std 518
518
Std
Std 519
519
Std
Std 576
576
841
Std 841
"Polychlorinated Biphenyls
“Polychlorinated
Biphenyls(PCBs)
(PCBs)ManuManufacturing, . Processing,
Distribution
in
Distribution
in
Commerce,. and
andUse
UseProhibitions"
Prohibitions”
Std 844
Std 1015
Requirements, Terminology,
Terminology, and
and
Standard Requirements,
Test Procedures for
for NeutralGrounding
Grounding
Devices
for Safety in AC
AC
Substation
Guide for
Substation
Grounding
of Electricalandand
Standard Dictionary of
Electronics Terms
Terms
Recommended Practicefor Electric Power
Distribution for Industrial Plants (Red
Book)
of
Recommended Practice for Grounding of
Industrial and Commercial
Commercialpower
Power
Systems
Recommended Practicefor Protection and
Coordination of
of Industriai
Industrial and CommerCommerCoordination
cial Power
PowerSystems
Systemsp(Buff
u f f Book)
Recommended Practice
Practice for Industrial and
Commercial
Power Systems Analysis
Commercial
Power
Systems
(Brown Book)
Book)
Guide
Installation of
Guide for the Design and Installation
. Cable
Generating
Cable Systems
Systems in Power
Generating
Stations
Stations
Recommended Practice for Emergency
Emergency
and Standby
for Industrial
Standby Power Systems
Systems for
Industrial
and Commercial
CommercialApplications
Applications
for the Design of
Recommended Practice
Practice for
of
Reliable Industrial
Industrial and
andCommercial
CommercialPower
Power
Systems
(Gold Book)
Book)
System (Gold
Standard for the
Installation
the Testing,
Testing,Design,
Design,
Installation
and Maintenance
Resistance
Maintenance of
of Electrical
Electrical Resistance
Heat Tracing
Tracingfor Industrial Applications
Applications
Guide
Guide for the
the Installation
Installation of
of Electrical
Electrical
Equipment
Equipment to
to Minimize
Minimize Noise
Noise Inputs
Inputs to
to
Controllers
Controllersfrom
from External Sources
Sources
Recommended Practice
Practice and Requirements
Requirements
for
Harmonic
Control
for Harmonic Control in
in Electric
Electric Power
Systems
Systems
RecommendedPractice
Practice for
for Installation,
Installation,
Termination,
and Testing of
Termination,
and
Testing
of Insulated
Power
Power Cable
Cable as
as Used
Used in
in the
thePetroleum
Petroleumand
and
Chemical
ChemicalIndustry
Industry
Std 1100
c2
C2
C57.12.00
(37.12.00
C57.12.01
(257.12.01
C57.92
(37.96
C57.96
C57.106
(37.111
C57.111
(37.121
C57.121
NACE8
NACE*
RP0169
RP 0169
F 3 0176
0176
RP
RP 0675
RP0675
of External
External Corrosion
Corrosion on
on UnderUnder- .
Control of
Control
Metallic Piping
ground or Submerged Metallic
Systems
Systems
Corrosion Control
Controlof
of Steel Fixed Offshore
Wshore
Corrosion
Platforms Associated with
with Petroleum
Petroleum
Platforms
Production
Production
Control of
of External
External Corrosion
Comsion on
on Offshore
Offshore
Control
Steel
Steel Pipelines
Pipelines .
NEMA9
NEMA9
ICs 11
ICS
ICs 6
ICS6
MG 1
MGl
6United
Environmental Protection
Protection Agency/National
6United States
States Environmental
Agency/National Center
Center
for
for Environmental
Environmental Publications,
Publications, P.O.
P.O. Box
Box 42419,
42419, Cincinnati,
Cincinnati, Ohio
Ohio
45242-2419.
45242-2419.
7Institute
71nstitute of
of Electrical
Electrical and
and Electronics
Electronics Engineers,
Engineers, 445
445 Hoes
Hoes Lane,
Lane,
Piscataway,
NJ 08855-1331.
08855-1331.
Piscataway, NJ
Recommended
Practice
Recommended
Practice for
for Chemical
Industry
Severe
Duty
Squirrel-Cage
Industry Severe Duty Squirrel-Cage InducInducandBelow
tion
tion Motors
Motors 600 Volts
Volts and
Below
Recommended
Practice
Recommended
Practice for
for Electrical
Impedance,
and
Skin
Impedance, Induction,
and Skin Effect
Heating of
ofPipelines and
and Vessels
Vessels ,,
Recommended
Practicefor
Recommended Practice
for Applying
Applying LOWLowVoltage
Breakers
UsedUsed in IndusVoltage Circuit
Circuit
Breakers
trial and
andCommercial
CommercialPower
Power
Systems
(Blue Book)
Book)
Recommended
Recommended Practice for
for Powering and
and
Grounding Sensitive
SensitiveElectronic Equipment
NationalElectrical
.
Electrical Safety Code
General
Requirements
Requirements for LiquidImmersed Distribution,
Distribution, PoweK
Power, and Regulating Transformers
Transformers
Standard General
General Requirements for Drytype Distribution
Transformers
Distribution and Power Transformers
Including those with Solid-cast and/or
Resin-encapsulated Windings
Windings
Guide for Loading Mineral-oil-immersed
Mineral-oil-immersed
Power Transformers
Transfomers Up
Up to and Including
100 MVA with 55°C or 65°C Average
Winding Rise
Winding
Guide for Loading Dry-Type Distribution
Guide
Distribution
Transformers
and Power Transformers
Guidefor Acceptance and Maintenance
Guide
Maintenanpe of
Insulating Oil
Oil in Equipment
Guide for Acceptance
Acceptance of
of Silicone InsulatInsulatGuide
ing
Fluid
andFluid and Its Maintenance
Maintenance in
in
ing
Transformers
Transformers
Guidt?for Acceptance
Acceptance and Maintenance
Maintenance of
of
Guide
Hydrocarbon Fluid in
in
Less Flammable Hydrocarbon
Transfomers
Transformers
General Standards for
for Industrial
Industrial Control
Control
General
and Systems
Systems
and
Enclosures for
for Industrial
IndustrialControls
and and
Enclosures
Controls
Systems
Systems
Motors and
andGenerators
Generators
Motors
1440 South
South Creek
Creek Drive,
Drive, Houston,
Houston, Texas
Texas
8NACE International,
International, 1440
8NACE
77084.
77084.
North 17th
17th
gNational Electrical
Electrical Manufacturers
ManufacturersAssociation,
9National
Association, 1300
1300 North
Street, Suite
Suite1847,
1847,Rosslyn,
Rosslyn, VIrginia
Viiginia 22209.
22209.
Street,
--
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STD*API/PETRO RP 540-ENGL
L999 M O732290 0615543 877
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e
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ELECTRICAL
INSTALLATIONS
PROCESSING
PLANTS
PETROLEUM
IN PETROLEUM PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
IN
MG2
MG 2
WC3
WC 3
WC5
WC 5
WC 7
WC7
WC88
WC
Safety Standard for Construction
Construction and
Selection, Installation
Installation and Use
Use
Guide
Guide for Selection,
of
Motors and
of Electric Motors
andGenerators
Generators
Rubber-Insulated Wire and Cable
Cable for the
Transmission and Distribution
ElectriTransmission
Distribution of Electrical Energy
Energy
Thermoplastic-Insulated
Wireandand
Cable
Thermoplastic-InsulatedWire
Cable
for the Transmission
Transmission and Distribution of
of
Electrical Energy
Energy
Cross-Linked-Thermosetting-PolyethyleneCross-Linked-Thermosetting-PolyethyleneInsulated Wire
Wire and
andCable
Cablefor the TransmisTransmission and Distribution
Distributionof
of Electrical Energy
Energy
Ethylene-Propylene-Rubber-Insulated
Ethylene-Propylene-Rubber-Insulated
Wire
and Cable
Cable for the Transmission
Transmission and
Wire and
of Electrical Energy
Energy
Distribution of
ULll
uL1'
674
674
698
698
913
913
1242
1242
30
37
54
69
70
70E
77
90A
91
91
110
110
325
496
497
499
780
780
l<lNational
?National Fire Protection
Protection Association, 11 Batterymarch
Batterymarch Park,
Quincy, Massachusetts
Massachusetts
02269. 02269.
Electric Motors
andand Generatorsfor
Generatorsfor Use
Use in
Hazardous Locations,
Locations, Class
I, Groups
Groups C
Hazardous
Class I,
and D, Class
E, F:
F, and G
Groups E,
Class II, Groups
Industrial
Control
Equipment
for Use
Control
Equipment
Use
in in
Locations
Hazardous (Classified)
(Classified)Locations
Intrinsically
Safe Safe Apparatus and Associated Apparatus for Use
Use in Hazardous
((C1assiJ;ed)
Classified) Locations
Intermediate
Conduit
Intermediate Metal Conduit
1.3.2 The
followingpublications
publicationsare
arenot
not
specifically
referThe following
specifically
referenced in this recommended practice,
practice, but
butprovide
provideguidance
guidancein in
the design
forfor
petroleum
facilities:
design of
ofelectrical
electricalsystems
systems
petroleum
facilities:
IEEE7
EEE7
Std493
Std 493
NFPA'O
Protection Handbook
Fire Protection
Handbook
Flammable and Combustible
Combustible Liquids Code
Code
Combustion
Standard for Stationary
Combustion
Engines and Gas
Gas Turbines
Turbines
Fuel Gas Code
Code
Prevention Systems
Explosion Prevention
Systems
National Electrical Code
Code
Electrical Safety Requirements for
Employee Workplaces
Workplaces
Electricity
Recommended Practice
Practiceon Static Electricity
Standard for the Installation
Installation of
of Air CondiConditioning and Ventilating
Ventilating Systems
Systems
Standard for Exhaust Systems for Air ConConveying of
Materials
of Materials
Emergency and Standby Power
PowerSystems
Systems
Guide to Fire Hazard Properties
Flamof FlamProperties of
mable Liquids,
Liquids, Gases,
Gases, and Volatile
VolatileSolids
Standard for Purged and Pressurized
Enclosures for Electrical Equipment
Liquids,
Classification
of Flammable
Liquids,
Classijîcation of
of Hazardous
ClassiGases, or Vapors
Vapors and
andof
Gases,
Hazardous Classified) Locations for Electrical Installations
fied)
Installations
in Chemical Process
ProcessAreas
Areas
Classification
Classification of
of Combustible
Combustible Dusts and of
of
Hazardous (Classified)
Locationsfor
Hazardous
(Classijîed)Locations
for Electrical Installations in
Process
in Chemical
Chemical Process
Areas
Lightning Protection
ProtectionCode
Code
3
Std 739
IES12
IES'*
RP7
W 7
Practice for the Design of
RecommendedPractice
of
Reliable Industrial and
andCommercial
CommercialPower
Power
Systems
Practice for Energy ConRecommended
Practice
Conservation and Cost Effective
EffectivePlanning
Planning in
Industrial Facilities
Facilities
Lighting
Handbook
Practice for Industrial
Lighting
Handbook
ISA13
1 ~ ~ 1 3
RP
RP 12.1
12.1
Information Pertaining to
Definitions
andand Information
Hazardous
Instruments in Hazardous
Electrical
Instruments
Locations
HazInstrument Purging for Reduction of
of HazS12.4
AreaClassification
Classification
ardous Area
Intrinsically Safe Systems
Systems
Installation of
RE' 12.6
Installation
of Intrinsically
RP
Hazardous (Classified)
for Hazardous
(Classijîed)Locations
Part I, Pe$ormance
Peiformance Requirements,
Requirements, ComSI2.l3,
512.13,
Combustible Gas Detectors
RP 12.13,Part Part II,
MainteII, Installation Operation
Operation and Maintenance of
of Combustible
Combustible Gas
Gas Detection
Instruments
Instruments
FlammaNote: Includes former
former Bureau of Mines Bulletin 627,
627, FlammabilityCharacteristics
Characteristics of
Gases and Vapors
of Combustible
CombustibleGases
Vapors (no
longerin
longer inprint).
S12.16
S12.24.01
SI2.24.01
I,
Electrical Apparatus for Use
Use in Class
Class I,
Hazardous (Classified)
Locations:
Zone 1I Hazardous
(Classified) Locations:
Type
Protection-IncreasedSafety
Safety "e"
Type of
of Protection-Increased
Electrical Apparatus for Explosive Gas
Atmospheres,
Classijîcationsof
of Hazardous
Atmospheres, Classifications
(Classified)
(Classìjìed)Locations
l1Underwriters
11Undenvriters Laboratories,
Laboratories, Inc., 333
333 Pfingsten
Pfingsten Road, Northbrook,
lllinois
Illinois 60062.
12111urninating
120 Wall
America,120
12111uminating Engineering Society
Society of North America,
Street,
York, New
Street. Floor 17,
17. New
NewYork.
NewYork 10005-4001.
10005-4001.
13Intemational
Society for Measurement and Control
131n&nationalSociety
Control (ISA),
(ISA), P.O.
Box 12277,
12277, Research Triangle
Triangle Park, North Carolina 27709-2277.
Copyrighted material licensed to IDOM.
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07322qO
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44
API
PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
S51.1
S51.1
ProcessJnstrumentation
Process Instrumentation Technology
Technology
David
for Oil
David N. Bishop,
Bishop, Electrical
Electrical Systems
Systems for
Oil and Gas
Gas ProProduction
Facilities,
duction Facilities,
P.
P.J.J. Schram and
and M. W.
W. Earley,
Earley, Electrical
Electrical Installations
Installations in
in
Hazardous
Hazardous Locations
Locations
Ernest
Hazardous
Ernest C.
C . Magison,
Magison, Electrical
Electrical Instruments
Instruments in
in Hazardous
Locations
Locations
D.
D. G.
G. Fink and
and H.
H. W.
W. Beaty,
Beaty, Standard Handbook
Handbookfor
for ElecElectrical
trical Engineers
Engineers (12th
(12th ed.),
ed.), McGraw-Hill,
New York,
York, 1987
1987
NACE9
NACE9
RP0176
RP 0176
RP0675
RP 0675
Corrosion
Control of
CorrosionControl
of Steel
Steel Fixed Offshore
Oftshore
Platfonns
Associated
"With
Plat$oms
With Petroleum
Production
Production
Control
Control of
of External
External Corrosion
Corrosion on
on Offshore
Offshore
Steel Pipelines
Pipelines
NFPAIO
NFPA'O
499
499
Classification
Dusts and of
ClassiJicationof Combustible
Combustible
Dusts
of
Hazardous
Hazardous (Classified)
(Classijìed)Locations
Locationsfor ElecElectrical
trical Installations
Installations in
in Chemical
Chemical Process
Process
Areas
OSHA14
osml4
29CFR
29 CFR
Part
Part 1910
1910
Occupational
Occupational Safety
Safety and Health
Health Standards
Standards
Part
Part 1929.K
1929.K Electrical
Electrical Standards/or
Standardsfor Construction
Construction
140ccupational
140ccupationalSafety
Safetyand
and Health
Health Administration,
Administration, U.S.
U.S. DepartDepmment of Labor,
Labor, 200
200 Constitution
Constitution Avenue,
Avenue, N.W., Washington,
Washington, D.C.
20210.
20210. The
The Code
Code oj
of Federal
Federal Regulations
Regulations is
is available
availablefrom
fromthe
theU.S.
US.
Government
Printing
Office,
Washington,
D.C.
20402-9325.
GovernmentOffice,
Printing
Washington, D.C. 20402-9325.
~~
STD-API/PETRO RP
m
Copyrighted material licensed to IDOM.
540-ENGL
0732i?70
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Lq79
Ob15545 b 4 T . E '
SECTION 2-CLASSIFIED
LOCATIONS OR ELECTRICAL
2-CLASSIFIED LOCATIONS
ELECTRICAL EQUIPMENT
EQUIPMENT
2.1
PURPOSE
2.1
PURPOSE
2. Class IIIB
IIIB includes
includesthe
theliquids
liquidsthat
thathave flash
flash points
points at
at
or above
(200°F).
above93.3°C
93.3"C(200°F).
This section
classification
of flammable
sectionbriefly
brieflyreviews
reviewsthethe
classification
flammable
liquids
liquids and gases,
gases, the
theclassification
classificationof locations
locations where
wherefire
fireor
explosion
hazards
may
exist
due
to
flammable
gases
or
explosionhazards
duetoflammablegases
vapors, or flammable
of of
electrical
vapors,
flammable liquids,
liquids,and
andthetheapplication
application
electrical
equipment
locations.
equipment ininclassified
classified
locations.
2.3.3Flammable
Flammable
Gases-Lighter-than-Air
Gases-Lighter-than-Air
Lighter-than-air gases that commonly
commonly areencountered
Lighter-than-air
encountered
include
methane and aamixture
include methane
mixture of methane
methane with small
smallquanquantities of low-molecular-weight
hydrocarbons, the mixtures
low-molecular-weight hydrocarbons,
mixtures
tities
generally being lighter-than-air.
lighter-than-air. Hydrogen
Hydrogen must be given a
special
mixture
consideration
because
of its propelties:
properties: a
special mixture consideration
(explosive)-mixture range,
range, ahigh
flamewide flammable
flammable (explosive)-mixture
high
flamepropagation velocity,
velocity, aa low
low vapor
vapordensity,
density, a low
low minimumrninimumignition-energy level,
high
ignition
level,and
anda relatively
a relatively
high
ignition temperature [585°C
[585"C (l085°F)].
(1085"F)I.
2.2
SCOPE
SCOPE
This section
guidelines
peltainsection discusses
discussesonly
onlythethegeneral
general
guidelines pertaining to the classification
classification of
oflocations.
locations.A more detailed
detailed discusdiscussion of
of the
theclassification
classification of locations
be found
locations can be
found in API
RP
F
P 500, Recommended Practice
Practice for Classification
Classijïcation of
of Locafor
Electrical
Installations
at
Petroleum
Facilities
tions
tions
Installations Petroleum FacilitiesClasClasI,
Division
sified
as
Class
1I and Division 2 and API RP 505,
505,
siJied Class I,
Practice for Classification
Recommended Practice
ClassiJication of
of Locations for
Electrical Installations
Facilities Classified
Classijïed as
Installations at Petroleum
Petroleum Facilities
Class
I, Zone 0,
Class I,
O, Zone],
Zone 1, and Zone
Zone 2.
Gases-Heavier-than-Air
2.3.4Flammable
Flammable
Gases-Heavier-than-Air
Liquefied
Liquefied petroleum
petroleum gases
gases include
includepropanes,
propanes,butanes,
butanes,and
having
densities
from
1.5 times to
mixtures
mixtures of the twohaving
densities
from1.5
timesto
approximately 2.0 times
times that
that of air.
air. Vapor
Vaporpressures
pressuresof these
approximately
gases
(40
pounds per square
(40 pounds
square
gases exceed
exceed276
276kilopascals
kilopascalsabsolute
absolute
inch
inch absolute)
absolute)at 37.8°C
37.8"C (lOO°F).
(100°F).
2.3 CLASSIFICATION
CLASSIFICATION
FLAMMABLE
AND
OFOF
FLAMMABLE
AND
COMBUSTIBLE
COMBUSTIBLE LIQUIDS
LIQUIDSAND
ANDGASES
GASES
Note: Classifications
Classifications used for defining
defining liquids and gases should not
classifications used for hazardous
be confused with the NFPA 70 classifications
(classified)
(classified) locations.
2.4CLASSIFICATION
CLASSIFICATION
OF LOCATIONS
OFLOCATIONS
The National
National Electrical
Electrical Code,
Code, NFPA 70, has established
established
criteria for classifying
contain
classifying locations
locations that do or maycontain
flammable
gases
vapors,
flammable
liquids,
combustible
flammable
gases
or
vapors,
flammable
liquids,
combustible
As defined
are
defined by
byNFPA
NFPA30,
30,flammable
flammableliquids
liquids
are liquids
liquids that
that
dust, or ignitable fibers
fibers or flyings.
flyings. Once a location
location has been
dust,
have aaflash
below
37.8°C
flashpoint
point
below
373°C (lOOOP)
(100°F) and a vapor
vaporpressure
pressure
classified,
70
specifies
equipment
requirements for
specifies
requirements
classified,
NFPA
exceeding276
276
kilopascals
absolute
persquare
square
not exceeding
kilopascals
absolute
(40 pounds
pounds per
each
classification.
The
effort
involved in
particular
classification.
major
inch absolute)
absolute) at 37.8°C
liquids are
aredivided
divided
373°C (lOO°F).
(100°F). These liquids
classifying
a
location
is
determining
whether
flammable
classifying
location
determining
flammable
into the following
followinggeneral
generalclasses:
classes:
gases
gases are likely
likely to exist in the location to be classified
classified and, if
a.
a. Class IA includes
includes the
the liquids
liquidsthat
thathave
haveflash
flashpoints below
they may
may exist,
exist, under what
what conditions
conditions and for how much
much of
of
22.8°C
below
37.8°C
223°C (73°F)
(73°F) and
andboiling
boilingpoints
points
below
373°C (lOOOP).
(100°F).
the time.
b. Class IE
IB includes
includes the
the liquids
liquids that
thathave
haveflash
flashpoints
pointsbelow
below
A Class I location
location is a location
location in which flammable
flammable gases
gases
22.8°C
at or above
223°C (73°P)
(73°F) and
andboiling
boilingpoints
points
above 37.8°C
373°C (lOO°F).
(100°F).
or vapors are or may
may be present in the air in quantities
quantities suffiClass IC includes
includes the liquids
at or
c. Class
liquidsthat
thathave
haveflash
flashpoints
points
at or
tö produce
explosive or ignitable
ignitable mixtures.
mixtures. NFPA 70
cient to
produce explosive
above
below
37.8°C
above 22.8°C
223°C (73°F)
(73°F)and boiling
boilingpoints
points
below
373°C (lOOOP).
(100°F).
recognizes
locarecognizes two systems
systems for the classification
classificationof Class
Class I locations,
tions, the Division system and the Zone system.
system. In the DiviDiviofCombustible
Liquids
2.3.2 Definition
Definition
of Combustible
Liquids
sion system,
system, Class
Class I locations
locations are subdivided
subdivided into Division 11
Division
2.
Division
1
indicates
flammable mixmixand
2.
Division
1
indicates
that a flammable
As defined
defined by NFPA 30, combustible
combustible liquids
liquids are liquids
liquids
ture
may
present
normal
operating
conditions,
and
may
be
under
operating
conditions,
that have
flash
points
at
or
above
37.8°C
(lOOOP).
These
liqhave flash points at above 373°C (100°F).
Division
2
indicates
a
flammable
mixture
indicates
that
a
flammable
mixture
may
be
uids are
arealso
also divided
divided into
intogeneral
generalclasses:
classes:
present only
onlyin the event of abnormal
abnormal operating
operating conditions
conditions or
a.
Class n
theliquids
liquids
that
have
points at or
II includes
includes the
that
have
flashflash
points
a. Class
equipment
the Zone system,
equipment malfunction.
malfunction. In the
system, Class I locaabove 37.8°C
boiling
points
below
60°C60°C
(140°F).
37.8"C(lOOOP)
(100°F)and
and
boiling
points
below
(140°F). tions
O, Zone 1,
l, and Zone 2. In a
tions are subdivided
subdivided into Zone 0,
b. Class III
Ill includes
includes the
the liquids
liquids that
that have
haveflash
flashpoints
pointsabove
above
similar
similar manner to the Division
Division system,
system, NFPA 70 contains
contains
( 140"F), and
andClass
Class
liquids are
aresubdivided
subdivided
follows:
60°C (140°F),
III liquids
as follows:
criteria for defining
onpossibility
the possibility of
defining Zones basedonthe
releases.
releases. In both systems,
systems, locations
locations that are not classified
classified asas
1.
flash
points
at
1. Class InA
I L 4 includes
includes the
theliquids
liquidsthat
thathave
have
flash
points
Division 1,
1, Division 2, Zone 0,
O, Zone 1, or Zone 2 are
are termed
or above
(140°F) and
andboiling
boilingpoints
pointsbelow
below93.3"C
93.3°C
above 60°C (140°F)
(200°F).
unclassified.
unclassified.
(200°F).
2.3.1
Definition
of Flammable
Liquids
2.3.1Definition
ofFlammable
Liquids
55
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6
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
Once the existence and degree
degree of ignitable substances
substances in
an area has been determined,
determined, the physical boundaries
boundaries of the
the
classified
classified location
location must be determined.
determined. The most important
important
factor to consider is that flammable
flammable gas or vapor alone
alone will
not produce
produce an ignitable
ignitable atmosphere;
atmosphere; flammable
flammable gas
gas or
vapor must mix with a sufficient
sufficient amount of air to become
ignitable.
ignitable. Other factors
factors to consider are the quantity
quantity and
physical characteristics
characteristics of whatever substance
substance might be libliberated and the natural
of gases or vapors
natural tendency
tendency of
vapors to disperse in the atmosphere.
atmosphere.
Once established,
andand
boundaries
established, aalocation's
location'sclassification
classification
boundaries
of the
the process
processequipment
equipment for a
can be drawn on a plot plan
plan of
given area.
area. Such
Such a drawing is a convenient
convenient reference
reference source
source
when selecting
selectingelectrical
electrical equipment for and locating
locating it in the
classified
area. The classification
until
classifiedarea.
classification is incomplete
incompleteuntil
the the
dimensions
dimensions around
around aa source
sourceof liquid or gas
gas are defined and
documented.
Typicalheight,
height,width,
width,
documented. Typical
andand length dimensions
dimensions
are available
available ininAPI RP 500
500 and 505
505 as
as well
wellas NFPA 497.
497.
API RP 500 and 505
505 are
are practical
practical guides
guides that specifically
specifically
theNFPA 70 classification
apply the
classificationcriteria
criteria to electrical
electrical installainstallafacilities. The recommended
recommendedpractices
practices
tions
tions in petroleum
petroleumfacilities.
cover the factors
be considered
considered in area classificafactors that must be
classification;
tion; they provide a questionnaire-type
questionnaire-type procedure
procedure for
for deterdeterminingthe
the
proper
classification
of a location; andthey
they
proper
classification
ofalocation;
of of
a a
illustrate
illustrate methods
methods for
for establishing
establishingthe
thedegree
degreeand
andextent
extent
location to be classified.
classified.
Sound judgment
accompany
the use
judgmentmust
must
accompany
theofuse
the recommenrecommenof
dations
in
API
RP
500
and
RP
505.
When,
in
opinion
505.
When,
the
opinion
ofaa
dations
qualified person,
person,particular
particularconditions
conditionsare better or worse than
than
qualified
average,
thepertinent
pertinentrecommendations
recommendationsshould
should
be modified
average, the
be modified
accordingly.
accordingly.
EQUIPMENT
FORFOR
CLASSIFIED
2.5ELECTRICAL
ELECTRICAL
EQUIPMENT
CLASSIFIED
LOCATIONS
LOCATIONS
Each location
must
location in
in aa petroleum
petroleumfacility
facilitythat
thatis isclassified
classified
must
be carefully
ensure that
thatproper
properelectrical
electricalequipequipcarefully evaluated to ensure
ment is selected.
selected. Most
in petroleum
Mostclassified
classifiedatmospheres
atmospheres
in petroleum
facilities
however, certain
certainareas
areas
may
facilities are
are Class
Class I, Group
Group D;
D; however,
may
involve
groups:
in particular,
ClassClass
I, Groups
Groups
involve other
otherclasses
classesand
and
groups:
in particular,
II, Group
Group F.
F. (See NFPA 70 and NFPA 499
B and C and Class IT,
for further
further discussion
discussion of
ofClass
ClassIT
II locations.
locations. See
See'NFPA 70 and
497 for the correlation
correlationof material
material groupings
groupingsfor Division
Division and
and
Zones)
NFPA 70,
70, electrical
electrical equipment
equipment suitsuitZones) To comply with NITA
thespecific
specificarea
area
classification
be used.
able for the
classification
mustmust
be used.
One indication
indication that electrical
electrical equipment installed in classified locations
locations is suitable
suitable for the defined locations
locations is that it
approved by a Nationally
Nationally Recognized
Recognized Testing
Testing Laboratory
Laboratory
is approved
(NRTL).
(NRTL). Certain
Certain electrical
electrical equipment,
equipment, such as induction
induction
motors for installation
installation in Division 2 and Zone 2 areas,
areas, are
specifically permitted in NFPA 70 and do not require
require spespespecifically
approvals for use in classified
classified areas.
cific markings
markings or NRTL approvals
cific
2.6ALTERNATIVE
ALTERNATIVE
DESIGN IN
DESIGN
IN CLASSIFIED
LOCATIONS
LOCATIONS
For applications
necessary to install
applications where it is necessary
install equipment
that is not suitable
suitable or available
available for the classification,
classification,the folfollowing
alternativedesigns
designs may be utilized.
Theseapplicaapplicalowingalternative
utilized.These
tions
desirable because equipment
suitably
tions may bedesirable
equipment is notsuitably
manufactured
particular classification,
classification, it is
is more cost
manufactured for a particular
or design
effective
effective totosecure
secure the alternative
alternativeequipment,
equipment,
design preferpreference prohibits
prohibits such equipment.
equipment.
2.6.1
Physical
Isolation
2.6.1Physical
isolation
Physical isolation is an effective,
effective, and perhaps the most
commonly used, method for installing electrical equipment
not otherwise
otherwise suitable for classified
classified locations.
locations. For example,
where motors are located
located in aa classified
classified location, the motor
starters and control equipment can be installed outside the
classified
expensive
classified location.
location. This permits the use of less expensive
equipment in locations that are more convenient for maintenance.
Rooms and Enclosures
2.6.2Pressurized
Pressurized Rooms
Enclosures
According
locations may be
According to NFPA 70,
70, classified
classifiedlocations
reduced or eliminated
eliminated by adequate
adequate positive-pressure
positive-pressureventilaventilation. Authoritative
Authoritativeinformation
informationon design
design criteria
criteria is provided
in NFPA 496. Positive-pressurization
Positive-pressurization and
and purging
purging are based
on the principle
principle that an enclosure
enclosure or room located
locatedin a classiclassified
location
can
be
purged
with
clean
air
or
inert
gas
at
suffisuffified location can
with cleanair
and positive
positive pressure
pressuretoto
reduce the
cient,
cient, continuous
continuous flow
flowand
reduce
original
safe
original concentration
concentration of flammable
flammable gas or vapor to a safe
level
this level.
level.
level and
andtotomaintain
maintain
There are three types
purging, each having
specific
typesofofpurging,
havingspecific
design
design requirements:
requirements:
a. Type X purging reduces
within
an encloreducesthe
theclassification
classification
within
enclosure
sure from
from Division
Division11 to unclassified.
unclassified.
Type Y purging reduces
reducesthe classification
classification within
withinan encloenclob. Type
sure
2.
sure from
from Division
Division 11totoDivision
Division
c.
within
an encloc. Type
Type Z purging reduces
reducesthe
theclassification
classification
within
enclounclassified.
sure from
from Division
Division 2 to unclassifi(!d.
sure
Safe
Installations
2.6.3Intrinsically
Intrinsically
Safe
Installations
One approach
approachto the application
applicationof electrical
electrical equipment
equipment in
classified
classified locations
locationsis to use intrinsically
intrinsically safe devices
devices and
andwirwiring methods:
methods, This
This method is used primarily
primarily for instrumentainstrumentation and
andprocess
process
control.
Intrinsically safe equipment
control.
Intrinsically
equipment and
wiring are
areincapable
incapable of releasing the
theelectrical
electrical or thermal
conditions, to
energy necessary,
necessary,under
undernormal
normal or abnormal
abnormal conditions,
ignite
specific hazardous
hazardousatmospheric
atmosphericmixture
mixture in its most
ignite a specific
ignitable
ignitable concentration.
concentration. Inforniationon
Information'on the design and
andevaluevaluintrinsically safe
safeequipment
equipment and wiring
wiringto be used
usedin
ation of intrinsically
classified
Intrinsically safe
safe
classified locations
locations is provided
provided in
in UL 913. Intrinsically
installations
with
Article 504.
504.
installations should
shouldcomply
comply
with
NFPA 70 Article
Copyrighted material licensed to IDOM.
STD-API/PETRO RP 540-ENGL
1999 E 0732290 Ob15547 412
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ELECTRICAL
INSTALLATIONS
PETROLEUM
ELECTRICAL
INSTALLATIONSIN
IN PROCESSING
PLANTS
PETROLEUM PROCESSING PLANTS
2.6.4
Other
Other
Alternatives
2.6.4.2Alternatives
2.6.4.1
2'6'4'1 NFPA 70
70 describes
describes several other
Other acceptable proprotection
techniques
for
electrical
equipment
tection techniques for electrical equipment and
and installations
installations
in classified
classified areas.
areas. These
These include:
include: oil
oil immersion,
immersion, nonincennonincendive,
dive, and
and hennetically
hermetically sealed.
sealed.
77
2.6.4.2 Adequate
methods and
Adequate ventilation
methods
usethe use of combustible gas detection,
in API RP 500 and RP
detection, as defined
defined in
505, are
are techniques
techniques that
that
may
allow
the
reduction of
of the
the area
area
505,
may allow the reduction
classification.
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SECTION 3-ELECTRICAL
3-ELECTRICAL ENERGY
SECTION
ENERGYEFFICIENCY
EFFICIENCY
3.1
3.1
PURPOSE
Therefore, efficiency
efficiencycan
canalso
alsobe defined
defined ininterms
termsofoflosses
losses
and power input
This section reviews energy efficiency
efficiency as it applies
applies to the
selection
selection of electrical
electrical equipment
equipment for
forpetroleum
petroleumfacilities
facilitiesand
and
application of the equipment
equipment in those facilities.
facilities.
to the application
Power input
input -losses
- losses
losses
Efr
.
loss~s
(3)
o r == 11 -- Power
= Power
Efficiency
lClency =
Power
or
input
Power mput
input (3)
Power input
3.2 SCOPE
or in terms
power
output:
termsofoflosses
lossesandand
power
output:
Electrical efficiency
efficiency isis discussed
discussedasasa a part of the
the broader
concept of energy
energy conservation.
conservation.The definition
definition of efficiency is
given,
considerations are reviewed
forspecific
specific
given, and design considerations
reviewed for
. types of equipment.
equipment. Economic
Economicevaluation
evaluationis addressed.
addressed. Other
Other
efficiency
relatedtopics,
topics,such
such as power factor
efficiency related
factor and demand
demand
control,
control, are
are briefly
briefly discussed.
discussed. Useful
Usefuldefinitions
definitionsand conversion factors
factorsare provided atatthe end of the section.
section.
3.3
' .
Eff
lClency =
Efficiency
= 11 --
THE
ROLE OF ELECTRICAL EFFICIENCY
EFFICIENCY
THE ROLE
3.5
3.6 ECONOMIC
EVALUATION
ECONOMICEVALUATION
3.6.1
EvaluationFactors
Evaluation
Factors
Competitive
Competitive pressures
pressures to reduce the cost of processing
processing
have provided an incentive
incentive for adding
adding capital investment
investment
that can cut
cutthe energy cost per barrel processed. The cost of
adding new equipment,
equipment, or replacing inefficient
inefficient equipment
must be offset
offset by
by future
future energy cost savings.
savings. An
An economic
economic
evaluation is necessary to determine
determine if the equipment
equipment costs
will be offset
offset by the future
future energy
energy savings.
savings. Energy
Energy efficient
efficient
electrical equipment
equipment normally
normally demands
demands a premium price.
price. It
is useful to develop
factor
developa adollar-per-kilowatt
dollar-per-kilowatt
factor to determine
the value of saved energy
energyfor projects at a specific
specificsite.
site. Several different methods
for
developing
a
$IkW
factor
methods
developing $/kWfactor are covered in the following
following sections.
sections.
Efficiency
Efficiency is defined
defined asasthe
theratio
ratioof power output
outputto power
input or energy
energy output to energy
energyinput:
input:
(1)
Power output
equipment
output can be related
related to power losses
losses in equipment
by the following:
following:
Poweroutput
output =
input -losses
= Powerinput
- losses
SPECIFICATIONCONSIDERATIONS
CONSIDERATIONS
specification of electrical
electrical equipment
include
The specification
equipment should
should include
consideration
efficiency. The operating
consideration for energy
energy efficiency.
operating points
points for
which efficiency
specified.
Usually
efficiencydata are desired
desiredshould
shouldbebe
specified.
Usually
1/2,
'h, 1/4,
1/4,and full
full load
load data
dataare
arerequested.
requested.For large equipment,
equipment,
requested. Guaranteed
Guaranteedeffieffianefficiency
efficiency
curve
should be requested.
curve
should
ciency values,
values, rather than nominal
nominal or average
average values,
values, should
should
be specified.
specified.
An economic
kWh) should
economic evaluation
evaluationfactor
factor (in dollars
dollarsper
perkwh)
be included
included in the specification.
specification. See 3.6. Any economic
economic penpenclauses should
should be clearly stated,
stated, and the operating
operating point
point
alty clauses
at which efficiency
efficiencywill
willbe evaluated
evaluated should
shouldbe specified.
specified.
The testing method
method to be used for determining
determining efficiency
efficiency
should be stated.
stated. Witnessed
Witnessed testing is recommended if
if economic penalty factors
factors are involved.
involved. Payment
Payment terms
terms that are
the test results
to be contingent
contingent on receipt ofthe
results should
should be
clearly stated.
stated.
DEFINITION
OFEFFICIENCY
EFFICIENCY
DEFINITIONOF
' .
Power output
Energy output
Eff
=
Efficiency
lClency =
.
or
.
Power mput
Energy mput
input
input
(4)
(4)
All the
the above
aboveformulae
formulaecan
canbe applied
applied totoenergy
energyby substituting kWh for power.
power.InIn either case, higher
higherefficiency
efficiency is
achieved by reducing
reducing operating
operatinglosses.
losses.
achieved
a.
systemsprovide
provideanan
important
opportunity for
a. Electrical
Electricalsystems
important
opportunity
conservation. The
The electrical
electrical losses
losses in
in the
the distribution
distribution
energy conservation.
refinerypower
power
system can
and utilization
utilizationequipment
equipment of a refinery
system
range as high
highas 20%. For aa60 megawatt (MW) facility
facility operoperating 8,000
kilowatt-hour
8,000hours per
peryear and paying
paying$0.07 per kilowatt-hour
(kWh),
$6.5 million
(kWh), the cost of these losses
losseswould
wouldexceed
exceed
millionper
Asimilar
similar
efficient
electrical
year.
year.-A
plantplant
using using an energy
energyefficient
electrical
design could
$1 million per
could have
have 15%
1.5%fewer
fewerlosses
lossesand
andsave
save$1
year compared
design.
compared to the less
lessefficient
efficient
design.
In addition
direct benefits
benefitsof increased
increased electrical
electrical effieffiaddition to the direct
ciency,
ciency, there
there are also some indirect
indirect benefits.
benefits. Reduced
Reduced losses
losses
electricalequipment
equipmentcan result in lower operating
operatingtemperatemperain electrical
tures and prolonged
prolonged equipment
equipmentlife.
life.For indoor applications,
applications,
reduced losses
lossesalso decrease
decrease the heat load
loadon air conditioning
conditioning
equipment.
equipment.
When considering electrical
electrical efficiency,
efficiency,it is also useful to
recall that, due to losses in the generation,
generation, transmission,
transmission,and
and
distribution
distribution of electricity,
electricity,aa 11 kWh reduction in electrical
electrical
equivalent of 4 to 5 kWh of raw fuel.
fuel.
usage saves
savesthe equivalent
3.4
losses
Power output +
+ losses
losses
(2)
(2)
99
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API
PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
10
10
3.6.2
Simple
3.6.2 Payback
Simple Payback
hh == hours
hours of
of operation
operationper
per year,
year,
The
complex
dollar-per-kilowatt
The least
leastcomplex
dollar-per-kilowatt
factorfactor is
is based
based
onon
simple
simple payback,
payback,which
whichdoes
doesnot
notaccount
account for
for the
the depreciated
dèpreciated
value
value ofoffuture
futuresavings:
savings:
N
in evaluation
period,
N == number
number of
of years
yearsinevaluation
period,
TT .== income
incometax
taxrate
rate paid
paid by
by the
the user,
user,
=
ii = effective
effectiveinterest
interest rate
rate
$/kW
$ k W == ChN
ChN (1
(1 - TT))
(5)
(5)
where
where
$1
powerusage
usage by
$1kW
kW =
= profit
profit to
to the
the user
user for
for reducing
reducingpower
by
lkW,
1 kW,
C
of e1ecnicity,
in dollars
C == cost
cost
of
electricity,
in
dollarsper
per kWh,
kwh,
hh =
hours
of
operation
per
year,
= hours of operation
year,
N
in evaluation
period,
N =
= number
number of
of years
yearsinevaluation
period,
Using
TT = income
tax
rate
income
tax
rate
paid
bypaid by the
the user.
user.
The
ofthethe factor
The use
useof
factor isis demonstrated
demonstrated in
in the
the following
following
example.
Assume
a
piece
of
electrical
eqUipment
example.
Assume
a
piece of electrical
equipment
operatesoperates
continuously
location
where the
continuouszy at
ataalocation
where
the cost
cost of
of electricity
electricity is
is
$0.05/kWh,
and
the
desired
payback
period
is
$O.OSkWh, and the desiredpaybackperiod
is 55 years.
years.
Income
at
Incomeis
is taxed
taxed
rate.
40%
at aa 40% rate. The
The factor
factorwould
would be
be calculated
calculated
as
as follows:
follows:
$/kW=
== $1,314/kW
$/kW=-!~:x87:;hx5yrX(1_0.40)
$005x8760hx5yrx(l-0.40)
$1,314/kW (6)
(6)
yr kWh
One
=-
+R2_1
1 = - -1
1+R,
1
.
(8),
(81,
11+Rl
+R,
Rl
annualescalation
escalation rate
R1 =
= anticipated
anticipatedannual
rate for
for cost
cost of
of
electricity,
electricity,
R2 ==
= desired
desired
annual
rate rate of
of return
return
on
investment.
R2
annual
on inves1:lnent.
'
the example
example,of
equation 55 along
along with
witha15%
rate of
of
Using the
of equation
a 15% rate
return
return and
and an
an 8%
8%power
power cost
cost escalation
escalation rate,
rate, the
the dollar-perdollar-perkilowatt
kilowatt evaluation
evaluation factor
factor would
would be
be calculated
calculated as
as follows:
follows:
i1' =
=--1 + 0.15 -11 == 0.0648
0.0648
11+0.08
+ 0.08
(9)
(9)
5C
1+ O.064SJ - 1
$1
$ / kkW
W=
= (1
( I _- 00.40)
.40x
) ~ 1 + 0.0648 - 1
55
0.0648
0.0648 (1
(1+
+0.0648)
0.0648)
(10)
(10)
== $1,093/kW
$1,093 I kW
. This
factor
is
the
expected
cost
for
continuously
operatThis factor is the expected cost for continuously operatThis
includethe
thetime
time
value of
ing
then
ing aa load
load of
of one
one kW
kW for
for 55 years.
years. This
This cost
cost factor
factor isisthen
This equation
equation is aa useful
useful way·
way to
toinclude
value
of
money,
and
is
suitable
for
most
economic
evaluations
of
compared
compared to
to the
the ratio
ratio of
of the
the price
price premium
premium for
for high
high effieffimoney,and issuitableformosteconomicevaluationsof
energy
projects itit may
ciency
ciency equipment
equipmentdivided
divided by
by the
the loss
loss reduction.
reduction. If
If the
the ratio
ratio
energyefficiency
efficiency improvements.
improvements. For very large projects
may
be
is
be desirable
desirableto
to use
use an
an evaluation
evaluation method
method which
which further
furtherrefines
refines
is less
less than
than $1,314,
$1,314,then
then itit pays
pays to
to spend
spend the
the money
money for
for the
the
the preceding
equations to
factors as
high
efficiency equipment.
an energy
high efficiency
equipment. For
For example,
example, if
if an
energy effieffi- the preceding
equations
to allow
allow for
for such factors
as depreciadepreciation,
variableescalation
escalationrates.
rates.
cient
tax inves1:lnent
investmentcredits, and variable
cient transformer
transformer costs
costs $4,000
$4,000 more
more than
than aa standard
standard transtranstion, tax
former,
kW, the
the incremental
incremental
former, and
and itit reduces
reduces the
the losses
losses by
by 55 kW,
cost
3.7
ANDENERGY
ENERGYRECOVERY
RECOVERY
($4,00015 kW)
kW) or
or $800/kW.
$SOOkW. The
The energy
energy efficient
efficientunit
unit
3.7 COGENERATION
COGENERATIONAND
cost is
is ($4,000/5
should,
should, therefore,
therefore, be
be selected.
selected.
Power
Power costs
costs can
can be
be reduced
reduced by
by investing
investingin-plant
in-plant generageneration.
The
generation
normally
is
added
in
the
form
of
cogention.
The
generation
normally
is
added
in
the
form
of
cogen-.
3.6.3
3.6.3 Time
TimeValue
Value of
of Money
Money
eration.Cogeneration
means using
using the
the waste
waste heat
heat from
from aa
eration. Cogeneration means
Equation
of
power·
does not
not take
take into account
account the
the time
time value
value of
Equation 55 does
power generating
generating cycle
cycle for
for process
process heating;
heating; or
or conversely,
conversely,
money.
savings should
should be
for increases
using
plant process
money. Future
Future savings
be adjusted
adjusted for
increases in
in
to generate
generate power.
power. .
using waste
waste heat
heat from
from aa plant
process to
power
the required
required cost
The
power costs and the
cost of
of capital.
capital. The
The following
following
The generation
generation cycle
cycle thermal
thermal efficiency
efficiency thus
thus can
can be
be
equation
that
allows
for for increased
equation provides
providesaadollar-per-kilowatt
dollar-per-kilowattfactor
factor
that
allows
from about
about 25%
25% (typical
(typical industrial
industrial generating
generating
increased from
power
efficiency)
power cost
cost inflation
inflationand
and desired
desiredrate
rate of
of return
returnon
on inves1:lnent.
investment.
efficiency) to
to about
about 70%
70% when
when waste
waste heat
heat is
is recovered.
recovered.
Power
Power generated
generated in
in the
the cogenerating
cogenerating mode
mode is
is normally
normally less
less
expensive
expensive than purchased
purchased power
power and
and results
results in
in direct
direct savsav$1
kW =Ch (1 _ T) 1l +
+ i/N-- 11
ings
(7)
(7)
ings to
to the
the plant.
plant. Typical
Typical utility
utility generating
generating units
units operate
operate at
at
$IkW=Ch(l-T)
it
i(1
i(1 ++i>*
35%
so the
the higher
higher efficiency
efficiency of
of cogenerating
cogenerating can
can
35% efficiency,
efficiency,so
make
make itit an
anattractive
attractiveoption.
option.
where
One of
where
cycles power
of two
two power cycles are
are used
used for
for cogenerating,
cogenerating,
depending
processes used
used to
to absorb
absorb the
the waste
waste
depending on
on the
the plant processes
$1
$1kW
kW =
= profit
profit to
to the
the user
user of
of reducing
reducing power
power usage
usage by
heat.
The
Brayton
cycle
includes
a
gas
turbine
to
generate
heat. The Brayton cycle includes gas turbine to generate
1kW,
1 kW,
power,
to
to generate
generate steam
steamfrom
from the
the hot
hot
power, and
and aa waste
wasteheat
heatboiler
boiler
0
500°C
to
600°C
C
=
cost
of
electricity,
in
dollars
per
kWh,
(",
950
P
to
l1oo°F)
exhaust
gases.
In
C = cost ofelectricity, in dollars per kwh,
500°C to 600°C (= 950°F to 1100°F)exhaust gases. In some
some
Copyrighted material licensed to IDOM.
(STD*API/PETRO RP 540-ENGL
1999 orR
0732270
No further reproduction
distribution
permitted. Ob35550 T O T H
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL
INSTALLATIONS IN PETROLEUM PROCESSING PLANTS
PLANTS
ELECTRICAL
INSTALLATIONS
11
11
Fuel
Fuel
Electric
Electric power
power
recovery
Heat recovery
steam generator
generator
f
f
c
--------1I
"
"
"
"
1
Gas turbine
turbine
Process
Process
1
heat
1
___
1__ -
I
1
I
1
I
1I
.1
Condensate
treating
Figure
Cogeneration Cycle
Cycle
Figure 1-Brayton
1"Brayton Cogeneration
instances,
furnace
instances, the exhaust flow
flow can be
besent
sentinto
intoa process
a process
furnace
to heat process
recovery of the turbine
processfeed.
feed.The recovely
turbine exhaust
exhaustheat
heat
required to
toprovide
providean
an
reduces the
reduces
the amount of fuel
fuel normally required
plant.
The value
equal amount
amount of
ofthermal
thermalenergy
energytotothethe
plant.
value of
ofthe
the
saved
saved fuel can be subtracted
subtracted from
from the
the cost of the fuel
fuel to
to the
the
gas
thethe
cost of power generated.
gas turbine
turbine totoarrive
arriveat at
generated.
The Brayton
(gas-turbine)
cycle
is
considered
Brayton (gas-turbine) cycle considered aa "topping"
"topping"
cycle
cycle because it consumes
consumes fuel
fueland provides by-product
by-product heat
heat
to a consumer
at a lower
By contrast,
consumeroperating
operating
lowertemperature.
temperature.
contrast, aa
"bottoming"
"bottoming" cycle
cycle consumes
consumes by-product
by-product heat
heat from
from a higher
temperature process
processand
andproduces
produces
electric power.
temperature
electric
TheCarnot
Carnot
cycle
a and
boiler
andturbine
a steam
cycle
usesuses
aboiler
asteam
to turbine to
as a topping
thermalpower,
power,and
and
be configured
recover thermal
cancan
be configured
as a topping
cycle,
cycle, or a bottoming
bottomingcycle.
cycle.
When configured
configuredas topping cycle,
cycle,
the plant steam
boilers generate
at a higher
steam boilers
generatesteam
steam
higherpressure
pressureand
and
temperature than isisneeded
neededfor
forheating
heating
plant
processes.
temperature
plant
processes.
TheThe
steam
steam
while
reducing
extractfrom
fromthethe
steam
while
reducing
steam turbine
turbineis used totoextract
the pressure
pressure and
and temperature
temperature from
from boiler
boiler steam
steamconditions
conditionstoto
process conditions.
conditions. The
The extra
extrafuel
fuelcost
cost for raising
raising the steam
steam
process
pressure and temperature above
above process
process conditions
conditions is the fuel
fuel
cost for
power
developed
by the turbine.
forgenerating
generatingthethe
power
developed
turbine.
A typical bottoming cycle uses
uses aa steam turbine
turbine to extract
power from
steam
being
generated
from
process
from steam being generated from process waste
waste heat,
heat,
or steam being
pressure level
being let
letdown
downfrom
from one plant steam pressure
level
to a lower
lower level,
level,ororbeing
beingsent
sentto a condenser
condenseron
onthe
theway to a
cooling tower.
tower.The bottoming
bottoming cycle
cyclefinds
findsuseuse
plants,where
where
cooling
in plants
amountsof waste
waste heat are available
available from
fromthe
thecooling
cooling
of
large amounts
exothenmc
processes. This
generateselectricity
electricityfrom
from
exothermic processes.
This cycle generates
whichwould
would othelwise
some of the heat which
othelwise be sent into the
atmosphere at the cooling
coolingtower.
tower.
atmosphere
Hot exhaust from
fromgas turbine
turbine generators
generators is sometimes
sometimes used
used
directly
using
a heat
recovery
steam
directly in a process
processwithout
without
using
a heat
recovery
steam gengen-
c
3
High
High pressure
pressure
boiler
I
Low pressure
pressure
boiler
boiler
I
Process
Process
heating
heating
Figure
2-Carnot
ToppingCycle
Cycle
Figure 2-Carnot
Topping
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
I
12
RECOMMENDED PRACTICE
PRACTICE 540
API RECOMMENDED
open-circuited. These losses include eddy current
of direct heating
open-circuited.
currentlosses,
losses,hyshyserator. Three
Threeexamples
examplesof
heating with
with turbine
turbineexhaust
exhaust
dielectric losses,
losses, and losses
losses due to the resisof products in transport pipelines;
teresis losses, dielectric
are: reducing
reducing the
theviscosity
viscosityof
pipelines;
excitation current.
tance of the
the primary
primarywinding
windingto excitation
current.The eddy
heating process
processfeeds
feedsto process units;
units;and supplying thermal
thermal
compoabsorption refrigeration
most significant
significantcompocurrent and hysteresis
hysteresislosses are the most
energy for absorption
refrigerationcycles.
cycles.
lower viscosity
viscosity and reduce
nent of
ofno-load
no-loadlosses.
losses.
Because these losses
lossesoccur in the
the core
Heating viscous products will lower
energy
required
to
transport the products
sometimes referred
referred to
of the transformer,
transformer, no-load losses are sometimes
the pumpingenergy
required
totransport
theproducts
as core losses or iron losses.
losses. For a given
givenvoltage,
voltage,no-load
this.
pipelines. Fired
Firedheaters
heatersare
arenormally
normallyused
used
no-load
through pipelines.
forfor this.
constant.
losses can
canbebeconsidered
considered
to be constant.
When gas turbines are
aresometimes
sometimesused as generator drives
drivesto
Load losses
lossesvary with
with the
the flow
flowofofload
loadcurrent
currentand
and
include
provide power
power for the transport
transport pump
pumpmotors,
motors,or are used
used to
drive the
I2R losses,
losses, and stray
12R
losses, eddy
eddycurrent
currentlosses,
strayload
loadlosses.
losses.The 12R
12R
the pumps
pumps directly,
directly, the
theexhaust can be passed through
an exchanger to
toheat
heatthethe
product,
instead
of using
losses are the most
of
most significant
significant and
andare
arecaused
causedby the flow of
product,
instead
of using
a fireda fired
Using the
thewaste
wasteheat
heat from the gas turbine's exhaust
exhaust
load cunent
currentin both
both primary
primaryand
andsecondary
seconday windings. Highet
Higher
heater. Using
will save
efficiency
copper
windings
to minefficiency transformers
transformersusually
usuallyhave
have
copper
windings
to
savethe
thecost of the fuel
fuelused
usedfor a fired heater.
heater.
In process plants,
gas
turbine
exhaust
is
used
to
heat
feed
J2R
losses.
Where
forced
cooling
is
specified,
addiimize
12R losses. Where forced
specified, addiplants,
turbine exhaust is used
stocks
tionalenergy
tional energyis consumed
consumed by fans
fans or oil circulating
circulatingpumps.
pumps.
stocks to
toprocesses,
processes,or to preheat combustion
combustion air for the proprocess furnaces.
While transfonners
transformers should
should be sized on the basis of maxifurnaces. This displaces
displaces much
muchofofthe fuel
fuel that
thatwould
wouldotherwise
mum load,
load, they should be designed
designed for maximum efficiency
efficiency
erwise be consumed.
consumed.
The absorption
refrigeration cycle
cycleuses
uses
a heat
source to
at normal
nolmal operating
operating load,
load, and
and efficiency
efficiencyshould
shouldbe evaluated
evaluated
absorption refrigeration
a heat
source
change the
accordingly.
transformers,
the the
loadload
at which
accordingly.When
Whenspecifying
specifying
transformers,
thestate
state of a refrigerant.
refrigerant.The hot exhaust from
froma agasgasturbine generator
cycle
to proefficiency will
willbebeevaluated
evaluatedshould
should
be given.
given.
generatorcan
can
be used with an
anabsorption
absorption
cycle
vide cooling.
manufacturers
cancan
cooling.Absorption
Absorptioncycle
cycleequipment
equipment
manufacturers
provide pre-engineered
elements
to match
the exhaust
pre-engineeredsystem
system
elements
to match
the
3.8.2 Motors
andGenerators
Generators
Motorsand
flow
of gas
flow conditions
conditions ofofa number
a number
of turbines.
turbines.
Motor loads
loads are
arethe major consumers
consumersof energy
energy in process
from
Sometimes
Sometimes there
there are
areopportunities
opportunitiestotorecover
recoverenergy
energy
from
plants. Typically,
Typically, they can account
for
70%
of the
the electrical
account
for
70%
electrical
process
process or utility
utility streams.
streams.One
Onemethod
methodof energy recovery
recovery isis
vary from
65%
energy
consumption. Motor efficiencies
65% for
for
energy
consumption.
efficiencies
from
the power recovery turbine,
catalytic
turbine, which is often used on catalytic
HP
motors,
to
98%
for
the
largest
motors.
High
the
smallest
smallest
motors,
largest
motors.
cracking
energy from
fromthe
theregenerator
regenerator
flue
cracking units to recover
recover energy
flue
designs are
the standard
are available
available for motors
motors in the
standard
efficiency designs
gases.
through
an expander
whichwhich efficiency
gases. The flue
flue gases
gasesare
aredirected
directed
through
an expander
frame
size
range.
In
the
United
States,
the
1992
Energy
PolPolframe
size
range.
In
States,
the
1992
Energy
wives
generator.
The
drives the unit's air blower,
blower, and
andananelectric
electric
generator.
The outicy
Act
requires
energy
efficient
motors
for
most
motor
cateAct
requires
energy
efficient
motors
motor
cateput of the
megawatts to
thegenerator
generatoris usually
usually in the
the range
range of
of5 megawatts
gories.
gories.
10
(MW).Typically,
Typically,
an induction
generator is
10 megawatts{MW).
aninduction
generator
Motor
Motor losses
losses consist
consist of the following:
following:
used for
for this
this service.
service.
A high-pressure fuel
fuel gas
petroleum facility
gas feed
feed to a petroleum
facility can
a.
a. Stator
Stator I2R
12Rloss~
loss.
used
as
a
source
of
electric
power
by
dropping
thethe
line
also
be
also be
as source electric power by dropping
line
b.
b. Rotor I2R
12Rloss.
loss.
pressure
expander
instead
pressure totoplant utility
utility pressure
pressurethrough
throughanan
expander
instead c.
c. Core
Core loss
loss (hysteresis
(hysteresisand eddy
eddy current).
current).
of a let-down
let-downvalve.
valve.The
The expander
expander is used to
to drive
driveaninducan inducd.
d. Friction and
and windage.
windage.
tion
generator
adding
power to the
electric
system. The
tiongenerator
adding
power
theelectric
system.
e.
Stray-loadloss.
loss.
e. Stray-load
inajority
majority of the
the gas
gas flow
flow goes
goes through
through the
the expander,
expander, while
whileaa
f.f. Excitation
Excitation equipment losses
.
losses (for
(forsynchronous
synchronousmachines)
machines).
. pressure
control
valve.
pressure control
controlflow
flow goes
goes through
througha aparallel
parallel
control
valve.
Manufacturing
Manufacturing design
design parameters
parameters that
thataffect
affectmotor
motorlosses
losses
include:
include:
3.8
CONSIDERATIONS
3.8 DESIGN
DESIGNCONSIDERATIONS
3.8.1
3.8.1 Transformers
Transformers
Transformer efficiencies
efficienciesvary,
vary,depending
depending on
on transformer
transformer
characteristics.
High-efficiency units can
can be purchased
characteristics. High-efficiency
purchased that
provide
efficiencies in
of
in excess
excess of 99%.
99%. The
The importance
importanceof
provideefficiencies
transformer
transformer efficiencies
efficienciesis
is that
that all
all power
power received
receivedfrom
fromutiliutilities
received
from
in-plant
generation)
ties (and
(and much,
'much,ififnot
notall,all,
received
from
in-plant
generation)
is
times to
to reach
reach utilization
utilizationvoltage
voltage
is transformed
transformedone
one or more
more times
levels;
levels; thus,
thus,the
the 11or 2%
2% losses
lossesoccurring
occurringin
in transformers
transformers are
are
applied
appliedto
to large
large blocks
blocksof
of power.
power.
Transformer
losses
consist of
losses
Transformerlosses
consist
of no-load
no-loadlosses
andand load
load
losses.
No-load
losses
are
losses
resulting
from
energizing
losses. No-load lossesare losses resultingfrom energizingthe
the
primary
winding
primary winding
winding at
at rated
rated voltage
voltage with
withthe
thesecondary
secondary
winding
a.
steeL .
a. Quality
Quality and thickness of lamination steel.
b. Size
Size of the
the air gap.
gap.
c.
c. Stator
Stator and
and rotor
rotorresistances.
resistances.
d.
d. Slot
Slot configurations.
configurations.
e.
designspeeds
speeds result
e. Number
Number of
of poles
poles (lower
(lowerdesign
result in
in lower
lower
efficiencies).
efficiencies).
Much
to optimize
optimize these
these parameters
parametersbecause
because
Much effort
effort is
is made
made to
they also
inrush
current,
and and
startstartalso affect
affect motor
motorpower
powerfactor,
factor,
inrush
current,
ingtorque.
ing torque.
Operating
conditionsalso
also affect
efficiency.TypiTypiOperatingconditions
affect motor
motorefficiency.
cally,
motor
efficiency
cally,motor
efficiency
fallsfalls off
off rapidly
rapidly as
as motor
motor load
load is
is
decreased
below
one-half
of
rated
load.
Operating
a
motor
at
decreased below one-half of
rated load. Operating amotor at
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONSIN
IN PETROLEUM PROCESSING PLANTS
PLANTS
-
13
13
less
less than
than rated
ratedvoltage
voltagewill
willcause
cause a decrease
decreasein efficiency
efficiencydue
due
horsepower
horsepower reduction.
reduction. For example,
example, reducing
reducing the flow
flow to
to
to
to higher
higher stator
statorlosses
lossesand rotor
rotor losses.
losses. Operating
Operatingat
at overvoltovervoltone-half its
its initial
initial value
value by lowering
lowering the speed
speed of the load
load
age
age decreases
decreases efficiency
efficiencybecause
becausehigher
highermagnetizing
magnetizingcunent
current
will
will cause
cause the
the brake horsepower
horsepower of the
the load to
to be reduced
reduced
and
and saturation
saturationcause
cause increased
increased stator
statorand
andcore
core losses.
losses. OperatOperatto
to one-eighth
one-eighth of its
its initial
initial value.
value.
ing
willwill
increase
losses
(due to
neging with
with unbalanced
unbalancedvoltages
voltages
increase
losses
(due
A typical
typical pump
pumphead-flow curve
curve is
is depicted
depicted in Figure
Figure 33 to
to
ative
sequence
torque)
and
result in higher winding
ative
sequence
torque)
and
result
in
higher
winding
further
illustrate
the
attractiveness
of
using
speed
further illustrate the attractiveness using speed adjustment
adjustment
temperatures.
Motors
connected to
speed
drives
temperatures.Motors
connected
to variable
variablespeed
drives
to
to the
the lower
lower left
left
to control
control flow
flow rate.
rate. The
The darker-shaded area
area to
experience
experience higher
higherlosses
lossesbecause
becauseof the harmonic
harmonic content
contentof
of each
power
required
for
each operating
operatingpoint
pointindicates
indicatesthethe
power
required
for that
the supply
supply voltage
voltageand
andthe
theload
load current.
current. This
This is
is due
due to
to higher
higher
operating
operating point.
point. The
The lighter-shaded
lighter-shaded area
afëaindicates
indicatesthe
thepower
power
than normal
eddy
cunents
induced
in theinstator
normalhysteresis
hysteresisand
and
eddy
currents
induced
the statorsavings
thatresult
resultfrom
from
using
speed
reduction
savings that
using
speed
reduction
ratherrather
than than
and
byby
the harmonic
harmonic cunents.
currents.
and rotor
rotorsteel
steel
throttling
general,
a steep
system
throttling to control
control flow
flow rate.
rate.InIngeneral,
asteep
system
curve,
the potential
potential
curve, or a steep
steep pump
pump curve,
curve, will
will accentuate the
3.8.3Lighting
Lighting
Equipment
Equipment
power
static head
headinvolved,
involved,the
the
power savings.
savings. Also,
Also, the
the lower the static
greater
the
power
savings
will
be as
aa percentage
of overall
as
percentage
overall
greater
the
power
savings
will
Although
percentage
of
Although lighting
lightingdoes
doesnot represent
represent a amajor
major
percentage
power
power consumption.
consumption.
the
facility, it
the electrical
electlical energy
energy consumption
consumption of aa petroleum facility,
The
conventional
methods
The
conventional
methods for
for achieving
achieving speed
speed adjustment
adjustment
nonetheless
nonetheless provides
provides another
anotherarea
areawhere
whereenergy
energysavings
savingscan
include
hydraulic
couplings,
adjustable
sheave
belt
systems,
include
hydraulic
couplings,
adjustable
sheave
belt
systems,
be achieved.
in an
achieved. The
The following
following guidelines
guidelinescan
canresult
result
in energy
an energy
eddy
current
clutches,
and
wound-rotor
motors.
These
eddy
current
clutches,
and
wound-rotor
motors.
These
efficient
efficientlighting
lightingsystem:
system:
devices
inefficient,
however,
devices are
arerelatively
relatively
inefficient,
however,and
andusually
usuallyrequire
require
aa. Use the
thehighest
highestefficacy
efficacy[lumens
[lumens
(lm/W)]
perper
wattwatt
(lmnV)]
lamplamp
frequent
maintenance.DC
DC
motors
allow
adjustment
frequentmaintenance.
motors
allow
speedspeed
adjustment
that
that isiscapable
capableof directing
directing light
light to
to the
thetask
taskarea
area involved.
involved.
with
to to
requiring
frewith improved
improvedefficiency
efficiencybut
butarearealso
alsoprone
prone
requiring
freb.
(e.g.,electronic
electronicballasts
ballasts for
b. Select
Select efficient
efficient ballasts (e.g.,
for fluofluoquent
maintenanceand
and
are difficult to apply
classified
quentmaintenance
aredifficult
applyininclassified
rescent fixtures).
fixtures).
areas.
Electronicadjustable-frequency
adjustable-frequencycontrollers
controllers also
areas.Electronic
also proproc.
vide
improved
over
the
c. Maximize
Maximize use
useof floodlights
floodlights totoilluminate
illuminategeneral
generalprocess
process
vide speed
speed adjustment
adjustmentand
andhave
havebeen
been
improved
over
the last
last
areas.
areas.
decade.
decade. They
Theyare
arenow
now the
the method
method of
of choice
choice when
when adjustable
adjustable
speed drives
The
these
drivesare
areneeded.
needed.
The maintenance
maintenancelevel
levelforfor
these concond.
lIse photocell
outdoor lighting
lighting
d. Use
photocell or time
time controls
controlsto turn
turn off outdoor
trollers
alternativemethods,
methods,
however,
trollers is
is the
the lowest
lowest of the
thealternative
however,
during
during daylight
daylighthours.
hours.
these drives
which
may
drivescreate
create voltage
voltage and
aildcunent
currentharmonics
harmonics
which
e.
Use
manual
controls for tower
lighting
controls
e.Use
manual
controls
towerlighting
withwith
controls
require
to the
require remedial
remedialmodifications
modifications
the power
powersystem
system and
and drive
drive
located
located at the
the tower
towerbase.
base.
motor. Adjustable-frequency
Adjustable-frequencycontrollers
controllershave
haverelatively
relativelyhigh
f.f. Monitor
Monitorlighting
lightinglevels
levelsand
andreduce
reducethem
themwhere
whereappropriappropriefficiencies
andcan
canbebe
used
induction
efficienciesand
used
withwith
induction
motorsmotors which
whch
ate.
Forbuilding
building
lighting, this
additionalenergy
energy
ate.For
lighting,
this produces
producesadditional
require
are readily
readily available
availablefor
forclassiclassirequire low maintenance
maintenance and
and are
savings
because of the
reduced
load on air conditioning
thereduced
load
conditioning
savingsbecause
fied
fied areas.
areas.(See
(Seealso
also Section
Section2.)
equipment.
equipment.
The
driveequipment
equipmentis is
The capital
capital cost
cost of adjustable-speed
adjustable-speeddrive
g.
g. Keep
Keep lamps
lampsand reflectors
reflectors clean
cleanto
to obtain
obtain maximum
maximum light
light
higher
than
for
constant
speed
equipment,
so
an
economic
higher
than
for
constant
speed
equipment,
so
an economic
output.
output.
evaluation
as
outlined
in
3.6
is
required
to
determine
if the
3.6
is
required
to
determine
the
evaluation as outlined
potential
energy
savings
offsets
the
increased
cost.
A
major
potential energy savings offsets
A major
3.8.4 Adjustable
Adjustable
Speed
Motor
Control
Speed
Motor
Control
factor
in such
will be the
cycleofofthethe
factor in
such an
an evaluation
evaluation will
the duty
duty cycle
Centrifugal
pumps,
fans,
and compressors
constitute
a
Centrifugalpumps,
fans,
andcompressors
constitute
a
equipment
equipment involved;
involved; i.e.,
i.e., the
the percentage
percentage of time
time that equiplarge
motor-drivenloads
loads
a petroleum
large percentage
percentage of the motor-driven
in ainpetroleum
ment will
will function
function at
less horsehorseat operating
operating points
points requiring less
facility.
torquerequirements
requirements of these
facility. The torque
these centrifugal
centrifugal loads
power than
than the
the design point.
point. If
If the
theequipment
equipmentis
is expected
expected to
to
vary
vary as the
the square
square of the speed;
speed; thus,
thus, the
the brake
brake horsepower
horsepower
operate
percentage of
operate at close
close to
to its
its design
design point
point for
for a high percentage
required
required vades
variesas
as the cube
cube ofofthe
the speed.
speed.
time,
adjustable-speed
drive
system
is probably
time, then
thenusing
usinganan
adjustable-speed
drive
system
is probably
Traditionally,
to
Traditionally,centrifugal
centrifugalloads
loads have
have been
beendesigned
designed
to operopernot wan·anted.
warranted. It is
is also
also important
important to
to remember
remember that
thatthe
the appliappliate
ate at
at constant
constant speed
speed with
with the
the process
processflow
flow being
being controlled
controlled
cation
the
cation of adjustable-speed
adjustable-speeddrives
drivesrequires
requires
the consideration
considerationof
by some
some type
type of throttling
throttling means
means (pump
(pump control
control valves,
valves, fan
fan
other
as
equipother design
designfactors,
factors,such
such
as avoiding
avoiding the
the operation
operation of
of .equipdampers,
dampers, or compressor
compressor inlet
inlet guide
guide vanes).
vanes).The
The energy
energy losses
losses
ment
evaluating the effects
system
ment at critical
critical speeds
speeds and evaluating
effects of system
from
from throttling
throttling can
canbe substantial.
substantial.
harmonics
thatmay
may
generated by adjustable
frequency
harmonics that
bebe
generated
adjustable frequency
As an alternative
alternative to throttling,
throttling, the speed of the centrifucentrifudrive
drive equipment
equipment. (See
(See also
also 6.10.4.)
gal
gal load can be controlled to obtain
obtain the desired flow
flow rate
without producing
producing excessive
excessive pressure.
pressure. Because the flow
flow
3.8.5Conductor
Conductor
Sizing
Sizing
rate varies
varies directly
directly with
with speed
speed while
while the horsepower
horsepower
requirement
Power
another
source
Powercables
cablesareare
another
s o m e of energy
energyloss
lossin an
an electrielectrirequirement varies
varies as
as the cube
cube of the
the speed,
speed, using
using speed
speed
reduction
cal
reduction to
to lower flow
flow rates
rates will
will result in
in aa significant
significant
cal system.
system. The
The magnitude of the energy
energy loss depends on the
the
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14
API RECOMMENDED
RECOMMENDED PRACTICE 540
540
PRACTICE
API
Throttled operation
Throttled
operation
I
l
Nonthrottled
operation
f
\
J.
I
I
I
I
I
I
I
I
-------1""-I
I
I
I
I
I
I
I
I
I
I
Flow
Flow
____f
Reduced
Reduced
flow
flow
Figure
Figure 3-System
+System Energy
EnergyLosses:
Losses:Adjustable
Adjustable Speed
SpeedVersus
VersusThrottling
Throttling
Full
Full
flow
flow
~
STD-APIIPETRO RP
~~
Copyrighted material licensed to IDOM.
540-ENGL
No further reproductionI
or distribution permitted.
1999
0732290 Ob15554 652 pI
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL
INSTALLATIONS IN PETROLEUM PROCESSING PLANTS
PLANTS
ELECTRICAL
INSTALLATIONS
15
15
resistance of thecable
ofcurrent
resistance
cable as well as theamount
amount
of current
expected to flow in the circuit. After
After power
power cables
cables have
have been
been
sized to
capactomeet
meetthe governing criteria (voltage
(voltagedrop,
drop,spare
spare
capacof NFPA
70),
ity, and
70), a check
checkshould be made
made
andthetherequirements
requirements
of NFPA
to determine if the anticipated energy loss in the cable would
the the
nextnext
largerlarger
size cable.
justify purchasing
purchasingand
andinstalling
installing
size cable.
3.9
RELATIONSHIP
RELATIONSHIP TO POWER
POWER FACTOR
FACTOR
The apparent
apparent power consumed
consumed by an electrical
electrical system is
is composed
composed of
ofaa
expressed
expressed in kilovolt-amperes
kilovolt-amperes (kVA)
(kVA),, and is
kilowatt(kW)
(kW)
component
and a kilovolt-ampere
component
andakilovolt-ampere
reactive reactive
(kvar)
component.The
The kW component
representsthe
thereal
real
(kvar) component.
component represents
Real power (kW)
work extracted
from
the
power
system.
The
kvar
component
extracted from the power system.
component
represents
the
magnetizing
energy
necessary
for exciting
representsthe
magnetizing
energy
necessary
forexciting
Figure &Power
Relationship
Figure
4-Power
Relationship
electrical
well
electrical equipment
equipmentsuch
suchas motors
motors and
andtransformers,
transformers,as as
well
as the inductive
inductive and capacitive
capacitive components
components of other
other devices
devices
d.
powerfactor
factor
correction
capacitors to supply
the
d. Usingpower
correction
capacitors
supplythe
on the system. Power factor
the ratio
ratioofof kW to kVA and
factor is the
of
inductive
loads.
reactive
requirements
reactive
requirements
of
inductive
loads.
provides
measure of the percentage
kVA that is doing
provides a measure
percentage ofkVA
doing
the excitation
excitationfrom
from in-plant
in-plant generators.
generators.
e. Increasing
Increasing the
useful work.
work.
Installing aa static
staticvar compensator.
compensator.
The total current
thethe
power
system
compocurrentpassing
passingthrough
through
power
system
compo- f. Installing
g.
Controlling
voltage
so
as to avoid
Controlling
voltage
avoidovervoltage
overvoltageconditions.
conditions.
(e.g.,transformers,
transformers,
cables,
transmission
lines, switchnents(e.g.,
cables,
transmission
lines,switchgear) produces
proportional
to the square
producesheating
heatinglosses
losses
proportional
square of the
When
applied
to induction
motors,
When capacitors
capacitorsareare
applied
to induction
motors,
the greatgreatcurrent
current (I2R).
(12R). The total current is proportional
proportional to
to the
thekVA,
kVA, so
est benefit isisobtained
obtained if the capacitors
capacitors are
areinstalled
installed at the
by reducing kVA,
kVA,losses
lossescan
canbe reduced. To reduce kVA,
kVA, it is
motor terminals,
on on
and off with the motor.
motor.
terminals,and
andareareswitched
switched
only
practicaltocut
to exciting
cut exciting
onlypractical
energyenergy
(kvar).(kvar). In addition
additiontoto
factorcorreccorrecbe taken
takenininthe
theapplication
application
of power factor
Care must be
energythrough
through
transmission
losses,
excessive
wastingenergy
transmission
losses,
excessive
kvar kvar
tion capacitors.
capacitors. Proper attention must be given to the
the effect
loadinguses
uses
up transformer,
and transmission
line
uptransformer,
cable,andcable,
transmission
line
that capacitors
on on
harmonic
resonance,
thermal
overload
capacitorshave
have
harmonic
resonance,
thermal
overload
capacity,
capacity, causing
causing the
the supplying utility to overbuild
overbuild their
their syssizing,
switching
capability,
the lengthening
of
sizing, circuit
circuitbreaker
breaker
switching
capability,
the lengthening
tem.
control this, utilities pass on the excess
excess cost
cost through
through
tem. To control
motoropen-circuit
open-circuit
time
constants,
and the possibility of
time
constants,
andthepossibility
the use
power
contracts.
To To motor self-excitation.
useof power factor
factorpenalty
penaltyclauses
clausesin in
power
contracts.
self-excitation.
avoid
power
factor
mustmust
be kept
avoid paying
payingthese
thesepenalties,
penalties,
power
factor
be above
kept above A synchronous
synchronouscondenser
condenser
cancan
alsoalso be used to improve
improve
a fixed
0.94.
fixedvalue-normally
value-normally between 0.90
0.90and
and
This device
device is used mainly
mainlybybyutilities,
utilities,however,
however,
power factor.
factor.This
The large
large number of induction motors
motors typical
typical in a process
and isisnot
in most industrial
notpractical
practical
industrialplants.
plants.
plant can result in aa low
lowoverall
overall power factor
factor on the
the system
(0.85
(0.85 power factor
factor or less).
less). Motors
Motors that are lightly
lightly loaded
3.10 DEFINITIONSAND
ANDCONVERSION
CONVERSIONFACTORS
FACTORS
accentuate
accentuate the problem because motor power factor
The following
andand
conversion
factors
following is a list
listofofdefinitions
definitions
conversion
factors
decreases
decreases rapidly with decreasing
decreasing load.
load. The low power facfacoften
useful
in
energy
discussions:
that
are
often
useful
in
energy
discussions:
tor results
results in higher-than-necessary
higher-than-necessary currents on the
the distribudistribusystem, resulting
Improving the power
tion system,
resulting in higher losses. Improving
a.
thermalunit
unit(Btu)
(Btu)
equals the heat required
required to
a. 1 British
British thermal
equals
factor will increase
increase the overall efficiency
efficiency of
of the power sysraise
waterby
by1°F.
1OF.
raise the temperature
temperature.ofof1 pound of water
tem. An improved
improved power factor
factor can also reduce or even
b. 1 quad (quadrillion
(quadrillionBtu) equals
equals 1,015
1,015 Btu.
eliminate
eliminate power factor
factor penalty charges
charges if utility contracts
contracts
c. 11 therm equals
equals 100,000
100,000 Btu.
contain such provisions.
provisions.
d.
d. 11 horsepower
horsepower (Hp)
(HP)equals
equals0.746
0.746kW.
The following
actions can increase
power
factor,
followingactions
increasepower
factor,
and and
e.
e. 1 kWh equals
equals 3,413 Btu.
theassociated
associatedlosses:
losses:
reduce the
approximately 10,000
10,000 Btu of raw fuel
Note: Due to
to thermal losses, approximately
consumed to produce
produce11kWh of
of electricity
electricity inina conventional
conventional utilutilare consumed
a. Using high
high power factor
equipment,such
such as high
factor rated equipment,
ity generating
generating station.
station.
power factor
factorlighting
lighting
ballasts.
ballasts.
b. Using synchronous
unity,
f.f. One 42-gallon barrel of
of fuel
million
synchronousmotors
motors which can
canbe operated at unity,
fuel oil contains about 66 million
Btu.
or leading
factor.
leading (capacitive)
(capacitive)power
power
factor.
g. One cubic
1,000Btu.
cubicfoot
foot of natural gas
gas contains
contains about
about1,000
Operatinghigh
induction
motors
at at close to
c. Operating
highefficiency
efficiency
induction
motors
design horsepower.
h. One ton of coal contains
containsabout
about25 million
million Btu.
Btu.
horsepower.
~
~
~
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STD-API/PETRO RP 54O-ENGL
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SECTION
POWER SYSTEMS
SYSTEMS
SECTION 4-FACILITY
&FACILITY POWER
4.1
PURPOSE
4.1 PURPOSE
Unit
in Figure
6,
in isoUnit construction,
construction,illustrated
illustrated
in Figure
6, can
can bebeused
used
in isolated
With
this construction,
each generator
has
lated power
powerstations.
stations.
With
this construction,
each generator
has
This
This section
section discusses
discussesthe
the design
design considerations
considerationsthat
thatmust
must
its
turbine,
mainmain
bus, and
or
its own
own boiler
boileroror
turbine,
bus,boiler,
and boiler,
or turbine
turbine auxilauxilbe
of
effecbe evaluated
evaluatedfor
forthethedevelopment
development
of aa reliable
reliableand
andcost
cost
effec- iary
Nonnally, the
thetietiecircuit
circuit
breaker
between
the main
iary bus. Normally,
breaker
between
the main
tive
facilities.
tive power
powersystem
systemfor
for continuously
continuouslyrun
runpetroleum
petroleum
facilities.
buses
event of
of aa fault
fault on
on either
either
buses is
is closed but will
wili open in the event
bus.
operates
much
the the
same
as two
bus. In
Ineffect,
effect,the
thearrangement
arrangement
operates
much
same
as two
4.2
SCOPE
4.2
SCOPE
independent
independentpower stations
stations tied
tiedtogether.
together.The
Themain
main buses
buses are
are
tied
dUling normal
nOimaloperation,
operation, so
mustbe
be
so each
each side must
tied together during
All
aspects of facility
power systems,
systems, from
point at
All aspects
facility power
from the
the point
at
rated
for
the
total
fault
duty
resulting
fromfrom
both generators.
rated
for
the
total
fault
duty
resulting
both
generators.
which
introduced
into
which power
poweris is
introduced
into the
the facility
facility to
to the
the points
points ofofutiutiA
in
A synchronizing
synchronizingbus
busscheme,
scheme,shown
shown
in simplified
simplifiedform
form in
in
lization,
lization, are
arecovered
coveredby this
this section.
section.Topics
Topicsinclude
includeincoming
incoming
Figure
7,
is
often
used
for
aa power
station
bus.
This
scheme
Figure
7,
is
often
used
for
power
station
bus.
This
scheme
lines
purchased power,
substations,
lines for
for purchased
power, in-plant
in-plant generation,
generation, substations,
offers a high degree of
of flexibility
flexibilityto
to add
add or
or remove
remove generators
generators
transfonners,
distribution
systems,
volt-volt- offers a high degree
transformers,switchgear,
switchgear,overhead
overhead
distribution
systems,
of fault
and
loads.
The
reactors
serve
to to
limit
the amount
and
loads.
The
reactors
serve
limit
the
amount
fault
of duty
duty
age
systemarrangements,
arrangements,
protective
relaying,
age levels,
levels,system
protective
relaying,
fault fault
imposed
on
anyone
busand
and to
isolate
voltage dips,
to
imposed
on
any
one
bus
to
isolate
voltage
dips,
toaa
currents,
currents,and
and system
systemstability.
stability.
degree,
degree, during
during faults.
faults. In
In this
this aITangement
arrangement the
the loads
loads on
on each
each
on that
to
bus
generating
capacity
bus are
arematched
matchedto the
to the
generating
capacity
onbus
that
to minminbus
4.3
POWER
SOURCES
4.3POWER
SOURCES
imize
imize the
the amount
amount of
of load
loadtransfer
transferthrough
throughthe
thesynchronizing
synchronizing
bus
operation.
bus under
undernormal
normal
operation.
4.3.1
Generated
Power
4.3.1
Generated
Power
powerstation
stationbus
busarrangement
alTangement
should
The
The design
design of
of the power
should
Facility
Facility power
power stations
stationsnot
not connected
connected to
to public
public utility
utility syssysallow
as
allow for
for future
futureexpansion,
expansion,such
such
as expanding
expandinga asingle
singleor
or dual
dual
tems
tems must
must be
bedesigned
designedwith
with redundancy
redundancy to
to ensure
ensureaa self-sufself-sufbus
arrangementtoto
a synchronizing
bus arrangement. The
busarrangement
asynchronizing
busarrangement.
The
ficiency
operating contingencies.
ficiency for
for various
various operating
contingencies. These
These power
power
design
of generating
generating capacity
capacity
design should
should also
also minimize
minimizethe
the loss
loss of
stations
stations should
should have
have provisions
provisionsfor
for aa cold
cold (black)
(black) start
start and,
and,
which
a single
faultfault
or
which would
wouldoccur
occurduring
during
a single
or operating
operating error.
error.
as
100%of
of plant
plant
as aa minimum,
minimum, should
should be
be designed
designed to
to supply
supply 100%
electrical
electrical loads
loads after
after the
the loss
loss of
of any
any single
single major
major component
component
4.3.1.3Power
Power Station
Systems
Station Excitation Systems
of
of the
the power
power generating
generating system.
system. Other
Other contingencies,
contingencies, such
such
The
task perThe reliable
reliable generation
generationof
of reactive
reactivepower
poweris aisvital
a vital
task peras
as the
the capability
capability of
of motor
motor starting
starting at
at reduced
reduced generation,
generation,
fonned
by
the
generator
field.
The
field
is
powered
from
an
formed
by
the
generator
field.
The
field
is
powered
from
an
should
should be
be considered.
considered.
voltageregulator
regulator system
excitation
system controlled
controlled by
excitation system
by aa voltage
system
that
that maintains
maintainsdesired
desiredbus
busvoltage
voltageconditions
conditionswhen operated
operated
4.3.1.1
Power Station
Auxiliaries
4.3.1.1Power
StationAuxiliaries
in isolation.
the
.in
isolation.When
When operated
operated in
in parallel
parallel with
witha autility,
utility,
the voltvoltage
regulator
is
biased
to
maintain
a
fixed
reactive
age
regulator
system
is
biased
to
maintain
a
fixed
reactive
Facility
powerstations
stations
produce
process
steam and
Facilitypower
thatthat
produce
process
steamand
power or
or power
power factor.
factor.The
The two
two types
typesof
of excitation
excitationsystems
systemsin
in
auxilelectricity
electricity must
mustbe
be provided
provided with
with highly
highly reliable
reliablestation
station
auxil- power
general
use
are
brushIess
exciters,
which
are
similar
to
those
general
use
are
brushless
exciters,
which
are
similar
to
those
iaries.
iaries. The
The auxiliaries
auxiliaries should
should be
be spared
spared and
and supplied
supplied from
from aa
onbrushless
.brushlesssynchronous
synchronous
motors; aud
used on
motors;
and static
static exciters,
exciters,
prominimum
minimum of
of two
two independent
independentsources
sourcesdevoted
devotedsolely
solelyto to
pro- used
which
feed
power
through
slip
rings
to
the
generator
field.
which feed power
slip rings the generator field.
viding
air, fuel,
fuel, and
and water
water
viding auxiliaries.
auxiliaries. Critical
Criticalauxiliaries
auxiliariesfor
for air,
be
provided
to
ensure
With
either
system,
means
should
With either system, means should
be provided to ensure conconsupplies
spares.
suppliesshould
should have
havesteam-driven
steam-driven
spares.
tinued"
generator
fault-current
output
tinued- generator fault-currentoutput for
for faults
faults in
in close
close elecelectrical
trical proximity
proximityto
to the
the generator
generator terminals,
terminals,since
since these
these faults
faults
4.3.1.2 Power
Power
Station
Bus
Arrangements
Station
Bus
Arrangements
will
severely
depress
the
generator
bus
voltage.
This
This will
will
willseverelydepressthegeneratorbusvoltage.
The
for
require
The size
size and
and importance
importance of
of the
the power
power station
station will deterrequirethe
the use
use of
of power
powercurrent
currenttransfonners
transformers
for static
staticexcitaexcitathe
mine
tion
mine the
the type
type ofofbus
bus arrangement
arrangementutilized
utilizedfor
forthe
the main
main electrielectriconstant voltage
voltagesource
sourceforfor
the exciter
exciter field
field
tion systems
systemsor
or aa constant
cal
on
10 MW)
MW) frequently
frequently
cal connections.
connections.Small
Small stations
stations(less
(less than
than 10
on aa brushIess
brushlesssystem.
system.
have
have only
only aa single
single main
main bus as
as shown
shown in
in Figure
Figure 5.
5. Bus
Bus failfail4.3.2Purchased
Purchased
Power
ures
Power
ures are
are not
not common,
common,and
and fair
fair reliability
reliability is
is obtained.
obtained.ItItis
is necnecessary
preventive
essary to
to shut
shut down, however,
however, when
when performing preventive
When
powerispurchased
is purchased from
utility,thethe
following
Whenpower
from aautility,
following
maintenance
maintenance to
to the
the main
mainbus
busor
or when
when additions
additions are
are made
madeto
to
items,
items, as
as aa minimum,
minimum,should
shouldbe
be considered:
considered:
out
the
the main
main bus.
bus.Circuit
Circuitbreakers
breakers must
mustbebetaken
taken
out of
of service
serviceto
to
be
feeders.
a.
this problem
problem can
can be
be minimized
minimized by using
using
a. Source
Source and
andnumber
numberofof
feeders.
be worked
worked on,
on, but this
in dish.
drawout-type
disadvantages
can can
resultresult
drawout-typebreakers.
breakers.These
These
disadvantages
disin
b. Reliability
Reliabilityof
of utility
utility system.
system.
ruption
as
c.
as draft
draft fans,
fans,prepreruption to
to essential
essential station
stationauxiliaries,
auxiliaries,such
such
c. Capacity
Capacity and
and voltage
voltageof
of circuits.
circuits.
heaters,
d.
limitations.
aircompressors,
compressors,and
andlighting.
lighting.
heaters, boiler
boilerfeed
feed pumps,
pumps, air
d. Power
Power contracts
contractsand
anddemand
demand
limitations.
17
17
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18
18
PRACTICE
RECOMMENDED
API
API RECOMMENDED PRACTICE 540
540
Generator
Generator
11
Generator
2
~QI>
9QI)>
Main
Main bus
bus
i i .,ii
I)
I)
I)
I)
I)
! ! ! ! !1
\..
\
"Y
I)>
Station
Station
auxiliaries
auxiliaries
.J
J
Feeders
Feeders
1
MfM
Figure
5-Single Main
Figure 5-Single
Main Bus
BusArrangement
Arrangement
Generator
Generator
11
~Q
Generator
Generator
22
bus
Main bus
Main
Main bus
22
1
~
r'\
/)
Boiler
Boiler11
auxiliary
auxiliarybus
bus
I)
~
MfM
I)
I) I)
I)
cS cS cS
I) I) /)
!
!-----!
!
- -----Feeders
Feeders
I)
NC
Boiler
Boiler22
auxiliarybus
bus
auxiliary
Feeders
Feeders
I)
I)
I)
cS cS cS
Figure
Figure 6-Unit
6-Unit Construction
ConstructionBus
BusArrangement
Arrangement
I)
wl.
MfM
Copyrighted material licensed to IDOM.
STD*API/PETRO RP 540-ENGL
B999 W 0732290 0615557 3bB a i
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ELECTRICAL
INSTALLATIONS IN
INPLANTS
PROCESSING
PETROLEUM PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
PETROLEUM
19
19
Synchronizing bus
bus
Generator
1
Q
Generator
Generator
Generator
Generator
2
33
)
Bus
)
Q
)
Bus
I
1
I
I
2
,
i
I) 7; 1) I
Q
,
)
Bus
2,
) Bus
)
I
1)
)
I
I
Bus
)
,
I I)
'r 1'
I
3
3,
Y.1'
I
l
67
6 6-l"~A A- - l
6- 6 6ll"
-----....---
-----....---
Feeders
Feeders
Feeders
Station
Station
auxiliaries
auxiliaries
)
)
)
Station
auxiliaries
,
-----....--Feeders
Feeders
Feeders
Station
auxiliaries
Figure 7-Synchronizing
7-Synchronizing Bus
Bus Arrangement
Arrangement
Figure
e.
e. Parallel operation
operationof multiple incoming
incominglines.
lines.
f.f. Automatic
Automatic transfer
transfer scheme.
scheme.
g.
Voltage regulation.
regulation.
g. Voltage
Harmonic distortion,
distortion, or harmonic
harmonic current
currentlimitations.
limitations.
h. Harmonic
i.i. Short-circuit
Short-circuit current.
current.
j. Coordination
Coordination with
with utility
utilityrelaying.
relaying.
starting requirements.
requirements.
k. Motor starting
1.1. Reclosing
procedures.
Reclosingprocedures.
m.
m. Substation
Substationand metering
meteringrequirements.
requirements.
n. System
System maintainability.
maintainability.
o.
potential additions
additions or modifications
petroo. Future
Future potential
modifications to the petroleum facility.
facility.
the frequency
frequency and
and nature
nature of service disturbances,
disturbances, the existreclosures,
ence and speed of automatic
automatic reclosures, and the'length
the' length of
outages.
outages. Performance
Performance records
records should
should also be examined to
any actions
determine
determine if any
actions have been taken to prevent recurrences of previous
previousinterruptions.
interruptions.
rences
4.3.2.3 Capacity
Capacity
and
Voltage of Circuits
and
Voltage
Circuits
Circuits should be
be sized
sized so that if any
one circuit isis out
outof
of
Circuits
anyone
service,
remaining circuits
service, the remaining
circuits have
havethe
thecapacity
capacitytotocarry
carrythe
continuously. Circuit
Circuit voltage
cases will depend
voltage in most cases
load continuously~
power
onutility
utility
standards and the amount of purchasedpower
standards
required. When the voltage
voltageof incoming feeders
feeders is higher than
required.
transfomers of proper
the voltage
voltageselected
selected for the facility,
facility, transformers
4.3.2.1
Source
Number of Feeders
4.3.2.1Source
andand
Number
Feeders
voltage
generally be included
voltage rating will generally
included in each substation
substation
majorportions
portionsofofthethe
plant
load
supplied
by purWhen major
plant
load
are are
supplied
by purwhere utility
utilityfeeders
feedersare terminated.
terminated.
chased
increase
chased power, multiple
multiple feeders
feedersshould
shouldbebeprovided
providedto to
increase
service
reliability.Circuits
Circuitsshould
should
have
maximum
electrical
servicereliability.
have
maximum
electrical
Contracts
andand
Demand
Limitations
4.3.2.4Power
Power
Contracts
Demand
Limitations
isolation
Wherepossible,
possible,circuits
circuits
should be
isolation or redundancy.
redundancy. Where
should
totaloutage
outage
separately
possibility ofoftotal
separately routed to minimize the possibility
form of and terms set forth
forth in power contracts
contracts
The exact form
resulting
to fire
or to mechanical
mechanical damage.
damage.
resulting from
fromexposure
exposure
to fire
country. Energy
vary with
withthe
theutility
utilityand
and region of the country.
will vary
4.3.2.2
4.3.2.2
Reliability
Reliability of Utility System
provide information
routing,
Utilities should provide
information concerning
concerning routing,
construction, and the extent to which their cirthe type of construction,
cuits
cuits are protected against outage.
outage. Performance
Performance records of
determine
pertinent
pertinent utility feeders
feeders should be examined
examined to determine
charges
charges include
includefuel
fuel adjustment
adjustment costs
costs as part of the contract.
contract.
Demand charges
fac-facchargesare based both on kilowatts
kilowattswith
withpower
power
toradjustments
adjustmentsand
and on kilovolt-amperes.
kilovolt-amperes. Power
Power contracts
contracts
may have maximum
maximum demand
demand limitations
limitations or provisions
provisions under
under
supplied on an
which demands
demands beyond
beyondspecified
specifiedlevels
levels are supplied
interruptible
determine the most favorable
favorablerate,
interruptiblebasis only.
only.To determine
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
20
20
API RECOMMENDED
PRACTICE
540
API
RECOMMENDED
PRACTICE
540
From
From power
power source
source
)
NC
)
NC
Tie breaker
----Ir----~--_.r_----~~~----,_--~~--_r---NO
)
)
)
)
Feeders
Feeders
Feeders
Feeders
Figure
8-Purchased
Power:
Divided
Feeder
Operation
Figure 8-Purchased
Power:
Divided
Feeder
Operation
From
Frompower
powersource
source
1NC
f .f f
Feeders
Feeders
Figure
9-PurchasedPower:
Power:Parallel
ParallelFeeder
Feeder
Operation
Figure %Purchased
Operation
Copyrighted material licensed to IDOM.
STD-API/PETRO RP 540-ENGL
L999 orm
0732290
No further reproduction
distribution
permitted.Ob15559 L 3 4 . M
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL
INSTALLATIONS
IN
PROCESSING
PLANTS
ELECTRICAL
INSTALLATIONS
IN PETROLEUM
PETROLEUM
PROCESSING
PLANTS
21
21
itit is
is essential
essential totoknow
knowfirm
firm demand
demandand
andenergy
energyrequirements
requirements
as
as well
wellas
asdaily
daily and
andseasonal
seasonalload
loadprofiles.
profiles.
known
starting
andand
pr~tective
relay
sothat
that its
itseffect
effecton
onmotor
motor
starting
protective
relay
known so
settings
settingscan
canbe
be determined.
determined.
4.3.2.5
4.3.2.5
4.3.2.10
4.3.2.1 O Coordination
Coordinationwith
withUtility
Utility Relaying
Relaying
Parallel
ParallelOperation
Operation of
of Incoming
IncomingLines
Lines
Proper
Proper coordination
coordinationbetween
betweensubstation
substationand
and utility
utility protecprotecThe
The preferred
preferred operation
operationof
of incoming
incoming utility
utilitylines
lines isis to
to parpartive
relaying
is
essential
to
minimize
the
number
and duration
tive relaying is essential to minimize the number
and duration
allel
them on
onthe
the
substation
Typical
arrangements
allel them
substation
bus.bus.
Typical
arrangements
are are
of
selected
by
of power
power outages.
outages.The
The proper
properrelaying
relayingshould
shouldbebe
selected
by
shown
be
and9.
9.Suitable
Suitablerelaying
relayingmust
must
be provided
provided
shownininFigures
Figures88 and
the
the user
userin
in collaboration
collaborationwith
with the
the utility
utility company.
company.
for
for proper
proper system
system protection,
protection,and,
and,before
beforethe
thefeeders
feeders can
can be
operated
protection
must
be(e.g.,
provided (e.g.,
operated in
in parallel,
parallel,protection
mustbe
provided
Requirements
4.3.2.1 1 Motor
MotorStartingRequirements
through
of of
synchronization
check
relays)
to verify
that that4.3.2.11
through the
theuse
use
synchronization
check
relays)
to verify
the
the voltages
voltagesof
of the
the feeders
feedersare
areequal
equaland
and synchronized.
synchronized.
The
dropwhich
whichoccurs
occurs
on plant
the plant
bus during
The voltage
voltage drop
on the
bus during
motor
starting
should
be
calculated
to
ensure
that
motor starting should be calculated to ensure that plant
plant and
and
4.3.2.6
Automatic
Transfer
Scheme
4.3.2.6Automatic
Transfer
Scheme
utility
company
limitations
are
met.
The
voltage-drop
utility company limitations are met. The voltage-dropcalcucalculation
starting of
ofthe
theplant’s
plant'slargest
largest
lation should be
.bebased
based on
on the starting
When
incoming circuits
automatic
When incoming
circuits cannot
cannot be
be paralleled,
paralleled, automatic
aU
other
required
plant
loads
in
operation.
motor.
with
motorwithall
other requiredplantloadsinoperation.
transfer
between the
should be
Load
transferbetween
the circuits
circuitsshould
be considered.
considered.Load
Reduced-voltagestarting
startingor
or an
an auxiliary
auxiliary starting
starting driver
driver may
may
requirements
testrequirementsshould
shouldbe
be checked
checkedcarefully,
carefully,and
anda regular
a regular
test- Reduced-voltage
be
required
when
the
utility
system
is
not
stiff
enoughtoto
be required when the utility system is not stiff enough
ing
method
forautomatic
the automatic
ingmethod
forthe
transfer transfer scheme
scheme should
should be
be
allow
allowfull-voltage
full-voltagestarting.
starting.
included.
included. Fast
Fast transfer
transfer schemes
schemesmust
mustconsider
consider the
the effects
effects of
of
residual
residualvoltage
voltageon
on motors
motorsand
and driven
drivenloads.
loads.
4.3.2.7
Voltage
Regulation
4.3.2.7Voltage
Regulation
4.3.2.12
Reclosing
Procedures
4.3.2.12Reclosing
Procedures
Utilities
automatic
reclosing
schemes on
Utilities may
may employ
employautomatic
reclosing
schemes
on
overhead
because
the
faults
which
occur
on
overhead
overhead
lines
because
the
faults
which
occur
on
overhead
Where
(to(to
unacceptable
levels),
Where utility
utilityor
orplant
plant voltage
voltagevaries
varies
unacceptable
levels),
lines
in
lines are
areoften
oftentransient
transient
in nature.
nature.The
The delay
delay time
timeand
andnumber
number
automatic
load-tap-changing
transformers
or
other
methods
automaticload-tap-changing transfomers orothermethods
of
automatic
reclosures
are
based
on
a
review
of
such
factors
should
for for
maintaining
closeclose
voltage
regulation.
shouldbebeconsidered
considered
maintaining
voltage
regulation. of automatic reclosuresare based on a review of such factors
as
and
thethe
feeding
of the
plant
as the
the voltage
voltagelevel
levelofofthe
thefeeder
feeder
and
feeding
of the
plant
from
either
a
radial
distribution
feeder
or
a
tap
on
a
transmisfrom
either
a
radial
distribution
feeder
or
a
tap
on
a
transmis4.3.2.8
Harmonic
Distortion,
Harmonic
Current
4.3.2.8 Harmonic
Distortion,
oror
Harmonic
Current
sion
automatic
sion tie
tie line.
line. The
The delay
delay time before
before and
and between automatic
Limitations
Limitations
reclosures
and
the
number
of
reclosures
are
required
reclosures and the number of reclosures are requiredfor
forthe
the
design
Harmonic
distortion,
typically
generated
by
nonsinusoidal
of
protective
relaying
and
system
control
schemes.
Harmonic distortion, typically generated by nonsinusoidal
design of protective relaying and
system control schemes.
waveforms
adjustable
waveformsoriginating
originatingfrom
fromSCR
SCRrectifiers,
rectifiers,
adjustablespeed
speed
drives,
and similar
voltageand
and
frequency
4.3.2.13
Substation
Metering
Requirements
4.3.2.13Substation
andand
Metering
Requirements
drives,and
similar electronic
electronicvoltage
frequency
con- controlled
trolled devices,
devices,can
can cause
cause serious
seriousproblems
problemsin
in electrical
electrical syssysCharacteristics
facilitysubstation,
substation,should
should
Characteristics of
of aafacility
taketake
into into
tems.·
overheating of
tems. Problems
Problems can
can include
include overloading
overloading and
and overheating
of
consideration:
consideration:
phase
systems; problems associated
associated with
phase and
and neutral power systems;
with
ofelectronic
electronic
high
electrical noise
the system;
a.a. Largest
high electrical
noise on
on the
system; inability
inability of
Largestsingle
singleload.
load.
hardware
b.
hardware to
to synchronize;
synchronize; failure
failure of
of frequency-sensitive
frequency-sensitivecircirb. Total
Totalconnected
connectedload.
load.
cuits
speed
c.
Maximunl allowable
of adjustable
adjustablespeed
cuits such
such as
as lighting
lighting ballasts;
ballasts; failure
failure of
c. Maximum
allowablevoltage
voltagedrop.
drop.
drives
d.
drives and
andmotor
motorwindings
windingsdue
due to
to reflected
reflected waves;
waves;and
andmany
many
d. Utility
Utilityreliability.
reliability.
other
abnormalities. IEEE
Std 519
e.e. Substation
user).
IEEE Std
Std 399
399 and
and Std
519 should
should be
be
other abnormalities.
Substationownership
ownership(utility
(utilityversus
versus
user).
reviewed
for systems
appreciablenonsinusoidal
nonsinusoidal
f.f. Primary
reviewedfor
systems with
withappreciable
har-harPrimary versus
versussecondary
secondarymetering.
metering.
monics.
monics. Often,
Often, utilities
utilities will
will impose
impose limitations
limitationson
on the
the maximaxig.
g. Spare
Sparetransformer
transformercapacity.
capacity.
mum
amount of
currentbeing
being generated
of harmonic
harmonic current
generated by
by the
the
mum amount
h.
requirements.
h. Future
Future load
loadgrowth
growthand
andexpansion
expansion
requirements.
customer
i.i. Grounding.
customerinto
intothe
the utility
utility supply.
supply.
Grounding.
j.j. Isoceraunic
(lightning
frequency)
Isoceraunic(lightning
frequency)
level level and
and protection
protection
4.3.2.9
Current
schemes.
4.3.2.9 Short-Circuit
Short-CircuitCurrent
schemes.
k.
k. Facility
Facilitylife.
life.
The
designed to
The electrical
electrical system
system must
must be designed
to accommodate
accommodate
1.1. Maintainability
Maintainabilityas
as itit would
would affect
affectsubstation
substationdesign.
design.
the
current
thatthat
would
result
the maximum
maximumshort-circuit
short-circuit
current
would
result from
fromthe
the
combined
combined effect
effectof
of both
both utility
utility and
andin-plant
in-plantsources.
sources.All
All syssys4.3.2.14
System Maintainability
4.3.2.14System
Maintainability
tem
tem components,
components, such
such as
as circuit
circuit breakers,
breakers, transformers,
transformers,and
and
The
electricaldistribution
distributionand
andutilization
utilization
system
must
buses,
ratings that
thatcan
canadequately
adequatelywithstand
withstandand
and
The electrical
system
must
be be
buses, must have ratings
designed
andand
maintained
on a regular
interrupt
effects of
sothat
thatititcan
canbebeinspected
inspected
maintained
on a regular
designedso
interrupt the effects
of the
the fault
fault currents
currents to
to which
which they
they are
are
basis
maintenance of
exposed.
must
alsoalso
be
basis to
to assure
assure reliable
reliable operation.
operation. Often,
Often, the
the maintenance
of
exposed.The
The minimum
minimumutility
utilityshort-circuit
short-circuitlevel
level
must
be
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permitted.. .
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API RECOMMENDED
PRACTICE
540
RECOMMENDED
PRACTICE
540
22
Restoration
Procedures
4.3.3.3Service
Service
Restoration
Procedures
electrical
a petroleum
facility
are maintained
at the at the
electrical facilities
facilitiesforfor
a petroleum
facility
are maintained
same maintenance intervals as other process
process equipment.
equipment. The
The
Various fault
fault or switching
switching conditions
conditions may cause facility
facility
connection
process equipment
equipment should
should be
be avoided
avoided
connection of unrelated process
and
utility
generating
systems to separate. The usual
utility
generating
systems
to
separate.
if ititcannot
shutdown
during
the primary
facilityfacility
shutdown.
.
cannotbebe
shutdown
during
the primary
shutdown.
sequence
disturbance
affecting
sequence involves
involvesa afault
faulttransient
transient
disturbance
affecting both
systems
recovery of the
systems until
until separation
separation occurs,
occurs,followed
followedby recovery
Additions
or Modifications
4.3.2.15Facility
Facility
Additions
or Modifications
isolated systems.
systems.The fault
fault transient
transient may cause aa voltage
voltage dip
if if
prowill
cause
motors
to
drop
off
the
line;
however,
line;
however,
prowhich
will
cause
motors
drop
Design of electrical
electrical systems
systems should take into considerconsidercess
conditions
allow,
important
drives
can
have
their
control
conditions
allow,
important
drives.
can
control
ation any potential
potential additions
additions or modifications
modifications of the facility.
facility.
restarting automatically
automatically when
whenplant
plant
equipped to permit their restarting
equipped
This
is
especially
important
when
selecting
equipment
This especially
selecting equipment fault
fault
voltage
recovers.
voltage
recovers.
duty ratings and designing provisions
provisions for future
future expansion
expansion
Operation
Operation of plant generation
generationafter separation
separation may
mayrequire
additions.
or additions.
automatically
adjusting the
theload
load on plant generation
generation to the
automatically adjusting
restart automatically
automatically and
load level
levelthat
that it can successfully
successfully restart
and
4.3.3 Parallel
Parallel
Operation
with
Purchased
Operation
with
Purchased
andand
supply continuously
supply
continuously with
withacceptable
acceptablevoltage
voltageand
andfrequency
frequency
Generated Power
Power
th.e public
levels.
levels. If
If the plant
plant has
hasbeen
beenreceiving
receivingpower
powerfrom
from
the
utility,
voltage
and
frequency
will
fall
unless
load-shedding
utility,
voltage
and
frequency
will
fall
unless
load-shedding
When aautility
supplies
a
part
of
the
facility
power
requireutility supplies a
facility power requirerestores the proper balance
restores
balanceor the plant turbine-generators
turbine-generatorscan
can
ments and operates
operatesinin
parallel
generated
the
ments
parallel
withwith
plantplant
generated
power,power,
the
If
the
had
been
sendincrease
output
to
the
proper
level.
increase
output
the
proper
level.
If
plant
had
following
considered:
following must
mustbebe
considered:
ing power to the public
electrical
publicutility
utilitybefore
beforeisolation,
isolation,
electrical outouta. Division and interchange
reactive
power.
interchange of
ofreal
realand
and
reactive
power.
reduction on plant
put must
mustbebereduced.
reduced. The effect of this reduction
steam system conditions
conditionsmust
mustalso
also
determined.
steam
be determined.
b. Protective
Protective relaying.
relaying.
of
the
plant
generation
and the utility system
system
Paralleling
Paralleling
of
the
plant
generation
and
c. Service
Service restoration
restoration procedures.
procedures.
breakers that are
should be possible
possible only
only at selected circuit breakers
equipped
with
synchronizing
switches these
connecting these
equippedwith
synchronizing
switchesconnecting
4.3.3.1
Division
and
Interchange
of Real
4.3.3.1 Division
and
Interchange
of Real
andand
breakers
into
the
plant
synchronizing
system.
Other circuit
breakers
synchronizing
circuit
Power
Reactive Power
breakers where inadvertent paralleling
possible should be
breakers
paralleling is
is possible
equipped
equipped with
with synchronizing-check
synchronizing-checkrelays that prevent
prevent closclosPower interchanges
interchanges between utility and industrial
industrial sysing unless
unless voltage
conditions
at both
terminals
voltageand
andfrequency
frequency
conditions
at both
terminals
tems can vary due to excess
excess plant power generation,
generation, utility
within prescribed
Relays which
of the breakers are within
prescribedlimits.
limits. Relays
power restrictions,
restrictions, or load adjustments
adjustments to maintain
maintain constant
during fault
faultconditions
conditionsmust
must be applied
protect the system
system during
demand on the utility system.
system. Contracts
Contracts for the purchase of
setcarefully
carefullyto prevent
separationfrom
fromoccurring
occurringduring
during
and set
prevent separation
utility power should
include the amount of kilowatts and
should include
and
synchronizing swings.
swings.
synchronizing
kilovars
kilovars and the division
division ororinterchange of them between the
A power system
system study
studyis normally required
required to
to provide the
facility. If
If the utility line voltage is subject
subject to
utility and the facility.
protective
relaying
and
settings
as
well
as
proper
protective
relaying
and
settings
the generatgeneratwide variations,
variations, amethod
method for controlling
kilovar
intercontrolling
intering
system
load
shedding
system
parameters
system
and
shedding
parameters
necessary
change as well as regulating voltage
voltage should be considered.
considered.
for system
recovery transients.
the fault
fault and recovery
transients.
system stability
stabilityduring
during
methods include automatic
Possible methods
automatic load-tap changers
changers on
transformers, power factor
transformers,
factor correction
correction capacitors,
capacitors, and power
4.4 SYSTEM
SYSTEM VOLTAGES
factor control of the generator or synchronous
synchronous motor excitation systems.
systems.
4.4.1
Selection
4.4.1
Selection
4.3.3.2
4.3.3.2
Protective
Relaying
ProtectiveRelaying
Protective
Protective relaying
relaying must be provided to protect the plant
generation from faults
faults or power loss in the utility
and its generation
system. The relaying
relaying must protect against adverse
adverse interacinteracsystem.
tions between the systems
systems and,
and, if necessary for system
system stability,
generation from the utility
bility, must act to isolate plant generation
system.
system. Impedance,
Impedance, reverse power, directional
directional overcurrent,
overcurrent,
incoming
or underfrequency relays may be used to trip the incoming
If
plant
load
exceeds
generation,
supply circuit breakers.
breakers. If
exceeds generation, an
automatic load-shedding system should be provided to
r0
automatic
relieve
relieve generation
generation overloads
overloads after isolation
isolation and to maintain
plant system stability.
stability.
The selection
is based priselection of
of system
systemvoltages
voltagesinina afacility
facility
marily on economics,
economics, with
withconsideration
considerationgiven to the followfollowing factors:
factors:
a.
thethe
utility.
a. Class
Class of service
service available
availablefrom
from
utility.
b. Total
Total connected
connectedload.
load.
c.
C. Planning for future
future growth.
growth.
d.
standardizationof equipment.
d. Plant standardization
equipment.
Density and
anddistribution
distribution
of load.
load. .
e. Density
of the
f. Safety.
Safety.
g~
Interconnection to existing
existing systems.
systems.
g: Interconnection
availability.
h. Equipment availability.
i.1. Practical conductor
equipment
sizes.
conductorand
and
equipment
sizes.
~
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STD.API/PETRO RP 540-ENGL
L999
111 07322.70
692..m
ELECTRICAL
INSTALLATIONS IN
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING
PLANTS
ELECTRICAL
INSTALLATIONS
PLANTS
Levels
4.4.2Voltage
Voltage
Levels
The voltage
voltagelevels
levelsin aa facility
facilitycan
canbebe
divided
as follows:
follows:
The
divided
as
a. Less
Less than
than or
orequal
equalto
to 600
600 V (low).
(low).
a.
to 69,000
69,000V (medium).
(medium).
b. From
From 601
601V to
b.
c. Greater
Greater than 69,000
69,000V (high).
(high).
c.
The low-voltage
low-voltagelevel
normally
usedused to
to supply
supplysmall
The
levelisis
normally
small
motors, lighting, and
The medium-voltage
medium-voltage level is
is
motors,
and controls.
controls. The
normally used for
for larger
largermotors
motorsand
andforfordistribution
distribution
small
normally
of small
to
medium blocks of
and medium
of power.
power. Voltage levels of
of 34,500
34,500 V to
69,000 V may be used for large blocks of power.
power. The
The highhigh69,000
voltage level
level is
is used for
for the
the transmission
transmission and distribution
distribution of
voltage
power.
bulk power.
4.5POWER
SYSTEM
ARRANGEMENTS
POWER
SYSTEM
ARRANGEMENTS
23
23
fault
be be
dropped,
faultwill
willcause
cause half the
theload
loadto to
dropped,but service
servicecan
can be
be
restored
quicklythrough
throughmanual
manual or
operation of
restored quickly
or automatic
automatic operation
the
Investment
costscosts
of this
this system
system are
are
the secondary
secondarytietiebreakers.
breakers.
Investment
relatively
relatively high.
high.
4.5.4
Secondary-Selective
Parallel
System
4.5.4Secondary-Selective
Parallel
System
The
Figure
The secondary-selective
secondary-selective parallel
parallel system,
system, shown
shown in Figure
l3,
continuity
and and
voltage
reg13,provides
provides unintenupted
uninterruptedservice
service
continuity
voltage
ulation
The
breaker
is
ulation totoallallloads.
loads.
The unit substation
substationtietie
breaker
is normally
normally
closed
will
the source
sourcesupplies
supplies
closed and
andananintenuption
intemption of either
either of the
is by
not intenupt
interrupt any of the
the loads.
loads.This
Thisconfiguration
configuration
is far
far the
the
most
complex
and
costly,
but
may
be
justified
based
on
conmost complex and costly,
justified based on consequences
associatedwith
with
process
disruption. A considerconsidersequencesassociated
process
disruption.
ation
loads
ationis is that disturbances
disturbances on one bus may affect
affectloads
connected
connected to
to the other bus. Equipment fault ratings must be
sized
all all
sources.
sized for
for the total
total fault
faultduty
dutyfrom
from
sources.
basic types
typesof power system
system anangements
arrangements are
are availFour basic
able: the
primary-selective
radial,
the secondaryable:
theradial,
radial,thethe
primary-selective
radial,
the secondary4.6POWER
POWER
SYSTEM
STUDIES
SYSTEM
STUDIES
selectiveradial,
andand the
thesecondary-selective
parallel.
The The
selective
radial,
secondary-selective
parallel.
systemanangement
arrangement
is governed by
by factors
factors such
such
selection of a system
is
selection
4.6.1
General
4.6.1
General
as service continuity,
continuity,flexibility,
flexibility,regulation,
regulation,efficiency,
efficiency,operatoperatas
The
design and operation
The planning,
planning,design
operation of a power system
system
ing costs,
costs,
and reliability
source.
costs,investment
investment
costs,
reliability of the power source.
requires
continual
and
comprehensive
analyses
to
evaluate
requires
continual
and
comprehensive
analyses
evaluate
Maintainability
of
equipment
should
be
carefully
considered
Maintainability
performance and to establish
current system
system performance
establish the
theeffectiveness
effectiveness
because it affects
affects all
allofofthese
these
factors.
Systems
utilize
factors.
Systems
that that
utilize
mul- mul- cunent
of
altemative
plans
for
system
expansion.
alternative
plans
for
system
expansion.
tiple supplies,
supplies,loops,
loops,and
and
quitecomplex.
complex.The numnumtiesties
can be quite
ber of relays,
relays,switches,
interlocksrequired
switches, and interlocks
required by these
avoidshutdowns
shutdowns
systems necessitates
necessitates careful
careful engineering
engineeringtotoavoid
4.6.2System
System
Studies
Studies
resulting
failures
or improper
resulting from
fromequipment
equipment
failures
improperoperation.
operation. .
Studies
Studies that
thatwill assist
assist in the
theevaluation
evaluationof initial and
andfuture
future
system
performance,
reliability,
safety
and
ability
grow
system
performance,
reliability,
safety
and
ability
to
4.5.1Simple
Radial
System
4.5.1
Simple
Radial
System
with production
are:
production and/or
and/oroperating
operatingchanges
changes
are:
easiest system
systemto understand,
understand, operate,
operate,and
and
troubleshoot
The easiest
troubleshoot
a.
a. Load flow.
flow.
10. It is the
the least
least
radial system
system shown
shownininFigure
Figure10.
is the simple radial
b.
Cable
ampacity.
ampacity.
expensive system
expandable. The disadvandisadvanexpensive
systemto install and is expandable.
tage of the simple
radialsystem
systemis that it provides no alternate
simple radial
alternate
c. Short-circuit.
Short-circuit.
source ofpower.
power. A failure
failure inin the primary breaker,
breaker, cable,
cable,
Protective Device
d. Protective
DeviceCoordination.
Coordination.
switch, or transformer can
shutdown.
Placswitch,
can result
resultinina aprocess
process
shutdown.
Plac- e. Stability.
Stability.
ing aa single
singleload group or process unit
uniton a radial
radial feeder
feederwill
will
starting ..
f. Motor starting.
reduce the effects
ofa circuit
a circuit
failure
on the overall
overallfacility.
facility.
effects of
failure
g. Insulation Coordination.
Coordination.
h. Reliability.
Reliability.
4.5.2Primary-Selective
Radial
System
Primary-Selective
Radial
System
i.Grounding.
Grounding.
primary-selective radial
radial system
systemshown
shown in Figure 11
The primary-selective
11
Harmonics.
j. Harmonics.
provides better
better service continuity and
and more flexibility
flexibility than
than
the simple radial system
system because only half
half the transformers
for performing
perfonningthe
theabove
above system studies
The procedures for
are on one feeder.
affectedloads
loadscan
can
feeder. Should a feeder fail,
fail, the affected
many
publications
devoted
are outlinedininmany
publications
devoted
to to the subject.
feeder. Voltage
be switched to the other feeder.
Voltage regulation
regulation in
in aa pripriIncluded among these are the following:
following:
simple
mary-selective
radialsystem
system
is comparable
of a simple
mary-selective radial
comparable to that of
80.
a. IEEE Std SO.
radial system;
system; however,
however, the initial investment in
in a primary141 (Red Book).
selective radial
radialsystem is higher.
b. IEEE 141
Book).
c. IEEE Std 242 (Buff Book).
4.5.3Secondary-Selective
Radial
System
Secondary-Selective
Radial
System
d. IEEE Std 399 (Brown
(Brown Book).
Book).
e.
IEEE
Std
493
(Gold
Book).
The secondary-selective
radialsystem,
system,
shown
in Figure 12,
secondary-selective radial
shown
provides service
regulation. A feeder
f. IEEE Std 519.
service continuity and voltage regulation.
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API
PRACTice
API RecoMMENDED
RECOMMENDED
PRACTICE540
540
24
24
From
Frompower
powersource
source .
I,Y
'1
I
A
¿
UL
UL
Feeders
Feeders
FeederS
Feeders
Figure
1a-Simple
Radial
System
Figure 10-Simple
Radial
System
From
Frompower
powersource
source
rvr'
I)
I) I)
~
~
~
Feeders
Feeders
~
I)
1
Feeders
Feeders
Figure
RadialSystem
System
Figure 11-Primary-Selective
11-Primary-Selective Radial
I)
~
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25
25
ELECTRICAL
INSTALLATIONS
IN
ELECTRICAL
INSTALLATIONS
PETROLEUM
IN PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
From
From power
powersource
source
I
I
I
I
Feeders
Feeders
Note:
is interlocked
Note: For
For automatic
automaticmode
modeof
of operation,
operation,tietiebreaker
breaker
is interlocked
to
transformer
breaker
is open.
to prevent
preventclosing
closingunless
unlessone
one
transformer
breaker
open.
is
Figure
12-Secondary-SelectiveRadial
RadialSystem
System
Figure 12-Secondary-Selective
From
From power
powersource
source
fYJ:' fYJ:'
fYJ:' fYJ:'
I)
I)
I
I
f"'\
I)
NC
I)
I)
t t t t
Feeders
Feeders
I
I
f"'\
I)
NC
I)
I)
t t t t
Feeders
Figure
13-Secondary-SelectiveParallel
ParallelSystem
System
Figure 13-Secondary-Selective
Feeders
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26 ,
!
API RECOMMENDED PRACTICE 540
g.
g. IEEE
IEEE Std
Std 1015
1015 (Blue
(Blue Book).
Book).
Protective Relaying
h.
h. Protective
Relaying
for Power Systems,
Systems,Volume I and Volume n,
byStanley
Stanley H. Horowitz,
American Electric
II, edited by
Horowitz,American
Electric
15
Power Service
ServiceCorporation.
Corporation.15
4.7SYSTEM
SYSTEM
PROTECTION
PROTECTION
Considerations
4.7.1Fault
Fault
Considerations
When aafacility's
system
facility'selectric
electricpower
power
system
has to be
be designed
designed
and the appropriate
appropriate equipment needs
needs to be selected,
selected, the folfollowing fault
should
be considered:
faultconsiderations
considerations
should
be considered:
a. Possible
Possible or likely places
places where
wherefaults
faultsmay
mayoccur.
occur.
b. Amount of fault
fault current that
that the
thesystem
systemcan deliver.
c.
c. Possible
Possible damage
damagethat
thatmay result from
from faults.
faults.
4.7.1.1Location
Location of Faults
Faults
Although faults
in in
an an
electrical
system,
faultscan
canoccur
occuranyplace
anyplace
electrical
system,
the probability
variesatat
different locations.
probability of occun'ence
occurrencevaries
different
locations.
Switchgear,
Switchgear, transformers,
transformers,and buses have
have relatively
relativelyfew
fewshort
short
circuits;
machines, when maintained and procircuits; and rotating
rotating machines,
tected against
surges, are
arenot
notprone
prone to failure.
against voltage surges,
failure. Bare
overhead distribution
distribution systems,
systems,however,
however,experience
experiencethethehighhighest incidence
incidence of faults.
faults.
4.7.1.2Fault-Current
Fault-Current
Magnitudes
Magnitudes
Devices used for fault-current
fault-current interruption
interruption must have
interrupting and momentary
momentary withstand
withstandratings that can adeinterrupting
quately handle the available
available fault currents.
currents. Inadequate
Inadequate ratfailure of the equipment to perform its
ings can result in failure
intended function.
function. Such
Suchaafailure
failure can destroy
destroy the equipment
and can result in potential danger to personnel and to other
equipment.
equipment.
Interrupting-device
on the maxiInterrupting-device ratings
ratings should
should be
be based on
mum fault
fault current
current of the system
system at the point of application.
application.
The magnitude
magnitude of fault current
current which
whichthe
thesystem can deliver
depends
depends on the
thesources
sources of current
current and the impedance
impedancebetween
sources and the fault.
fault. The sources
sources of
of current
current include
include inthe sources
plantgenerators
generators
and motors
and connections to external
andmotors
andconnections
external
power sources
sources such as electric
electric utilities.
fault-current
utilities. The fault-current
capabilities
capabilities of simple
simple systems
systems may
maybe hand-calculated;
hand-calculated; those
complex systems
systems will
will require
require study
study using
using computer
computer
of more complex
programs
available. When
Whenselecting
selecting equipprograms that are readily
readily available.
ment,
ment, future
future expansion
expansionof the electrical
electrical system must be considered totoensure
ensure
ratings are adequate
adequate for the future
future
thatthat
ratings
at the time of the
current duty. Driving
Driving point
pointvoltage
voltage(voltage
(voltage
fault)
fault) must be
bedetermined.
determined.It is not uncommon
uncommonto see systems
systems
operating
1 .O5 to 1.10
l.10per unit voltage.
voltage.
operating atat1.05
15
Available from
lSAvailable
from IEEE,
EEE.
4.7.1.3Damage
Damage
From
Faults
From
Faults
Faults
Faults which are not promptly
promptly isolated
isolated from the source
source of
power can be very damaging:
damaging: electrical
electrical and other apparatus
apparatus
can be damaged,
damaged, fires
firescan be started,
started, and lives
livescan
canbebeendanendanLengthy production
production interruptions
interruptions are a likely
likely result of
gered. Lengthy
this
this kind of damage.
damage.
Clearing
Considerations
4.7.2Fault
Fault
Clearing
Considerations
Procedure
4.7.2.1
Procedure
remove a fault
fault from the electrical system,
system, it
To properly remove
bya a fault
must initially
initially be detected by
fault sensing device.
device. The
fault
fault sensing
sensing device then sends
sends a signal
signal to one or more fault
devices which will
operate to isolate the faulted
faulted
clearing devices
will operate
segment
segment of the system.
system. This process
process takes place automatiautomatically and quickly in order to minimize the damage
damage caused
by the fault.
fault. The fault clearing
clearing devices
devices must have adequate
adequate
interrupting
interrupting and momentary
momentary withstand
withstand ratings as discussed
discussed
in 4.7.1.2:
4.7.1.2.
4.7.2.2Dual-Purpose
Dual-Purpose
Devices
Devices
Some electrical
both the sensing
the
electrical devices provide both
sensing and the
interrupting
the the
interinterrupting functions
functions in the same
sameenclosure
enclosurewithout
without
interdevices. Examples
action of peripheral devices.
Examples of these devices
devices are as
follows:
follows:
..
a.
a. Fuses of all
all voltage
voltageratings.
ratings.
b. Molded-case circuit breakers and insulated~case
insulated-case circuit
breakers.
breakers.
These devices
devices have internal
internal sensors
sensors(thermal,
(thermal,magnetic,
magnetic,or
static)
of fault
through the
static) that detect the flow
flow of
fault currents
currents and,
and, through
the
direct molecular
mechanical action
actionof these
these sensors,
sensors, operopermolecularor mechanical
fault.
ate to clear the fault.
4.7.2.3Single-Purpose
Single-Purpose
Devices
Devices
Many electrical
electrical fault
faultclearing
clearingdevices
devicesreceive
receivean electrical
electrical
signal
signal to operate
operate from
from aa relay
relayor set of relays.
relays. These
Thesedevices
devices
take the relay signal,
process
that
signal,
and
then
operate
signal,
signal,
operate a
interrupt
the flow
electric
curset of mechanical contacts
contactsto to
interrupt
the of
flow
of electric
current running
running through
through them.
them. Examples
Examples of these fault
fault clearing·
clearingdevices are as
as follows:
follows:
devices
a. Circuit breakers of all types
typesother than the types discussed
discussed
in 4.7.2.2.
4.7.2.2. These include
include sulfur
(SFg), oil,
oil, air,
air,
in
sulfur hexafluoride
hexafluoride (SF6),
and vacuum circuit breakers in
in aavariety
variety of configurations.
configurations.
Often,
breakers are mountedinin
a lineup of
often, these circuit breakers
alineup
switchgear,
discussed
in 4.10.
switchgear, ananarrangement
arrangement
discussed
in 4.10.
b. Circuit switchers
high-voltage
switchers which
whichare usually
usually found
found on high-voltage
circuits
circuits for transformer
transformerand feeder
feeder protection.
protection.
Since relays
are a key element in the proper operation
operation of
relays are
these
protectivedevices,
devices,
some of the important
theseprotective
some
important considerconsiderations
addressed
in 4.7.3.
4.7.3.
ations regarding
regardingrelays'are
relays-are
addressed
in
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ELECTRICAL INSTALLATIONS IN PETROLEUM PROCESSING PLANTS
4,7.2.4
Coordination of Devices
4.7.2.4Coordination
Devices
27
4.7.3.3Relay
Relay
Selectivity
Selectivity
Generally,
zoneofofprotection
protection is established
around each
Generally, a zone
established around
operating
Many relays have settings which allow
allow their operating
system
bus, transmission
characteristics
system element,
element,such
suchas a bus,
transmission line,
line, generator,
generator,or
characteristics to be changed.
changed. Relays can be made,
made, for
transformer,
anda fault
a fault
should be cleared
cleared by the
thefault
fault
transformer, and
in a zone should
example,
example, to operate
operate at different
different times when installed to
clearing devices
patticular
zone.
For the
devicesaround
aroundthat
that
particular
zone.
Forfault
the cleat-fault clear-look at the same
same set of abnormal
abnormal system conditions.
conditions. Used
ing devices
devices to
toproperly
properlyisolate
isolatea faulted
a faulted
section
a system,
section
of aofsystem,
in conjunction
conjunction with fault clearing devices,
devices, they can be used
used
device
mustmust to establish the coordination
they must be properly
properlycoordinated.
coordinated.A Acoordinated
coordinated
device
coordination of the fault clearing devices
devices
protect the equipment in
in a zone
4.7.2.4. Desired protection canonly
zone and should be selective with
discussed in 4.7.2.4.
only be
This means that
ensured
thatthe
theprotecprotecupstream and
anddownstream
downstreamdevices.
devices.
ensured by choosing relays of the proper types and operative device closest to a faulted
faulted section
section should
should open
open and
andinterintertion ranges and by determining
determining the correct relay settings.
settings.
ruptthe
the flow
Careful
currentbefore
before
other
devices onthe
the
flowofof faultcurrent
other
devices
Careful studies must be made of each switching
switching configuraelectrical
This does not
other
devices
notmean
meanthatthat
other
devices tion for various plant operating
electrical system
systemoperate.
operate.
operating load conditions
conditions to arrive
arrive at
will
notsee
seethe
thefault
fault
current
flowing,
thatthey
they
will not
current
flowing,
butbut it means that
settings that will permit maximum load to be
the proper settings
should not
protecting for mininot have
havehad
hadtime
timeto take any
any action
actiontoward
towardopening
openingto to placed on line and carried while still protecting
cleat·
at·ound
a a mum fault levels.
clear the fault.
fault. If
If a malfunction
malfunctionofofthe
thedevices
devicesoccurs
occurs
around
levels.
particular zone,
zone,fault
fault
clearing
devices
next
zone upstream
patticular
clearing
devices
in the in
nextthe
zone
upstream
should operate
clear
a fault.
Obviously,
the upstream
devices devices
4.7.3.4 Relay
RelayTesting
and
Inspection
operatetoto
clear
a fault.
Obviously,
the upstream
Testing and
Inspection
should delay
clearing
devices
delay long
longenough
enoughtotogive
givethetheprimary
primary
clearing
devices
Testing and inspection of protective relays for proper setTesting
achance
chance
to operate; however, theupstream
upstream
fault
clearing
tooperate;
fault
clearing
tings
tings and operation
operation should
shouldbe
beconducted
conductedwhen the
the relays
relays are
are
devices
tootoo
longlong
or the fault
be be
devices should
shouldnot
notdelay
delay
faultdamage
damagecould
could
placed in service;
service; testing
testing and
and inspection
inspection should
should then
thenbe
beconconmore extensive.
extensive.
ducted
intervalsthroughout
throughout
ducted at established.
established,intervals
thethe life ofthe
the
Selectivity
Selectivity between
between fault
faultclearing
clearingdevices
devicesininseries
seriesshould
should
relays.
possible, testing
as possible,
testingshould
shouldbe done
done by simurelays. As
Asmuch
muchas
maintained. The procedures
procedures for detennining
be maintained.
determining coordination
coordination
lating
appropriate current
voltages on the primaries
primaries or
lating appropriate
current and voltages
margins (time
are outlined in
in
(timeinterval
intervalbetween
betweendevice
device curves)
curves) are
secondaries
the
instrument
transformers
secondaries ofthe
instrument
transformers
that that serve
serve the
many publications
publications devoted
devoted toto the subject.
Includedamong
among
subject. Included
relays.
Many static
staticrelays
relays have self-test
self-test programs
programs to alarm ifif
relays. Many
these are the following:
following:
the relay
malfunctioning.
relayis malfunctioning.
a.
141.
a. IEEE
WEE Std 141.
b. IEEE Std 242.
4.8 FUSES
242.
FUSES
c. IEEE Std 399.
399.
Uses Uses
4.8.1
d.
Relaying. 15
d. Applied Protective Re1~ying.I~
Fuses
Fuses are used
used on
on facility
facility power
powersystems
systemstotoprotect
protectequipequipFault clearing
facility
clearing device
device coordination
coordination is vital to afacility
conditions and to interrupt
ment and
andcables
cablesfrom
fromoverload
overload conditions
system. Particular
Particular attention
attention must
must be
bepaid to obtaining
obtaining
power system.
fault currents
currents when they
they occur.
occur. When
Whenapplying
applyingfuses,
fuses,singlesinglefault
optimum settings
settings and to recalculating
recalculating and maintaining
maintaining setpossibilitiesshould
shouldbebe
considered.
Since fuses
phasing possibilities
considered.
Since
fuses are
tings
tings as system
system conditions
conditions change.
change.
single-phase
devices, only
only one fuse
blowonona a singlesingle-phase devices,
fuse may blow
shgleon a polyphase
phase fault,
fault, leaving
leaving single-phase
single-phasepotential
potential
polyphasecircir4.7.3Relaying
Relaying
Considerations
Considerations
cuit. Also to be considered
after repeated operation
consideredis isthatthat
operationat a
fuse may become
current near the fuse’s
fuse's melting point,
point, the fuse
4.7.3.1Relay
Relay
Dependability
Dependability
damaged and
andoperate
operate
quicker than desired.
desired.
damaged
quicker
A relay detects
detects abnormal
abnormal system
system conditions
conditions and often iniinitiates breaker operation.
operation. Although a breaker may be proppropAvailability
4.8.2
Availability
erly selected and applied,
applied, it is useless if it fails
fails to operate
operate at
Fuses
at least
the proper time and aa nuisance
Fuses may be obtained in every
every voltage
voltagelevel
levelupupto to
nuisance if it operates
operates when it should
138,000
V. There are varieties
varieties which
which are
are current
current limiting
limiting so
138,000V.
setting or application
application of the relay.
relay.
not because of improper setting
that the energy allowed
allowedto flow
flow during
during aafault
fault condition
condition is limavailable on
on the
the supply
supplyside
side of the
lower level
levelthan available
ited to a lower
Selection
4.7.3.2Relay
Relay
Selection
fuse,
fuse, and there are
are many
many fuses
fuses designed for special
special applicaapplicaElectromechanical
Electromechanical and
and static
staticrelays
relays must be selected
selected with
with
tions such
suchas for use in motor starter
startercircuits.
circuits.
care
types are available
everysystem
system
care becausetypes
available for almost
almostevery
requirement.
is is
requirement. The proper selection
selection and application
application ofofrelays
relays
4.8.3Coordination
Coordination
Considerations
Considerations
electrical system
system and requires
thorough
importanttoto the electrical
requires thorough
fuses available
available allows
The variety ofof fuses
allowssome
someflexibility
flexibilityin in
study. Relays
Relaysassociated
associatedwith
withfacility
facility
power
systems
study.
power
systems
are are
usedused
protective device
device coordination.
coordination.Each fuse
fuse has a time-current
time-current
protection of feeders,
protective
and
primarily for the protection
feeders, transformers,
transformers,and
characteristic envelope
envelopecurve whichis
which ,is used to develop
develop coorcmrcharacteristic
rotating machines.
machines.
Copyrighted material licensed to IDOM.
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PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
540
28
2t and let-through
dination
dination plots
plots for
for the
the power
power system.
system.112t
let-through curcurrents
fuses.
rents must be considered
considered when
whencoordinating
coordinating
fuses.
4.10
SWITCHGEAR
SWITCHGEAR
4.9CIRCUIT
CIRCUIT BREAKERS
BREAKERS
Circuit
used on both AC and DC systems,
systems, are
are
Circuit breakers,
breakers, used
widely
widely used
usedin facility
facility power systems.
systems. Found
Found at almost every
.every
voltage level
levelon
onthe
thesystem,
system,circuit
circuit
breakers
protect
electrical
breakers
protect
electrical
systemcomponents
from overloads
overloadsand
andand isolate
isolate
system
components from
andfaults
faults
parts of the system
systemwhen these conditions
conditions occur.
occur.Many circuit
breakerapplications
applications
involve
switchgear,
and switchgear
involve
switchgear,
andswitchgear
applications
in 4.10.
applications are
arediscussed
discussed
The term switchgear
switchingand
and interrupting
switchgear covers
coversswitching
interrupting
devices and their combination with
metering, prodevices
with control,
control, metering,
tection, and regulating
tection,
regulating devices
devices and also
also covers
coversthe
theassembly
assembly
associated interconnections,
interconnections, accessoaccessoof these devices
devices with
with associated
ries, enclosures,
and supporting
enclosures,and
supporting structures.
structures. Switchgear
Switchgear is
used primarily in connection
connection with the generation,
generation, transmistransmission,
sion, distribution,
distribution, and
andconversion
conversionof electric
electric power. ApplicaApplications include
controlling
circuits
serving
generators,
include controlling circuits serving generators, large
large
motors,
transformers, power circuit feeders,
motors, transformers,
feeders, and other large
electrical
electrical equipment.
equipment.
4.9.2
Types
Types
4.10.2
Medium-Voltage
Switchgear
4.10.2Medium-Voltage
Switchgear
Circuit breakers
breakersused
usedonon
electrical
systems
with nominal
electrical
systems
with nominal
system voltages
voltagesless
lessthan
thanor equal to
to 600 V come
come in a variety
variety
system
of styles.
styles. Some, like
the
molded-case
circuit
breakers,
like the molded-case circuit breakers, do not
dependon
onexternal
external
relays for sensing
overloadsand
and
faults
relays
sensingoverloads
faults
while
others, like
like the
theair-break
air-break power circuit
have
while others,
circuit breakers, have
,external
sensors and
and static
staticrelay
relaymodules
modulesfor
forsensing
sensing
.external current sensors
abnormal conditions.
conditions.These
These
devices
are installed
in a variety
of
abnormal
devices
are installed
in a variety
equipment,
switchboards,
and and
switchgear.
equipment, such
suchasaspanelboards,
panelboards,
switchboards,
switchgear.
Circuit
breakers used on systems
withnominal
nominal
system
Circuitbreakers
systemswith
system
V-15,000 V are generally
voltages of
voltages
of600 V-15,000
generally installed
installedininswitchswitchlineups. These
Thesebreakers
breakersuse
userelays
relays
sensing fault
fault concongear lineups.
for sensing
ditions.
ditions. The interrupting
interrupting medium
medium isis generally
generally air or vacuum
vacuum
in this voltage
voltageclass.
class.
Circuitbreakers
breakers used on systems
withnominal
nominal
system
systemswith
system
voltages of
15,000 V-35,000
switchof 15,000
V-35,000 V may be installed in switchgear.
gear. Most
Mostbreakers
breakersforforhigher voltage systems
systems are individual
individual
free-standing outdoor
outdoortypes,
types,and
and
these
higher voltage devices
devices
free-standing
these
interruptingmedium. Relays are used for
use oil or SF6 as the interrupting
sensing
sensing fault
fault conditions
conditions at all these
these installations.
installations.
In general,
medium-voltage switchgear
general, the
the 5-kV
5-kv to 15-kV
15-kv medum-voltage
switchgear
used in facilities
facilities is the metal-clad type with drawout circuit
breakers and all
contained
within
allpertinent
pertinentauxiliaries
auxiliaries
contained
within their
own individual
above
the the
15-kV
class
individualenclosures.
enclosures.Switchgear
Switchgear
above
15-kV
class
may be
or stationary
type.type.
OtherOther
equipment
bethe
themetal-clad
metal-clad
or stationary
equipment
installed in the switchgear
switchgear is necessary buses, disconnecting
devices,
current
and voltage
transformers,
control power
devices,current
andvoltage
transformers,
controlpower
transformers,
transformers, interlocks,
interIocks, meters,
meters, relays,
relays, and control devices.
The switchgear
5-kv to 38-kV
38-kv class
class with
switchgear is generally
generally in
in the 5-kV
current ratings
classifiratingsupupto 3,000 amperes,
amperes,and
andinterrupting
interrupting
classifications
ranging from 250 MVA to 1,500
MVA.
1,500 MVA.
cations ranging
4.9.1
4.9.1
UsesUses
4.9.3
Location
Location
Circuit breakers
breakers are
are not
not listed by NRTL for direct use in
classified locations.
locations. They
Theyare,
are,therefore,
therefore,installed
installed in nonclassified locations,
locations,either
eitherindoors
indoors or outdoors,
outdoors, or when installed
installed
sified
in a classified
classified location,
location, they
they must be installed
installed in approved
approved
enclosures
enclosures suitable
suitable for the location.
location.
4.9.4 Inspection
Inspection and Testing
Because many
many types
typesof
ofcircuit breakers are available,
available, it is
Because
not possible
possible to discuss
discuss in
in this recommended
recommended practice
practiceinspecinspection and
and testing
testingprocedures
proceduresfor all circuit
circuit breakers.
breakers.AAregular
regular
preventive
estabfished. The
preventive maintenance
maintenance program
program should
should be established.
manufacturer's installation
installationand operating
operating instruction
instructionbooks or
manufacturer's
a reliable
reliableelectrical
electricaltesting
testingfirm
firm should
should be consulted
consulted,to estabestablish maintenance
requirements
and intervals.
maintenance and
andtesting
testing
requirements
intervals.
4.10.1
General
4.10.1General
Switchgear
4.10.3Low-Voltage
Low-Voltage
Switchgear
Switchgear
Switchgear rated at 600 V is available
available for
forsmall
smallloads
loads that
cannot be
be served
served economically
economically at 5 kV
k v and above.
above. The preferred
air-break
or vacferred construction
constructionisismetal-enclosed,
metal-enclosed,using
using
air-break
uum,
low-voltage
power
circuit
breakers.
uum,drawout-type
drawout-type
low-voltage
power
circuit breakers.
Continuous
6,000 amps,
amps, and
Continuous current
current ratings
ratings are available
available to 6,000
interrupting
range from
interrupting current
current ratingsrange
from 30,000 amps
amps to
200,000
200,000 amps.
amps.Integral
Integral current limiting
limitingfuse
fuse devices
devices are used
to achieve
duties.
achievehigher
higherinterrupting
interrupting
duties.
4.10.4
Medium
4.10.4 Interrupting
InterruptingMedium
several options
options to consider when selecting
selecting the
There are several
interrupting
switchgear.AirAirinterrupting medium for medium-voltage
medium-voltageswitchgear.
break and oil-immersed
oil-immersed circuit breakers
being
breakers are rapidly being
phased out by vacuum and
breakers. An assessand SF6
SF6 circuit
circuit breakers.
ment of the circuit breaker installed
installed cost,
cost, operating
operating characcharacteristics,
teristics, and maintenance
maintenance requirements
requirements is required and
andmust
must
be evaluated
evaluated to determine
determine whichtype
typeshould
should be applied.
Low-voltage
commonly either air-break
Low-voltage switchgear
switchgear is most commonly
or vacuum-break.
Where an interrupting
interrupting medium is considered for an appliapplication
cation for the first
first time,
time, interrupting
interrupting characteristics
characteristics should
rated..conditions.
conditions. Maintenance
reviewed at rated
Maintenance procedure
procedure
be reviewed
details
understood prior to the selection.
details should be fully
fully understood
selection.
~~
STD.API/PETRO RP
Copyrighted material licensed to IDOM.
540-ENGL.1999
0732290
No further reproductionE
or distribution
permitted.Ob155b7
ZOO
EI.
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ELECTRICAL
INSTALLATIONS
IN
PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
IN PETROLEUM
PETROLEUM
PROCESSING
PLANTS
4.10.5
Location
Location
29
29
Manufacturers
listlist
switchgear
as
Manufacturersdodonotnot
switchgear
as suitable
suitablefor
for use
use in a
classified
process
In practice,
practice, switchgear
switchgearthat
thatserves
serves
process
classified location.
location.In
units
units must
mustbebeeither
eitherlocated
located adjacent
adjacent to the
the classified
classifiedlocation
location
or installed
room.
installed inina pressurized
a pressurized
room.
Processing
takes
the
Processing plant
plantswitchgear
switchgearfrequently
frequently
takes
the form
form of a
of a transformer
(singleunit
substation,
which
consists
unitsubstation,
which
consists
ofatransformer
(singleutilization
ended)
ended) or transformers
transformers (double-ended)
(double-ended)that
thatsupply
supply
utilization
voltage
voltage to a group
groupofoffeeder
feeder circuit breakers.
breakers.Unit
Unitsubstations
substations
may be purchased
units well
welladapted
adaptedforfor
purchased as
as neat,
neat, compact
compact units
either
switcheither indoor
indoor or outdoor
outdoor plant
plantuse.
use.Transformers
Transformersand
and
switchgear may
maybebepurchased
purchased
separately and installed
indoors or
separately
installed indoors
outdoors
outdoors as
as desired.
desired.
with
between inspections
with the
the time interval
intervalbetween
inspections varying
varying with
environment
and
service.
The
range
of
intervals
environment
service. The range intervals is
is usually
usually 11
to
years, with experience
experience with the particular
particular installations
installations
to 5 years,
dictating
maintedictating any
any changes
changes to
to the
the schedule.
schedule. Preventive
Preventive maintenance
nance should
should include
include all
all tasks necessary
necessary to
to assure
assure the
the relireliable
able operation
operation of the
the switchgear
switchgear during
during the
the maintenance
maintenance
interval.
interval. This
This maintenance
maintenance should
should include
include inspecting
inspecting the
the
overload
overload unit settings
settings and
and other
other breaker
breaker parts,
parts, such
such as
as concontacts and
andarc
arc chutes
chutes for
for air circuit
circuit breakers;
breakers; or vacuum
vacuum interintertacts
rupter,
rupter, vacuum
vacuum integrity,
integrity, and contact
contact erosion
erosion indicators
indicators on
on
vacuum
vacuum circuit
circuit breakers.
breakers. Maintenance
Maintenance also
also includes
includes checkchecking
ing the
the trip devices
devices by a test set
set available
available from
from the equipequipment manufacturer.
manufacturer.
4.10.6
Installation
Types
4.10.6Installation
Types
4.11
TRANSFORMERS
4.1 1TRANSFORMERS
4.10.6.1
Indoor
Switchgear
4.10.6.1Indoor
Switchgear
4.11.1
4.11.1
General
General
Indoor
(NEMA1 1 or NEMA
Indoor switchgear
switchgear(NEMA
NEMA 12
12 enclosure)
enclosure) is
is
This information
informationisisconfined
primarily
todistribution
and and
This
confined
primarily
to distribution
not
expensive as
(NEMA 3R
whichare
are
power
transformers. Other
notasasexpensive
as outdoor
outdoor switchgear
switchgear(NEMA
3R or
Or 4X
4x
powertransformers.
Other types
types of transformers
transformerswhich
enclosure);
enclosure);however,
however, the former
former requires
requires indoor space
space which
which applied
withinwithin
the petroleum
industry
are mentioned
briefly, briefly,
applied
the petroleum
industry
are mentioned
affects
affects the
the overall
overall cost.
cost. The
The cost
cost of providing
providing the
the indoor
indoor
but these
these other
other types
typesusually
operate
as part of
ofanan
electrical
but
usually
operate as
electrical
location
by
the maintenance
reduced maintenance and
location may
be be offset
offset
by
the
reduced
equipmentpackage.
equipment package.
equipment
costsand
and
the increased
reliability
resulting
equipmentcosts
byby
theincreased
reliability
resulting
from
a more
benign equipment
environment.
fromamore
benignequipment
environment.
Acommon A common
4-11.2 Transformer
Transformer Types
Types
4.11.2
location
motor
location is often
often used to
to house
house both switchgear
switchgear and motor
control
1.2.1
4.1
Distribution
and
Transformers
PowerTransformers
equipment.
control equipment.
4;11.2.1
Distribution
and Power
Distribution
transformers
are
Distribution and
andpower
power
transformers
are used to
to isolate
isolate difdifferent
voltage
systems
from
each
other
and
to
reduce
ferentvoltagesystems from eachotherand
reduce or
Outdoor
switchgear
is switchgear
basically indoor switchgear
Outdoor
switchgear
basically
is
indoor
increase
levels. These
These
increase voltages to
to their
their optimum
optimum utilization levels.
mounted in
The
ina aweatherproof
weatherproofenclosure.
enclosure.
The following
following types
typesof
of unit
substations and
transformers
integralparts
partsof unit
transformers may be integral
substations
enclosures
enclosures are
areavailable:
available:
motor
motor control
control centers,
centers, or they
they may be located
located at a remote
remote site.
site.
Unit
substation
transformers
are
mechanically
and
electriUnit
substation
transformers
are
mechanically
and
electrian
aisle.
a.
Enclosure
",ithout
a. Enclosure withoutan aisle.
cally
or motor
control
cally connected
connectedto
to unit
unit substation
substationequipment
equipment
motor
or
control
b.
b. Enclosure
Enclosure with an
an aisle
aisle in front
front of
ofthe
the switchgear.
switchgear.
centers.
Aside
from
the
physical
size
and
certain
features
centers. Aside from the physical size and certain features of
c.
aisle between
betweentwo
twoswitchgear
switchgear
c. Enclosure
Enclosure with aa common aisle
construction,
applied in
inthe
the
lineups.
construction, unit substation transformers are applied
lineups.
same
same manner
manner and
and for
for the
the same
same purposes
purposes as
as distribution
distribution and
and
An
An aisle
aisle facilitates
facilitates the
the maintenance
maintenance and
and operation of the
the
power
power transformers.
transformers.
switchgear.
switchgear.
Power
used
to
Power transformers
transformersare
arefrequently
frequently
used
to step-down
step-down plant
plant
distribution
voltage
to
motor
utilization
levels
(e.g.,
13.8
kV
13.8
kv
distribution
voltage
to
motor
utilization
levels
(e.g.,
4.10.6.3 Electrical
Centers
ElectricalPower
PowerCenters
to
4,160
V
or
6,600
V).
Often,
a
captive
transformer
is
used
to
to 4,160 V 6,600
Often, a captive transformer
is
The
The use of
of prefabricated
prefabricated electrical
electricalpower
powercenters
centers is
is approapprosupply
supply a single
single large
large motor,
motor, usually
usuallygreater
greaterthan
thanor equal
equal to
to
priate
the site
site is
is to
to be
priate for
for some
some applications
applications where
where work
work at the
2,500
2,500 HP.
HP.The
The added
added impedance
impedanceof the
the captive
captive transformer
transformerin
minimized.
minimized. These
These prefabricated
prefabricated electrical
electrical power
power centers
centers are·
are
the
the motor supply circuit lowers voltage and starting
starting in-rush
in-rush
modular
with
lighting,
heating.
and ventimodular structures
structuresequipped
equipped
with
lighting,
heating,
and venti-current.
current. The
The captive
captive transformer
transformer should
should be designed
designed for
for the
the
lating
lating equipment.
equipment.Requiring
Requiringonly assembly
assembly and
andinternal
internalconconrequired
required motor
motor starting
starting and
and operating
operating duty.
duty.The
The captive
captive transtransnections
nections on site,
site, they
theycan
canbe shipped
shipped as
as a unit
unit or in modular
modular
former-motor
former-motor combination
combination may be
be selected
selected over the
the directdirectsections
withswitchgear,
switchgear,motor
motor
control
centers, and other
sections with
control
centers,
other
connected
motorfor
forreason
reason of design,
stability,oror
connected motor
design, system
system stability,
equipment
equipment already
alreadyinstalled.
installed.
motor
motor economics.
economics.
Step-up
Step-up power
powertransformer
transformeror transformer/rectifier
transformedrectifier sets
sets are
are
4.10.7Preventive
Preventive
Maintenance
Maintenance
often
processes
where
the the
often used
usedfor
for desalting
desalting and
andprecipitation
precipitation
processes
where
plant voltage must be
be increased
increased to
Preventive
to the
the level
level required
required at
at the
the
Preventive maintenance,
maintenance, including
including inspection
inspection and
and testing
testing
of switchgear,
desalter
switchgear, should
should be carried
carried out on aa regular
regular schedule,
schedule,
desalter or precipitator
precipitator electrodes.
electrodes.
4.10.6.2Outdoor
Outdoor
Switchgear
Switchgear
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30
30
. API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
4.11.2.2
Instrument
Transformers
4.1 1.2.2 Instrument
Transformers
Instrument
Instrumenttransformers
transformersare
are used
used for
for metering
metering and
and relayrelaying,
of
ing,have
havea ahigh
highdegree
degree
ofaccuracy,
accuracy,and
andhave
havelimited
limitedcapaccapacity.
depends
on the
ity. The
The accuracy
accuracy .of
of transformation
transformation
depends
on
the
application
metering and
different
application because
because meteling
and relaying
relaying require
require different
accuracies.
is als.o
to the
accuracies. The
The degree
degree of
of accuracy
accuracyis
also subject
subjectto
the
and
effects
effects.ofofload
load
andfault
faultcurrent.
current.
Voltage
are employed
employed toto step
Voltagetransf.ormers
transformers are
step down
down primary
primary
voltage
voltage t.o
to aa secondary
secondary voltage.
voltage, normaIly
normally 120
120V,
V, atat the
the rated
rated
pl1mary
primary voltage.
voltage.Current
Currenttransf.ormers
transformersare
areemployed
employedtototranstransfon11
t.o atosecondary
current,
normally
55amps,
amps,
formprimary
primarycurrent
current
a secondary
current,
normally
atat the
rated primary
primarycurrent.
current.For
Forsome
some
applicati.ons,
current
the rated
applications,
current
transformers
primary
transformerswith
withmultiratio
multiratio
p'imary taps
taps are
areused.
used.
4.11.2.3
Autotransformers
4.11.2.3Autotransformers
The
single-windingtransformer
transformer in
The autotransfon11er
autotransformer isis aasingle-winding
in
which
the
lower
v.oltage
is
obtained
by
a
tap
positi.on
which the lower voltage is obtained
by a tap positionbetween
between
the
Unlike
a two-winding
distribution or
the line
line terminals.
terminals.Unlike
atwo-winding
distribution
or
P.ower
transf.ormer,asingle-winding
a single-winding
transformer
powertransformer,
transformer
doesd.oes n.ot
not
isolate
windings.
isolatethe
thehigh-voltage
high-voltageand
andlow-v.oltage
low-voltage
windings.
Autotransformers
are
frequently
used
to
Autotransformers are frequently used to provide
provide an
an ec.oeconomical
tie
between
two
systems
of
different
voltage
nomical tie between two systems of different voltagelevels
levels
(e.g.,
(e.g., aa4,160-V
4,160-Vto
toaa2400-V
2400-Vsystem
systemand
andaa138-kV
138-kvtotoaa69-kV
69-kv
system).
They
are
also
used
for
motor
control
in some
sometypes
types
system). They are also used for motor controlin
of
packages.
ofreduced
reduced voltage
voltagestarter
starter
packages.
4.11.2.4
Other
Transformers
4.1 1.2.4 Other
Transformers
Other
Other specialty
specialtytransformers
transformersare
are zigzag
zigzag grounding,
grounding,conconstant
voltage,
and
low-noise
isolation
transformers.
Zigzag
stant voltage, and low-noise isolation transformers. Zigzag
grounding
groundingtransformers
transformersare
areused
used to
to derive
deriveaa neutral
neutralfor
forsyssystem
grounding
purposes
and
can
be
used
to
provide
tem grounding purposesandcanbe
used to provideaa
ground
groundconnection
connectionfor
fordelta-connected
delta-connectedtransformer
transformersecondsecondaries.
They
permit
ground-fault
relaying
aries. They permit ground-fault relayingand
andeliminate
eliminatehigh
high
transient
transient voltages
voltages that
that can
can.occur
,occuron
on ungrounded
ungrounded systems.
systems.
Constant-voltage
Constant-voltagetransformers
transformersprovide
provideaa stable
stable power
power supsupply
for
instrumentation
and
other
loads
requiring
ply for instrumentation and other loads requiringaaconstant
constant
voltage.
areused
usedtotosupply
supply
voltage.Low-noise
Low-noiseisolation
isolationtransformers
transformersare
power
to
digital-based
systems,
such
as
computers,
power to digital-based systems, such as computers,that
that are
are
highly
highly susceptible
susceptible to
to voltage
voltage transients.
transients. Transformers
Transformersare
are
frequently
frequently applied
applied to
to provide
provide isolation
isolation for
for the
the input
input to
to
adjustable
adjustablespeed
speeddrives.
drives.AAthree-winding
three-windingtransformer
transformer(a(asinsingle
)
gleprimary
primary with
with aa wyewye- and aa delta-connected
delta-connectedsecondary
secondary)
can
canbe
be used
usedto
toreduce
reducepower
powersystem
systemharmonics
harmonicsthrough
throughharharmonic
moniccurrent
currentcancellation.
cancellation.
4.11.3
Ratings
4.1 1.3Ratings
4.11.3.1
Voltage
and
Frequency
4.11.3.1Voltage
and
Frequency
The
isisdetermined
Thevoltage
voltagerating
ratingfor
fortransformers
transformers
determinedprimarily
primarily
by
the
system
voltage
available
and
the
utilization voltage
voltage
by the system voltage available and the utilization
required,
For60-Hz
60- Hz
electric
power systems,
required.For
electric
power
systems, itit isis recomrecom-
mended
rating
conform
to one
mendedthat
thatthe
thevoltage
voltage
rating
conform
one
to of
of the
thevoltage
voltage
ratings
ratingsgiven
givenininANSI
ANSIC84,1.
(34.1.
voltageratings
ratings
Consideration
in the
Considerationin
the selection
selection of
of these
thesevoltage
could
due
couldresult
resultininprocurement
procurementand
andmaintenance
maintenanceeconomies
economies
due
to
to the
the ability
abilitytotoparallel
paralleland
andinterchange
interchangetransformers.
transformers.AttenAttention
ratingswill
will
permit
added
flexibility in
tion to
to voltage
voltagetapratings
permit
added
flexibility
in
matching
voltages.
matchingtransformers
transformerstotosystem
system
voltages.
Due
standardizati.on
Duetotoaaworldwide
worldwidelack
lackofof
standardizationof
ofAC
ACsystem
system
frequency,
the
transformer
frequency
should
always
frequency, the transformer frequency should alwaysbebe
specified.
specified.
4.11.3.2
Capacity
and
Duty
4.1 1.3.2 Capacity
and
Duty
The
(kVA)
Therecommended
recommendedkilovolt-ampere
kilovolt-ampere
(kVA)ratings
ratingsof
oftranstransformers
ANSI
or
ratings
NEMAstandards.
standards.These
These
ratings
formersare
aregiven
givenin in
ANSI
orNEMA
should
be
on
a
continuous
basis
without
exceeding
the
temshould be on a continuous basis without exceeding the temperature
perature limitations
limitationsfor
for continuous-rated
continuous-ratedtransformers.
transformers.CapCaptive
transformer
design
should
take
into
tive
transformer
design
should take into account
account the
the
magnitude
magnitudeof
ofstarting
startingcurrent,
current,the
theduration
durationof
ofmotor
motoracceleraacceleration,
permissible
starting
frequency
of
tion,and
andthethe
permissible
starting
frequency
ofthe
themotor,
motor.
4.11.3.3
Temperature
Rise·
4.11.3.3Temperature
Rise
The
The rated
ratedkVA
kVAof
of aa transformer
transformerisis the
the load
load which
whichcan
can be
be
carried
carriedcontinuously
continuouslyatatrated
rated voltage
voltage and·
and frequency
frequencywithout
without
exceeding
temperature
transformer
exceeding the
the specified
specified
temperature
rise. rise. AA transformer
VA ififthe
should
life
shouldhave
havea anormal
normal
lifeatatits
itsrated
ratedkkVA
thespecified
specifiedtemtemperature
rise
is
not
exceeded,
the
ambient
temperature
does
perature rise is not exceeded, the ambient temperature does
not
(104"F), and the
the ambient
ambient temperature
temperature
not peak
peak above
above 40°C (104"F),
not
rise
above
30"C
(86°F)
for
a
24-hour
average.
does
does not rise above 30°C (86°F)for a 24-hour average.
Oil-filled
temperaOil-filledtransformers
transformers are
are limited
limited to·
to aa winding
winding temperaof
65°C
(117°P)
55°CI
ture
rise,
as
measured
by
resistance,
ture rise, as measured by resistance, of 65°C (1 17°F)oror
55"C/
65°C
(99°F/117°F)
and
a
hottest-spot
winding
temperature
65°C (99"F/117"F) and a hottest-spot winding temperature
rise
80°C(144°F).
(144°F).Dry-type
Dry-typetransformers
transformersare
aredivided
dividedinto
into
riseof
of 80°C
the
riserise
specifications:
thefollowing
followingtemperature
temperature
specifications:
a.a. Class
150CC has
has Class
ClassBB winding
winding insulation
insulationand
andisis limlimClass 150
ited
to
an
average
rise
of
80°C
(144°F)
with
a
hot
spot
ited to an average rise of 80°C (144°F) with a
spot of
of
110°C
110°C(198°F).
(198°F).
b.b. Class
windinginsulation
insulationand
andisislimited
limited
Class185
185CChas
hasClass
ClassFFwinding
to
an
average
rise
of
115°C
(207°F)
with
a
hot
spot
to an average rise of 115°C (207°F) with a hot spotof
of 145"C
145°C
(261°F).
(261°F).
c.c. Class
limited
Class220
220CChas
hasClass
ClassHHwinding
windinginsulation
insulationand
andis is
limited
to
an
average
rise
of
150°C
(270°F)
with
a
hotspot
of
to an average rise of 150°C(270°F) with ahot spot of 180°C
180°C
(324°F).
(324°F).
More
More detailed
detailedinformation
informationon
on temperature
temperaturerise
rise specificaspecifications
is
contained
in
IEEE
C57.91
and
IEEE
C57.96.
tions is contained in IEEE C57.91 and IEEE C57.96.
If
the
If operated
operated .outside
outside of
of these
these temperature
temperature limitations,
limitations, the
transformer
must
be
rerated
on
the
basis
of
the
actual
load
transformer must be rerated on the basis of
actual load
cycle
to
cycleand
andambient
ambienttemperature
temperature
toattain
attainitsitsnormal
normallife
lifeexpectexpectancy.
The
transf.ormermanufacturer
should
be
consulted
ancy. The transformer manufacturer shouldbe consultedfor
for
these
insulation
life
thesefigures.
figures.As
Asaarule
ruleofofthumb,
thumb,
insulation
lifeisiscut
cutininhalf
half
for
foreach
each10°C
10°Crise
risein
inoperating
operatingtemperature,
temperature.
When
load
is
applied
transformer, the
and
When load is applied to
to aa transformer,
the heating
heatingand
cooling
curves
vary
exponentially.
The
time
constant
for
the
cooling curves vary exponentially. The time constant forthe
..
~
~
Copyrighted material licensed to IDOM.
STD-APIIPETRO RP 540-ENGL
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0732270
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONS IN
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
windings
windings isis 55 toto 10
10minutes
minutesand
andfor
forthe
theoiloilisis 22 to
to 44 hours.
hours.A
A
time
equal
to
approximately
five
time
constants
is
required
time
to approximately five time constants is required
for
for the
the items
items to
to reach
reach their ultimate temperature.
temperature. Short-time
overloads
overloadsof
of 1I hour
hour or
or less
less are
arepermissible,
permissible,however,
however, as
as long
long
as
copper
temperature
does
as the
the hottest
hottestspot
spot
copper
temperature
doesnot
not exceed
exceed150°C
150°C
(302°F)
(302°F)for
for an
an oil-filled
oil-filledtransformer.
transformer.Overloads
Overloadsofofmore
morethan
than
one-hour
one-hourin
in duration
durationshould
shouldbe
be avoided.
avoided.
Transformers
toaltitudes
altitudesgreater
greater
than 1,000
Transformers operated to
than
1,000 m
m
(3,300
ft)
above
sea
level
are
subject
to
special
rating
con-ec(3,300 ft) above sea level are subject to special rating correction
may
be obtained
from from
the manufacturer.
tion factors
factorswhich
which
may
be obtained
the manufacturer.
4.11.3.4
Insulation
4.11.3.4Insulation
indicatesa a transThe
basicimpulse
impulse
Thebasic
levellevel (BIL),
@IL), which
whichindicates
transformer's
withstandtransient
transientover-voltages,
over-voltages,and
andthe
the
former’s ability
ability to withstand
manufactUl-er'stesttest
voltages
arein given in IEEE
applicable
IEEE
applicablemanufacturer’s
voltages
aregiven
C57J2.00
C57.12.00 for
for liquid-filled
liquid-filledtransformers,
transformers,and
andIEEE
IEEEC57.l2.01
C57.12.01
for
The
transformfordry-type
dry-typetransformers.
transformers.
Thedielectric
dielectricstl-ength
strengthofof
transformers
thatdepend
depend
air for insulation
ersthat
onairon
forinsulation
decreasesdecreases as
as altitude
altitude
increases.
Insulation-class
correction
factors
for
altitudes
for altitudes
increases.
Insulation-class
correction
factors
greater
than 1,000
are covered
in IEEE
1,000 m
m (3,300
(3,300 feet)
feet)are
coveredinIEEE
greaterthan
C57.12.0l.
C57.12.01.
4.11.3.5
Efficiency
Regulation
4.11.3.5Efficiency
andand
Regulation
manufacturer's
Efficiency
Efficiency and
and regulation are
are fixed
fixed by
by the manufacturer’s
design,
efficient
designs
are available
at
design,although
althoughmore
more
efficient
designs
are available
at higher
higher
cost,
cost,ifif the
theloss
lossevaluation
evaluationwarrants
warrantsthem.
them.
31
31
for a
switchgear
roomwith
with
a secondary
throat connection
switchgearroom
asecondary
throatconnection
fora
bus
way supply
wallwall
of
thethe
switchgear.
busway
supplythrough
throughthethe
ofthe
theroom
roomtoto
switchgear.
4.11.4.2
Grounding
4.11.4.2Grounding
Neutral
secondaties should
shouldbebe
Neutral grounding of
of transformer
transformer secondaries
considered.
on factors
considered.The
The type
type of
ofgrounding
groundingchosen
chosenis based
is based
on factors
such
as
voltage
levels,
ground-fault
levels,
and
continuity
such as voltage levels, ground-fault levels, and continuity of
service.
service.The
The neutral
neutral ground
ground is obtained by
by bringing
bringing out the
neutral
connection
on
a
wye-connected
secondary
or
neutral connection on a wye-connected secondary
orby
by using
using
aa zigzag
zigzagtransformer
transformeronon
a delta-connected
secondary.
adelta-connected
secondary.
The The
neutral
neutral isiseither
either solidly
solidly grounded
groundedor
or grounded
grounded through
throughl-esisresistance
tance or
or reactance.
reactance.
4.11.4.3
Parallel
Operation
4.11.4.3Parallel
Operation
Proper
Proper operation
operationof
of parallel
parallel transformers
transformersrequires
requiresthat
thatthe
the
transfOlmers
be
connected
properly
and
that
their
characteristransfo1mersbe connected properly and that their characteristics
certaintolerances-refer
tolerances-refer
tics be
be within
within certain
to to IEEE
IEEE C57.l2.OO
C57.12.00
and
and IEEE
IEEE C57.I2.01
C57.12.01 for
for acceptable
acceptable tolerances for
for parallel
parallel
operation.
operation.To
To divide
dividethe
theconnected
connectedload
loadaccording
accordingto
to the
the ratrating
following
must
be the
ing of
of the
the parallel
parallelbanks,
banks,thethe
following
must
the
be same:
same:the
the
internal
impedance, the
the transformation
transformationratio,
ratio,and
andthethe
phase
internal impedance,
phase
relationship.
delta-wye or
relationship. It
It isis not
not possible
possible to parallel delta-wye
or wyewyedelta
bank
because
of
30”phase
phase
delta banks
bankswith
witha adelta-delta
delta-delta
bank
because
of the
the 30°
shift
present
in the
shiftthat
thatis is
present
in secondary.
the secondary.
4.11.4.4
Testing
and
Maintenance
4.1 1.4.4 Testing
and
Maintenance
A
testing·and
andmaintenance
maintenance
program
should
A systematic
systematic testing
program
should
be be
established
established for
for transformers.
transformers. ItIt should include the
the inspection
inspection
and
testing
andand
gas gas
analysis
of transThe
impedance is expressed
expressed as
transand cleaning
cleaningofofbushings,
bushings,thethe
testing
analysis
of
The impedance
as aa percentage of
of the
the transformer
cleaning
of dry-type
transformers.
former
kilovolt-ampere rating
rating and is
former oil,
oil,and
andthe
thevacuum
vacuum
cleaning
of dry-type
transformers.
former base
base kilovolt-ampere
is determined
determined by
by the
the
internal
ofthe
the
transformer,
which
include its
The
each
transformer
should
be be
internal characteristics of
transformer,
which
include
its
The manufacturer's
manufacturer’stest
testreport
reportforfor
each
transformer
should
core
geometry
of windings.
The
kept
core design,
design,resistance,
resistance,and
and
geometry
of windings.
The manumanukept on
on record.
record. This
This report
report contains
contains results
results of
of dielectric
dielectric tests
tests
facturer's
with
ANSI
stanimpedance,
and
stanfacturer’sstandard
standardimpedance,
impedance,ininaccordance
accordance
with
ANSI
andmeasm-ements
measurementsof
of resistance,
resistance,excitation
excitationcurrent,
current,
impedance,
acceptable
to facilitate
parallel
operation
and
dards,
ratio,
phase
relation.
The
dards,isisnormally
normally
acceptable
to facilitate
parallel
operation
and
ratio, temperature
temperaturerise,
rise,polarity,
polarity,and
and
phase
relation.
Thedielecdielecminimize
may
be
tric
strengthofofnew
new
transformer
oil should
less than
minimizecost.
cost.In
In some
someinstances,
instances,it it
may
be desirable
desirableto
to install
install
tric strength
transformer
oil should
not benot
lessbethan
aatransformer
greater-than-standard
impedance
to
30
with
ASTM
to limit
limitthe
the
transformerwith
with
greater-than-standard
impedance
ASTM D877.
D877. Refer
Refer
30kV
k v when
when measured
measuredininaccordance
accordance
with
sholt-circuit
to
In other
other instances,
instances,
short-circuit duty
duty on
onsecondary
secondaryswitchgear.
switchgear.In
to IEEE
IEEE C57.106
C57.106 for
formineral
mineraloiloiltesting,
testing,totoIEEE
B E E C57.111
C57.111 for
for
aa transformer
transformer with lower-than-standard impedance isis used
used to
to
silicone
fluid
testing,
and
to
IEEE
C57.121
for
Less
Flammable
silicone fluid testing, and
to IEW C57.121 forLess Flammable
facilitate
by reducing
the voltage
drop. drop.
facilitatemotor
motorstarting
starting
by reducing
the voltage
Hydrocarbon
HydrocarbonFluid
Huid testing.
testing.
When
dielectrictesting
testing of
windings isis perWhen dielectric
of transformer
transformer windings
per4.11.4
Applications
4.11.4Applications
formed,
limitations set
setforth
forthininthethe
stanformed, the
the test
test parameter limitations
standards
be exceeded
(see 4.11.3.4).
dards should
shouldnotnot
be exceeded
(see1.3.4).
4.1
4.11.4.1
Location
4.11.4.1Location
Dielectric
Dielectrictesting
testingof
of bushings
bushingsisisalso
also covered
coveredby
by standards.
standards.
High-voltage
DC test
test equipment
equipmentisis available
availableto
to provide
provide nonnonHigh-voltageDC
Transformers
associatedsecondary
secondaryswitchgear
switchgearshould
should
Transformers and associated
destructive
be
centers
as
of insulation.
insulation.This
This method
method of
of
destructiveand
and accurate
accuratetesting
testingof
as near
near tototheir
theirload
load
centers
aspractical
practical while
whileminiminibe located
locatedas
testing
procedures.
mizing
testing is
is preferable
preferable to
to high-voltage
high-voltage AC
AC test
testprocedures.
fireand
and mechanical
mechanicaldamage.
damage.The
The location
location
mizing exposm-e
exposure totofire
Power
wherethe
thetranstransshould
beunclassified.
unclassified. In
Power factor
factor tests
tests are
are also
also used to
to indicate
indicate the
the condition.
condition of
of
should preferably be
In cases
cases where
transformer
a program
of power
factorfactor
test- testformer
be inin aa classified
transformerinsulation.
insulation.When
When
a program
of power
classified location,
location, all
all auxiliary.
auxiliary devices
devices
former must be
ing
include
associated
transformer
must
be
ing isisplanned,
planned,the
the transformer
transformerfactory
factorytesting
testingshould
should
include
associatedwith
withthethe
transformer
must
be suitable
suitablefor
forthe
the classiclassiaa power factor
results will
will be
fication.
so that
that the results
be available
available for
for
factor test
test so
ForClass
ClassI,I,Division
Division2,2,or
orZone
Zone22 locations,
locations,ititisissomesomefication.For
comparison
field
testing.
times
comparisonwith
withlater
later
field
testing.
to locate
locate the
thetransformer
transformeroutside
outsidea apressurized
pressurized
times practical
practicalto
4.11.3.6
Impedance
4.11.3.6Impedance
Copyrighted material licensed to IDOM.
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API RECOMMENDED
PRACTICE 540
PRACTICE
RECOMMENDED
540
32
4.11.5
Construction
and
Accessories
4.1 1.5 Construction
and
Accessories
4.11.5.1
Oil-Filled
Transformers
4.11.5.1Oil-Filled
Transformers
Transformer
Transformer oil is used to insulate
insulate and cool the windings
windings
and to protect the core and windings
windings from corrosive
corrosive and
hazardous vapors.
vapors. Transformer
Transformer oil should include a suitable
suitable
oxygen inhibitor to prevent deterioration
dielectric.
deterioration of the dielectric.
The sealed-tank
sealed-tank system is standard
standard for transformers
transformers rated
basic
impulse
level
and less,
2,500 kVA, 200-kV
200-kv
impulse leveland
less, and is
often usedonon larger sizes
sizes as well. Inert-gas-pressurized
Inert-gas-pressurized
sealed tanks are sometimes
on larger or criticalsometimes provided on
service transformers.
transformers.
Standard accessories
accessories for oil-filled transformers
transformers include a
groundpad,
pad,a a nameplate,
no-load tap changer,
changer, a ground
nameplate, a liquidlevel gauge,
gauge, an oil temperature
temperature indicator,
indicator, a drain valve,
valve, aatop
filter
valve,
a
pressure-vacuum
gauge,
and
jack
bosses.
filter valve,apressure-vacuumgauge,
bosses.
Optional features
features pertain to the type of bushings,
bushings, fan
fan controls, winding
winding temperature
temperature indication,
indication, sudden
sudden pressure
relay,
relay, terminal
terminal blocks, junction boxes, disconnect
disconnect switches,
switches,
and throat connections.
connections. Where applicable,
applicable, terminal chambers must allow
allowadequate
adequate space
space for stress-relief terminations
terminations
on shielded
shielded cable. Current
Current and voltage transformers,
transformers, to
serve metering
metering and relaying,
relaying, are often provided in special,
special,
separate termination
termination chambers.
chambers. Multi-ratio
Multi-ratio current
current transtransformers
formers are often located within the
the transformer
transformer tank.
tank. Consideration
sideration should be given to a hottest-spot
hottest-spot temperature
temperature
detector where the system
system operation
operation may
may subject
subject the transformer to emergency
where autoemergency loading
loading conditions
conditions (e.g., where
matic bus transfer between two
two transformers
transformers is provided).
provided).
Transformer
Transformer gauges can be provided with alarm contacts
contacts to
allow
All
transformer problems.All
allow remote annunciation
annunciation of transformer
transformer accessories
accessories must be suitable
suitable for the area classiclassification
fication where the transformer
transformer is to be installed.
installed.
4.11.5.2
Transformer
Fluid
4.11.5.2Transformer
Fluid
4.11.5.2.1
4.11.5.2.1
Mineral Oil-Filled Transformers
Transformers
Mineral
fire
hazard, and are substitutes
fire hazard,
substitutes for the PCB-type transformtransformers.
ers. The less-flammable,
less-flammable, hydrocarbon
hydrocarbon type has
has several
several specific
cific restrictions
restrictions on indoor use; while the silicon insulating
insulating
fluid-type
may be used indoors with only the same
vault
fluid-type may
same vault
requirement
35 kV that applies for PCBrequirement for ratings
ratings over 35
filled
70). Silicon
Silicon insulating fluid
fluid is
filled transformers
transformers (see NFPA 70).
generally
kV.
generally not used above
above 35 kv.
4.11.5.3
Dry-Type Transformers
4.11.5.3Dry-TypeTransformers
Ventilated
Ventilated dry-type
dry-type transformers,
transformers, as distinguished
distinguished from
sealed dry-type
dry-type transformers,
transformers, are used for indoor locations.
locations.
Weatherproof units are available
available for outdoor use, primarily
for lighting
lighting services
services where the primary voltage is usually
480 V. They are lightweight
lightweight compared
compared to oil-filled
oil-filled transformers,
formers, making them more economical
economical to install.
install. Only
minimum maintenance,
maintenance, including a periodic cleaning of the
windings, is required.
required.
windings,
Ventilated
dry-type
transformers
have several
disadvanVentilateddry-type
transformers
haveseveral
disadvantages,
or fluid-filled
tages, compared
comparedwith
withliquidliquidfluid-filled transformers:
transformers:
a.
a.
b.
c.
c.
d.
lowerstandard
standardbasic
basicimpulse
impulse level.
level.
They have a lower
They lack
lack an
an overload
overloadrating.
rating.
mayresult
resultinina higher
a
level.
Their use may
noise level.
Their windings
to to
thethe
environment.
windings are
aremore
moreexposed
exposed
environment.
Surge
andarresters
arresters can be installed
Surge capacitors
capacitorsand
installed to compensate for the lower
lower basic
basicimpulse
impulse level,
level, and
andforced-air
forced-air cooling
equipmentcan
can be used to increase
transformer
increase transformer capacity.
capacity.
Where the environment
environment presents
presents corrosive
corrosive vapors,
vapors, the
the transtransformers
formers can be obtained as completely
completely sealed,
sealed, nitrogen-presnitrogen-pressurized units.
4.11.5.4
Cast-Coil
Transformers
4.1 1.5.4 Cast-Coil
Transformers
Cast-coil transformers
with
a solid
transformersare
arefabricated
fabricated
with
a dielectric
dielectric
completely
encapsulating the primary and
andsecondary
secondary coils,
completely encapsulating
coils,
are mounted
mounted in a suitable,
ventilated enclosure. This
This
which are
suitable, ventilated
results in atransformer
transformerthat
that is contaminant
andmoisture
moisture
contaminantand
resistant,
resistant, has low
low maintenance,
maintenance, and
andhas
hasimpulse
impulse ratings
ratings comcomdry-typetransformers.
transformers.
parable to other dry-type
Regulations
Regulations require
require users
users of transformers
transformers containing
containing polypolychlorinated biphenyls
biphenyls(PCBs)
(PCBs)totomaintain
maintainspecific
specific
records,
records,
to
chlorinated
comply with specified procedures
procedures in
in case
case of leakage
leakage and
and for
of PCB-filled
disposal,
Users
disposal, and to fulfill
fulfill other
otherrequirements.
requirements.
Users
of PCB-filled
4.1 1.5.5 Transformer
Taps
4.11.5.5.
Transformer
Taps
or PCB-contaminated
transformers should
shouldconsult
consult
PCB-contaminated oil-filled transformers
applicable federal
federaland
and
state regulations.
regulations. Transformers
Transformerscontaincontainapplicable
state
Transformers
Transformers should
shouldbe provided with fully
fully rated kVA taps
ing PCBs are
federal
envi-enviareno longer manufactured
manufacturedbecause
becauseof of
federal
suitable
conditions. Tap
suitable for tap changing
changing under no-loadconditions.
ronmental
40 CFR
CFR Part 761.).
761.).
ronmental and health regulations
regulations (see 40
steps above
above
changers are
are designed
changers
designed in uniform 2.5% or 5% steps
and below
voltage.
The number of taps above
belowrated
rated
voltage.
above and
andbelow
below
4.11.5.2.2
Hydrocarbon Fluid
4.11.5.2.2 Less-Flammable
Less-Flammable Hydrocarbon
rated voltage
voltage and
and their
their magnitude
magnitude will
willdepend on individual
individual
Silicon Insulating
InsulatingFluid-Filled
Fluid-Filled
and Silicon
requirements. Two 2.5% taps above
above and
andbelow
belowrated
ratedvoltage
voltage
requirements.
Transformers
Transformers
are often specified.
specified.
Large powertransformers
transformersmay
may
autoTransformers
hydrocarbon fluid
be be equipped
equipped withautoTransformers with less-flammable
less-flammable hydrocarbon
fluid and
and
matic,
fully
kilovolt-ampere
taps
suitable
adjusting
fully
rated
kilovolt-ampere
taps
suitable
for
adjusting
silicon insulating
fluid
insulation
media,
are
available
for
insulating fluid insulation
available
voltage under
conditions.
use where mineral oil-filled
transformers would constitute
underfull-load
full-load
conditions.
oil-filled transformers
constitute a
I
.
,
Copyrighted material licensed to IDOM.
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ELECTRICAL
INSTALLATIONS IN PETROLEUM PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
4.11.5.6
Forced-Air
Cooling
4.11.5.6Forced-Air
Cooling
' -
properly designed
designedelectrical
electricalsystem
systemwill
willseldom
seldom
require
A properly
require
may,
the emergency
emergency loading
loadingof
oftransformers.
transformers.System
Systemgrowth
growth
such loading
loading necessary,
necessary, in which case IEEE
however, make such
C57.91
C57.91 should be consulted.
consulted.
4.12OVERHEAD
OVERHEAD
ELECTRIC POWER
ELECTRIC
POWER
DISTRIBUTION
DISTRIBUTION
4.12.1
General
General
The use of open conductors,
conductors, pre-assembled or field-spun
field-spun
supported by poles or strucstrucaerial cable, and spacer
spacer cable supported
tures for distribution
distribution systems
systems outside of process limits,
limits, utility areas,
areas, and operational
operational areas
areas should be subject to
engineering
engineering approval.
approval. Overhead
Overhead electrical distribution
distribution systems should be designed and installed in accordance
accordance with
the requirements
requirements of NFPA
NFPA 70,
70, ANSIlIEEE
ANSUEEE C2,
C2, and applicastate and local codes.
ble state
~
design,material,
andand
workmanship.
SpecialSpecial
are similar in design,
material,
workmanship.
structures,
suchasasA-Frame
A-Frame or H-Frame structures,
structures, such
structures, maybebe
a line or a group
group of lines whose
whose
required for
for the
thesupport
supportofof
a line
safely
or economically
loading isisininexcess
excess of that which
whichcan
canbe be
safely
economically
supported on single
single poles or other simple
simplestructures.
structures.
supported
deterThekilovolt-ampere
kilovolt-ampererating
rating of the transformer
transformer is determined by the temperature
temperature rating of the winding insulation.
insulation.
One means of increasing
increasing transformer
transformer capacity
capacity isistotokeep the
winding insulation
insulationwithin
within
byincreasing
increasingthethe
effective
winding
its rating by
effective
cooling
accomplished with
cooling of the transfOlmer.
transformer. This can be accomplished
4.12.3Aerial
Aerial
Cable
Cable
forced-air
is anticipated,
forced-air cooling.
cooling.Where
Whereload
loadgrowth
growth
anticipated, considconsidshouldbe given to providing
fans for forced-air
forced-air coolcooleration should
providing fans
cable provides
providesananalternative
alternativeto to
disAerial cable
open conductor dising; or to providingthe
temperature
switch,
and and
ing;
thebrackets,
brackets,
temperature
switch,
tribution. Aerial cable
cable isisavailable
available in singlehibution.
single- and three-conthree-conwiring necessary
the the
future
necessarytotoaccommodate
accommodate
future addition
addition of
offans.
fans.
types, shielded
shieldedor nonshielded;
nonshielded; and
andaerial
aerialcable
cable
with
with
a a
ductor types,
allows increased
increased
transformer also allows
Forced-air cooling of a transformer
self-supporting
preferred. Messengers
Messengers of
self-supporting synthetic jacket is preferred.
capacity while
while holding
holdingthe
theimpedance
impedanceto a value
value that
that permits
permits
self-supporting
be grounded
groundedatatfrequent
frequentinterinterself-supporting cable
cable should be
the use
lesser
interruptuseof secondary
secondaryswitching
switchingequipment
equipmentof of
lesser
intermptvals.
Surge arresters
beinstalled
installed at terminal
poles
vals.Surge
arresters should be
terminalpoles
ing capacity.
capacity. Forced-air-cooled
Forced-air-cooled transformers
transformers should
should be conwhere aerial
aerialcable
cable is connected to open conductors.
conductors.
when automatic
automaticbus
bustransfer
transferis is
provided
between
sidered when
provided
between
the the
secondaries
arrangement, the
the
secondaries of
of two
two transformers.
transformers.With this arrangement,
4.12.4Metal-Clad
Metal-Clad
Cable
Cable
transformer may be more economically
normal
economicallyloaded
loadedunder
under
normal
messenger
Metal-clad (Type MC) cable
cable supported
supported by a messenger
operation.
also
permits
carrying
additional
operation. Forced-air
Forced-aircooling
cooling
also
permits
carrying
additional Metal-clad
may
as
an
alternative
to
aerial
cable.
Metal-clad
cable
be
used
alternative
aerial
cable.
Metal-clad
cable
load
transfOlmers) without
2?? on"large
on'large transformers)
without exceeding
exceedingthe
the
load,(up
(up to 2/3
consists
more
conductors
with
necessary
insulation,
consists
of
one
or
more
conductors
insulation,
specified
specified temperature
temperaturelimits.
limits.
shielding,
shielding, and
and fillers
fillersover
overwhich
whicha asuitable
suitablemetallic
metallicsheath
sheath is
applied.
A
is
normally
supplied
over
the
sheath.
Generapplied.
A
jacket
normally
supplied
over
sheath.
Gener4.11.5.7
Forced-Oil
Cooling
4.1 1S.7 Forced-Oil
Cooling
ally,
grounding conally, this
this sheath
sheath should
shouldnot
notbe
berelied
reliedon
onas a grounding
conForced-oil
Forced-oil cooling
cooling isis another
another method
method of increasing
increasing transtransductor;
should
be installed
in thein
cable
ductor; a grounding
groundingconductor
conductor
should
be installed
former
capacity
because it reduces oil temperature.
former
capacity
because
temperature. The
interstices
manufacture.
interstices during
during manufacture.
purriping and
and circulating
circulatingofofoiloilis is
common
in the
design
pumping
common
in the
design
of of
larger (above
MVA) power transformers.
transformers.
(above8 MVA)
4.12.5
Accessibility
Accessibility
4.1 1.6 Loading
Loading
4.11.6
I
33
33
parts of
of the overhead
overhead distribution
distributionsystem
system that must
must be
All parts
examined
during
normal
operation
should
be
examined or adjusted
adjustedduring
normal
operation
should
be
readily
readily accessible
accessibleto authorized personnel.
personnel. Provisions
Provisions should
should
be made totoensure
working
spaces,
ensure adequate
adequate climbing
climbingspaces,
spaces,
working
spaces,
working
clearances between
working facilities,
facilities, and clearances
between conductors.
conductors. The
electrical
accordance with
with
electrical clearances
clearances must
must be established
established in accordance
codes.
ANSIlIEEE
any applicable
applicable state
stateand
andlocal
local
codes.
ANSIAEEE C2 and any
4.12.6
4.12.6
Isolation
andGuarding
Guarding
Isolationand
To provide
provide for the safety of
of employees
employees not
not authorized
authorized to
approach
approach conductors
conductorsand
andother current-carrying
current-carrying parts
partsofofelecelectrical supply
supply lines,
lines, the arrangement
arrangement of live parts
parts must
mustensure
ensure
adequate
adequate clearance
clearance to ground,
ground, or guards
guards should
shouldbe installed
installed to
isolate these parts effectively
effectively from
from accidental
accidental contact.
contact.
isolate
4.12.7Grounding
Grounding of Circuits
and Equipment
Circuits and
Grounding
andequipment
equipmentshould
should conform
Grounding of circuits
circuits and
conform to
ANSIIIEEE C2 and any
anyapplicable
applicable state
localcodes.
codes.
state and local
ANSUEEE
Metallic sheaths,
sheaths, conduits,
conduits,metal
metalsupports,
supports,fixtures,
fixtures,
frames,
frames,
Materials
4.12.2
Materials
cases,
cases, and other similar
similar noncurrent
noncurrent carrying
carryingparts
partsshould
shouldbebe
properly grounded.
temporary
ground
for maintenance
properly
grounded.A A
temporary
ground
maintenance purMost pole-line
pole-line materials
materialsconform
conformto the standards
standardsand sugsugsecure mechanical
mechanical connection
connection toto aa
poses should consist of a secure
gested specifications
Edison
Electric
Institute
(EEI)16
or
specificationsofofthethe
Edison
Electric
Institute
(EEI)16
buried metallic
metallic structure
structureor driven ground
ground rod.
rod. Resistance
Resistance of
of
suchaground
a ground
should limit touchand
and step
should
step potentialstoto
16Edison
Institute, 701
16Edison Electric
Institute,
701 Pennsylvania Avenue, Washington,
Washington,
D.C. 20004.
acceptable
withwith
IEEE
80.
80.
acceptable levels
levelsininaccordance
accordance
IEEE
Copyrighted material licensed to IDOM.
STD.API/-PETRO
.!m.
RP 540-ENGL
9 9 7 -orU
07322.70
No further 4
reproduction
distribution
permitted.0645.572 67.8
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34
34
PRACTICE
RECOMMENDED API·
API. RECOMMENDED
4.12.8
Clearances
4.12.8
Clearances
The
The clearances
clearancesspecified
specifiedfor
forconductors
conductorsininANSIIIEEE
ANSVIEEE C2,
C2,
Section
23,
are
a
minimum
recommendation.
Any
applicable
Section 23, are a minimum recommendation.
Any
applicable
local
requirements
must
also also
be
local and
andstate
state
requirements
must
be considered.
considered.
PRACTICE
540
540
structed
of exposure
exposuretotowhich
which
structedto
to withstand
withstandthe
the particular
particulartype
typeof
they
of the
the
they will
will be
be subjected.
subjected.This
This may
may require
requireovednsulation
overinsulationof
exposed
use of
exposed sections
sections of
of lines,
lines, the
the use
of materials
materials to
to withstaud
withstand
the
of the
spray,
or
thecorrosive
corrosiveeffects
effects
of the
spray,
orother
othermeasures.
measures.
4.12.9
Location
4.12.9
Location
4.12.9.3
Petrochemical
Exposure
4.12.9.3Petrochemical
Exposure
4.12.9.1
Routing
4.12.9.1
Routing
When
overhead lines
Whenoverhead
lines are
are exposed
exposed to
to petrochemicals
petrochemicals or
or
other
other similar
similar contaminants,
contaminants, the
the lines
lines should
should be
be designed
designed to
to
withstand
such contaminants.
withstand
thethe effeCts
effects of
of
such
contaminants.
Specially Specially
approved
approvedsilicon-type
silicon-typegrease
greaseon
on the
the insulators,
insulators,bushings,
bushings,and
and
similar
similar items
items provides
provides aa strong deterrent
deterrent to
to current
current leakage
leakage
and
and insulator
insulator flashover.
flashover. Silicon tends
tends to
to absorb
absorb the
the foreign
foreign
matter
deposited
on
the·
dielectric
material
and
continually
matter
on the dielectric material and continually
provides
nonconducting,water-repellent
water-repellent exterior
provides aanonconducting,
exterior seal
seal for
for
the
theequipment.
equipment.
The
The recommended
recommended routing
routing for
for overhead
overhead lines
lines isis along
along
facility
facility roads
roads or
orstreets.
streets. When
When lines
lines must
must be
be located
located in
in tauk
tank
areas
areas or
or other
other locations
locations that
that are
are not
not reached
reached by
by roadways,
roadways,itit
isis recommended
recommended that
that the
the lines
lines be
be routed
routed along
along eru1hen
earthen firefirewalls,
walls, the
the toe
toe of
of dikes,
dikes, or
or other
other logical
logical routes.
routes.The
The location
location
of
of overhead
overhead lines
lines should
should comply
comply with
with the requirements
requirements of
of
applicable
applicable fire
firecodes;
codes; and
and wherever
whereverpossible,lines
possible, lines should
shouldbebe
routed
fires
so as
as to
to minimize
minimize exposm'e
exposure to
to damage
damage from
fromfires
routed so
originating
originating in
in equipment
equipment or
or structures
structures along
along their
their routes.
routes.
Lines
Lines should
should not be
be run
run in
in areas
areas where
where interference
interference with
with
crane
crane booms
booms and
and similar
similar apparatus
apparatus isis likely
likely during
duringnormal
normal
plant
or routine
routine maintenance.
maintenance.
plant operation
operationor
4.12.9.2
WaterSpray
Spray
Exposure
4.1 2.9.2 Water
Exposure
Overhead
Overhead lines
linesshould
shouldbe
be located
locatedfar
far enough
enough from
from cooling
cooling
towers,
andand
otherother
sources
towers,spray
sprayponds,
ponds,
sourcesof
of water
waterspray
sprayto
to avoid
avoid
fouling
parts.
When
foulingtheir
theirinsulation
insulationand
andcorroding
corrodingtheir
theirmetal
metal
parts.
When
this
practical, the
this isis not
not practical,
the lines
lines should
should be
be designed
designed and
and concon-
4.12.9.4
LinesAdjacent
Adjacent to
4.12.9.4 Lines
to an
an NFPA
NFPA 70
70Defined
Defined
Class
I
Location
Class I Location
When
When installed
installedadjacent
adjacentto
to or
or traversing
traversingClass
ClassII locations,
locations,
overhead
lines
should
be
placed
so
that
the
current-canying
overhead lines should be placed so that the current-carrying
components
componentswill
willbe
be outside
outsidethe
the space
spacethat
that may
may contain
containflamflammable
mablegases
gases or
or vapors
vapors (see
(seeAPI
API RP
Rp 500).
500).Conventional
Conventionaloveroverhead-line
head-line construction
construction normally
normally meets
meets this
this requirement
requirement
because
because of
of the
the isolation
isolation naturally
naturally afforded
affordedby
by the
the horizontal
horizontal
distauce
distancefrom,
from, or
or elevation
elevationabove,
above, the
the classified
classifiedlocation.
location.
,,.
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SECTION 5-GROUNDING
5-GROUNDING AND
SECTION
ANDLIGHTNING
LIGHTNINGPROTECTION
PROTECTION
5.1
5.1
PURPOSE
PURPOSE
recommended:
is
practice
The
grounding
following grounding practice is recommended:
following
a.
than or equal
480 V that supply
supply
a. Systems
Systems rated at less than
equal to 480
phase-to-neutral
loads
must
be
solidly grounded. These
phase-to-neutralloads
mustbe
solidly
grounded.
These
include
three-wiresystems;
systems; 208YI
include 120/240-V,
120/240-V, single-phase, three-wire
208Y/
120-V,
three-phase,
four-wire
systems;
and 480Y/277-V,
120-V,three-phase,
four-wire
systems;
and480Y/277-V,
three-phase,
four-wire
systems.
three-phase, four-wire systems.
b. Low-voltage
(480-V
andthree-wire
600-V),systems
three-wire systems
Low-voltage(480-V
and600-V),
should be either high-resistance
high-resistancegrounded
grounded
or grounded.
grounded.
should
or solidly
c.
other
plant
distribution
systems maybebe resistance
resistance
c. Allother
plant
distribution
systems
grounded.
These include
include2,400
2,400 V through 34,500-V,
34,500-V, threethreegrounded. These
phase,
(Open.
wiredistribution
phase, three-wire
three-wiresystems.
systems.
(Open
wire distribution may
require solid
require
solid grounding.)
grounding.)
section provides
provides aa guide
guide to
to the general principles
This section
principles of
grounding
andlightning
lightningprotection
protection as they apply
apply to petrogrounding and
petroprocessingplants.
plants.
leum processing
5.2
SCOPE
SCOPE
This
to the
theconsideration
considerationofof
grounding
This section is limited to
grounding
practices in the
thefollowing
followingcategories:
categories:
a.
equipment
a. System
System grounding:
grounding:The
Theprotection
protectionofofelectrical
electrical
equipment
and the reliability
reliability of an
an electrical
electrical system.
system.
b. Equipment
Equipment grounding:
grounding:The protection of
of personnel
personnelagainst
against
electric
electric shock.
shock.
c. Lightning
hazards
of fire
Lightning protection
protectionagainst
againstthethe
hazards
fire and
andexploexplosion, as well as
equipment,
caused
by by
sion,
asdamage
damagetotoelectrical
electrical
equipment,
caused
lightning.
lightning.
A full
relative merits of
full discussion
discussion of the relative
of the
thevarious
varioussyssystems is not within the scope
scope of this section,
section, but aa brief
briefsumsummary of the principal
principal features
features is included.
included.AAmore
moreextensive
extensive
discussion
discussion of the subject can be found
found in IEEE Std 142.
142.
5.3 STATIC ELECTRICITY
ELECTRICITYAND
ANDSTRAY
STRAY
CURRENTS
CURRENTS
5.4.2Ungrounded
Ungrounded
System
System
application of bonding
The application
bonding and
andgrounding
grounding for protection
protection
against the
effects
of
static
electricity
and
stray
currents
the effects static electricity
stray currents(such
(such
as cun·ents
covered
currents associated
associatedwith cathodic
cathodic protection)
protection)is not covered
in this section.
section. These
Theseimportant
importantsubjects
subjectsare discussed
discussed ininAPI
API
RP 2003 and NFPA
NFPA 77.
77.
5.4
SYSTEMGROUNDING
GROUNDING
5.4.1
General
5.4.1
General
Electric
is concerned
Electric power distribution
distributionsystem
systemgrounding
grounding
concerned
with the
of an intentional
thenature
natureand
andlocation
location
intentional conductive
conductiveconcon(or derived neutral)
nection between
betweenthetheneutral
neutral
neutral) of the system
andtheground
the ground
classifications of
(earth).(earth). The common
commonclassifications
grounding
in industrial
distribution
grounding methods
methodsused
used
industrial plant
plantpower
power
distribution
systems
follows:
systems are as follows:
a. Ungrounded.
Ungrounded.
b. Low-resistance
Low-resistance grounded.
grounded.
c.
High-resistancegrounded.
grounded.
c. High-resistance
d.
Reactance grounded.
grounded.
d. Reactance
e. Solidly
Solidlygrounded.
grounded.
The nature of
ofsystem
systemgrounding
groundingsignificantly
significantlyaffects
affects
thethe
steady-state
magnitude of line-to-ground
line-to-ground voltages
voltagesunder
underboth
both
steady-state
and transient
transient conditions.
conditions. Without
Withoutsystem
systemgrounding,
grounding,severe
severe
overvoltages
overvoltages can occur;
occur; reducing
reducing insulation
insulationlife and presentpresenting ahazard
a hazard to personnel.
personnel. System
System grounding
grounding can control
levels.Further,
Further, NFPA 70
these overvoltages
overvoltages to acceptable
acceptablelevels.
requires that certain
be solidly
requires
certainsystems
systems
solidly grounded.
grounded.
For these reasons,
type of system
reasons,some
some
system grounding
grounding is generally recommended.
recommended.
35
35
In an ungrounded system, there is no intentional
intentional connecconnectiontoground,
to ground,
but the· system is capacitively
grounded
butthesystem
capacitivelygrounded
because of the capacitance
capacitance coupling
couplingto ground of
of every
every enerenerconductor. The operating
operating advantage
gized conductor.
advantage of this
this system
system is
that a single
fault
a trip-out
of of
singleline-to-ground
line-to-ground
fault will not
notresult
resultin in
a trip-out
charging
current
the circuit because
becausethere
there is only aaminor
minor
charging
current
flowing
will
flowing to ground.
ground. During
During such
suchaafault,
fault,the
theother
otherphases
phases
will
equal
to the fulliine-tobe subject totoline-to~ground
line-to-groundvoltages
voltages
equal
full line-toline
used
in such
line voltage;
voltage; therefore,
therefore,insulation
insulationforforequipment
equipment
used
in such
a system must be properly
properly rated for this condition.
condition. Further,
Further,
because of the
capacitance
coupling
to
ground,
the to ground, the
because
capacitance
coupling
ungrounded
systemis subject to overvoltages
overvoltages (five times nornorungrounded system
mal or more)
result of an intermittent-contact
more) as a result
intermittent-contact ground
fault
fault (arcing
(arcing ground)
ground) or a high inductive-reactance
inductive-reactanceconnected
connected
from one phase
phaseto ground.
ground.
advantage of the
theungrounded
ungroundedsystem
systemwill
will
The advantage
be be
lost if the
ground is allowed
allowed to persist until
until aa second
secondground
groundoccurs.
occurs.A
second
would cause an outage
outageif if it is on another
second ground would
grounddetection
detectionsystem,
system,along
along
with
phase. An adequate
adequate ground
with
a a
program for removing
removing grounds,
grounds, isisessential
essentialfor
forsatisfactory
satisfactory
operation of an ungrounded
ungrounded system.
system.
5.4.3
Grounded
Systems
GroundedSystems
Resistance
grounding
a resistor connected
Resistance
grounding
employs
resistor
aemploys
connected
ground.
between the
thesystem
systemneutral
neutraland
and
ground. This resistor is in
parallel with
reactance.
withthe total system-to-ground
system-to-groundcapacitive
capacitive
reactance.
The high-resistance
high-resistance grounded
grounded system
system employs
employsaaresistance
resistance
value equal
equal to
to or slightly
slightly less
less than
than the
the total
total system-to-ground
system-to-ground
capacitive
reactance.(The
(The
resistor
is normally
isnormally
capacitivereactance.
size size of theresistor
expressed
expressed in amperes.)
amperes.) This will
will limit
limitth~
the ground-fault
ground-faultcurrent
current
to a few
willwill
eliminate
the high
overvoltfew amperes
amperesand
and
eliminate
the transient
high transient
overvolt-
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36
36
'
API
540
API RECOMMENDED
RECOMMENDEDPRACTICE
PRACTICE
540
b.
ages
canbe
be created
b. Provides
Provides an
an effective
effective path
path over
over which
which fault
fault currents
currents
ages that can
created by
by an
an inductive
inductive reactance
reactance conneeted
connected
involving
:fi'om
ground or
involving ground
ground can
can flow
flow without
without sparking
sparking or
or overheating
overheating
ftom one
one phase
phasetoto
ground
or from
from an
an intermittent-contact
intermittent-contact
to
ground
The high-resistance
high-resistancegrounded
groundedsystem
systemalso
alsoproproto avoid
avoid ignition
ignitionof
of combustible
combustibleatmospheres
atmospheresor
or materials.
materials.
ground fault. The
vides
meansforfor
detection
of and alarm
vides aa convenient
convenientmeans
detection
ofand
alam on
on aa
equipment
which
ground
theuse
useofof
5.5.2
Equipment
5.5.2 Grounded
GroundedEquipment
ground fault
fault and
and facilitates the
equipment
which
can can
determine
thefault
faultlocation
location
without
electrical
system
determinethe
without
electrical
system
shut-shutThe
The metal
metal framework
frameworkof
of all
allbuildings
buildingsand
andstructures
structureshoushousdown.
ungrounded
sys- sysIn addition,
addition, this
this system
systemisis similar
similartotothethe
ungrounded
down.In
Or
supporting
electrical
equipment
and
all noncurrenting
ing
or
supporting
electrical
equipment
and
all
noncurrenttem
inthat
that
it can
continue
operation
with aline-tosingle line-totem in
it can
continue
operation
with a single
canying
of electrical
electrical equipment
equipment and
and devices
devices
carrying metal
metal parts
parts of
ground
(and
totaltotal
system-togroundfault
faultif
if the
themaximum
maximum fault
faultcurrent
current
(and
system-toshould
be
grounded
by
connection
to to
a grounding
system.
In
In
should
be
grounded
by
connection
grounding
a
system.
ground
ground capacitive
capacitive charging
charging current)
current) is
is limited
limited to
to less than 10
10
general,
equipment
grounding conductors
should
be
congeneral,
equipment
grounding
conductors
should
be
coninformation). The
amps
amps (see
(see IEEE
IEEE 142
142 for additional information).
The ground
ground
nected
nected as
as directly
directly as
as practicable
practicable to
to the
the electrical
electrical system
system
fault,
oncedetected,
deteeted,should
shouldbebe cleared.
fault, once
cleared.as
as soon
soon as
as possible
possible
ground.
Routing
the
grounding
conductors
as
close
as
practias
close
as
practiground.
Routing
the
grounding
conductors
because
with
the the
ground
because the
thesystem
system isis not
notdesigned
designedtotooperate
operate
with
ground
cable
to
supply
conductors
will
minimize
the
voltage
drop
cable
to
supply
conductors
will
minimize
the
voltage
drop
fault
fault condition
conditionindefinitely.
indefinitely.
under
under fault
fault conditions.
conditions.
The
resisThe low-resistance
low-resistancegrounded
grounded system
system uses
uses aavalue
valueof of
resistance
tance that
that isis sized
sized to
to give
give aa ground-fault
ground-fault current
current value
value suitsuit5.5.3
GroundingSystem
System
5.5.3 Equipment
EquipmentGrounding
able
able for
for relaying
relaying purposes
purposes (see
(see IEEE
IEEE 32
32 for
for resistor
resistor time
time
rating).
The
equipment
grounding
rating). Typical
Typical current
current values
values will
will range
range from
from 200
200 amps
amps on
on
The principal
principalrequirement
requirementofofan an
equipment
groundingsyssyssystems
window-type current
of structures
tem
earth of
systems using
using sensitive.
sensitive ,window-type
current transformer
transformer
tem is
is to
to maintain
maintain the
the resistance
resistance to earth
structures and
and
equipment
With
an an
ground-sensor
ground-sensorrelaying
relaying to
to 2,000
2,000 amps
amps on
on the
the larger
larger systems
systems
equipmentenclosures
enclosuresat
at the
the lowest
lowestpracticable
practicablevalue.
value.
With
using
adequate
system,
the
potential
to
ground
during
fault
condiusing ground-responsive
ground-responsiverelays
relays connected
connected in
in current
current transtransadequate system, the potential to ground during fault conditions
to personnel
(because
former
former residual
residual circuit~.
circuits. This
This system
system provides
provides a controlled
controlled
tions will
willnot
notbebedangerous
dangerous
to personnel
(because of
of equalizequalizvalue
.
ing
of
ground-fault
current
and
eliminates
the
overvoltage
of
potentials)
and
equipment,
and
protective
devices
value of ground-fault current and eliminates the overvoltage
ing of potentials) and equipment, and protectivedevices will
will
the ungrounded
the action
problems
operate
problems of
ofthe
ungrounded system,
system, but
butthe
action of
of aa
operate properly.
properly.
three
to clear
Grounding-system
connections
three phase
phase circuit-switching
circuit-switching device
device is
is required
required to
clear aa
Grounding-system
connections
maymay be
be made
made in
in various
various
single
ways.
single line-to-ground
line-to-ground fault.
fault.
ways.The
The grounding
groundingsystem
systemfor
for aa large
largeor
or complex
complexplant
plant may
may
involve
an extensive
extensivenetwork
networkof of
equipment enclosures
involve an
equipment
enclosures and
and
systems requires
requiresthat
that
Installation
Installation of
of resistance-grounded
resistance-grounded systems
structure
structureground
groundgrids
grids interconnected
interconnectedby
by cables
cables to
to provide
provide an
an
equipment
equipmentbasic
basic impulse
impulse levels
levels as
as well
well as
as the
the application
applicationof
of
overall
plant-grounding
system.
Specific requirements
overallplant-grounding
system.
Specific
requirements for
for
surge
reviewed
carefully.
surgearresters
arrestersbebe
reviewed
carefully.
grounding
NFPA 70,
70, and
and detailed
detailedinforinforgrounding systems
systemsare
are given
given in
inNFPA
The
The solidly
solidlygrounded
groundedsystem
system gives
gives the
the greatest
greatest control
control of
of
mation
is
included
in
IEEE
Std
142.
matiòn
is
included
in
IEEE
Std
142.
overvoltages
overvoltagesbut
but develops
developsthe
the highest
highest ground-fault
ground-faultcurrents.
currents.
These
These high
high currents
currents may
may cause
cause damage
damage in.
in equipment
equipment and
and
may
may create
create other
other shock-hazard
shock-hazard problems
problems for
for personnel
personnel if
if
equipment
equipment grounding
grounding is
is inadequate.
inadequate. However,
However,thethe high
high
magnitude
magnitude ground
ground current
current may
may be
be desirable
desirableto
to ensure
ensure effeceffective
tive operation
operation of
of phase-overcurrent
phase-overcurrenttrips
trips or
or interrupters.
interrupters. .
Cable
Cable shields
shieldsmust
mustbe
be sized
sized to
to carry
carry the
the available
availablegroundgroundfault
of the·
fault without
fault current
current for
for the
the duration of
the'fault
without exceeding
exceeding
cable
cable therrnallimitations.
thermal limitations.
Reactance-grounded
Reactance-grounded systems
systemsare
are not
not ordinarily
ordinarily employed
employed
in
notnot
be discussed
here. here.
in industrial
industrial power
power systems
systems and
andwill
will
be discussed
5.5
GROUNDING
5.5 EQUIPMENT
EQUIPMENTGROUNDING
5.5.1
5.5.1 Purpose
Purpose
Equipment
thethe
following:
Equipmentgrounding
groundingaccomplishes
accomplishes
following:
a.a. Ensures
Ensuresthat
that all
allof
of the
the parts
parts of
of aa structure
structureor
or an
an equipment
equipment
enclosure
enclosure are
are not
not at
at aa voltage above
above ground
ground that.
that would
would be
be
dangerous
groundconnections
connections and
dangerous to
to personnel.
personnel. Adequate ground
and
devices
devices should to
to ensure
ensure that
that abnormal
abnormal conditions,
conditions, such as
as
willwill
notnot
raiseraise
the
ground
ground faults
faultsororlightning
lightningstrokes,
strokes,
the potential
potential
of
level.
of the
the structure
structureor
or enclosure
enclosureto
to aadangerous
dangerous
level.
5.5.4
GroundingApplications
Applications
5.5.4 Specific
SpecificGrounding
5.5.4.1
ProcessEquipment
Equipment
5.5.4.1 Structures
StructuresandProcess
Steel·
Steel building
building frameworks,
frameworks, switchgear
switchgear structures,
structures, and
and
similar
similarinstallations
installationsshould
should be
be grounded
groundedat
at several
severalpoints
points (at
(at
least
per structure)
to the
the
least two
two per
structure) with
with substantial
substantial connection
connection to
grounding
grounding system
system grid.
grid. Tanks,
Tanks, vessels,
vessels, stacks,
stacks, exchangers,
exchangers,
and
or bolted
bolted to
to
and similar
similarequipment
equipment not
not directly
directlysupported
supportedby
by or
aa grounded
grounded supporting
supportingstructure
structureshould
shouldbe
be grounded
grounded using
using aa
minimum
of two
two connections
connections to
to the
the grounding
grounding system
system grid.
grid.
minimum of
Special
Special attention
attention should
should be
be paid
paid to
to piping
piping systems
systems to
to assure
assure
the
the pipe
pipe is
is adequately
adequately grounded.
grounded. Inadequate
Inadequate grounding
grounding
could
could result
result in
in aa difference
difference of
of potential
potential if
if for
for example
example the
the
pipe
was separated
flange to
This
pipewas
separated at
at aaflange
to replace
replace aa gasket.
gasket. This
could
could result
result in
in arcing,
arcing, sparking,
sparking,or
or aa shocking
shocking an
an employee
employee
performing
performing the
the work.
work.
5.5.4.2
5.5.4.2 . Motors
Motors and
and Generators
Generators
Motor
conneeted
Motor and
and generator
generatorenclosures
enclosuresshould
shouldbebe
connectedto
to the
the
overall
overall plant grounding
grounding system
system... This
This connection
connection is
is accomaccomplished
with
a mechanically
and continuous
electrically continuous
plishedwith
amechanically
andelectrically
.'
Copyrighted material licensed to IDOM.
No further reproduction
distribution
permitted.
STD.API/PETRO RP 540-ENGL
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ELECTRICAL
PETROLEUM
lNSTALLATlONS
IN
PROCESSING PLANTS
PLANTS
ELECTRICAL
INSTALLATIONS
IN PETROLEUM PROCESSING
equipment-grounding
is routed
with
equipment-groundingconductor
conductorthat
that
is routed
with the
thephase
phase
conductors
conductorsof the machine.
machine.This may be a conductor
conductorrun with
phase
conductorsinside
inside
a conduit,
a continuous-threaded
phaseconductors
aconduit,
acontinuous-threaded
rigid conduit system,
system, a cable
cable tray
tray system,
system,or another
another NFPANFF'A70-approved
70-approved method.
method. In any case,
case, the
the grounding
grounding connection
connection
mustprovide
provide
a low-impedance
machine
alow-impedance
circuit circuit from
from the
themachine
enclosure
back
to
the
electtical
system
ground.
Where
enclosure back to the electrical system ground. Where conconduit
be made up
tightly,and
and
duit or trays
trays are
are used,
used, joints
joints must be
up tightly,
bonding
bonding jumpers
jumpers should
should be
be installed
installed at expansion
expansion joints and
similar
similar locations.
locations. The
The bonding
bonding jumpers
jumpers should
should be inspected
inspected
periodically
periodically totoinsure
insure a low impedance
impedance connection.
connection.
Supplemental
be provided
Supplementalgrounding
groundingprotection
protectionshould
should
provided by
connecting
additional
grounding
conductor
connectinganan
additional
grounding
conductor
from from each
each
machine
to
the
local
grounding
system
grid.
The
purpose
machine to
grid. The purpose of
this
connection
is
to
equalize
potentials
theimmediate
immediate
thisconnection is toequalizepotentials in the
vicinity
vicinity ofofeach
eachmachine.
machine.
5.5.4.5 Enclosures
Enclosures
Electrical
Equipment
forfor
Electrical
Equipment
5.5.4.3Metallic-Sheathed
Metallic-Sheathed
Metallic-Shielded
andand
Metallic-Shielded
Cables
Cables
5.5.5Portable
Portable
Electrical
Equipment
Electrical
Equipment
37
37
Switchgear,
centers,and
andsimilar
similar
electrical equipSwitchgear, control centers,
electrical
equipment should
the
shouldinclude
include a ground
groundbus.
bus.Where
Where
the equipment
equipment conconsists
lineup oftwo
two or more
sections,two
two
grounding
sists of a lineup
moresections,
grounding
connections
system
grid,grid,
one
connections totothe
thegrounding
grounding
system
one on each
each end
endof
the
the ground
ground bus,
bus,are
arerecommended.
recommended.
5.5.4.6
Fences
Fences
Metal
and gates
gates enclosing
Metal fences and
enclosing electrical
electrical equipment or
substations
substations must
mustbe connected
connected to the
the grounding
grounding system
systemgrid.
grid.
A number
number of factors
involved here, including
including the resisfactors are
are involved
tance
ground of the
the substation grounding
grounding system,
system, the
the disdistance to grotmd
tance
fencefrom
fromgrounding
grounding
electrodes,
voltage
tance of the
the fence
electrodes,
andand
voltage
gradients
information, see
see IEEE
gradients in the
the soil.
soil. (For additional
additional information,
Std
80 and
and Std
Std 142.)
142.)
Std 80
This paragraph
elecparagraph is
is limited
limited to
to consideration
consideration ofofportable
portable
electdcal
trical equipment
equipment operating
operatingat less
less than
than or equal
equal to
to 600
600 volts;
volts;
The
andand
metallic
shieldshield
(if applicable)
of any of any
The metallic
metallicsheath
sheath
metallic
(if applicable)
portable
operating at higher
voltagesisisapplied
applied
portable equipment
equipment operating
higher voltages
power
cableshould
should
be continuous
over
therun
entire
powercable
becontinuous
overthe
entire
and run and
infrequently
special
consideration.
IEEE
Std 142
142
infrequently and
andrequires
requires
special
consideration.
IEEE
Std
should
grounded atateach
eachend.
end.Grounding
Grounding of the
the shield
should be grounded
shield at
provides
portable
electrical
equipment
operatprovides information
informationonon
portable
electrical
equipment
operatboth ends
to circulating
circulating
endsmay
mayrequire
require the cable
cable totobe derated
derated due
dueto
ing at
at higher
higher voltages.
voltages.
currents.
is is
permissible
if a 25-V gradigradicurrents. Grounding
Groundingatatone
oneend
end
permissible
Portable
poses one
Portable electrical
electrical equipment
equipmentposes
one of the
the greatest
greatest
(see(see
IEEE Std 422
method
of estimating
ent isisnot
notexceeded
exceeded
422forfor
method
estimating
potential
hazards to personnel,
mandatorythat
thatthethe
so it is
is mandatory
potential hazards
personnel, so
shield
shield voltages).
voltages). If
If any
any metallic-sheathed
metallic-sheathedor metallic-shielded
metallic-shielded
enclosures
enclosures of portable equipment
equipment of
ofany type
type be maintained
maintained
cables
cables are
are spliced,
spliced,care
caremust
mustbe taken to obtain
obtain continuity
continuity as
at
at ground
groundpotential
potentialor be protected
protectedby an approved
approved system
systemofof
well as
effective
physical
connection
the metallic
as aneffective
physical
connection
withthewith
metallic
double
double insulation.
insulation.
sheath
at the
WhereWhere
metallicmetallic
armor is armor
used over
sheath ororshield
shield
at splice.
the splice.
over
Portable
Portable electrical
electrical equipment
equipmentthat
thatis
is without
without double
double insulainsulametallic
metallic sheath,
sheath, sheath and armor should be bonded
bonded together
tion and
50 V must be
be provided
providedwith
witha acord
cord
and is operating
operating above
above50
and
and connected to
to the ground
ground system at each
each end of the
the cable
cable
containing
conductor
which
terminates
in in
containing aaseparate
separategrounding
grounding
conductor
which
terminates
and
The
metal-clad
and at
at any
any accessible
accessiblesplices.
splices.
The metallic
metallicsheath
sheathonon
metal-clad a grounding-type plug that is used with a matching receptacle.
grounding-type plug that
with a matching receptacle.
cable
also be used
usedas
as an
an equipmentequipment-grounding
groundingconductor
conductor The
cable may also
be properly
tied to
The grounding
groundingcontact
contactof the receptacle
receptaclemust
must
be properly
tied
if the
corrugated
tube.
However,
a sepathesheath
sheathisisa continuous
a continuous
corrugated
tube.
However,
a sepa- a grounding
groundingsystem.
system. NFPA 70
ground-faultcircuit
circuit
70 requires
requiresground-fault
rate
cable interstices
intersticesdurdurrate grounding
groundingconductor
conductorinstalled
installedin the cable
interrupters
for all
and2020 amp
interrupters for
all 125
125 V single-phase
single-phase 15
15 amp
amp and
amp
ing
manufactureisrecommended.
is recommended. The
ingmanufacture
The distinctions
distinctions between
receptacle outlets
used
for for
maintenance
or or
outletson
ontemporary
temporarywiring
wiring
used
maintenance
sheaths,
armoring,and
and
shields can be obscure.
obscure. An overall
overall
sheaths,armoring,
shields
construction.
An
assured
grounding
program
is
an
acceptable
assured
program
an acceptable
construction.
welded metal
as
metal covering
covering isisreferred
referredto to
as a sheath
sheathbut itit may
may act
alternative
toground-fault
ground-faultcircuit
circuit
interrupters
additional
alternativeto
interrupters
(for(for
additional
as
a shield
(see
as an
an armor
armorand
and
a shield
(seeIEEE
IEEE Std
Std 100
100for
for additional
additionalinforinforinformation
ground-faultcircuit
circuit
see NFPA
NFPA 70,
70, 305-6). The
Theground-fault
information see
mation).
applications
may
mation). Adjustable
Adjustablespeed
speeddrive
drive
applications
may require
require that
that
interrupter
personnel
safety
and isand
not to
interrupter isisforfor
personnel
safety
is
to be
notconfused
confused with
with
one end
cable
ungrounded
to preendofofthethe
cable metallic
metallic shield
shieldremain
remain
ungrounded
preground-fault
requirements for
foritems
items
ground-fault protection of equipment
equipment requirements
vent common
voltages
andand
circulating
ground
currents.
commonmode
mode
voltages
circulating
ground
currents. such
elements.
as electrical
electricalresistance
resistanceheating
heating
elements.
such as
5.5.4.4Conductor
Conductor
Enclosures
Enclosures
5.5.6
NFPA 70 requires
requires that
that exposed
exposedmetallic
metallicnoncurrent-carrynoncurrent-carrying
enclosures
of electrical
This
ingenclosures
ofelectrical
devices devices be grounded.
grounded. This
includes
conduit,
wireways,
materials.
includesconduit,
wireways,
and and similar
similar wiring
wiringmaterials.
Where
Where the continuity
continuity of the enclosure
enclosure is assured
assured by its conconstruction,
at its termination
struction, aa grounding
grounding connection
connection at
termination points
points
will be adequate.
adequate. IfIfcontinuity
continuityis not assured
assuredby the construcconstruction,
care
must
be
taken
to
provide
adequate
connections of
tion, care must taken to provide adequate connections
all
all sections
sectionsto
to the
the grounding
groundingsystem
system grid.
grid.
Special
considerations apply
apply to instrument
grounding. All
All
Special considerations
instrument grounding.
grounding
be tied together
grounding systems
systemsshould
should
togetherininaccordance
accordancewith
with
NFPA 70.
In
general,
a
power
supply,
equipment,
and
cable
70. general, power supply,
cable
shields
to atosingle
point point
on theon
overall
shields should
shouldbebebrought
brought
a single
the plant
grounding
allow for safe
safe
grounding system
system(procedures
(proceduresare
arenecessary
necessaryto allow
troubleshooting
that
may
require
a
momentary
separation of
troubleshooting
may require a momentary separation
the
tie to
overaUplant
plantgrounding
grounding
system). (See
the tie
to the overall
system).
( S e e 9.8
9.8 and
and
IEEE Stda
518
and
1100
for
additional
information.)
Stds 518 and 1100for additional information.)
Instrument
Grounding
InstrumentGrounding
1
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API
PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
38
38
I
5.6
CONNECTIONS
CONNECTIONS
EARTH
TO TO EARTH
5.6.1
Acceptable
Ground
Resistance
5.6.1Acceptable
Ground
Resistance
Ideally,
ground connection
connection would
would have zero
Ideally, aa ground
zero resistance,
resistance,
but this is impossible.
impossible. The
The resistance
resistance of a ground
groundconnection
connection
isafunction
a function of soilresistivity
resistivity and the
geometry of the
thegeometry
grounding
system. In soils
of resistivity,
high resistivity,
extensive
groundingsystem.
soilsofhigh
extensive
arrangements
acceptable lowlowarrangements may be required to obtain an acceptable
resistance
ground.
resistance ground.
The allowable
inversely
withwith
the fault
allowableresistance
resistancevaries
varies
inversely
fault curcurrent to ground:
thethe
fault
ground: the
thelarger
larger
fault current,
curient, the lower
lower the resisresistance.
substations and generating
stations,
tance. For large
largesubstations
generatingstations,
the the
resistance
resistance of the system
system grounding
grounding grid
gridshould
shouldnot
notexceed
exceed11
ohm.
andand
for
ohm. For
Forsmaller
smallersubstations
substations
for industrial
industrialplants,
plants,a resisa resistance of
should be obtained,
obtained, if practicable.
practicable.
'tance
of less
less than
than 5 ohms should
NFPA 70
70 approves
approves the use of a single-made
single-made electrode
electrode if its
resistance
resistancedoes
does not exceed 25
25 ohms.
ohms.
5.6.2
Grounding
Electrodes
GroundingElectrodes
in.
Driven ground rods,
rods, 5fs
5/8 to 1 in. in diameter,
diameter, and 8 or 10
10 ft
ft
long,
type of grounding
electrodes;
are the most common
common type
grounding electrodes;
long, are
however,
however, aa single
singleground
groundrod
rodis not adequate
adequatewhen
whenrelatively
relatively
low resistance
-in.
x
100ft
ground
rod
resistance is
is required.
required.A single
single 3/
3/4-in.
10-ft
ground
rod
4
will have
ohms, even
evenin soil
soil
have aa resistance
resistanceto ground of over 66 ohms,
of low
lowresistivity
resistivity (2,000
con(2,000 ohm-em).
ohm-cm). A number
number of rods connected by
to obtain
buried cable
cable can
canbebeused
used
obtain lower
lowerresistance,
resistance,
byburied
and longer
can be used where
cond~tions permit;
permit;
longer rods
rods can
where soil
soil conditions
however,
because
of
mutual
effects,
ground
resistance
does
mutual
ground resistance does
however,
or
length
not decrease
in
direct
proportion
to
the
number
decrease direct proportion the
length of
rods.
Buried
metallic
piping
or
other
existing
underground
rods. Buried metallic piping
existing underground
metallic
electrodes,
for
metallic structures,
structures,including
includingconcrete-encased
concrete-encased
electrodes,
for
example,
70,Article
Article
example, rebar
rebarin concrete
concrete foundations
foundations (see
(seeNFPA 70,
250),
frequently
electrodes.
250), are
are also
alsofrequently
usedused as
as grounding
groundingelectrodes.
Ground mats
matsconsisting
consisting of buried cables
cableswith
with or without
without
ground rods at cable
form a portion
portion
cable intersections
intersectionscommonly
commonlyform
of the grounding
grounding electrode
electrode system
system used at substations. (See
(See
IEEE
IEEE Std 142
142 for
for additional
additionalinformation.)
information.)
5.6.3 Step
Step
and
Touch
Potentials
and
Touch
Potentials
Where current
current flows
flows into
into the
the soil from a grounding electrode,
trode, potenti'al
potentialgradients
gradientsare
arecreated
created in the
the soil.
soil.The groundgrounding configuration
configuration should
should ensure
ensure that the potential gradients
gradients
will not create
create a hazard
hazard to personnel
personnel standing
standingor walking
walking on
the ground
ground in the
the vicinity
vicinityof a grounding
grounding electrode,
electrode, or touchtouching aa grounded
current.
(See
IEEE
groundedstructure
structurecarrying
carryingground
ground
current.
(See
Std 80
80 for
for additional
additionalinformation.)
information.)
5.6.4
I
I
Ground
Resistance
Measurement
Ground
Resistance
Measurement
In
installations, it is
the resish many
many
installations,
is necessary
necessary to
to measure
measure
the
resistance to earth
grounding system
earth of the grounding.
system to determine
determine if the
actual
is within
design
limits.·
actual value
value of this resistance
re&tance within
design
limits.
Meth-Methods
networkresistance
resistance are
are discussed
discussed
ods for measuring
measuring ground network
briefly
in
briefly
IEEE
Std
in IEEE Std 142,
142,
the
more
detail
ininand
and in more detail in the Standard
Standard
7
Handbook For Electrical Engineers.
Engineers?
5.6.5
Corrosion
Problems
CorrosionProblems
Copper is commonly
used for grounding
commonlyused
grounding system grids
grids
because of its resistance
resistance to corrosion
corrosion and high conductivity.
conductivity.
Because of the galvanic
couple between copper
galvanic,couple
copper and steel,
steel, an
extensive
extensive copper grounding
grounding system grid may accelerate
accelerate corcorrosion of steel
piping
and
other
btiried
structures
that
are
steel
buried structures
are
connected
to
the
system.
Under
this
condition,
galvanized
connected
system.
condition, galvanized
steel
steel ground
ground rods
rods and insulated
insulated or coated
coated copper conductors
conductors
could be used,
but care must be
be taken to ensure that the
used, but
grounding
grounding electrodes
electrodes do not corrode
con-ode and reduce
reduce their effeceffectiveness;
tiveness; and that the use of insulated
insulated or coated
coated conductors
conductors
does
does not prevent the overall
overall grounding
grounding system
system from
from mainmaintaining
taining safe step
step and touch
touch potentials.
potentials. Cathodic
Cathodic protection
protection
of the
the buried steel
steel subject to corrosion
corrosion should
should be considered
considered
to alleviate
alleviate this
this problem.
problem.
5.7
LIGHTNING
PROTECTION
5.7LIGHTNING
PROTECTION
5.7.1
General
5.7.1
General
Lightning
large electrical
electricaldischarge
discharge in the atmoatmoLightning is a very
very large'
sphere between
between the
theearth
earthand
andaacharged
chargedcloud
cloudor between two
two
oppositely
The energy
stroke
can can
oppositely charged
chargedclouds.
clouds.
energy inina lightning
a lightning
stroke
readily ignite
vapors;
andand
damage
to
to equipment
equipment and
igniteflammable
flammable
vapors;
damage
structures
can
result
from
the
flow
of
lightning
structures can resultfrom
flow lightning discharge
discharge curcurrent through
through any resistance
in
its
path.
Lightning
protection
resistance its path. Lightning protection
systems
(rods,masts,
masts,
or overhead
ground
air terminals
terminals (rods,
or overhead
ground
systems use air
wires) to intercept
intercept lightning
lightningstrokes
strokesand
andto divert
divert the lightning
lightning
current
of low
electrical
impedance.
currentto ground
ground through
throughcircuits
circuits
of low
electrical
impedance.
5.7.2 Zone of Protection
Protection
The zone of protection
protection of an air
air terminal
terminal is
is defined
defined by aa
circular
through
the tip
circular arc concave
concaveupward,
upward,passing
passing
through
theof the
theair
air
terminal
terminal and
and tangent
tangentto the ground
ground plane.
plane. For
Forcomplete
complete protection,
of the
tection, the
theradius
radius
of arc
arc must
mustbe less
less than the striking
strikingdisdistance
conservative to
tance of
of the lightning
lightning stroke.
stroke.In practice, it is conservative
use aaradius
(100 ft).
fi).For air terminals
terminals less than 15
15 m
radius of 30 m (100
(50.
ft)
above
the
ground,
the
zone
of
protection
may
(50 ft) abovethe ground,
protectionmay be
assumed
to
be
a
cone
with
its
apex
at
the
top
of the air
air termitenniassumed
its apex
nal
base radius
height. All
All
the air
air terminal
terminal height.
na1 and a base
radius equal
equal to the
structures
structures completely
completely within
within the zone
zone of protection
protection may be
considered
considered essentially
essentiallyimmune
immune from
from direct
direct lightning
lightningstrokes.
strokes.
(See NFPA 780
780 for
for additional
additional information.)
information.)
5.7.3Need
Need
for for Protection
Protection
A number of factors
should be taken
into consideration
factors
should
taken
into
consideration
when deciding
whether
or
not
lightning
protection
devices
are are
deciding whether
lightning protection
devices
The major
major factors
factorsto
to be
be considered are
are as
as follows:
follows~
required. The
a. The frequency
frequency and.severity
and severityof thunderstorms.
thunderstorms.
b. Personnel
Personnel hazards.
hazards.
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL
INSTALLATIONS
IN PETROLEUM PROCESSING PLANTS
ELECTRICAL
PROCESSING
PETROLEUM
PLANTS
lNSTALLATlONS
IN
c. Inherent
Inherentself-protection
self-protectionof
of equipment.
equipment.
c.
d. Value
Value or
or nature
nature of
of the
the structure
structureor
or contents
contents and
and of
of other
other
d.
structuresthat
that might
might be
be involved
involvedif
if lightning
lightningcaused
caused aa fire
fireor
or
structures
explosion.
explosion.
e.
by
e. Possible
Possibleoperating
operatingloss
losscaused
caused
by plant
plant shutdowns.
shutdowns.
39
39
protection
would
protection through
throughsurge
surgearresters
arresters
would be
be ininaddition
additionto
to the
the
types
of
shielding
outlined
in
5.7.4.2.
(See
IEEE
Stds
141
and
types of shielding outlined
in 5.7.4.2. (SeeIEEE Stds 141and
242
242for
for additional
additional infonnation.)
information.)
Arresters
should be
aspossible
possibleto the
to the
Arrestersshould
be installed
installed as
as close
closeas
equipment
protected.
They
equipmenttotobebe
protected.
They are
are recommended
recommendedas
as follows:
follows:
a.
andlow-voltage
low-voltageterminals
terminals
of distribution,
a. At
At both
both highhigh- and
of distribution,
and
open
bushings.
and power
power transfonners
transformerswith
with
open
bushings.
5.7.4.1 Steel
Structures,
Tanks,
Vessels,
and
5.7.4.1
Steel
Structures,
Tanks,
Vessels,
and
b.
b. At
At the
the junction of
of aa tranSfOlTI1er
transfolmer feeder
feeder cable
cable and
and openopenStacks
Stacks
wire
wire line
line for
for completely
completely enclosed
enclosed tranSfOlTI1ers.
transfolmers. Depending
Depending
on
on the
the cable
cable length
length and
and the
the arrester
arrester rating,
rating, surge
surge arresters
arresters
Ordinary
steelstructures,
structures,process
process
columns,
vessels,
Ordinary steel
columns,
vessels,
steelsteel
may
be
required
at
the
transformer
tenninals
as
well.
may
be
required
at
the
transformer
terminals
as
well.
storagetanks,
tanks, and
andsteel
steelstacks
stacks
a petroleum
processing
storage
of aofpetroleum
processing
plant plant
c.
a cable
junction
is
c. On
On open-wire
open-wirelines,
lines,atateach
eachpoint
pointwhere
where
a cable
junction
is
or
notbebeappreciably
appreciably
damaged
or similar
similar installation will
will not
damaged
by by
made.
made.
direct
However, itit is
ground
direct lightning
lightning strokes.
strokes. However,
is necessary
necessary to ground
d.
d. At
At the
the terminals
terminals of
of dry-type
dry-type transfonners
transformers when
when fed
fed from
from
the taller
tallerstructures
structuresadequately
adequately
to prevent
preventpossible
possibledamage
damageto
to
the
to
an
an exposed
exposed line.
line.
their
their reinforced
reinforced concrete
concrete foundations,
foundations, and
andto
to provide
provide aa zone
zone
e.
e. At
At the
the tenninals
terminals of
of important
important motors
motors fed
fed from
from an
an
of
of protection
protection for
for electrical
electrical apparatus
apparatusand
andother
other equipment
equipment inin
exposed
exposed line
line or
or supplied
supplied by aa transformer
transformer fed
fed from
from an
an
the
area. (See
(See API
W 2003
2003 and
780 for
for
andNFPA
NFPA 780
the immediate area.
M I RP
exposed
exposed line.
line.
additional infonnation.)
information.)
additional
f.f. On
On the
the secondary
secondary side
side of
of aa transfonner
transformer fed
fed from
from an
an
exposed
line,
for
the
protection
of
a
group
of
motors
(usuthe
protection
of
a
group
of
motors
(usuexposed
line,
for
5.7.4.2
Electric
Power
Distribution
Systems
5.7.4.2Electric
Power
Distribution
Systems
ally
ally combined
combined with
with surge
surgecapacitors
capacitors at
at the
the motor
motor terminals).
terminals).
Electric
Electric power
power distribution
distribution systems
systems should
should be
be protected
protected
Arresters
against
strokes to
Arresters installed on
on systems
systems connected
connected to
to utility
utility power
against lightning
lightning strokes
to avoid
avoid damage to
to equipment,
equipment, aa
should
utility.
should be coordinated
coordinated with
withthethe
utility.
plantshutdown,
shutdown,
personnel
andand
personnel
shock shock hazards.
hazards. Overhead
Overhead
lines can
can be
be shielded
shielded from
from lightning
lightning strokes
strokes by the
the installainstallalines
5.7.6 Instrument
LightningProtection
Protection
InstrumentLightning
tion of overhead
overhead ground
ground (static
(static shield)
shield) wires
wires that provide
provide a
triangle of protection
protection for
for the
the phase
conductors. Similarly,
Similarly,
triangle
phase conductors.
Process
systems,
remote
tanktank
gaug-gaugProcess instrument
instrument and
andcontrol
control
systems,
remote
substations
substations and outdoor
outdoor switching
switching equipment
equipment can
can be
ing
systems,
and
other
similar
low-energy
systems
can
ing systems,
other similar low-energy systems can be be
shielded
shielded by lightning
lightning towers
towers or overhead
overhead static
static shield
shield wires,
wires,
damaged
by
lightning-induced
eventhough
though they
damaged
lightning-induced transients even
but these
these shielding
shielding devices
devices must be connected
connected to
to an
an adeadeare
protected
from
direct
lightning
strokes.
Protection
against
are protectedfrom direct lightning strokes. Protection
against
grounding system
system to be effective.
effective. Aerial
Aerial cable
cable nornorquate grounding
such
transients
can
be
provided
by
combinations
of
such transients can be provided
combinations series
series
protected by its
its messenger
messenger cable
cable ifthethe
mallywill
will be protected
resistors
withZener
Zenerdiodes,
diodes,metal
metal
oxide
varistors, or other
resistors with
oxide
varistors,
messenger
messenger is
is adequately
adequately grounded
grounded at
at intervals
intervals defined
defined in
devices
to
bypass
voltage
surges
to
ground.
devices
voltage surges to ground. Most
Most equipment
equipment
ANSIlIEEE
ANSMEEE C2.
C2. If the cable
cable has a metallic
metallic sheath
sheath or armor,
armor,
of
transient
suppression
to
suppliers
can
recommend
methods
suppliers can recommend methods of transient
suppression
to
sheath or armor should
should be bonded to the messenger
messenger
the sheath
protect their equipment;
these
recommendations
should
be
equipment; these recommendations should
cable
cable at each
each grounding
grounding point. Feeders
Feeders consisting of cables
followed:
devices
must
be confollowed. To
To .be
be effective,
effective,the
theprotective
protective
devices
must
conin metallic
metallic conduit
conduit are
are essentially
essentially self-protecting;
self-protecting; but conconnected to an adequate
adequate grounding
groundingsystem.
system.
duits and
metal sheaths
and metal
sheaths should
should be properly
properly grounded
grounded and
bonded to the equipment
equipment at each end.
end.
5.7.7Surge
Surge
CapaCitors
Capacitors
5.7.4
Protected
Equipment
5.7.4Protected
Equipment
5.7.5Surge
Surge
Arresters
Arresters
Whenelectrical
electrical
equipment is connected
equipment
connected to an
an electric
electric
power distribution
distribution system
systemthat
thatis exposed
exposed to direct lightning
lightning
strokes,
surgescaused
caused by indirect
strokes, or to voltage surges
indirect lightning
lightning
strokes,
should
strokes, the
theelectrical
electricalequipment
equipment
should
be protected by
by suitsuitable surge
surge arresters.
arresters.Arresters
Arresters
have
the ability
able
have
the ability
not only to pass
essentially no current at line voltages
voltages but also
also to pass ,very
essentially
very
current at surge voltages
voltages with little
little voltage
voltage drop.
drop. This
high current
Surge
used to reduce
Surge capacitors
capacitors are
are,used
reduce the rate-of-rise of
ofvoltvoltage
age surges
surges to protect AC rotating
rotating machines
machines and
andother
otherequipequipment having
or turn-to-turn
havinglow
lowelectrical
electricalimpulse
impulse
turn-to-turn insulation
insulation
strength.
strength. They
They are usually applied in conjunction
conjunction with
with surge
surge
arresters
The capacitor voltage
arresters and
andconnected
connectedline-to-ground.
line-to-ground.
voltage
rating must
mustmatch
matchthe
the
system
voltage
for
system
voltage
andand be designed
designed for
surge
surge protection applications.
applications. The counection
connection leads
leads between
between
the capacitor
capacitor and each phase and
andbetween
betweenthe capacitors
capacitors and
and
ground must
as short as
as possible.
mustbe as
~~
Copyrighted material licensed to IDOM.
.
I
I 0732290 Ob15578
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
STD.API/PETRO RP 540-ENGL L999
~~
09b I
I
SECTION
SECTION 6-MOTORS
6-MOTORS AND CONTROLLERS
CONTROLLERS
PURPOSE
6.1 PURPOSE
6.1
that motors type
severe-duty
manufacturers
offer
Many
manufacturers
offer severe-duty type motors that
pelform well
petroleum
facility
atmospheres
(see (see IEEE
wellinin
petroleum
facility
atmospheres
This
This section
section serves as
as aa guide
guide for
for selecting and
and applying
841).
Std
This
standard
requires
Severe duty
duty
features,
high
Std
841).
This standard requires severe
features,
high
motors
the varied demands
motors and controllers
controllers to meetthe
varied
demands of theand efficiency and having
having Class
Class FF insulation
insulation with
class B
B rise.
with Class
rise.
petroleum industry.
motor would
normally have
have aa 1.15 service factor,
factor, and
and if
if
industry. It highlights considerations
considerations which must
The motor
The
would normally
be
be addressed
addressed in
in accordance with
with API Stds
Stds 541,
541, 546,
546, and
and
IEEE Std 841.
84 l.
operated1.0
service
factor
(full-load
nameplate
rating),
operated
at 1.0 service
factor
(full-load
nameplate rating), it
experience extended
extended insulation
insulationand bearing life
life because
because
will experience
of a lower
temperature.
loweroperating
operating
temperature.
6.2
SCOPE
SCOPE
Because
in in
Because of its broad
broad application,
application,the
thematerial
materialpresented
presented
sectionwill be
be general
general in nature and
andreflect
reflectcurrent
current
petrothis section
petroindustry practice.
practice. Industrial
Industrial motors
motorsand
and controllers
controllersare
are
leum industry
manufactured in accordance
accordance with applicable
manufactured
applicable standards
standards pubpubWhenmore
morespecific
specific
EEE, NEMA,
NEMA, ANSI,
ANSI,and API. When
lished by IEEE,
or detailed
detailed information
information is required,
required, the
the equipment
equipment manufacmanufacturer should
shouldbebeconsulted.
consulted.
driven equipment
equipmentisisconstant
constant
speed.
Three-phase
Most driven
speed.
Three-phase
AC AC
motors are well suited to these
these applications.
motors
applications. DC motors are
because
additional
not common in petroleumfacilities
facilities
because
additional
requirements
requirements would be necessary for their installation
installationin classified locations.
locations. The hgh
equipment and
and maintenance
maintenance costs
costs
sified
high equipment
of DC motors and
andcontrols
controlscompared
comparedwith
with
three-phase
three-phase
ACAC
motors
motors also make the DC
DCequipment
equipmentunattractive.
unattractive.
i
I
LOCATIONS
OFOF
MOTORS
ANDAND
6.4 RELATIVE
RELATIVE
LOCATIONS
MOTORS
CONTROLLERS
CONTROLLERS
common practice to
It is common
to use
usemagnetically
magneticallyoperated
operatedconcontrollers and to install
install them
them remotely
remotely from
from the
the motors.
motors.These
These
trollers
remotely mounted controllers will
will be group-mounted
group-mounted in one
or more assemblies,
assemblies, usually
usually motor
motor control
control centers
centersor switch
switch
racks. It is generally
generallynot
notpractical
practical
controllers
racks.
to to locate
locate the controllers
adjacent
in a typical
adjacent totothethemotors
motors
typicalfacility.
facility.
6.5
FREQUENCIES
FREQUENCIES
A frequency of 60 Hz is recognized
recognized as the preferred
preferred stanstansystems and
dard for
for all
all AC systems
and equipment
equipmentininNorth
NOlthAmerica.
America.
Standard motors
motors are also
also available
available for
for operation
operation at frequenfrequenStandard
cies of 25 Hz and 50 Hz.
cies
6.3 RATING
MOTOR
RATING
EFFICIENCV
MOTOR
AND
EFFICIENCY
STANDARD
6.6 ANDVOLTAGE
6.6
STANDARD VOLTAGE FOR MOTORS
MOTORS
Motors
Motors have been rerated at various
various times, usually resultresulting in smaller frame
framesizes
sizes for given
given horsepower
horsepower ratings.
ratings.The
last rerate
rerate program
resultedinin
programresulted
thethe NEMA T-frame series
series
(143T
approximately %
3/4 HP through
through 250
250HP).
HP).
(143T through
through445T, approximately
These motors
motors are rated 200 V, 230 V, 460 V, and 575
575 V.
Class
insulation is the minimum
minimum insulation
insulation used,
used,but
butClass
Class
Class B insulation
F insulation
insulation is normally
normally specified.
F
specified. Individual
Individual manufacturers
manufacturers
should be consulted
assignments.
consulted for frame
frame and
andhorsepower
horsepower
assignments.
Since
motorsmay
mayoperate
operate at
Since standard-efficiency
standard-efficiency T-frame motors
insulationand
and
bearing
temperatures,
recommended
higher insulation
bearing
temperatures,
it is recommended
care be exercised
loads.
They
that care
exercised in
insizing
sizingtheir
theirassociated
associated
loads.
They
should also
also be operated
operatedas near to rated voltage
voltageand
andfrequency
frequency
as possible.
possible.
Most of the motors
motors used in the industry
industry have
have voltage
voltage ratratings as indicated in
in 6.7.
6.7.InInaddition
additionto the ratings
ratingslisted,
listed,other
standard
areavailable
availableaqd
andareare
sometimes
used. For
standard ratings are
sometimes
used.
information
motor
ratings,
the user
information regarding
regardingstandard
standard
motor
ratings,
the should
user should
manufacturers.
refer to catalogs
catalogs and
andother data available
availablefrom manufacturers.
Additional
Additional information
information may be obtained
obtained from
from current ANSI
ANSI
and NEMA
NEMA standards.
standards.
6.7MOTOR
MOTORVOLTAGESELECTION
VOLTAGESELECTION
6.7.1
Single-Phase
Motors
6.7.1Single-phase
Motors
Most manufacturers
high- and premium-effimanufacturers now offerhighciency
price. Where
run conciency motors
motorsat an
an increase
increase in price.
Wheremotors
motorsrun
tinuously
time, the reduction
reduction in
tinuously or for long
long periods
periodsof time,
in power
power
cost will usually justify the extra
extra cost
cost of the high-efficiency
high-efficiency
motors. The justification is based on power
power cost and rate
rate of
vary
return required
required for
for the additional
additional investment.
investment. This will vary
with different
andand
types of projects.
differentcompanies
companies
types
projects. Section
Section3 3proproU.S. Energy
assistance with
with economic
economicevaluation.
evaluation.The U.S.
vides assistance
1992 (implemented October
Policy Act
Act of 1992
October 24,
24,1997)
1997)effeceffectively removes
removes standard-efficiency,
standard-efficiency, horizontal-footed
horizontal-footed motors
motors
200 HP from
market
within
rated through200
from the new motormarket
within
the the
has taken place in Canada.
United States.
States. Similar
Similaraction
action
Canada.
41
41
Single-phase motors driving
Single-phase
driving fixed
fixed equipment
equipmentusually
usually are
rated to operate at 115
115115
V V
115V or 230 V.
V. For portable
portablemotors,
motors,
is generally
generallypreferred,
preferred,except
exceptwhere
where
there is reason to
touse
use
there
equipment
lower voltage,
voltage, such
such as 32 V.
equipment designed
designed for some lower
Becausesingle-phase
single-phase
units
frequently
potentially
units
frequently
employemploy
potentially
sparking
sparking mechanisms,
mechanisms,care should be exercised
exercised in the application of this type
typeof motor in classified
classified areas.
areas.
6.7.2Three-phase
Three-Phase
Motors
Motors
Depending
localpower
powersystem
systemutilization
utilization
practice,
Depending upon local
practice,
either 460-V
460-V or 575-V ratings are preferred for 60 Hz lowvoltage
service (less
Motorswith
witha rating
a rating of
voltage service
(less than 600 V). Motors
460
V or 575
have
a voltage
460V
575VV
have
avoltage
tolerancetolerance of ±10%
f l O % (per
480-V or
1) and are
are generally
generally supplied from
from a 480-V
NEMA MG 1)
Copyrighted material licensed to IDOM.
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PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
42
'
600-V power
Motors
withwith
ratings
of 200of 200tinuously
powersystem,
system,respectively.
respectively.
Motors
ratings
tinuously or
os for extended
extended periods,
periods, the continuous
continuous duty ratinstances
V, 208 V, and 230
230V are generally
generallynot used
usedexcept
exceptin in
instances ing of the motors
motors should be reduced by some amount based
on the operating
where power
power is readilyand
andeconomically
economically
available at the
available
operating ambient temperature.
temperature. Refer to NEMA
voltages, and where 480-V
480-V or 600-V
600-V service
service
specified at ambient
ambient air temperatemperarelated service voltages,
MG 1 if the motor is to be specified
would entail undue
undueexpense.
expense.
ture exceeding
exceeding 40°C (104°F).
(104°F).
For service
servicein excess
excess of 600 V, the preferred
preferredrated
ratedvoltages
voltages
for induction
induction motors
motorsare 2,300 V and 4,000
4,000V for motors
motors up
6.8.2 High
High
Temperature
Operation
Temperature
Operation
thethe
preferred
rated motor voltHP. For larger
largesmotors,
motors,
preferred
voltto 5,000
5,000 HP.
installed where the ambient
ambient temperMotors that are to be installed
ages are
V, 6,600 V, and 13,200
thesevoltages
voltages
are4,000
4,000
13,200V; one of these
ature
will
normally
exceed
40°C
(104°F)
should
be
normally
40°C
(104°F)
be considconsidmust be
be selected
selected to suit each specific
specific application.
application. Synchrospecial.
should
provide
dependable
ered
as
special.
They
should
be
able
to
dependable
nous motors usually have
have nameplate
nameplate voltage
voltage ratings
ratings that
thatare
are
service
temperature; this includes
service at the expected
expected ambient
ambient temperature;
includes
identical
the service
identical to the
service voltage
voltage of the system to which they
fulfilling
the
requirements
for
satisfactory
lubrication
at
fulfilling
requirements
satisfactory
lubrication
are connected.
connected.
abnormally
abnormally high temperatures.
temperatures. Motors are available
available with
design ambient
ambient temperatures
temperatures nameplated higher than 40°C
6.7.3Voltage
Voltage
Breakpoint
Breakpoint
(104°F),
4SOC (113°F)
(104"F), usually 45°C
(113°F) and
and 50°C (122°F).
(122°F).
economic breakpoint
installation
of the
The economic
breakpointbetween
betweenthethe
installation
of the
low-voltage
motors (600 V class)
andthethe
medium-voltage
class)and
medium-voltage
low-voltagemotors
6.8.3 Low
Low Temperature
TemperatureOperation
motoss (2,300
(2,300V and higher)
higher)is usually ininthe
therange ofof250
250
motors
HPWhere
Whese ambient
ambient temperatures
temperatures of
of less
less than
than 10°C
10°C (50°F)
(50°F) will
300 HP.
W. Motors
Motors with
withratings
ratingsof 2,300 V and 4,000
4,000V are used
encountered
for
extended
periods,
consideration
should
be
encountered
for
extended
periods,
consideration
should
be
for sizes
sizesupup
between 2,300
V and
to to 5,000 HP.
HP. The choice
choice between
2,300V
given
to
requirements
for
lubrication
at
low
temperatures.·
The.
requirements
for
lubrication
at
low
temperatures.
The
4,000 V will depend
depend on
onthe
theeconomics
economicsof the individual
individual plant
plant
motor
manufacturer,
and
API
Stds
541
and
546
should
be
conStds
541
be
conmanufacturer,
and
HF', the economic
economic
consideration.For
Formotors
motors
above
5,000
under consideration.
above
5,000
HP,
sultedforfor
low-temperature
considerations. In many
otherother
low-temperatuse
considerations.
breakpoint may
the use of 4,000
breakpoint
maydictate
dictate'the
4,000 V or 6,600 V, with or
or
instances,
a
low-temperature
grease
issuitable.
suitable.For
For
temperainstances,
a
low-temperature
grease
is
temperawithout captive
os even
even 13,200
13,200V.
captivetransformers,
transformers,or
tures
less
than
-20°C
(-4°F),
special
material
and
machining
less than -20°C (IlOF), special material and machining
depending on the
The economic
economic breakpoint
breakpointwill
will vary depending
the local
local
required.Close
Close
coordination
the equipment
may be required.
coordination
withwith
the equipment
manu- manuconditions and the relative number of large and
and small
small motors
motorsto
to
facturer
Duty"service.
service.
facturer is suggested for
for':Arctic
"ArcticDuty"
anan
economic
be served
served at
atthe
thelocation
locationunder
underconsideration.
consideration.If If
economic
has not
not already
alreadybeen
beenestablished,
established,ititis recommended
breakpoint has
6.8.4 Elevation
that an engineering
before an installation
engineering analysis
analysis be made before
installation is
is
dividing
lihe,
begun. This analysis
analysis will
willdetermine
determinethe
theeconomic
economic
dividing
line,
Motors
are are
suitable
for installation
at ele- at eleMotors of
ofstandard
standarddesign
design
suitable
for installation
taking into
into account
accountthe
thecost
costofofnecessary
necessarytransformers,
transformers,controlcontroltaking
this
vations
up
to
1,
O
OO
meters
(3,300
feet).
Applications
above
vations
up
1,000
(3,300
feet).
Applications
above
lers, breakers,
breakers,and
andallall
other
applicable
elements.
lers,
other
applicable
elements.
elevation will
result
in in
increased
heating
and and
will require
derat- deratwill
result
increased
heating
will
require
been
After the
thebreakpoint
breakpoint has been established
establishedand
andhas
has
been
.ing
h g of the standard
standard motors, or special
special design
design and
andmanufacturmanufacturused asasa guide
a
making installations
installationsat a particular
particularplant
plant
for making
or
operating
elevation
should
specified
ing. The operating
elevation
should be specified
so that
location,
location, it is recommended
recommended that
that the
theeconomics
economicsbe restudied
manufacturers
can
make
the
necessary
allowances
for for
applicamanufacturers
can
make
the
necessary
allowances
applicaregularly to make certain
certain the previously
previously established
establisheddividing
dividing
above
1,000
meters
(3,300
feet).
When
operated
at elevations
above
1,000
meters
(3,300
feet).
When
operated
line
Allowance should be made
made for the value of
of
line still holds. Allowance
specific rating and
tions above 1,000
1,OOO meters (3,300 feet), the specific
maintaining
same
maintaining interchangeability
interchangeability between
between motors
motors of the same
altitude
should
bebe
stamped
on the
nameplate.
altitude
should
stamped
the
nameplate.
ratings and types.
types.
6.9OTHER
OTHER
CONDITIONS
AFFECTING
DESIGN
CONDITIONS
AFFECTING
DESIGN
AND APPLICATION
APPLICATION
6.7.4Supply
Supply
Voltage
Voltage
Supply
voltage
and frequency at themotor
motor
terminals
Supplyvoltage
andfrequency
terminals
should
should be maintained within
withinthe limits
limits of NEMA MG I.
l.
6.8 TEMPERATURE
ANDALTITUDE
ALTITUDE
TEMPERATUREAND
CONSIDERATIONS IN
IN MOTOR
CONSIDERATIONS
APPLICATIONS
APPLICATIONS
When motors
to unusual conditions
motorsarearesubjected
subjected
conditions and
andthere
there
is doubt about the
when
ordering,
the manufacthespecifications
specifications
when
ordering,
turer should
should be advised
advised of the unusual
unusual conditions
conditions to be met,
met,
especially
especially when
when the
the motors are
aie to be used under the condicondil.
shownininTable
Table
tions shown
1.
6.8.1
Normal
Temperature
Operation
6.8.1Normal
Temperature
Operation
6.10 TYPES
TYPES OF MOTOR
CONSTRUCTION
MOTORCONSTRUCTION
Motors of
of standard
standard design
design and construction
construction are suitable
suitable
for operation at their standard ratings,
ratings, provided the ambient
ambient
temperature
however, for
temperature does not exceed 40°C (104°F);
(104°F); however,
conditions
temperatures prevail conconditions where higher ambient
ambient temperatures
~~
~
~~
6.10.1
Usual Types
6.10.1
UsualTypes
Most of the motors used
used in petroleum facilities
facilities are of the
three-phase,
squirrel-cage
induction..type.
type. Other types
three-phase,squirrel-cage
induction
types of
~
~~
~~
~~
S T D - A P I L P E T R O R P 540-ENGL
iqSS m 0732270 Ob35580 744 14
No further reproduction or distribution permitted.
Copyrighted material licensed to IDOM.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL INSTALLATIONS IN
lNSTALL4TlONS
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
have special
economicadvantages;
advantages;
motorshave
special applications
applications or economic
their uses are
aredescribed
describedininthe following
following paragraphs.
paragraphs.
6.10.2
HorsepowerMotors
Motors
6.10.2 Fractional Horsepower
It is a common
commonand
andconvenient
convenientpractice
practice to use single-phase
single-phase
as 1/2
horsemotors for all ratings up
uptotoa a fixed
fixed size,
size, such as
'/2 horsehorsepower, and
andtoto
three-phase
motors for
useuse
three-phase
motors
power or 1 horsepower,
higher horsepower ratings. When a three-phase, low-voltage
low-voltage
supply is readilyavailable,
available,
there
economical
there
may may be aneconomical
advantage
small
three-phase
motors.
Three-phase
advantage to usingsmall
three-phase
motors.
Three-phase
motors
from
a maintenance
motors are advantageous
advantageousfrom
amaintenance
and and safety
safety
standpoint
because
they
contain
no
contact-making
device.
standpoint
they contain no contact-making device.
An engineering analysis to determine
determine if
if small
small three-phase
three-phase
motors can
used
should
be made
for each application
canbebe
used
should
be made
applicationwhen
when
the answer is not obvious.
supobvious. The
The difference
difference in
in the cost of supthe two
two types,
types, when considplying current
current to the motors
motors of the
considfactors, is often sufficient
ered with
with other cost factors,
sufficient to
todetermine
determine
installationshould
shouldbe made.
which installation
6.10.3
Synchronous
Motors
SynchronousMotors
Generally,
synchronousmotors
motorsareare
considered for
Generally, synchronous
considered
for largeslow-speed applications
applications where power factor
factor
horsepower and slow-speed
43
improvements are
are justified and
characteristics
improvements
andwhere
where other characteristics
suit the applications.
Low-speed
engine-type
synchronous
applications.Low-speed
engine-type
synchronous
motors are
are well suited
suited for
for use as drives
drives for
forslow-speed
slow-speedequipequipsuchas reciprocating compressors
compressorsand
andpumps.
pumps.
Synchroment such
Synchrooften
are used instead
instead ofinduction
motors,
induction
motors,
nousmotors
motors
often are
pmticularly
practical
par&icularly at speeds
speeds less
less than 514 rpm where it is practical
to avoid
avoid the
the use
useof gears or other speed-reducing
speed-reducing equipment.
equipment.
are well adapted for use as
High-speed synchronous motors m·e
large rotating
rotatingequipment
equipmentsuch
suchas as
fans, blowers, and
and
fans,
drives for lm·ge
centrifugal
centrifugalpumps. When
Whenthe resulting improvement
improvementininpower
power
satisfactoryrate
rate of return on
factor
factor or efficiency will yield aa satisfactoly
additional investment
required, synchronous
synchronous motors
are
the additional
investment required,
motors are
prefelred
squirrel-cageinduction
induction motors.
motors.
prefelTed over squilTel-cage
A 1.0 power factor
factor synchronous
synchronous motor
motoris usually the most
it will have a lower pullout
efficientselection;
selection;
however,
however,
itwillhave
factor synchronous
synchronous motor.
motor. This
torque than a leading
leading power
power factor
may be a significant
significant consideration
considerationif system voltage dips
dips are
expected during
duringoperation.
operation.
now used
Brushless synchronous
synchronous motors
motors are now
usedextensively
extensively
in"
brushless system
in' petroleum facilities.
facilities. For excitation,
excitation, the brushless
an AC exciter
shaft-mounted diode
dioderectification.
rectification.
uses an
exciter with shaft-mounted
exciter, in tum,
turn, receives
excitation and control
The AC exciter,
receives its excitation
assembly
andand rheostat
rheostat fed from
from aasmall
smallrectifier
rectifier
assembly
from the
Table 1-Conditions
Affecting Motor Design
1-Conditions Affecting
Design
plied
Conditions
Generally
Conditions
Exposed to
tochemical
chemicalfumes.
fumes.
Operated in
indamp
dampplaces.
places.
Should
Should use
usea chemical-type
chemical-typemotor.
motor.
Driven at speeds
speeds ininexcess
excessof rated speed.
speed.
Consult manufacturer.
manufacturer.
Exposed
Exposed totosteam.
steam.
Should
enclosed.
Shouldbebetotally
totally
enclosed.
Operated ininpoorly
spaces.
poorlyventilated
ventilated
spaces.
Oversize
Oversize the
themotor.
motor.
For large
or TEWAC
enclosure.
largemotors,
motors,consider
considerTEPV
TEPV
or TEWAC
enclosure.
Operated
Class I locations.
locations.
Operated in Class
See 6.13.
Generally Applied Types
Should
or or
sealed
insulation
system
and
Should use
useadditional
additionalimpregnation
impregnation
sealed
insulation
system
space heater
motor
enclosure
and main terminal box.
heaterwithin
withinthethe
motor
enclosure
box.
(50°F)
Exposed
(50°F) or over
over40°C
40°C(104°F).
(104°F).
Exposed tototemperatures
temperaturesunder
underlOoC
10°C
andand
materials.
Consider
lubrication,
Consider special
specialinsulation,
insulation,
lubrication,
materials.
Exposed to
tooil
oilvapor.
vapor.
Consider totally
totallyenclosed
enclosedmotors.
motors.
Exposed to
tosalt
saltair.
air.
andand
severe-duty
motors.
Should
construction
Should use
usetotally
totallyenclosed
enclosed
construction
severe-duty
motors.
Exposed to the weather.
weather.
or weather-protected
Type Type
II motors.
Consider
Consider totally
totallyenclosed
enclosed
or weather-protected
abnormal shock
shockororvibration
vibration
from
external
sources.
Exposed to abnormal
from
external
sources.
manufacturer.
Consult manufacturer.
Where departure
departurefrom
fromrated
rated
voltage
exceeds
the limits
specified
Where
voltage
exceeds
the limits
specified
in
NEMAMGl.
NEMA
MG 1.
manufacturer.
Consult manufacturer.
whereparallel
paralleloperation
operation
of motor-driven
generator
manufacturer.
Applications where
of motor-driven
generator
is is Consult manufacturer.
where
two or
more
required
required ororsimilar
similarapplications
applications
where
two
more motors
motorsneed
need
to speed-torque
characteristics.
to be
bematched
matchedaccording
according
to speed-torque
characteristics.
i
I
I
Unbalanced
Unbalanced
voltage.
supply supply voltage.
Operatedatelevations
at elevations greater
sea
level.
geater than 1,000
1O
, OOm (3,300
(3,300ft)
ft) above
abovesea
level.
Other
unusual
conditions,
such
as
extended
period
of
idleness,
speOther unusual conditions, such as extended period of idleness, special torque
or or
unusual
operating
duty. duty.
torquerequirements,
requirements,
unusual
operating
Adjustable speed
applications.
speed applications.
Consult manufacturer.
manufacturer.
Should
(consult
manufacturer).
Should bebederated
derated
(consult
manufacturer).
Should bebederated
derated
(consult
manufacturer).
Should
(consult
manufacturer).
Consult manufacturer.
manufacturer.
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
~
i
API RECOMMENDED
RECOMMENDED PRACTICE
PRACTICE 540
540
API
44
44
same AC
AC source
source as
as the
the motor,
motor, or
or from
from aa shaft-driven
same
shaft-driven permapermanent-magnet generator.
There are
are no
no brushes,
nent-magnet
generator.There
brushes, commutator,
commutator,oror
collector rings;
rings; these
these have
have been
been the
the disadvantages
disadvantages of
of synsyncollector
past. Since there are no arcing
chronous machinesininthethe
past.
used
devices ininthethe, brushless motor, it can beused
in in Class I,
Division 2, or Zone
Zone 2 locations.
synchronous motor
When a synchronous
motor installation
installation isis made,
made,it is recommended that
thatthe
themotor's
motor’s
DC excitation be arranged so that
it is not readily
readilyadjustable
adjustableby untrained personnel,
personnel, and
andit can
excitation
maintained. Otherwise,
be seen
seen that
thatthe
theproper
proper
excitation
is maintained.
Otherwise,it
may be found that
thatexcitation
excitationis not
is being maintained
maintainedatata nora norof
malvalue;
value; with the result thatthe
the
anticipated
amount
anticipatedamount
of
improvement is not being realized in actual serpower factor improvement
serof the motor may be adversely
adversely
vice. Also, the performance of
affected.
affected.
Unless there
thereis a clear economic justification
justificationfor prefening
a synchronous
motor
over
an
induction
motor
(under the presynchronous motor over an induction
motor
preceding conditions),
the
squirrel-cage
induction
conditions), squirrel-cage inductionmotor,
motor,genergenerrecommended because of its greater
ally, would
ally,
wouldbe recommended
greatersimplicity,
simplicity,
reliability, and maintainability.
reliability,
maintainability.
Adjustable Speed
SpeedDrives
Drives
6.10.4 Adjustable
The use of an
anadjustable
adjustable speed
speeddrive
drive and motor instead
insteadof a
constant
speed
motor
to
meet
process
service
conditions
constant
motor
service conditions or
save
an adjustable-speed
save energy
energyisisoften
oftendesirable.
desirable.Typically,
Typically,
adjustable-speed
following
types:
and
motor drive
drive isisone
oneofof
thethe
following
types:
a aDC
DC drive
drive and
andmotor,
motor, or a
motor,
motor, an adjustable-frequency
adjustable-frequency AC drive
driveand
wound-rotor motor
motordrive.
drive.
Although the
the applications
applicationsofofadjustable-speed
adjustable-speeddrives
drives are
are
somewhat
limited, their use in
intoday’s
today's
facilities is gaining
somewhat limited,
facilities
gaining
popularity.
compressor, and blower
popularity. Pump, compressor,
blower applications
applications may
may
allow
flow by
by speed
speed control
control without
without utilizing
utilizingconconallow changes
changesin flow
conventional control
trol
trol valves or dampers.
dampers. Elimination
Elimination of conventional
valves,
added energy
energy
valves, dampers,
dampers, and
and gearboxes
gearboxes may
may result in added
and
investment
savings;
the use
use of adjustabie-speed
adjustable-speed
andinvestment
savings;
and and the
drives
drives where
where load
loadvaries
varieswill
willallow
allowfor
for more
more efficient
efficientenergy
energy
utilization
utilization because
becausethese
these drives
drives can
can be
be very
very efficient,
efficient, even
evenat
at
reduced
reduced speeds.
speeds.
6.10.4.1
6.10.4.1
DC
MotorDrives
Drives
DCMotor
The
The DC
DC motor
motor design,.
design, one
one of
of the
the initial
initial arrangements
arrangements of
of
electromechanical
conversion, has
electromechanicalconversion,
has existed
existed for
for many
many years.
years.
DC
DC motors
motors may
may be
be used
used over
over their
their entire
entire speed
speed range,
range, from
from
0%
0% to
to 100%
100%of
of their
their rated
rated speed.
speed. Some
Some characteristics
characteristicswhich
which
make
adjustable
speed
DC motors
motorsdesirable,
desirable,besides
besides
adjustable
speed use,
use, are:
Fe:
make DC
excellent
starting
torque
characteristics;
relatively
high
excellent starting
characteristics; relatively high effiefficiency
ciencythroughout
throughoutthe
the speed
speedrange;
range;and
and reliability.
reliability.
Most
Most DC
DC motors
motors are
are powered
powered from
from AC-to-DC
AC-to-DC rectifiers,
rectifiers,
and
and the
the rectifiers
rectifiersare
are typically
typically installed
installedin
in locations
locationsthat
thathave
have
controlled
drives
controlled environments.
environments.These
These
drivesare
are available
availableinina wide
awide
range
rangeof
of sizes.
sizes.
drives are
areused
usedin
Some of
waysthat
of the ways
that DC
DC motor
motor drives
in petroleum
facilitiesare
areas
leum facilities
as follows:
follows:
a. Vessel agitators.
b. Conveyor systems.
systems.
c. Continuous mixers
mixers and
andextruders
extrudersand
and pelletizers (mainly
in the petrochemical
petrochemicalindustry).
industry).
d. Blenders.
e.Fans.
Fans.
f. Production drilling
drillingtop
topdrive
driveand draw works.
g. Production drilling
drillingmud
mudpumps.
pumps.
DC motor drives
disadvantages:
theythey
require
driveshave
havesome
some
disadvantages:
require
more maintenance
maintenance compared
comparedtotoother motor
types and, espeespemotortypes
cially in larger horsepower sizes,
sizes, they are
are more difficult to
apply in a classified location. DC motor drives
drives using
using AC-toAC-toDC rectifiers also have relatively
relatively poor power factors at low
low
speeds,
whichisistypical
typical
of
converterdrives.
drives.
of static converter
speeds, which
6.10.4.2 AdjustableFrequency
FrequencyDrives
Drives
Adjustable-frequency
drives are
are available
availableininsizes ranging
Adjustable-frequency drives
ranging
from fractional
P,
fractionalhorsepower
horsepowerunits
units to units over 60,000
60,000 HHP,
depending
onthe
themanufacturer.
manufacturer.Both squirrel-cage
induction
depending on
squirrel-cage induction
synchronous motors
motors may be used
adjustable-freand synchronous
used with adjustable-frequency drives. The AC drives typically.
quency
typically may operate within
10% to 100%
100% of their rated
speed, with some
the range
range of 10%
rated speed,
some
units capable
capable of operating in excess
excessofoftheir
rated
speed.
their
speed.
‘11,000 rpm at an output rating of
Speedsinin
excess
of of H,OOO
Speeds
excess
have been
beenachieved.
achieved.Use
Use
of the
higher
3,500 HP have
of the
higher
output rating
motors requires
requires care in application,
application, operaor higher speed
speed motors
tion, and maintenance.
maintenance.Some
characteristics
which
tion,
Some
characteristics
which make
adjustable-frequency AC
AC
drives
desirable,
besides
theirbesides their
adjustable-frequency
drives
desirable,
are their good
adjustable speed, are
adjustable
good starting-torque
starting-torquecharacterischaracteriseffitics; their
to provide
provide aa soft
soft start;
start; their high effitics;
theircapability
capability to
ciency; their
their reliability;
reliability;their
maintenance needs;
needs; and
ciency;
their low maintenance
their no-fault
no-faultcontribution.
contribution.
their
Large adjustable-frequency
adjustable-frequency drives
drives generally
generally use
use aa AC-toLarge
DC rectifier
rectifier coupled
coupledthrough
through
a smoothing
reactor
to aa DC-toDC-toDC
a smoothing
reactor
to
AC inverter.
inverter.The
The power
power module
moduleenclosure
enclosurefor
for large
large machines
machines
AC
requires aacontrolled
andand
adequate
clearhces
requires
controlledenvironment
environment
adequate clearances
for maintenance.
maintenance.
for
Among the
the uses
uses of
of adjustable-frequency
adjustable-frequencyAC
ACdrives
drivesin
in the
the
Among
petroleumfacilities
facilitiesare
are the
the following:
following:
petroleum
a. Continuous
pelletizers
(mainly
in
a.
Continuous mixers,
mixers,extruders,
extruders,and
and
pelletizers
(mainly in
the petrochemical
petrochemicalindustry).
industry).
the
b.Vessel
agitators.
b.
Vessel agitators.
c.Conveyors.
c.
Conveyors.
d.
d. Pumps.
Pumps.
e.Blowers.
e.
Blowers.
f.f.Compressors.
Compressors.
g.
g. Fans.
Fans.
are
Some disadvantages
disadvantagesofofadjustable-frequency
adjustable-frequencyAC
ACdrives
drivesare
Some
theirinitial
initialcost,
cost, which
whichisishigher
higherthan
thansome
someother
otherspeed
speed
control
their
control
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
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ELECTRICAL
lNSTALLATlONS IN PETROLEUM PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
45
systems,
controls,
which
may require
more space
systems, and
andtheir
their
controls,
which
may require
morethan
space than
weather. This applies particularly
drivers,and
andassoassoweather.
particularlyto pumps, drivers,
most other
These
drives
also also
produce
harmonics
otherdrive
drivesystems.
systems.
These
drives
produce
harmonics ciated equipment which are well-suited for outdoor
outdoor service.
service.
that,
cause
distribution
system
problems,
that, if not
notcontrolled,
controlled,may
may
cause
distribution
system
problems, In most cases, using equipment well-suited for outdoor
outdoor sersuch
as excessive
excessivedistribution
distribution· system voltage
voltagedistortion
distortionand
and
such as
vice
vice saves
saves substantial
substantial expenditures
expendituresfor buildings
buildings in which to
overheating of
of the
the driven
drivenmotor.
motor.These
Thesecharacteristics
characteristicsvary by
overheating
house
equipment. Since
house equipment.
Since these
these buildings
buildings tend to confine
confine and
manufacturer
accumulate
released
by the
process
manufacturer and
andchive
dive type and
and should
shouldbe
bereviewed
reviewedindividuindividuaccumulate the
thevolatile
volatilehydrocarbons
hydrocarbons
released
by process
ally.
of of
thethe
chive's
equipment
ally. Special
Specialconsiderations
considerationsmay
mayinclude
includefiltering
filtering
dive’s
equipment located
located within
within their
their walls
walls and in their immediate
immediate
output
overstress of the motor
motorwinding
windinginsulation
insulation
output to prevent overstress
area,
area, outdoor
outdoor installations
installations may also
also simplify
simplify the problem
problem of
motorwinding
windinginsulation
insulation
preventing
of such releases.
from excessive
excessive dvidt,
dvldt, or providing motor
preventing the
theaccumulation
accumulation
releases. Experience
Experience has
capable
thethe
additional
voltage
stress.stress.
capable ofofwithstanding
withstanding
additional
voltage
electric motors
motors is practical
shown that outdoor
shown
outdooroperation
operation of electric
practical
Operating
dutyrequirements,
requirements,
as efficiency,
and economical
equipment.
Operatingduty
suchsuch
asefficiency,
power power
economical with
withproperly
properlyselected
selected
equipment.
factor,
range,
andand
CUlTent
in-rush,
shouldshould
be
factor, harmonics,
harmonics,speed
speed
range,
current
in-rush,
be
specified
specified for all
all applications.
applications. Depending
Dependingon the criticality
criticality of
6.11.2
Outdoor
Service
6.11.2Outdoor
Service
arrangement,
or a backup chive,
the application,
application,a abypass
bypass
arrangement,
drive, or a
The following
following types
typesof totally
totallyenclosed
enclosedmotors
motors for outdoor
outdoor
drive control
controlmodule
moduleshould
should
be considered.
considered.
service
service are obtainable:
obtainable:
’
6.10.4.3
MotorDrives
Drives
6.1 0.4.3 Wound-Rotor Motor
The wound-rotor
motor
is similar to thesquirrel-cage
squirrel-cage
wound-rotormotor
issimilar
induction motor
motor except
exceptthat
thatthe
the rotor cage winding
winding is conconcollector
"slip") rings
carbon
nected to a set ofcollector
(or(or
“slip”)
rings andcarbon
brushes. An external
connected
to the
brushes.
external adjustable
adjustableresistance
resistanceis is
connected
to
collector rings,
collector
rings, which
which allows
allows the
themotor
motorspeed
speed to be varied.
varied.
Incremental
steps are obtained through
through an arrangement
Incrementalsteps
arrangement of
contractors
contractors and heavy
heavy duty
duty (cast
(castiron
ironororsteel)
steel)resistors.
resistors.Near
Near
infinite
is achieved
achieved with
withaaliquid
liquidrheostat
rheostatsystem.
system.
infinite variability is
wound-rotor motor
operates
within
the the
The wound-rotor
motordrive
drivetypically
typically
operates
within
250/0--100%
range
of
its
base
rated
speed.
As
other
adjustable250/0-100%
speed.
adjustablespeed drive
drive systems
systems have improved,
improved, the
the use
use of wound-rotor
speed
wound-rotor
motor drives
driveshas
hasdiminished.
diminished.
Some
characteristics which make
make the
thewound-rotor
wound-rotormotor
motor
Some characteristics
desirable
are: high
highstarting
startingtorque;
torque;reduced
reduced
in-rush
current;
desirable are:
in-rush
current;
suitability for high-inertia
high-inertia loads
and suitability
loads requiring
requiringclosely
closelyconcontrolled acceleration.
acceleration.
Except for the addition
the rotor circuit speed
addition of the
speed control,
control,
the starting
for the wound-rotor
wound-rotor motor
is similar
startingmethod
method
motordrive
drive
similar
to the
method
for the AC induction
thestarting
starting
method
induction motor.
motor.The uses of
of
the wound-rotor
wound-rotormotor
motordrive
drivein petroleum
petroleum facilities
facilities are rather
rather
limited,
though. Some
limited,though.
Some disadvantages
disadvantages of the wound-rotor
wound-rotor
driveareareas follows:
follows:
motor drive
a.
problemsinin
a. The motor collector
collector rings cause
cause enclosure
enclosureproblems
This motor is complicated
complicated to build because
becauseofof
classified areas.
areas.This
classified
the rotor.
rotor.
b. The limited
speedadjustment
adjustmentrange
rangeisisgenerally
generally
smaller
limited speed
smaller
othersystems.
systems.
than other
c. The motors have lower
lower efficiency
efficiency at lower speeds due
due to
dissipation of
ofrotor
rotorcurrent
current
through
external
resistors.
heat dissipation
through
external
resistors.
Slip
Slip recovery
recovery systems
systems can be
beused
usedto help improve
improveefficiency.
efficiency.
6.11
6.1 1 INSTALLATION
INSTALLATION
1
I
I
l
6.1 1.1 General
General
6.11.1
Generally,
Generally, electrical
electrical and
and mechanical equipment for petropetroleum
facilities
is
installed
outdoors
without
shelter
from
leum
facilities is installed outdoors without shelter from
thethe
a.
Nonexplosionproof.
a.Nonexplosionproof.
Explosionproof.
b. Explosionproof.
c. Pipe-ventilated,
eitherself-ventilated
self-ventilatedororforced-ventilated.
forced-ventilated.
c.
Pipe-ventilated, either
d.
d. Water-air-cooled.
Water-air-cooled.
e.Air-to-air-cooled.
Air-to-air-cooled.
Open weather-protected
weather-protectedmotors
motorsofofvarious
variousdesigns
designs(NEMA
Type II or II) are available,
available,with air
air filters
filters as an optional
optional accessory.
sizes above
above250 lIP,
H P , weather-protected
weather-protectedType
TypeII motors
sory. In sizes
have
been
used
have gained
gained wide
wideacceptance.
acceptance.Dripproof
Dripprooftypes
typeshave
have
been
used
in various
various applications
applications but
butare
arenot
notusually
usuallyrecommended
recommendedforfor
general
outdoor
in processing
plants. MG
(NEMA MG 1,
generaloutdoor
useuse
inprocessing
plants.(NEMA
Part 1,
provides aafull
of enclosure
1, provides
fulldescription
description
enclosuretype~.)
types.)
6.11.3Accessibility
6.11.3
Accessibility
motors should
shouldbebedesigned
designedto permit ready
ready removal
removal of
of
All motors
the rotor and the bearings
bearingsand facilitate
facilitate the flushing
flushingand
andrelurelubearings. To facilitate
facilitate inspections,
inspections, adjustadjustbrication of the bearings.
ments,
and
repairs,
all enclosed
brush-type
synchronous,
ments,and
repairs,
allenclosed
brush-type
synchronous,
enclosedwound-rotor,
wound-rotor,
enclosed
commutating
andand
enclosed
commutating
motors motors
should have
thethe
should
have removable
removable covers
covers to allow ready
readyaccess
accesstoto
brushes,
slip rings, and commutator.
commutator. Eyebolts,
Eyebolts, or the equivaequivabrushes, slip
lent,
lent, should
should be
be provided
providedfor
forlifting
liftingmotors
motorsor parts weighing
(150 lbs).
lbs).
more than 65 kg (150
OFTOTALLY
ENCLOSED
6.12CONSTRUCTION
CONSTRUCTION
OFTOTALLY
ENCLOSED
MOTORS
MOTORS
External housings
completely
encase
totally
enclosed
housingsshould
should
completely
encase
totally
enclosed
thestator
statorlaminations
laminationsform
form
a part
motors. Designs
Designsin which the
motors.
a part
of
enclosure,or in which
which the
thestator
statorlaminations
laminations
otherwise
the enclosure,
areare
otherwise
exposed
air, are not
notrecommended.
recommended.
exposed to the external
externalcooling
coolingair,
be’of
of cast
Motor frames and
and enclosures
enclosures preferably
preferably should
should be'
iron
iron because
becausemotors
motors
constructionareare
suited
for conof this construction
bestbest
suited
for conditions where they are
are used
usedoutdoors
outdoors or exposed
exposed to
to corrosive
corrosive
conditions.
small
conditions. Cast
Castiron
ironis not always
always available
availablefor
forthe very small
or very large horsepower
horsepower sizes.
sizes. For
Forthese
thesecases,
cases,steel
steelofofadeadequate
a proper
protective
coating
is acceptable.
acceptable.
quate thickness
thicknesswith
with
a proper
protective
coating
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46
46
API
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
540
The
Theconduit
conduitor
orterminal
terminalbox
boxshould
shouldbe
beof
ofcast
castconstruction
construction
and
andshould
shouldhave
havea ahub
hubthreaded
threadedfor
fordgid
rigid conduit.
conduit.For
Forlarger
larger
onlysheet
sheetsteel
steel
boxes may
horsepower
horsepowersizes,
sizes, only
boxes
may be
be available
available
devices
suchsuch
(see
841),particularly
particularlywhere
whereauxiliary
auxiliary
devices
(seeIEEE
IEEEStd
Std841),
asassurge
capacitors,
lightning
arresters,
or
differential
current
surge capacitors, lightning arresters,or differential current
transformers
transformersare
areused.
used.
Vertical
motors
have
a drip
Vertical motorsshould
should
have
drip
a shield
shieldover
overthe
thefan.
fan.
6.13
MOTORS
FOR
CLASS
I LOCATIONS
6.13MOTORS
FOR
CLASS
ILOCATIONS
6.13.1
Division
1 or
Zone 11
6.13.1Division
1or
Zone
repair
isisduly
by the
repairfacility
facilitywhich
which
dulyauthOlized
authorized(generally
(generally
by odgthe originalNRTL).
inal NRTL).
6.13.2
Division 22or
6.13.2 Division
orZone
Zone 22
6.13.2.1
Motors
Having
Arc-Making
Devices
6.13.2.1Motors
Having
Arc-Making
Devices
Motors
or
Motorsfor
foruse
useininClass
ClassI,I,Division
Division2,2,locations,
locations,
orininZone
Zone2 2
locations,
as
defined
in
NFPA
70,
shall
be
the
totally
enclosed,
locations, as defined in NFPA70, shall be the totally enclosed,
forClass
Class I,I, Division
explosionproof-type
explosionproof-typeapproved
approved for
Division 1,1,localocations
when
the
following
devices
are
used
in
the
tions whenthe following devicesare used in themotors:
motors:
a.a. Sliding
Slidingcontacts.
contacts.
b.b. Centrifugal
other
mechanisms,
Centrifugaloror
other
types types of
of switching
switchingmechanisms,
including
motor
overcurrent
devices.
Motors
including motor overcurrent devices.
Motorsforforuse
useininClass
ClassI,I,Division
Division1,1,locations,
locations,as
asdefined
definedinin
c.c.Integral
Integralresistance
resistance devices,
whilethethe
motors
NFPA
explosionproof
typetype
and must
be
devices, used
usedwhile
motors
are are
NFPA70,
70,should
shouldbebethethe
explosionproof
and must
besuitsuitable
thethe
specific
conditions
to betoencOlmtered
in in either
eitherstarting
startingor
orruooing.
running.
ablefuruse
for useunder
under
specific
conditions
be encountered
service.
on the
motor may
the specific
specificconditions,
conditions,aa motor
may
service. Depending
Depending on
IfIf these
provided
with
separate
explothesedevices,
devices,however,
however,areare
provided
with
separate
explohave
to
be
suitable
for
Class
I,
Groups
A,
B,
C,
or
D.
If
a
motor
B, C,
have to be suitable for Class I, Groups
A,or D. If a motor
sionproof
enclosures
approved
for
Class
I
locations,
then
motor
I
locations,
then
motor
sionproof
enclosures
approved
for
Class
size
available as
and B,
as explosionproof
explosionprooffor
for Groups
Groups A
A and
B,
sizeisis not
not available
enclosures
6.13.2.2
maymay
be
enclosurescomplying
complyingwith
with
6.13.2.2
beutilized.
utilized.
then
totally
enclosed
pipe-ventilated
motors,
totally
enclosed
then totally enclosed pipe-ventilated motors, totally enclosed
inert-gas-filled
submersible-type
motors·
must
inert-gas-filledmotors,
motors,ororsubmersible-type
motors
must
be be
6.13.2.2
Motors
Having
Arc-Making
Devices
6.13.2.2Motors
Having
NoNo
Arc-Making
Devices
used.
For
more
complete
details,
NFPA
70
may
bereferenced.
used. For more complete details, NFPA70 may be referenced.
An
type
"Ex“Ex
e"
In
2,locations,
locations, or
Anincreased
increasedsafety
safety
type
e”motor
motorisissuitable
suitablefor
forareas
areas
In Class
Class I,I, Division
Division 2,
or inin Zone
Zone 22 locations,
locations,
as
Zone
1,
but
not
for
Division
1
areas.
Motors
are
classified
NFPA
70
permits
the
installation
of
squirrel-cage
classified as Zone1, but not for Division 1 areas. Motors are
NFPA 70 permits the installation 6f squirrel-cageinduction
induction
motors
not
areas.This
Thistype
type
Thisisis
notrecommended
recommendedfor
forinstallation
installationininZone
Zone Oareas.
motorsininenclosures
enclosuresother
otherthan
thanexplosionproof-type.
explosionproof-type.This
permitted
because
it
of
motor
is
designed
to
have
excellent
winding
integrity;
limis
not
probable
that
a
motor
will
fail
fail elecof motor is designed to have excellent winding integrity; lim- permitted becauseit is not probable that a motor willelecits
andand
external
temperatures
duringduring
starting,
gases or
trically
tricallyduring
during those
those rare
rare periods
periods when
when gases
or vapors
vapors are
are
itsononinternal
internal
external
temperatures
starting,operoperquantities.
ation,
clearances
between
the the present
ation,and
andstalled
stalledconditions;
con&tions;defined
defined
clearances
between
presentininignitable
ignitable
quantities.
rotating
Amotor
rotatingand
and stationary
stationaryparts;
parts;and
and power
power terminals
terminals that
thathave
have
orZone
Zone22
A motorintended
intendedforforuse
useininClass
ClassI,I,Division
Division22or
provisions
service
constructed so
generallyaa TEFC
TEFCmotor,
motor,
provisionsagainst
against loosening.
loosening. ItIt isis generally
serviceshould
should be·
be constructed
so that
that induced
induced currents
currentswill
will
but
type.
not
nor
capable
Anintegral
integralpart
partof
ofthe
the
butcan
canbe
beof
ofany
anytotally
totallyenclosed
enclosed
type.An
notproduce
producearcing,
arcing,
norproduce
producesurface
surfacetemperatures
temperatures
capable
increased
"Ex
isisthe
of
of
increasedsafety
safetytype
type
“Exe"
e”motor
motorapplication
application
theuse
useof
ofaa
ofcausing
causingignition
ignition
ofthe
theflammable
flammablevapor.
vapor.
specific
motor toto limit
specificoverload
overloadrelay
relay with
with the
the motor
limittemperatures
temperatures
during
6.13.3
General
duringaastall
stallor
oroverload.
overload.
6.13.3General
6.13.1.1
Suitable
Types
6.13.1.1Suitable
Types
°
6.13.1.2
Nationally
RecognizedTesting
Laboratory
6.13.1.2Nationally
RecognizedTesting
Laboratory
(NRTL)
Approval
(NRTL) Approval
When
available,motors
motors
should bear
Whenavailable,
should
bear an
an NRTL
NRTL label
label of
of
approval
gas
approvalforforthethe
gasor
orvapor
vaporinvolved.
involved.The
Thelabel
labelshall
shallinclude
include
temperature
NFF’A 70
70for
for
temperaturelimits
limitsor
orother
otheritems
itemsas
asrequired
requiredby
byNFPA
approved
approvedequipment.
equipment.
Most
test larger
particularly
Most laboratories
laboratoriescannot
cannot test
larger motors,
motors, particularly
those
with
voltage
ratings
exceeding
600
V.
Where
600 V. Wherethird-party
third-party
those with voltage ratings exceeding
approval
is
desired,
the
manufacturer
approval is desired, the manufacturercan
cangenerally
generallyperform
perform
the
thetests
testsrequired
requiredfor
forconformance
conformanceatatthe
themanufacturing
manufacturingsite
site
and
the third
third party
party for
for approval.
approval.Site
Site
and submit
submitthe
the results
results to
to the
and
with
approval
approvalmay
mayalso
alsobeberequired
required
andthe
theuser
usershould
shouldwork
work
with
the
local
"authority
having
jurisdiction"
(see
the
NFPA
70)
(see the NFPA 70)toto
the local “authority having jurisdiction”
determine
or
determinethe
theapproval
approval
orlabeling
labelingrequirements.
requirements.
·6.13.1.3
Care in
6.13.1.3Care
inInspection
Inspection
The
approvallabel
label
becomes
voidthe
when the
The hazardous
hazardousapproval
becomes
voidwhen
motor
enclosure
is
opened
unless
the
work
is
performed
the work is performedby
byaa
motor enclosure is opened unless
6.13.3.1
Mechanical
Requirements
6.13.3.1
Mechanical
Requirements
Motors
Motorsfor
foruse
useininaaClass
ClassIIarea,
area,either
eitherDivision
Division11or
orDiviDivision
2,
should
be
nonsparking
mechanically
as
well
as
as well aselectrielectrision 2, should be nonsparking mechanically
cally.
example, the
the fan
fan-cooled motor
motor
cally. For
For example,
fan or
or fans
fans of
of aa fan-cooled
should
of nonsparking
material.
shouldbebemade
made
of nonsparking
material.
6.13.3.2
OtherFactors
6.13.3.2
Other
Factors
’
Even
Evenwhen
when other
otherconsiderations
considerationsmay
may not
not dictate
dictatethe
the use
use
of
totally
enclosed
motors,
factors
like
dust,
dirt,
drifting
of totally enclosed motors, factors like dust, dirt, drifting
snow,
ofencloenclosnow,and
andcorrosive
corrosivefumes
fumesmay
mayinfluence
influencethe
thetype
typeof
sure
suretotobe
beused.
used.
6.13.4
Totally
Enclosed
Forced-Ventilated (TEFV)
6.13.4Totally
Enclosed
Forced-Ventilated
(TEFV)
Motors
as
Motors(also
(alsoknown
known
asTotally
TotallyEnclosed
Enclosed
Pipe
[TEPV])
VEPVI)
PipeVentilated
Ventilated
If
classified location
locationrequires
requiresaasynsynIf an
an application
application for
for a classified
chronous
or
wound-rotor
induction
motor,
a
motor
with
chronous or wound-rotor
motor, a motor with a
Totally
Enclosed
Forced-Ventilated
(or
TEPV)enclosure
enclosuremay
may
Totally Enclosed Forced-Ventilated(orTEPV)
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ELECTRICAL
INSTALLATIONS
IN
PROCESSING
PLANTS
ELECTRICAL
INSTALLATIONS
IN PETROLEUM PROCESSING
PLANTS
be used to meet the requirements
requirements of
ofthe classified location.
location.InIn
some
cases,
the
design
will
permit
a
pressurized
enclosure
some cases,
design will permit a pressurized enclosure
collector or slip
slip rings only;
only; an example
exampleof this type
type
around the collector
of motor
steel
metal
housing.
motoris one built
builtwith
witha gasketed
a gasketed
steel
metal
housing.
If
or slip
rings, it is recommended
If a motor
motorhas
hasbrushes
brushes
or slip
rings,
recommendedthat
that
its enclosure
enclosure be provided
provided with
withpressure-tight
pressure-tightwindows
windowswhich
which
the blush or slip-ring
sepapermit observation
observationofof
slip-ring operation.
operation.A A
sepaventilating air
airisprovided
is provided
fortype
this type of
rate source
source of ventilating
forthis
motor, usually
usually by a separate
separatemotor-driven
motor-driven
blower,
motor,
blower,
andand
the the
ventilating
air must be drawn
unclassifiedlocation.
location.
ventilating air
drawn from a unclassified
The air passage should
should also
also have
have filters
filters totominimize
minimizethe
theairborne dust.
dust.AAcommon
common
arrangement
interlock the
theblower
blower
arrangement
is to interlock
with the main
mainmotor
motorcontroller
controller so that the
the blower
blowermust
must be
andmust
mustremain
remainin operation
operation for some
some fixed
fixedperiod
periodtoto
started and
assure
assure that
that at least
least ten
ten air changes
changes have
have occurred
occurred before
before the
the
main motor can be
be started.
started. If
If air ventilation
ventilationisislost,
lost, interlocks
interlocks
are often
to to
shut down the main motor.
oftenprovided
provided
Other interlocks
interlocksare as follows:
follows:
a.
a. An auxiliary
auxiliary contact
contact to detect the opening
opening of the
the ventilaventilation motor
motorcontroller.
controller.
flow switch
switchinstalled
thethe
ductduct near the main
b. An air flow
installedinin
main
motor to detect
switchenclosure
enclosureshall
shall
detect actual
actual flow.
flow. The switch
be be
suitable for the location
location classification.
classification.
suitable
6.13.5 Totally
Totally
Enclosed
Inert
Gas-Filled
Enclosed
Inert
Gas-Filled
Pressurized
(TEIGF) Motors
Motors
Pressurized (TEIGF)
i
I
I
47
of the
the cooling
supply, water leakage
the cooler,
cooler,
cooling water supply,
leakage from the
and overheating
of
the
stator
windings
or
bearings.
overheating the
windings bearings.
c.
devicesrequired
requiredtoto
give the degree
protection
c. Other
Other devices
give
degree of protection
warranted
warranted for the particular
particularapplication.
application.
6.13.6 Totally
TotallyEnclosed
EnclosedWater-to-Air
CooledMotors
Motors
Water-to-Air Cooled
Totally
motors
useuse
water-toTotally Enclosed
EnclosedWater-to-Air
Water-to-AirCooled
Cooled
motors
water-toA source
cooling water
glycolair heat
heatexchangers.
exchangers.
A source of cooling
water or glycolmixture is
water mixture
is piped
piped to the motor
motor heat
heat exchanger,
exchanger,and
andthe
the
internal
thethe
exchanger
tubes.tubes.
This
internal air is circulated
circulatedover
over
exchanger
This cooled
air isisthen
through
the stator
and rotor
cool to
the cool the
thenpassed
passed
through
the stator
and cores
rotor tocores
majority of the heat generated
generated in the motor is
motor. The majOlity
taken up
portion
being
upby
bythe water supplied
supplied to ititwith
witha small
a small
portion
being
radiated from
fromthe
theframe.
frame.
enclosed
water-to-air-cooled
motors
have
Totally enclosed
water-to-air-cooled
motors have an
advantage when
whenmediummedium-and
andlarge-size
large-size
motors
required,
advantage
motors
are required,
and where
wherethere
thereisis
an
environment
that
is
hostile
to motor
an environment that
of NEMA
windings and
thethe
useuse
windings
and that
thatmight
mightotherwise
otherwiserequire
require
of NEMA
Type II weather-protected
weather-protected motors.
motors.Totally
Totallyenclosed
enclosed
Type I or Type
water-to-air cooled
cooled motors,
motors,however,
however,require
requireprotection
protectionfrom
from
the possibilities
possibilitiesof loss
loss of
ofcooling
coolingwater
wateror low flow.
flow. EmbedEmbedded winding
windingtemperature
temperaturedetectors
detectors
usually
areare·
usually
usedused
in thisin this
cases, the motor
motorenclosure
enclosure
may have
haveaa
motor. In many cases,
type of motor.
"make-up"
provide an
an air inlet for bearing seals.
seals.
“make-up” air inlet to provide
Even though the
the air
airflow
flow rate is
is relatively
relatively small,
small,this
thisair
airinlet
should be provided with
withadequate
adequate
filtration.
should
filtration.
6.14 MOTORS
MOTORS FOR CLASS
CLASS IIII LOCATIONS
LOCATIONS
For applications
induction
or synchronous
applications requiring
requiringa large
a large
induction
synchronous
location,aatotally
enclosed
motorinin a Class
ClassI,Division
I, Division 11 location,
totally
enclosed
6.14.1
Types
6.14.1 Suitable
SuitableTypes
motor,
with inert gas and arranged for
motor, pressurized internally with
Motors
Class
II locations,
cooling,
water cooling ororsurface-air
surface-air
cooling,
may be used
used (see
(seeNEMA
NEMA
Motors for
foruse
usein in
Class
locations, as
as defined in NFPA 70,
70,
shall
be
suitable
for
use
in
locations
that
are
hazardous
shall
suitable
for
use
locations
that
hazardous
notnot
MG 1 and NFPA 496).
496). TEIGF-type
TEIGF-type of motors
motorsare
arerare
rareandand
because of the presence
presenceof combustible
combustibledust.
dust.
housing
readily
application,the
themotor
motor
housing because
readily available.
available.In this type of application,
must be specially
specially designed
designedtotobebeairtight
airtightand to provide tight
tight
closure
closure around
aroundthe shaft to prevent
prevent excessive
excessiveloss
lossof the prespres6.14.2
Division
6.14.2Division
1 1
surizing
medium. In the eventofof apressure
pressure
failure,
surizingmedium.
failure,
it it is
Motors
third-party label of approval
Motors should bear a third-party
approval for
required to disconnect
disconnect the
the motor from its power source.
source. An
An
Class
II, Division 1, locations
or be totally enclosed pipeClass
locations
alarm should be provided
alarm
if if there is any
alarm
provided totosignal
signalanan
alarm
ventilated, meeting
temperature limitations
limitations for the speventilated,
meeting the temperature
increase
of the motor
design
limits.
increase inintemperature
temperature
motorbeyond
beyond
design
limits.
cific
cific dust
dust on
onthem or in
in their vicinity.
vicinity. Some explosionproof
preferredpressurizing
pressurizingmedium.
medium.
When
Nitrogen is the preferred
When
a a
motors approved
I, Division
Division 11 locations
locations are also
motors
approved for Class I,
motor uses
pressurizing medium,
uses nitrogen
nitrogenas
as its pressurizing
medium,the oil seals
seals
dust ignitionproof
ignitionproof and are approved
approved for Class II, Division
Division 1
should be of aatype
intointo locations.
typethat will prevent
preventoil from
from being
beingdrawn
drawn
locations.
the motor when the.
waterthe. motor isis shut down.
down. Where
Where a watercooled motor is used
usedinin this application,
coolingwater
water
application, the cooling
6.14.3
Division
6.14.3Division
2 2
continue to flow
exchanger
should continue
flowthrough
through the motor heat exchanger
when the motor is shut down.
down.
For Class II, Division
Division 2 locations,
locations, motors
motors should be
totally
totally enclosed pipe-ventipipe-ventitotally enclosed nonventilated,
nonventilated, totally
The following
following accessories
accessoriesshould
shouldbe considered:
considered:
lated, totally enclosed
enclosed fan-cooled,
fan-cooled, or totally enclosed dustdustlated,
a.
in the
a. Indicators to show whether cooling
coolingwater
wateris isflowing
flowing
in the ignitionproof.
ignitionproof. The maximum full-load
full-load external
external temperature
temperature
proper amount.
amount.
for these motors shall
(248°F) for operaoperashall not exceed
exceed 120°C
120°C (248°F)
alarms
automaticshut-off
devices
operate as
tion in
b.Warning
Warning
alarms or automatic
shut-off
devices to operate
in free
free air (not dust blanketed). Certain exceptions
exceptions are
permitted by
desired
70.
byNFPA 70.
loss of pressure
pressure inside
inside the motor, loss
loss
desired ininthe event of loss
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48
48
~
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
6.15
SERVICEFACTOR
FACTOR
6.15 MOTOR
MOTORSERVICE
i
To
motor
properly
economically,
its service
To apply aamotor
properly
andand
economically,
its service
factor
must
be
taken
into
account.
A
standard,
integral-horsefactor must be taken into account. A standard, integral-horsepower
or
power NEMA-frame
NEMA-frameopen
openmotor;
motor;
oraa high..:efficiency,
high-efficiency,totally
totally
enclosed
fan-cooled
motor
will
generally
a service
fac-facenclosed fan-cooled motor will generallyhave
have
a service
tor
of
1.15
and
will
carry
its
rated
nameplate
load
continucarry its rated nameplate
tor of 1.15 and
ously
withoutexceeding
exceeding its
temperaturerise.
rise. It
ouslywithout
its rated
ratedtemperature
It will
will
continuously
carry
115%
of
its
rated
full
load
without
attaincontinuously carry 115% of its rated full load without attaining
although
its
ing excessive
excessivetemperature.
temperature,
although
itsinsulation
insulationtemperature
temperature
insulation
limit
limit will
will be
be approached,
approached, thus
thus reducing
reducing winding insulation
life.
life. The
The bearings
bearings will
will also
also operate
operate at
at aa higher temperature,
temperature,
affecting
lubrication and
affecting bearing lubrication
and bearing
bearing life.
life. ItIt isis recomrecommended
mended that
thatthe
theservice
servicefactor
factor rating
rating be
be reserved
reservedfor
for contincontingency
use. Consideration
Consideration should
should also
also be
be given
given to
to the
the speed
speed
gency use.
and
and torque
torquecharacteristics
characteristicsof
of the
the motor,
motor, which
whichare
arebased
basedon
on aa
1.0
1.O service
servicefactor.
factor.
For
Forthe
the above
above NEMA-frame
NEMA-frame and
andother
other non-NEMA-frame
non-NEMA-frame
motors
1.O with
with no
nomargin
marginfor
for
motors the
the service
servicefactor
factorisis generally
generally 1.0
exceeding
exceedmg the
the nameplate
naineplate rating.
rating. ItIt isis not good
good practice
practice to
to
impose
impose continuous
continuous loads
loads in
in excess
excessofof the
the nameplate
nameplate rating
rating
on
on such
suchmotors;
motors;therefore,
therefore,itit isis advisable
advisableto
to determine
determinedefindefinitive
itiveload
load requirements
requirementsand
and to
to size
sizemotors
motors conservatively.
conservatively.
As
of
As an
an example,
example, aacertified
certifiedcopy
copy
of the
the characteristic
characteristiccurve
curve
of
a
centrifugal
pump
should
be
examined
over
its
entire
of a centrifugal pump should be examined over its entire
range
range to
to determine
determinethe
themaximum
maximumload
loadthe
the curve
curve can
canimpose
impose
on
its
driver,
Regardless
of
service,
,motors
with
a
service
facon its driver. Regardless of service, motors witha servicefacnot be
continuously nor
tor
1.0 should
shouldnot
be operated
operatedcontinuously
nor for
for
tor of
of 1.0
extended
periods at
exceeding the
rating.
extendedperiods
at loads
loads exceeding
the nameplate
nameplate rating.
When
loadingisispermitted,
permitted, itit should
When heavier loading
should be
be done
done only
only
with
theunderstanding
understanding that
reliabilityand
and
motor
withthe
that the
thereliability
motor
life life
expectancy
Additionally,
other
expectancywill
willbebereduced.
reduced.
Additionally,
otherspecifications
specifications
may
asAPI
API Std
Std610.
610.
may effect
effectmotor
motorsizing,
sizing,such
suchas
6.16
FREQUENCY OF
6.16FREQUENCY
OF STARTING
STARTING
NEMA-frame
arecapable
capable of
" A - f r a m e motors
motorsare
of multiple
multiple starts
starts per
per
hour.
The
number
of
which
is
defined
by
NEMA
Std
MG 1,1,
hour. The number of whichis defined by NEMA Std MG
paragraph
12.54.1,and
andNEMA
NEMAStd
StdMG-lO
MG-10paragraph
paragraph2.8.1.
2.8.1.
paragraph12.54.1,
in
their
Medium
voltage
motors
are
limited
startingcapacapaMedium voltage motors are limitedin their starting
bility,
bility, usually
usually to
to two
two starts
starts from
from cold
cold (or
(or ambient)
ambient)condition
condition
and
start from
from hot
hot (or
(or running
running temperature)
temperature) condition.
and one
one start
This
is
on
the
basis
of
a)
the
load
inertia
This is on the basis of a) the load inertiaisis within
withinNEMA
NEMAlimlimits,
its, b)
b) the
theload
load start
start curve
curveisis aa "square-of-speed"
"square-of-speed" type
type curve,
curve,
and
90%
and c)
c) the
the voltage
voltageat
at the
the motor
motor terminals
terminalsis
is greater
greater than
than90%
(see
(see6.20).
6.20). In
Inbetween
betweenstarts
starts(while
(whilethe
themotor
motorisis at
atrest),
rest),these
these .
staunits
unitsmust
mustbe
be cooled
cooled(generally
(generallyby
by convection)
convection)totoa lower
a lower
stator
temperatureprior
prior
tor and
and rotor temperature
to to another
another attempted
attempted start.
start.
Motors
API
Motorsthat
thatcomply
complywith
with
API Std
Std541
541or
or Std
Std546
546usually
usuallyhave
have
greater
Thistime
time between
betweenstarts
startsmust
must be
be
greaterstarting
startingcapabilities.
capabilities.This
coordinated
with the
coordinated with
the manufacturer
manufacturer for
for automatic-restart
automatic-restart or
or
frequentstart
frequentstartduty
dutyconditions.
conditions.
Note:
Note: Time
Time between
between hot
hot starts
startsmay
may exceed
exceed 11 hour.
hour. Motors
Motors driving
driving
high
high inertia
inertia loads,
loads, or operating
operating under
under high
high power system
system voltage
voltage
drops
special consideration.
dropsshould
shouldreceive
receive'special
consideration.
6.17
TEMPERATURE, VIBRATION,
AND
CURRENT
6.17TEMPERATURE,VIBRATION,
AND
CURRENT
INDICATORS
INDICATORS
Motors
Motors larger
larger than
than 1,000
1,000HP
HP and
and special-purpose
special-purpose motors
motors
frequeritly
requiretemperature,
temperature,current,
cun'ent,
vibration, air
frequently require
vibration,
air flow,
flow,
water
water flow,
flow,orordifferential
differentialpressure
pressuremonitoring.
monitoring.(See
(SeeAPI
APIStd
Std
541
541and
and 546
546for
for proper
properapplication.)
application.)
6.18
6.18 CONDUIT
CONDUITORTERMINAL
OR TERMINAL BOX
BOX
Attention
Attention should
shouldbe
be given
given totothe
the size
sizeand
and direction
directionof
of conconduit
duit entrances
entrances to
to motor
motor terminal
terminal boxes.
boxes. Sizing
Sizing requirements
requirements
of
of the
the local
local electrical
electricalcode
code should
shouldbe
be observed.
observed.Medium
Mediumand
and
high
terminalboxes
boxes
may
require
special
high voltage
voltage main terminal
may
alsoalso
require
special
construction.if
construction if ANSIiNEMA
ANSINEMA Type
Type II
II design,
design,space
space for
for stress
stress
cone-type
cone-type cable
cable termination, or
or auxiliary
auxiliary protection
protection devices
devices
are
are used.
used.
6.19
SPACE
HEATERS
6.19SPACE
HEATERS
6.19.1
Application
6.19.1
Application
In
motorwindings
windings are
In locations
locations where.
where motor
are likely
likely to
to be
be subsubjected
of excessive
moisture during
jected to
to accumulations
accumulations
of
excessive
moisture
during
be
extended
extendedperiods
periodsof
of idleness,
idleness,consideration
considerationshould
should
begiven
given to
to
winding
heating
the
the installation
installation of
of space
space heaters
heaters or
or direct
directwinding
heating
control
low
controlmodules
modules(which
(whichapply
apply
low power
powerdirectly
directlyto
to the
the stator
stator
winding)
This
winding) toto maintain
maintainthe
thewinding
windingabove
abovethe
thedew
dew point.
point. This
applies,
especially,
to
inotors
operating
at
greater
than
applies, especially, to motorsoperating at greaterthan or
or
equal
equal to
to 2,300
2,300V.
V. Space
Spaceheaters
heaters are
areparticularly
particularlyapplicable
applicableto
to
large
outdoors
and
largetotally
totally enclosed
enclosedmotors
motorsinstalled
installed
outdoors
and operated
operated
intermittently,
intermittently,and
andto
to vertical
verticalweather-protected
weather-protectedmotors,
motors,such
such
as
those used
used for
for water
water well
well service.
service. Space
Space heaters
heaters are
are also
also
as those
used
particularly
those
used in
in many
many large
largemotors
motorslocated
locatedindoors,
indoors,
particularly
those
that
that operate
operateintermittently.
intermittently..Some
Some designs
designs of
oftotally
totallyenclosed
enclosed
fan-cooled
fan-cooled motors
motorsare
areadaptable
adaptableto
to space
spaceheater
heater installations
installations
while
are also
alsorecommended
recommendedfor
for
while others
othersare
arenot.
not. Space
Spaceheaters
heatersare
terminal
terminal boxes
boxes that enclose
enclose surge
surge protection
protection components
components or
or
instrument
instrumenttransformers.
transformers.
6.19.2
Installation
Precautions
6.19.2Installation
Precautions
Space
Space heaters
heatersshould
shouldbe
be selected\and
selectedmdapplied
appliedin
in aamanner
manner
that
that prevents
prevents unsafe
unsafe surface
surface temperatures,
temperatures, and
and they should
should
possess
possess the
the correct
correctheater
heater rating
rating and
and element
element temperature
temperatureas
as
well
are necessary
necessary for
for obtaining
obtaining satisfacsatisfacwell as
as materials
materials that
that are
tory
tory operation
operation and
and long
long life.
life. Generally,
Generally, sheaths
sheaths made
made of
of
Monel
Monel or
or other
other normally
normally corrosion-resistant
corrosion-resistant material,s
.materialp
should
should be
be used.
used. The
The maximum
maximumsheath
sheath temperature
temperatureof
of space
space
heaters
to 80%
80% of
of the
the ignition
ignition temperature
temperature
heaters must
must be
be limited
limited to
of
of the
the gases
gases or
or vapors
vapors expected
expected within
within the
the area
area unless
unless there
there
are
are special
special reasons
reasons for
for aa lower
lower limit.
limit. ItIt isiscommon
common practice
practice
to
to operate
operate space
space heaters
heaters at
at half
half the
the rated
rated voltage
voltage (or
(or other
other
reduced
low-surface temperature
reduced voltages),
voltages), or
or to
to specify
specifylow-surface
temperature
[e.g.,
[e.g.. 200°C
200°C (392°P)]
(392'F)I to
to prevent
prevent excessive
excessivetemperatures
temperaturesand
and
-"
Copyrighted material licensed to IDOM.
STDmAPI/PETRO RP 540-ENGL
1111
0732290
0b3558b. 1b.Z E.;
No further1999
reproduction
or distribution
permitted.
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONSIN
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
to
to increase
increase heater
heater life.
life. Space
Space heater
heater leads
leads are
are often
often wired
wired
out
out to
to aa separate
separateterminal
terminalbox.
box.
6.19.3
Ratings
6.19.3
Ratings
Space
Space heaters
heaters usually
usually have
have an
an operating
operating voltage
voltage rating
rating of
of
115
V
or
230
V,
single
phase.
Heating
capacity
should
115 V or 230 V, single phase.
capacity should be
be
sized
thethe
winding
temperature
5°e
5°C to
to lOoe
10°C(10°F
(10°F
sizedtotomaintain
maintain
winding
temperature
to
20°F)
above
ambient
temperature.
to 20°F) above ambient temperature.
6.19.4
Operation
6.19.4Operation
When
When auxiliary
auxilia7 contacts
contacts are
areused
usedin
in the
the motor
motor starter,
starter,the
the
supply
heater
isis normally
supplycircuit
circuittotothethemotor
motor
heater
normally arranged
arrangedtotobebe
de-energized
automatically when
and
de-energized automatically
when the
the motor
motor isis started,
started, and
energized
when
the
motor
is
stopped.
If
used,
terminal
box
energized when the
is stopped. If used, terminal
or
heaters
heatersare
are normally
normallycontinuously
continuouslyenergized
energized
or controlled
controlledby
by
differential
temperature
thermostats.
A
local
nameplate
at or
or
differential temperature thermostats.A local nameplateat
near
auxiliary terminal
terminalbox
box or
near the
the space
space heater
heater auxiliary
or connection
connection
point
when
power
source
pointshould
shouldindicate
indicate
when aaseparately
separatelyderived
derived
power
source
isisemployed.
employed.
6.19.5
Low-Voltage
Winding
Heating
6.19.5Low-Voltage
Winding
Heating
Low-voltage
heating isis aa method
method for
Low-voltage winding
winding heating
for heating
heating aa
motor
This
This heating
heatingisis
motor winding
windingwhile
whilethe
themotor
motorisisshut
shutdown.
down.
accomplished
accomplishedby
by applying
applyinglow
low voltage
voltagedirectly
directlytotoone
onephase
phase
of
the
motor
winding.
The
amount
of
heating
voltage
necesof the motor winding. The amount of heating voltage necessary
sary to
to circulate
circulatethe
theproper
propercurrent
currentinin the
thewinding
windingand
and keep
keep
5°e
to
lOoe
(lOOF
to
20°F)
the
internal
temperature
above
the internal temperature 5°C to 10°C (10°F to 20°F) above
ambient
5% voltage
voltageisisnornorambientmust
mustbe
be selected.
selected.Approximately
Approximately5%
mally
sufficient
to
maintain
this
temperature.
A
mally sufficient to maintain this temperature. A low-voltage
low-voltage
contactor
interlocked
withwith
the
tokeep
keep
contactormust
mustbebe
interlocked
themain
maincontactor
contactorto
of
power
electrically
separated.
Low-voltage
the
two
sources
the two sourcesof power electrically separated. Low-voltage
itit
winding
winding heating
heatingisis normally
normally used
usedfor
for small
smallmotors
motorsbecause
because
isis usually
more
economical
to
use
space
heaters
for
motors
usually
to use space heaters for motors
over
over 100
100lIP.
HP.
6.20
BEARINGS
AND
LUBRICATION
6.20BEARINGS
AND
LUBRICATION
6.20.1
Horizontal
Motors
6.20.1
Horizontal
Motors
Motors
(ball
or
Motors are
are available
availablewith
witheither
eitherantifriction
antifriction
(ball
orroller)
roller)
or
hydrodynamic
radial
(sleeve)
bearings.
The
type
of
bearing
or hydrodynamic radial (sleeve)
bearings. The type of bearing
lubrication,
lubrication,whether
whetheroil,
oil,oil
oil mist.
mist,or
or grease,
grease,should
shouldbe
be chosen
chosen
Most
NEMA-frame
when
the
bearings
are
selected.
when thebearings are selected.Most NEMA-kame and
and
IEEE-841
motors
antifriction
IEEE-841motors
willwill have
have grease-lubricated
grease-lubricatedantifriction
bearings.
Motorsabove
above
NEMA
standard sizes
bearings.Motors
NEMA
standard
sizes should
should be
be
designed
according
to
API
Stds
541
and
546.
designed accordingto API Stds 541 and 546.
I
Most
Most sleeve
sleeve bearings for
for horizontal
horizontal motors
motors are
are oil-lubrioil-lubricated
forced-oil lubrication
lubrication
cated using
using oil
oil rings.
rings. Except
Except where aa forced-oil
consystem
system isis used,
used, the
the bearings should
should be
be equipped
equipped with constant-visible-level
stant-visible-levelautomatic
automatic oilers.
oilers. Wick
Wick or
or yarn
yarn oilers are
are
not
satisfactory
except
for
the
smallest
fractional
horsepower
not
satisfactory
except
for the smallest fractional
horsepower
motor
motorsizes.
sizes.
~
I
~~
49
49
An
An opening
opening should
should be
be provided
provided to
to permit
permit observation
observation of
of
the
the motor
stingers,
the oil
oil rings ifif the
motor isis in
in operation.
operation. Suitable
Suitable slingers,
pressure
to
pressureequalizers,
equalizers,and
andvents
ventsarearerequired
required
to prevent
prevent loss
lossof
of
lubricant
maintain
the proper
level. level.
lubricantand
andto to
maintain
the proper
For
HF'),sleeve-bearing
sleeve-bearingmotors,
motors, particularly
particularly
For large
large (1,000
(1,000lIP),
those
requires
forced-oillubricathose used
usedto
to drive
driveequipment
equipmentthat
that
requires
forced-oil lubrication,
also be
tousing
usingforced-oil
forced~oil
tion, consideration
consideration should also
be given to
lubrication
motors. API
lubdcation
lubrication for
for the
the motors.
API Std
Std 614
614 covers
covers lubrication
systems
systemsfor
forspecial
specialdrive
drivetrains.
trains.
Sleeve-bearing
Sleeve-bearingmotors,
motors,usually
usuallyininthe
the larger
larger sizes,
sizes,require
require
the
use of
couplingstokeep
to keep
the motor
theuse
of limited-end-float
limited-end-floatcouplings
themotor
rotors
Whenthe
thecouplings
couplings are
installed,
rotors centered. When
are properly
properly installed,
the
center.
themotors
motorswill
willoperate
operateatator
ornear
neartheir
theirmagnetic
magnetic
center.
Ball
bearingsforfor
holizontal
motors
are usually
Ballbearings
horizontal
motors
areusually
grease- greaselubricated,
the
lubricated,except
exceptinin
the larger
largersizes
sizesand
andin
in horizontal
horizontalmotors
motors
that
at
thatoperate
operateat
at higher
higher speeds.
speeds.Holizontal
Horizontalmotors
motorsoperating
operating
at
higher
use
higherspeeds
speedsoften
often
use oil-lubricated
oil-lubricatedball
ballor
orroller
rollerbearings.
bearings.
Some
providegrease-lubricated
grease-lubricatedball-bearbali-bearSome manufacturers provide
ing
ing motors
motors with
with sealed
sealedbearings
bearings that
that permit
permitseveral
severalyears
yearsof
of
operation
At At
the the
end end
of
operationwithout
withoutregreasing.
regreasing.
of these
theseperiods,
periods,thethe
bearings
replaced.
Because
many
bearingsare
are either
eitherrepacked
repackedoror
replaced.
Because
many bearbearing
result
overgreasingfailures
failuresarearethethe
resultof
of too-frequent
too-frequentgreasing,
greasing,
overgreasing,
permit
ing,or
ormixing
mixingof
of incompatible
incompatiblegreases,
greases,motors
motorswhich
which
permit
long
periods
between
regreasings
are
the
most
desirable,
parlong periods between regreasings are the most desirable,
particularly
plantsthat
that
lack
suitable
maintenance
personnel
ticularly inplants
lack
suitable
maintenance
personnel
and
regreasing
programs.
andcontrol
controlover
overtheir
their
regreasing
programs.
When
internal
andand
noncontactWhen oil
oil mist
mistlubrication
lubricationis isused,
used,
internal
noncontacting
external
shaft
seals
should
be
used.
The
seal
and
ing external shaft seals should be used. The seal and main
lead
shall
be compatible
with the
leadinsulation
insulationmaterial
material
shall
be compatible
with
theoiL
oil.
6.20.2
Vertical
Motors
6.20.2Vertical
Motors
The
The thrust
thrust bearings
bearings in
in vertical
vertical motors
motors include
include antifriction
antifriction
(ball
or
roller)
and
plate-type
thrust
bearings.
When
(ball or roller) and plate-type thrust bearings. When oil is oil is
used
oil oil
usedas
asthe
thelubricant
lubricantfor
foreither
eitherthrust
thrustor
orguide
guidebearings,
bearings,thethe
reservoir
should
be
deep
enough
to
serve
as
a
settling
chamreservoir should be deep enough to serve as a settling chamber
ber for
for foreign
foreign matter;
matter; should
should be
be provided
provided with
with drain
drain plugs
plugs
accessible
motor
housings; and,
accessible from
from outside
outside the
themotor
housings;
and, except
except
where
whereaaforced-oil
forced-oiltype
type of
of lubrication
lubricationsystem
systemisis used,
used, should
should
be
constant-visible-level automatic oilers.
oilers. In
be equipped
equipped with
with constant-visible-level
In
vertical
vertical motors,
motors,itit isis generally
generallypreferred
preferredthat
thatall
all bearings
bearings use
use
the
the same
same type
type of
of lubricant.
lubricant.The
The magnitude
magnitude and
and direction
direction of
of
. external
thrust,
operating
speed,
and
required
bearing
external thrust,operating speed, and required bearinglife
lifewill
will
determine
determinethe
thetype
typeof
of bearing
bearingused.
used.
Where
ititis
Whererequired,
required,
iscommon
commonpractice
practiceto
tosupply
supplymotors
motorsthat
that
are
equippedwith
withbearings
bearings
are
are subject to
to high
high thrust, equipped
thatthat are
capable
thrusts
fromfrom
drivendriven
equipment.
The
capableofofcarrying
carrying
thrusts
equipment.
Themotors
motors
on
vertical
pumps
are
examples
of
motors
equipped
bearon vertical pumps are examples
of motors equippedwith
with
bearings
of carrying
the
the
ingscapable
capable
of carrying
thehigh
high thrusts
thrustsfrom
from
thepump.
pump.When
When
high-thrust
high-thrust driven
driven equipment
equipment isis being
being used,
used, itit isis essential
essential to
to
specify
specifythe
themaximurp
m a x i m u thrust
thrustloads
loadsin
inboth
bothdirections.
directions.(For
(For ververtical
requirements,
see API
ticalmotor
motorbearing
bearing
requirements,
see
A P IStd
Std610.)
610.)
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STD APIJPETRO,. RP ..S.GO-.ENGL,
IRVI or distribution permitted.
No further reproduction
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50
API RECOMMENDED
PRACTICE
540
Table 2-Characteristic
6.21TORQUEREQUIREMENTS
Torques
Squirrel-Cage
Induction
Motors
Synchronous
Motors
6.21.1TorqueConsiderations
~
60%
Locked-rotor
torquea
40%
Locked-rotor torquea
Most motors usedin petroleum processing and associated
operations drive centrifugal or rotary pumps, centrifugal
60%
Pull-in torquea
30%
Pull-up torquea
blowers, centrifugal compressors, and other equipment that
do not impose unusually difficulttorque requirements. Nor175%
Pull-out
torquebJ
150%
Breakdown torquea
mal-torque motors are well-adapted to such equipment and
usually will have sufficient torque
to meet the normal condiaThe output torque varies approximately as the square
of applied
tions of service, provided the supply voltages are satisfacvoltage.
bThe output torque varies directlyas the applied voltage.
tory. The net torque delivered by the motors to the driven
cWith excitation constant.
equipment is less than the rated torque of the motors when
the voltages at the terminals of the motors are less than the
to avoid any delays or inconveniences thatmay be caused by
rated voltages of the motors. Table 2 shows characteristic
the failure of motor-driven equipmentstart
to satisfactorily.
torque variations of large squirrel-cage induction motors
and synchronous motors, with respect to applied voltage.
If reduced-voltage reactoror resistor starting is used, asubFor example, a motor capable of exerting a locked-rotor (orstantial amount of impedance is introduced into the supply
starting) torque of 100% (with respect to full-load running
circuit of the motor when the controlleris in the starting positorque) with its nameplate voltage at its terminals may be
ti,on.This impedance as well as the other impedance between
found to have only90% of its nameplate voltageat its termithe motor and its supply source must be taken into account.
nals at the instant it is started across the line, due to a 10%
All reduced-voltage starting applications should evaluatethe
voltage drop during this period of high current in-rush. The
startingtorqueavailableversusthatrequired
by the load
output torque developed by the motor is proportional to the
(acceleration torque) to determine that adequate torquemarterminal voltage squared times the full voltage locked-rotor
gin is availablefor starting the load.
torque; or, under a 10%voltage-drop condition,this is calcuA torsional analysis should be undertaken for high-speed
.lated to be: 0.9 x 0.9 x 100, or 81%.
synchronous motors to determine the effectsof torsional pulSimilarly, theentire starting torquecurve is reduced by the
sations during across-the-line start accelerationof the motor
same value. From NEMA MG 1 paragraph 20.41, a medium
and driven equipment.
voltageinductionmotorminimum
torque curve is 60%
lockedrotor; 60% pull-up;and 175% breakdowntorque
6.21.3Low-VoltageConsiderations
(under full voltage condition). Under
a voltage drop, this
20%
curve then becomes 38% / 38% / 112%. (See Figure 14.)
Voltage thatis lower than normal may exist, particularly during
starting, because of the system's design or characteristics.
Additionally, anyfurther reductions in voltage due to line loss
or auto-transformers will be added to the system drop. This
Some causesfor this lower-than-normal voltage areas follows:
figure also includes the typical "square-of-speed" type curve
a. The motor being started is large in relation
to the capacity
for centrifugalloads. The top line is for openvalve or
of
the
electrical
supply
system.
damper- type starting, while the lower line is for throttledb. The supply circuit's length and design cause
an unduly
type starting (this example is for a 50% closed valve/damper
high
voltage
drop
between
the
power
source
and
motor.
start). It can be seen from this example that the effect of
startreducing the voltage at the motor terminals may prevent
Where it is questionable whether the voltage received at
up unless the load-starting
curve can be reduced.
the terminals of the motor will be satisfactory, the voltageat
that point should be calculated under the most unfavorable
6.21.2TorqueAnalysis
conditions likelyto exist in actual service.In most cases, this
will be at the instant of starting, when the current inrush is
The maximum torque that can be developedby a motor is
several timesthe rated full-load currentand the powerfactor
proportional to the square of the voltage,resulting in acceleris low, usually inthe 0.2 to 0.4 range. If the circuit under conationtorquereduction
for reduced-systemvoltage.Power
sideration willbe used to carry other loads,the effect ofthese
system, motor, and load characteristics should
be evaluated to
other loads on voltage should be taken into account at the
assure adequatetorque during starting and acceleration. It
same time.
should also be evaluated during re-acceleration and re-synchronizing following voltage
sags and disturbances.
When a synchronous motor is to be used, voltage conditions
at the instant of pull-in should be checked. It must be
However, if the inspection of the available data does not
determined
that correct torque willbe developed atthe pull-in
yield a clear result, it is recommended that a detailed engineering analysis be performedto resolve marginal cases and
point with net voltage available
at the motor terminals.
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No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
O
e
I
I
..........
Breakdown torque
-, \
~
..
(D
J
O
7
160
/
S
7
_
f~ ~~~,~
Full load "'qu.
+-
r-JI
Slip -
"-,~V--~ A
.
m
ELECTRICAL
INSTALLATIONS
PROCESSING
PETROLEUM
PLANTS IN
~~---
140
120
,
Fii
~
~
/ )~
V / ~
r-~~~--~--r-~---r--~--~~~-r--~~---~-4---+--~~~~~~V
V ~" ~~
~
It
-.I
....V
/ LV
z
(fJ
~
.-
Pull-up torque
<ll
:::l
E'" 100
~
~
~ 80
f--.- /
Locked rotor
torque
•
_.
_~,,-
,
~
1<4--1-
O
(D
....:.
Z
'"tl
FV accelerating torque
VV
S
40
............
O
N
~
~iI'
s:
~V
'"tl
g
m
__ I---'"'''''"'"
....
______ ~~
):
z
til
" Throttled valve
..--..,.,__-
Z
G>
'"tl
I "";V"
.-~
_~r<
.
_ ...._.
load curve
r----:--r---l---t-----+--I
_i"""'"
50
60
70
80
90
100
3
40
2
30
-
Open valve
load curve
3
N
O
7
O
O
20
..."",.~
~/
./
~
(fJ
(j)
3
O
10
V'
RV accelerating torque
. . . . "",. ~
20
o
~
//1/'
_~V'tl"
Reduced voltage /',/
(85%V) curve
o
~
(fJ
_
Full vollage (100%V) CUN.
"
60
_
E
% Synchronous Speed
(]I
.....
51
Figure 14-Combined Motor and Load Speed-Torque Curve
STD.API/PETRO R P 540-ENGL ,1999 M 0732290 Ob15588 T35
180
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
52
52
6.21.4
Torque
Specifications
6.21 -4 Minimum
Minimum
Torque
Specifications
I
I
API
PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
,
Occasionally,
Occasionally, the
the normal
normal starting
starting torque
torque characteristic
characteristic of
of
the
themotor
motorwill
willnot
notbe
be sufficient
sufficientto
to accelerate
acceleratethe
theddven
drivenequipequipment.
these
marginal
the
ment.InIn
these
marginal
cases,cases, itit isis advisable
advisableto
to establish
establishthe
minimum
minimum motor
motortorque
torquecharacteristic
characteristicthat
thatisisacceptable.
acceptable.For
For
borderline
borderline cases,
cases, the
the motor
motor torque
torque charactedstic
characteristic (including
(including
any
voltagedrop
dropconsiderations)
considerations)
should
be specified to
any voltage
should
be specified
to be
be
10%
10%greater
greaterthan
thanthe
the dliven
drivenequipment
equipmentstarting-speed-torque
starting-speed-torque
curve
curvethroughout
throughoutits
its entire
entirerange.
range.
If
the
application
requires
than
nOlmal
torque,
itit will
If the application requiresmore
more
than
normal
torque,
will
be
appropriate
to
determine
which
will
be
more
economical:
be appropriate to determine which willbe more economical:
to
motor
with
higher
normal
to obtain
obtainaamotor
with
higher
thanthan
normal
torque,torque,
within within
or
to
improve
voltage
at
the
point
lizaavailable
limits,
available limits,or to improve voltage at thepoint of
ofuti
utilization.
In
an
extreme
case,
it
may
be
correct
to
do
both.
In
most
tion. In an extreme case,it may be correct to do both. In most
instances,
instances,satisfactory
satisfactoryresults
resultscan
canbe
be obtained
obtained most
mosteconomieconomically
torque
requirements and
cally by
by determining
determiningtorque
requirements
and specifying
specifying
these
these requirements
requirements to
to suit
suit the
the predetermined
predetermined voltage
voltage condiconditions
the terminals
terminalsof
of the
themotor.
motor.
tionsat
at the
In
In some
some cases,
cases,increased
increasedtorque
torquedesigns
designs require
requirehigher
higherininrush
drop,
which
in tum,
low-lowrush current,
current,increasing
increasingthethevoltage
voltage
drop,
which
in turn,
ers
ersthe
the net
netoutput
outputtorque.
torque.
ciently
until the
themotor-generated
motor-generatedvoltage
voltage has
ciently until
has decayed
decayed to
to aa
voltage. Otherwise,
Otherwise,high
high
value
of 25%
25% or
or less
less of
of the
the rated voltage.
value of
transient
be
thethe
mechanical
transienttorques
torquescan
can
be produced
producedthat
thatexceed
exceed
mechanical
limit
limitof
of the
themotor
motorshaft,
shaft,coupling,
coupling,or
orddven
drivenequipment.
equipment.
6.21.7
Additional
Torque
Requirements.
6.21.7Additional
Torque
Requirements.
Recognition
to
Recognitionshould
shouldbebegiven
given
to the
the requirement
requirementfor
for greater
greater
of
torque
torque under
undercertain
certainconditions
conditions
of operation.
operation. For
Forexample,
example,in
in
the
of aa centrifugal
centrifugal blower or
or centdfugal
centrifugal pump,
pump, more
the case of
torque
torque isisrequired
required to
to bring
bring the
themachine
machineup
up to
to rated
ratedspeed
speed with
with
itit closed.
the
open
than
withwith
the discharge
dischargevalve
valve
open
than
closed.If,
If, for
for some
somereareason,
practical totofollow
followthethe
customary
practice
son, itit isis not
not practical
customary
practice
of of
starting
blower
or
startinga acentrifugal
centrifugal
blower
orpump
pumpwith
withthe
thedischarge
dischargevalve
valve
closed,
start itit
closed, sufficient
sufficienttorque
torque should
should be
be made
made available
available to
to start
with
open.
with the
thedischarge
dischargevalve
valve
open.
6.22
METHOD OF
6.22METHOD
OF STARTING
STARTING
6.22.1
Starting
Control
6.22.1Starting
Control
Starting
same. In
Starting control
control for
for all
all motors
motors isis essentially
essentially the same.
In
the
larger
motor
sizes,
which
represent
a
considerable
investthe larger motorsizes, which representa considerableinvestment
ment of
of capital
capital and
and upon
upon which
which aa higher
higher degree
degree of
of dependdependof
starting
control
increases.
ability
is
placed,
the
complexity
ability
is
placed,
the
complexity
of
starting
control
increases.
6.21.5
High
Torque
6.21.5HighTorque
Larger
canrequire
requirepower
power
distribution
systems
with
Larger motors can
distribution
systems
with
For
For motors
motors used
used to
to drive
drive machines
machines that
that require
requireextra-high
extra-high
high
systemcapacity
capacity to
undesirablevoltage
voltage drops
high system
to prevent
prevent undesirable
drops
starting
(e.g.,most
most
conventional
pulverizers,
shredstarting torque
torque(e.g.,
conventional
pulverizers,
shredwhen
when the
themotors
motorsare
aresooted
startedat
atfull
full voltage
voltageunder
underload.
load.If
If these
these
or
fans),
it
is
advisable
ders,
crushers,
and
some
air
blowers
ders, cmshers, and some
air blowers or fans), it is advisableto
to
undesirable
effects are
reduced-voltagestarting
starting
undesirableeffects
are produced,
produced,reduced-voltage.
predetermine
the
voltage conditions
the
predeterminethe
voltage
conditions and
and to
to stipulate
stipulatethe
should
With
reduced-voltage starting,
the
should be
be considered.
considered.With
reduced-voltage
starting, the
torque
requirements
on
the
basis
of
anticipated
voltage
conditorque requirements on the
basis of anticipated voltage condi- motor
motor charactedstics
characteristicsmust
mustbe
be checked
checked to·ensure
to ensure that
that there
thereisis
tions,
be be
high,
eveneven
whenwhen
the the sufficient
asnet
net torque
torquerequirements
requirementsmay
may
high,
tions, as
sufficienttorque
torqueto
to accelerate
acceleratethe
the load
load atatthe
the reduced
reduced voltage.
voltage.
machine
is
started
unloaded.
High-torque
motors
are
availmachine is started unloaded.
motors are availIt
It isis also
also important
importanttotoconsider
considerthethecurrent
current in-rush
in-rush totovarivarirequiting higher-than-norhigher-than-norable
able for
for aa variety
variety of
of applications requiring
ous
dip.dip.
The
ous motors
motorsfollowing
followinga avoltage
voltage
The in-rush
in-rush during
during reacreacmal
torque.
mal
torque.
i
celeration
willnearly
nearlyequal
equal the
the starting
starting in-rush;
in-rush; so
so ifif
celeration often will
motors
the
motors are
are to
to operate
operatesatisfactorily
satisfactorilythrough
throughaa voltage
voltagedip,
dip, the
6.21.6
High-Inertia
Loads
6.21.6High-Inertia
Loads
system
must
be
stiff
enough
to
handle
the
subsequent
in-rush.
system mustbe stiff enoughto handle thesubsequent in-rush.
Control
provide for
reacceleration of
Control circuits
circuits which
which provide
for the
the reacceleration
of
For
For high-inertia
high-inertialoads
loadsand
andother
other loads
loads where
wherethe
themotor
motorisis
motors
are
complex
and
require
additional
considerations.
motors
are
complex
and
require
additional
considerations.
subjected
(0%to
to 100%
100%
subjectedtotoheavy
heavyloading
loadingduring
during acceleration
acceleration(0%
Reduced-voltage
thethe
net
Reduced-voltagecontrollers
controllersreduce
reduce
net torque
torqueexerted
exertedby
by
speed),
speed),calculations
calculationsshould
shouldbe
be made
madeto
toensure
ensureitit will
will have
havesufsufthe
motors
and,
in
some
cases,
may
complicate
the
starting
the
motors
and,
in
may
complicate
the
starting
ficient
capacity
to
ficienttorque
torqueand
andthermal
thermal
capacity
to bring
bring the
thedriven
drivenequipequipproblem,
problem,especially
especiallyfor
forsynchronous
synchronousmotors.
motors.
ment
ratedspeed
speed
under
actual
operating conditions
ment up
up to
torated
under
actual
operating
conditions
within
theallowable
allowable
length
of time. A
A motor
motor that
that drives
drives
withinthe
length
oftime.
6.22.2
Full-Voltage
Starting
6.22.2Full-Voltage
Starting
equipment
equipment that
that may
may be
be subject
subject to
to occasional
occasionalsudden,
sudden,heavy
heavy
speedshould
should be
loads
running at
In
loads while
whilerunning
at rated
ratedspeed
be checked
checked to
to
In general,
general, the
the full-voltage
full-voltage magnetic
magnetic controllers
controllers supplied
supplied
havesufficient
sufficient
breakdown
(induction
determine
contactors
with
air-break,vacuum-break,
vacuum·break, or
determine ifif itit will
willhave
breakdown
(induction
withair-break,
or oil-immersed
oil-immersedcontactors
motor)
(synchronousmotor)
motor) torque
offer
this
motor) or
or pull-out
pull-out(synchronous
torque under
under this
offer the
the simplest
simplest and
and most
most economical
economical method
method for
for starting
starting
condition
tokeep
keep itit from
losing
induction
motors.
See
Figure
15
for
an
example
of
a
simplicondition to
from stalling
stalling or
or fromabrupIJy
from abruptly losing
induction motors. See Figure 15 for an example of a simplihigh-slip motors,
speed.
fied,
starter
using
an
speed. The
The use
use of high-slip
motors, as
as well
well as
as the
the possible
possible
fied,full-voltage
full-voltagenonreversing
nonreversing
starter
using
an air-break
air-breakconconneed
considered
forfor tactor.
This
method
is
based
on
acceptable
motor-loading
need for
for additional
additionalflywheel
flywheeleffect,
effect,should
shouldbebe
considered
tactor. This method is based on acceptablemotor-loading
such
conditionsofservice.
of service. This
conditions
distribution
system
to
This type
type of
of problem
problem is
is not
not
suchconditions
conditionsand
andthe
the ability
abilityofofthe
thepower
power
distribution
system
to .
encountered
function
without
undue
voltage
disturbance
during
motor
encounteredoften,
often,but
butdoes
doescall
call for
for detailed
detailedconsideration
considerationof
of
functionwithoutunduevoltage
disturbance during motor
equipment
start·up.
Mostmotors,
motors,
particularly
medium
equipmentand
and load
load charactedstics.
characteristics.
start-up.Most
particularly
the the small
small and
andmedium
Following
a
shutdown
horsepower
motors,
of
a
motor
driving
a
high-inertia
are
designed
for
full-voltage
starting.
Following shutdown of a motor driving high-inertia
horsepower motors, we designed for full-voltagestarting.
load,
the
restarting
Synchronous
and
large
induction
motors,
usually
of
the
motor
should
be
delayed
suffiat
load,therestartingofthe
motor shouldbedelayedsuffiSynchronousandlargeinductionmotors,usually
at the
the
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53
53
ELECTRICAL
INSTALLATIONS
IN
PLANTS
ELECTRICAL
INSTALLATIONS
I N PETROLEUM
PETROLEUM PROCESSING
PROCESSING
PLANTS
higher
more
control
selectivity
because
their theirthe
highervoltages,
voltages,require
require
more
control
selectivity
because
the full-voltage
full-voltage statting
startingvalues.
values.This
This method
method should
should only
only be
be
size
large
portion
ofthe
used
sizemay
may represent
representananexceptionally
exceptionally
large
portion
of the availavailused ifif moderate
moderate starting
starting torque
torqueisissatisfactory.
satisfactory.This
Thisstarting
starting
able
In In
thisthis
connection,
circuit
method
able power
powersystem
systemcapacity.
capacity.
connection,
circuitbreakbreakan "open
"open transition"
transition" where
wherethethemotor
motor
method usually
usuallyrequires
requiresan
ers
breaker
dutyduty
cycle
may
ers operating
operatingatata nonnal
a normal
breaker
cycle
may provide
providethe
the
is
is disconnected
disconnectedfor
fora acouple
couple of
of seconds
secondswhen
when changing
changingfrom
from
dual
means.
of controller
controllerand
anddisconnecting
disconnecting
means.
dualservice
serviceof
the
motor
is reconthe wye
wye to
to the
the delta
deltaconfiguration.
configuration.When
Whenthethe
motor
is reconnected
to
the
delta
(run)
configuration,
the
power
system
will will
nected to the delta (run) configuration, the power system
6.22.3
Reduced-Voltage
Starting
6.22.3Reduced-Voltage
Starting
be
subjected
to
a
severe
current
in-rush
(approaching
the
fullbe subjected to a severe current in-lush (approaching the fullvoltage,
lockedrotor
rotor
current)
unless the
time is
voltage,locked
current)
unless
the transition
transitiontime
is
The
andand
resistor
types types
of
The autotransformer,
autotransformer,reactor,
reactor,
resistor
of reducedreducedmade
very
short
(less
than
0.1
second).
A
short
transition
time
made
very
short
(less
than
0.1
second).
A
short
transition
time
voltage
voltage controllers
controllersprovide
providemethods
methodsfor
for decreasing
decreasingthe
the startstartis not recommendeq for most applications because of
of the
the risk
risk
ing
andand
synchronous
motors.
ing in-rush
in-rushcurrent
currentofofsquirrel-cage
squin-el-cage
synchronous
motors. is not recommended for most applications because
of
mechanical
coupling
or
motor
winding
damage
that
could
of
mechanical
coupling
or
motor
winding
damage
that
could
See
anexample
example
of reduced-voltage
statting
16 for
foran
ofreduced-voltage
starting
See Figure
Figure 16
result
from
out-of-phase
the
power
system
result
from
out-of-phase
closure
between
the
power
system
using
using an
an autotransfonner.
autotransformer.Though
Thoughmore
morecostly
costlythan
thanthe
thefullfullvoltage
voltageand
andthe
the residual
residualmotor
motorvoltage.
voltage.
voltage
controller
method,
these
reduced-voltage
controller
voltage
method, these reduced-voltage controller
methods
high-inertia
loads
or or
methodsmay
may be
berequired
required where
wherespecific
specific
high-inertia
loads
6.22.5
Solid-state
Control
6.22.5Solid-state
Control
system
limitations
are
encountered
system limitationsare encountered
6.22.4
Starting
6.22.4 Wye-Delta
Wye-DeltaStarting
A
windings
connected
in
A motor
motor that
thatnonnally
normallyhas
hasitsits
windings
connected
in delta
delta
may
started by
wye. This
This
may be
bestarted
by connecting
connecting its
its windings
windingsinin
wye.
reduces
in-rush
and
reducesthe
thecurrent
current
in-rush
and starting
startingtorque
torqueto
to one-third
one-third of
of
Soft-start
controllers
(reduced
starting-current
Soft-startcontrollers
(reduced
starting-current
in-rush) in-rush)
using
using solid-state
solid-statedevices
devicesmay
may also
also be
be used
used with
with or
or without
without aa
standard
contactor
to
bypass
the
solid-state
statter.
standard
to bypass the solid-state starter. Starting
Starting
times
for
high
inertia
or high
torque
loads
times for high inertia
or high
torque
loadsshould
shouldbebereviewed
reviewed
with
supplier.
with the
thesoft-statt
soft-start
supplier.
Fuse
,
"
"
t
1..-_""""'--U
1
dl
Control
Controlpower
power
transformer
transformer
-
1
Start
Start
C
Contractor
Contractor
C
"
C
C
C
"
"
"
"
C
C
Contactor
~--------t---- Contactor
Relay
Motor
Motor
I
Stop
Stop
Figure
Wiring Diagram
Diagram for
Figure 15-Typical
15-Typical Wiring
for Full-Voltage
Full-VoltageStarting
Starting
coil
coil
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54
54
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
I
L3
Fuse
Control power
power
Confrol
transformer
\1
-"'''''-''-/'------'
Stop
Start
Trip
TR
-L
TR
I
T
'
I
1
Run
contactor
contactor
Starting
contactors
Relay
Autotransformer
Autotransformer
Motor
Motor
Figure
TypicalWiring
Wiring Diagram
Diagram for Autotransformer Method
Figure 1616-Typical
Methodof
of Reduced-Voltage
Reduced-VoltageStarting
Starting
Copyrighted material licensed to IDOM.
S T D . A P I . / P E T R O . R P 540-ENGL
1799 M 0732290 Ob15572
No further reproduction or distribution permitted.
466 3
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONS IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
6.22.6
AssistedStarting
Starting
6.22.6 Capacitor
CapacitorAssisted
Motors
started on "weak"
Motors to
to be started
“weak” power
power systems
systems can
can use
use aa
technique
is
technique where
where aarelatively
relativelylarge
largecapacitor
capacitorbank
bank
is switched
switched
onto
is
onto the
the same
samebus
busas
as the
the motor
motoran
an instant
instant before
beforethe
themotor
motor
connected.
provide most of the
reactive
connected. The
The capacitors
capacitorsprovide
thereactive
motorduring
during the
acceleration,
requirements
requirements of the
themotor
the motor
motoracceleration,
minimizing
the
system
voltage
drop.
As
the
motor
minimizing the system voltage drop.
As the motor accelerates
accelerates
to rated
speedand
andthethe
voltage recovers,
rated speed
busbus
voltage
recovers, the capacitor
capacitor
bank isisdisconnected.
disconnected. Surge
Surge arresters
arresters and surge
surge capacitors,
applied
terminals, are
forthis
this
appliedatat the motor terminals,
are recommended
recommendedfor
application
application to protect the
themotor
motorfrom
from switching
switching surges.
surges.
6.22.7
RotorControl
Control
6.22.7 Wound
WoundRotor
55
55
uid rheostat.
6.10.4.3for
for concerns
concerns regarding
regarding the
theinstallainstallarheostat.See
See 6.10.4.3
tion
tion of wound
woundrotor-type
rotor-typemotors.
motors.
6.23
CONTROLLERS
6.23 MOTOR
MOTORCONTROLLERS
Motor
controllers
provide the
to start,
regulate
Motorcontrollers
provide
the means
meanstostart,
regulate
speed,
speed, and stop
stop electric
electric motors.
motors.In addition,
addition, controllers
controllersafford
afford
protection
againstabnormal
abnormaloperating
operating
conditions
protection against
conditions
thatthat may
and exposure
result
result in production
production losses,
losses,equipment
equipmentdamage,
damage,
exposure
of personnel
personnelto
to unsafe
unsafe conditions.
conditions.
6.23.1
Equipment
6.23.1 Selection
Selection of
of Control
ControlEquipment
When selecting
selecting control
control equipment,
equipment,the
thepower
powersupply
supplysyssysof the
andand
operational
tem,
andand
sizesize
tem, the
thetype
type
theconnected
connectedmotor,
motor,
operational
and
and service
service conditions
conditions should
shouldbe taken
taken into account. Affecting these
appraisal are
these conditions and
and requiring
requiring careful appraisal
are the
the
power
supply,thethe
controller size
rating, and the
powersupply,
controller
size and
andrating,
the :frefrequency
quency of starting.
starting.
The
The typical
typical wiring
wiring diagram
diagramfor
foraawound
woundrotor
rotormotor
motor(Fig(Figure 17)
system
17)begins
begins with
withthe
thebasic
basiccontrol
control
systemfor
for aafull-voltage
full-voltage
type
type motor (see
(see Figure
Figure 15).
15). Rpm
Rpm adjustment
adjustment is
is obtained
obtained
through
of aa speed
rheostat
external
to theto the
through the
theaddition
addition
speedcontrol
control
rheostat
external
6.23.1.1
Supply
6.23.1 .I Power
PowerSupply
motor enclosure,
enclosure,and
andnear
nearthe
themotor control
control center,
center, in
in a safe
area.
resistance
is implemented
typically implemented
area. This
This variable
variableresistance
istypically
The
The ability
ability of the
the power distribution
distribution system
system to
to satisfactosatisfactothrough sets
andand
resistors,
or aa stepless
rily handle
loads
is
sets of
offixed
fixedcontactors
contactors
resistors,
steplessliqliqhandlemotor
motorstarting
starting
loads
is of major
major impOltance
impor&anceand
and in
in
L.
L.
L.
U
- 4
Contractor
Contractor
L..-..J'o,""""""_
il
C
Control
Control power
power
transformer
...L
Start
Stop
....--------1---- Contactor
Contactor
mil
coil
C
C
Relay
W
m
Motor
Speed control rheostat
Speed control rheostat
Figure
TypicalWiring
Wiring Diagram
Diagram for Wound-Rotor
Figure 1717-Typical
Wound-Rotor Motor
MotorControl
Control
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56
56
PRACTICE
RECOMMENDED
API
API
RECOMMENDED
PRACTICE 540
540
large
determinesthe
theselection
selection
of control.
large measure
measuredetermines
ofcontrol.
ThisisThis is
true,
whereobjectionable
objectionable
voltage
disturbances
true, particularly
particularlywhere
voltage
disturbances
are
are produced
producedby
by the
the starting
startingof
of aa few
few large
largemotors
motorsrepresentrepresenting
ing the
the bulk
bulk of
ofthe
thesystem
systemcapacity.
capacity.The
The full-voltage
full-voltagestarting
starting
motors and
andsynchronous
synchronous
current
current of
of squirrel-cage
squirrel-cage induction
induction motors
motors
(350%to
to 700%),
700%), so
so
motorsisis several
severaltimes
timesfull-load
full-loadcurrent
current(350%
the
system
capacity
must
be
able
to
supply
the
increased
the system capacity must beable to supplythe increasedkilokilovolt-amperes
withoutobjectionable
objectionable
system
disturbance. If
volt-ampereswithout
system
disturbance.
If
this
is
not
practical,
an
alternative
starting
method
must be
this is not practical, alternative starting method must
be
employed
employedto
to confine
confinethe
thecurrent
currentin-rush
in-rushand
andvoltage
voltagedrop
dropto
to
satisfactory
levels.
satisfactory levels.
automatic
automatic control
control device(s), to
to start
start and stop
stop the
the motor.
motor. In
general,
isis at
than
the
general,the
thecontrol
controlvoltage
voltage
at aalevel
levellower
lower
than
the equipequipment
mentutilization
utilizationvoltage.
voltage.
The
matchTheequipment
equipmentisis applied
appliedat
atstandard
standardvoltage
voltagelevels
levels
matching
Fuses,
ingthe
themotor
motorrequirements.
requirements.
Fuses,circuit
circuitbreakers,
breakers,or
or motor
motor
circuit
or
the
circuitprotectors,
protectors,separately
separately
or integrally
integrallymounted
mountedwithin
within
the
starter
enclosure,
provide
the
required
disconnect
and
shortstarter enclosure, provide the required disconnect and shortcircuit
protection.
Thermal
elements or
circuitprotection.
Thermal
elements
or current-sensitive
current-sensitive
devices,
connected
in
all
three
phases
of
devices, connected in
three phases of the control
control equipequipment,
provide
the
overload
protection.
Three-wire
ment,providetheoverloadprotection.Three-wirecontrolcontrol
provides
protection
against
automatic
restartrestart
providesthe
theundervoltage
undervoltage
protection
against
automatic
of
motors
after
the
restoration
of
failed
voltage.
Starters
of motors after the restoration of failed voltage.
Startersconcon6.23.1.2
Controller
Size
and
Rating
trolled
devices
are for
wired
for undervoltage
6.23.1.2 Controller Size and Rating
trolled by
by automatic
automaticdevices
arewired
undervoltage
. release
controlpermitting
permittingautomatic
automatic restart
release (two-wire control
restart after
after
Motor
Motorcontrollers
controllersare
arerated
ratedininhorsepower
horsepoweror
orcurrent-carrycurrent-carryvoltage
restoration).
The
selection
of
the
pushbutton
or
convoltage
restoration).
The
selection
of
the
pushbutton
or
coning
ing capacity
capacity and
and must
must be
be capable of
of interrupting
interruptingthe
the motor
motor
trollocation
may
be
made
totocomply
with
desired
operational
trol
location
may
be
made
comply
with
desired
operational
locked-rotor
motor
locked-rotorcurrent
currentat
atthe
the voltage
voltagespecified.
specified.Industrial
Industrial
motor
requirements.
requirements.
controllers
manufacturer's
nameplate
specifying.
controllers bear
bearthethe
manufacturer’s
nameplate
specifying
Where
continuity
Wherecontinuity
of of service
service or
or operating
operating conditions
conditions
their
rating,and
and
voltage.
Controllers are
their size,
size, horsepower
horsepowerrating,
voltage.
Controllers
are
isis available
totopennit
motors
demand,
time-delay
relaying
demand,
time-delay
relaying
available
permit
motorsto
to
supplied
dutyclassifications
classificationsand
and include
supplied in
in several duty
include the
the folfolride
through
voltage
dips.
The
delay
interval
is
ride
through
momentary
voltage
dips.
The
delay
interval
is
lowing
lowingtypes:
types:
critical
particularly in
inthe
the larger
critical because
because full
full voltage, particularly
larger sizes,
sizes,
a.a. The
is capable
should
to
residual
Thecontinuous-duty
continuous-dutytype,
type,which
which
is
capableof
ofindefinitely
indefinitely
shouldnot
notbebeapplied
applied
tode-energized
de-energizedmotois
motorshaving
having
residual
carrying
specivoltages
25% to
to 35%
35%rated
rated voltage,
voltage,unless
unlessthe
the motors
motors
carrying full-load
full-load motor
motor current
current without
without exceeding a specivoltagesabove
above25%
fied
have
fiedtemperature
temperaturerise
riseof
ofcurrent-carrying
current-carryingparts.
parts.
havebeen
beendesigned
designedfor
forsuch
suchapplications.
applications.
The
time-current
characteristics
protective
b.b. The
intennittent-duty
type,
which
is
used
on
cranes,
The time-currentcharacteristics of
of associated
associatedprotective
The intermittent-dutytype,which
is used on cranes,
device
and
relaying
equipment
should
be
coordinated
machine
tools,
or
other
equipment
requiring
less
sustained
deviceandrelayingequipmentshouldbe
coordinated to
to
machine tools, or other
requiring less sustained
ensure
selective
protection.
Overload,
locked-rotor,
and shortduty.
ensure selective protection. Overload, locked-rotor,
and shortduty.
circuit
circuit protection
protectionshould
shouldbebeprovided
providedby
by the
the protection
protectioncharcharIt
It isis recommended
recommendedthat
thatthe
theuser
user consult
consultwith
withthe
the manufacmanufacacteristics.
acteristics.
turer
for
conditions.
turerto
toselect
selectadequate
adequateequipment
equipment
forthe
theoperating
operating
conditions.
Medium-voltage
with
protective
Medium-voltage circuit
circuit breakers,
breakers, along
alongwith
protective
relays,
are sometimes
sometimesused
used
with
large
motors to
relays, are
with
large
motors
to serve
serve not
not
6.23.2
Manual
Operation
6.23.2Manual
Operation
only
.
only as
as controllers
controllersbut
but also
also as
as the
the means
means for
for disconnection
disconnection.
.
These
breakers
will
be
electrically
operated
and
can
provide
These
breakers
will
be
electrically
operated
and
can
provide
Manual
limited
use,use,
which
is customarily
for thefor the
Manualcontrol
controlhashas
limited
which
is customarily
automatic
that of
ofmagnetically
magnetically operautomatic control
control comparable
comparable to that
operhorsepower,single-phase
single-phasemotors
motors
starting
the
starting of
of fractional horsepower,
in in .the
ated
contactors;
however,
for
frequent
operation,
magnetiated
contactors;
however,
for
frequent
operation,
magneti120-V
120-Vto
to 240-V
240-Vrange.
range.Within
Withinthe
the 240-V
240-Vrange,
range,on-off
on-offcontrol
control
cally
contactors are
cally operated contactors
are more
more reliable
reliable because
because circuit
circuit
as
overload protection
protection isis provided
as wen
well as
as motor
motor overload
provided within
within the
the
breakers
are
not
designed
for
such
service.
are
not
designed
for
such
service.
breakers
control enclosure. The overload protection is provided by trip-
control enclosure.The overload protectionis provided by trip-
free
in at
freethermal
thermaldevices
deviceslocated
located
at
inleast
leastone
oneside
sideof
of single-phase
single-phase
6.23.4
ProtectiveRelaying
Relayingand
andAútomatic
AutomaticControl
Control
6.23.4 Protective
of three-phase units.
units
and in
three
phases
units. Fused
Fused
unitsand
inallall
three
phases
ofthree-phase
switches
breakers
providing
a line-disconnect
feature feature As
switchesororcircuit
circuit
breakers
providing
a line-disconnect
As aa rule,
rule,the
thefunction
functionof
of protective
protectiverelaying
relayingisis to
to discondisconand
short-circuitprotection
protectioncan
can
obtained in
and short-circuit
bebe
obtained
in combination
combination
nect
nect the
the faulty
faulty equipment
equipment from
from the
the source
source of
of the
the electrical
electrical
units
combined with
control in
inaacommon
commonenclosure)
enclosure) or
units( (combined
with the control
or
disturbance
as
supply
supplyas
asquickly
quicklyand
andwith
withasaslittle
littlesystem
system
disturbance
asposposcan
not be
can be
be separately
separatelymounted
mounted. Low-voltage
Low-voltage release
release may not
be
sible.
each
circuit
or
In a comprehensive
comprehensiveinstallation,
installation,
each
circuit
orpiece
pieceof
of
sible.In·a
available;
thethe
control
contacts
remainremain
closed dur~
available;consequently,
consequently,
control
contacts
closed durequipment
equipmentshould
shouldoperate
operateindependently
independentlyunder
underdistress,
distress,and
~d .
ing
thereby
causing
automatic
restarts
ingperiods
periodsof
ofpower
powerfailure,
failure,
thereby
causing
automatic
restarts the
so selective
selective that
that only
only the
the
the protective
protective relaying should
should be
be so
of
the
motor
upon
resumption
of
power.
Manual
control
is not
is not affected
of the motor upon resumption of power. Manual control
units are
In more
more detail,
detail, protective
protective
affectedunits
are de-energized.
de-energized. In
recommended
formotors
motorsgreater
greater
recommendedfor
thanthan 11 HP
HP or
or for
for motors
motors
relaying
between
abnormal
equipmenloperrelayingmust
mustdistinguish
distinguish
between
abnormal
equipment operthan
240
V
because
of
increased
risk
to
personnel.
greater
to personnel.
greater than 240 V because of increased risk
ation
failures.
ationand
andsystem
system
failures.
6.23.3
Contactor
Operation
6.23.3Contactor
Operation
6.23.4.1
Overload
Protection
6.23.4.1Overload
Protection
The
The application
applicationof
of magnetic
magneticcontactor
contactorcontrol
control isis the
the stanstandard
throughout
the
petroleum
industry.
Magnetic
contactor
dard throughout the petroleum industry. Magnetic contactor
pushbutton, or
control
magneticcontactor
contactor and
or
control utilizes
utilizes a magnetic
and aa pushbutton,
Overload
applied to
tode-energize
de-energizeoverloaded
overloaded
Overloadprotection
protection is
is applied
motors
automatically before
before winding
winding or
motors automatically
or conductor
conductor damage
has
beencaused
caused by
operatingtemperature.
temperature. The
hasbeen
by excessive
excessiveoperating
The
~
STD=API/PETRO RP
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1 7 9 9 or distribution permitted.
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ELECTRICAL
INSTALLATIONS
IN PETROLEUM PROCESSING
PLANTS
ELECTRICAL
PETROLEUM
INSTALLATIONS
IN
PROCESSING
PLANTS
motor controller
controllerthermal
thermaldevice,
device, actuated by a self-contained
self-contained
selected
heating element
elementresponsive
responsiveto motor line
linecurrent
currentand
and
selected
for coordination
withthethe type ofmotor
motorenclosure,
enclosure, is frecoordinationwith
frequently used and
or an autoavailable with
witheither
eithera manual
a manual
autoand is available
matic
reset. Overload
Overload relays
by
motors controlled
controlled by
matic reset.
relays used on motors
automatic
manual
reset.reset.
automatic devices
devicesmust
musthave
have
manual
onaa
NOlmally,
Noimally, the
the selection
selection of a thermal device
device is based on
standard air ambient temperature
temperaturereference
referenceof 40°C (104°P).
(104°F).
Por
fire rooms,
rooms, and
and similar
similarelevated
elevatedambient
ambient
For engine
engine rooms, fire
locations,
locations, SO°C
50°C (122°F)
(122°F)may
maybe chosen
chosen as the reference,
reference, but
but
consideration must
choice ofthermal
eleconsideration
mustbebegiven
given to the choice
thermal ele~
ments.
ments. This
This isis of particular note where the ambient
ambient temperatemperature at the motor
motor is higher than that
that at the remotely
remotely located
located
controller.
Thermalelements,
elements,
unless
temperature
compencontroller.Thermal
unless
temperature
compensated, are responsive
sated,
responsivetotovariations
variations in ambient temperature.
temperature.
The necessity
thelmalelements
elements
be prenecessity for oversized
oversizedthelmal
cancan
beprevented by carefully
carefully selecting
selecting control
controllocations
locationsand by ample
ample
shielding
When controllers
shielding against
againstheat
heatradiation.
radiation.
controllers are
arelocated
located
in areas
areas subject
subjectto unusual ambient
ambient temperature
temperature variations
variationsor
an ambient
ambientdifferent
differentfrom
from the motor,
temperature-commotor, the temperature-compensatedthermal
thermalrelay
relay
is available.
Large motors, greater
isavailable.
Largemotors,
than or equal
H€', frequently
frequently use embedded
embedded detectiondetectionequal to
to 250 HP,
type thermal protection as the best indication
indication of motor temperature.
folLow-voltagemotor
motorcontrollers
controllers generally
generally use
useone
one
Low-voltage
of the following devices:
devices:
57
fault
Motors
operated
on systems
grounded systems
fault protection.
protection.Motors
operated
ongrounded
greater than 600 V should
should be provided
providedwith
withground-fault
ground-faultproprotection.
Multifunction
motor
protection relays
tection.Multifunction
motor
protection
relays (solid-state
(solid-state
type) are
all all
of the
areavailable
availablethat can provide
providesome
someoror
the protecprotecsection.
tion discussed
discussedininthis
this
section.
Overcurrent
protection must be
Overcurrent relays used for overload
overload protection
of the long-time-delay type
type to eliminate
eliminate nuisance
nuisance tripping
onmotor
motor in-rush current.
thermal
current. Protective
Protective relays withthermal
detector inputs
242,
inputs are also available.
available. See
See IEEE
IEEE Std242,
9.
Chapter 9.
Partial and
and fully
fully automatic
automatic control
control are
areused
usedextensively
extensivelyin
petroleum processing
processing facilities.
facilities. Because
Because automatic
automatic control
control is
related to protective
relaying in its application,
application, both
both
protective relaying
closely related
should be
made.
beconsidered
considered when an overall
overall selection
selectionis made.
Control
areare
employed
for magnetically
Control power
powertransformers
transformers
employed
operated
controllershaving
havingmotor
motor
voltages
greater
operated controllers
voltages
greater
thanthan or
process
instruequal to 480 V;
V; they are also
alsoemployed
employedwhere
where
process
instrumentation is involved.
involved. Control
may
be be
Controlpower
powertransformers
transformers
may
applied
applied individually
individuallyto specific
specific equipment,
equipment,or may serve
serve aabus
bus
from which
whichseveral
severalcontrollers
controllers
operate.
Figures
15,and
16, and
operate.
Figures
15, 16,
17
theuse
use ofanan individual
controlpower
powertranstrans17 illustrate
illustratethe
individualcontrol
fOlmer
cir-cir120-V and
andmost
most240-V
240-V
former in a motor
motorcontroller.
controller.Both 120-V
derivecontrol
controlpower
power
directly
from
source.
cuits derive
directly
from
the the
source.
6.23.5 Types ofEnclosures
Enclosures
Control
personnel
andand
to
Control enclosures
enclosures are provided
providedtotoprotect
protect
personnel
meetservice
service and operating
conditions.
Several
operatingconditions.
Several
typestypes
are are
available, each
eachdesigned
designed
to a particular
particularapplicatiop,
application,such
such
available,
to meet
as being used in
in aa corrosive,
corrosive, wet,
wet, dusty,
dusty,or hazardous
hazardous atmoatmoThe sizing
sizing or setting
setting of these devices
devices is based on
onthe
themotor
sphere,
and in a general-purpose
general-purpose indoor
indoorlocation.
location. The cost
sphere, and
nameplate
full-load current,
current, the service
factor, the
the ambient
service factor,
ambient
nameplate full-load
varies with
withthe design,
design, increasing
increasing with
with the
theseverity
severityand
andnature
nature
varies
temperature
whether
temperature of the motor and
andcontroller
controller(specifically,
(specifically,
whether of the service
be met (see
service conditions
conditionstoto
(seeTable
Table3).
different ambient
ambient
the motor and controller are at the same or different
temperatures),
requirements.
temperatures), and
andNFPA 70 requirements.
6.23.6 Maintenance
and Cost
Maintenanceand
Cost
a.
nonadjustable melting
a. The nonadjustable
meltingalloy.
alloy.
bimetallic strip.
strip.
b. The bimetallic
c. Solid-state
Solid-statetype.
type.
6.23.4.2
6.23.4.2
Protectionfor
forLarge
LargeMotors
Motors .
Additional Protection
Protective
Protective relays,
relays, electromechanical
electromechanical or solid state,
state, are well
adapted to provide all
recommended
forms of protection.
protection.It is recommended
allforms
for motors with
that differential
differential relay
relayprotection
protectionbebeprovided
provided
with
ratings of 1,500
over,and
and this requires
requires that
that each
1,500 HP and over,
ratings
in the motor winding
phase of the
thewye
wyeconnection
connection
windingbebeaccessiaccessiresponsive to
ble. Differential
Differential relays are responsive
to changes
changes in the
the relarelationship
incoming and outgoing
tionship between
incoming
outgoing current.
current.
Undervoltage
Undervoltage relays,
relays,responsive
responsiveto voltage
voltage changes,
changes,are used
disconnect equipment
equipmentfrom the line when
when the
thevoltage
voltagefails
fails
to disconnect
or when dips
dips below
belowpredetermined
predeterminedvalues
values are encountered.
encountered.
Phase-sequence
Phase-sequence voltage
voltagerelays protect against
againstreversed
reversedphase
sequence;
voltage
and current-balance
sequence; and
andnegative-sequence
negative-sequence
voltage
current-balance
and
relays provide
provideprotection
protectionagainst
against phase
phase voltage
voltageunbalance
unbalance
current
respectively.lnduction
Inductiondisk
disk
overcurrent
current unbalance,
unbalance,respectively.
overcurrent
relays are
are frequently
frequentlyused with large motors
motors for overload
overload and
and
relays
The control
should satisfactorily
control equipment selected should
satisfactorily hanhandle the
theassigned
assignedduty.
duty.When
Whenborderline
borderline decisions
regarding
decisions regarding
equipment
equipment size are to be made, excessive
excessive long-range
long-rangemaintemainteapparent first-cost
first-cost savsavnance or replacement may offset an apparent
ings.
explosionproof
controllers
are
instances whereexplosionproof
controllers
are
ings. In instances
indicated
indicated for classified
classified locations,
locations, aa study
studyof
ofthe
thecomparative
comparative
costs of remotely
remotely located general-purpose
general-purpose or weathinstalled costs
erproof controllers
substantial
savings.
controllersmay
mayshow
show
substantial
savings.
Special
considerationshould
should be given
service
severeservice
Specialconsideration
given to severe
conditions, such
suchas humidity
and atmospheric
atmosphericor process
corconditions,
humidity and
process corrosion, which may damage
rosion,
damage or render control elements ineffective.
Availability
of corrosion-resistant
enclosure
parts
fective.Availability
ofcorrosion-resistant
enclosure
parts
should be
manufacturer. Also,
Also,
be discussed
discussed with the equipment manufacturer.
theinstallation
installation of control
centers or grouping
controlcenters
grouping of control
equipment
possible savings
savings and
equipment should
shouldbe considered
considered for
forthe possible
maintenance.
the convenience
convenienceofof
maintenance.
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RECOMMENDED PRACTICE
PRACTICE 540
API RECOMMENDED
58
3-NEMA Enclosure Types for AC Motor Controllers
Table 3-NEMA
Controllers
Type of
NEMA Typeof
Type Enclosure
1 General
purposepurposeindoor
'
Characteristics
Where Used
A Type 1 enclosure is designed to meet ,
Underwriters Laboratories' most recent general specifications for enclosures. This enclosure is intended primarily to prevent
accidental contact with the control apparatus.
Locations where enclosure prevents accidental
contact with live parts, and
indoor locations where
normal atmospheric conditions prevail.
Typical Application
in Plants
Office buildings,
warehouses, change
houses.
Comparative Cost
Combination Circuit
Breaker Type
Size 1
Size 4
1.0
1
.o
1l.D
.D
When a nonventilated enclosure is specified
of devices that
for equipment consisting of
require ventilation (electronic devices and
resistors), such devices may be mounted in
ventilated portions of the enclosure, provided
they are capable of operating satisfactorily
and without hazard when so mounted.
A Type 1 enclosure is suitable for generalpurpose applications indoors and under normal atmospheric conditions. It protects
but·
against dust, light, and indirect splashing but
dusttight.
is not
notdusttight.
1.1
1.1
Flush-type enclosures (designed for mounting
in a waH)
wall)have provisions for aligning with
the flush plate and compensating for waH
wall
thickness.
2 DripproofDripproofindoor
A Type 2 enclosure is similar
similar to a Type 1
enclosure, but it also
alsohas drip shields or their
equivalent.
equivalent.
Locations where condensevere.
sation may be severe.
Refrigeration rooms
and water pumphouses not classified
corrosive.
and not corrosive.
1.1
1.1
1.1
1.1
Locations subject to windwindblown dust and rain.
conOutdoors on constructionjobs
struction jobs and
dusty locations.
1.2
1.2
Locations subject to heavy
rain.
Outdoors at commercial installations
mercial
onconstruction
and on
jobs.
1.2
1.2
1.2
A Type
Type3S
3 s enclosure
enclosure is
is designed
designed to provide
provide
Locations subject to heavy
heavy
icing conditions.
protection
protection against
against windblown
windblown dust and water
water
conditions.
and to provide
providefor
for operation
operation when
when covered
coveredwith
extemal
external ice
ice or sleet.
sleet. It
may have
have auxiliary
auxiliaryproviSions
provisionsfor
for ice
icebreaking.
breaking.
ship
Outdoors on ship
Outdoors
decks or on concondecks
struction site
site subject
struction
to
to heavy
heavy icing.
icing.
1.7
1.7
1.6
A Type 2 enclosure is suitable for applications
applications
where condensation may be severe, such as in
cooling rooms and laundries.
laundries. It provides protection against dust, falling liquids, and light
splashing but is not dusttight.
dusttight.
3 Dusttight,
raintight, and
sleet resistant-outdoor
A Type 3 enclosure is designed to provide
protection against windblown
windblown dust and water.
water.
It is not sleetsleet- or iceproof.
iceproof.
A Type 3 enclosure is suitable for use
useoutoutdoors if ice is not a serious
serious problem.
3R Rainproof,
sleet
resistantresistantoutdoor
A Type 3R enclosure is designed to provide
provide
protection against rain. It is not
notdusttight or
snow-, sleet-, or iceproof.
A Type
Type 3R enclosure is suitable
suitable for
for use outoutdoors and will
will prevent the entrance of a rod of
0.125 inch diameter,
diameter, except
except at drain holes.
holes.
Types
Types 3 and 3R are
are usually
usually combined in one
one
enclosure type.
3S
3 s Dusttight,
raintight, and
sleet-proofsleet-proofoutdoor
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ELECTRICAL
INSTALLATIONS
IN
ELECTRICAL
INSTALLATIONS
PETROLEUM
IN PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
59
59
EnclosureTypes
Typesfor
for AC
AC Motor
Motor Controllers
Controllers (Continued)
(Continued)
Table 3-NEMA
3-NEMA Enclosure
NEMA
Type
T p
Type of
Type
Enclosure
Characteristics
Characteristics
Typical
Typical Application
Application
in Plants
Plants
Where Used
Comparative
Comparative Cost
Cost
Combination Circuit
Breaker Type
Type
Size
Size 1
Size
Size 4
Outdoor locations
locations or localoca- Outdoors at pumps
tions where
not in classified
where the starter
starter
classified or
might be subjected
corrosive
subjected to
corrosive locations.
locations.
splashing or
or dripping
dripping
water;
water; not suitable
suitable for
for subsubmersion in water.
water.
1.7
1.7
1.6
1.6
Type
Type 4 enclosures
enclosures are usually used for
for this
this
service.
service.
4
Watertight and
and A Type
Type 4 enclosure,
enclosure, intended for
for use indoors
indoors
Watertight
dusttight
outdoors, protects
protects the enclosed
enclosed equipment
or outdoors,
against
against splashing
splashing water,
water, seepage
seepage of water,
water,
falling
falling or hose-directed
hose-directed water,
water, and severe
severe
external condensation.
condensation.A Type
Type4 enclosure
external
enclosure is
sleet-resistant
sleet-resistant but not sleetproof.
sleetproof.
4X Watertight,
Watertight,
dusttight, and
dusttight,
corrosioncorrosionresistant
Type 4
A Type
Type 4X enclosure is the same
same as aaType
corrosion-resistant.
enclosure but is also corrosion-resistant.
Locations subject
subject to
splashing or dripping
dripping
water where
where corrosion
corrosion is
also a problem.
problem.
Outdoor locations
locations in
chemical
chemical plants.
plants.
2.0
1.7
1.7
6 Submersible
Type 6 enclosure is suitable for applications
applications
A Type
where the equipment may be subject to subsubwhere
mersion in water,
water, as in quarries, mines, and
manholes. The design of the enclosure
enclosure will
manholes.
depend
depend on the specified
specified conditions
conditions of pressure
and time. It is also dusttight and sleet resistant.
tant.
where the
Locations where
subject to
equipment is subject
submersion in water.
water.
Normally not
required.
4.0
4.0
7
Classified
location;
location;
Class 1IClass
air break (see
2)
Note 2)
A Type 7 enclosure is designed to meet the
application requirements for Class I locations
application
as defined in Article 500 of NFPA 70 and is
designed in accordance with the latest specifispecifiLaboratories. A letter
cations of Underwriters Laboratories.
suffix
suffix in the type designation specifies
specifies the
NFPA 70 group for which the enclosure is
suitable.
suitable.
Locations which are classified as Class I locations
according to Article 500
of NFF'
NFPA
A 70 due to the
presence of flammable
flammable
gases andvapors.
vapors.
Class I, Division 1
and 2 areas,
areas, Groups
A-D.
A-D.
2.1
1.6
1.6
8
Classified
Classified
location;
location;
Class I - o i l
ClassI-oil
immersed (see
Note 2)
Locations which are
A Type 8 enclosure is designed to meet the
are clasapplication requirements for Class I locations sified as Class I locations
according to Article 500
as defined in Article 500 ofNFPA
NFPA 70 and isis
designed in accordance with the latest specifispecifi- of NFPA 70 due to the
flammable
cations of Underwriters Laboratories. The
presence of flammable
apparatus is immersed in oil. A letter suffix in gases and vapors.
the type designation specifies the NFPA 70
group for which the enclosure is suitable.
Class I,
I, Division
Division 1
and 2 areas, Groups
A-D.
A-D.
2.5
2.5
1.8
1.8
Type 9 enclosure is designed to meet the
AType
application requirements for Class II locations
NFPA 70 and is
as defined in Article 500 of NFPA
designed in accordance with the latest specifispecifications of Underwriters Laboratories. A letter
letter·
suffix in the type designation specifies
specifies the
NFPA 70 group for which the enclosure is
suitable.
are clasLocations which are
sified as Class II locations
according to Article 500
of
NFPA 70 due to the
ofNFPA
presence of combustible
dusts.
Class II areas,
Groups E and G.
2.1
1.6
Locations that must meet
the latest requirements of
of
MSHA.
Normally not
required.
required.
9 Classified
location;
IClass I
lIGroups
E and
GroupsEand
G
10 MSHA,
U.S. A Type 10 enclosure is designed to meet the
MSHA,U.S.
Dept. of
ofLabor latest requirements of
of MSHA.
I
i
1
1
I
!
'
11
11 Corrosion
resistant and
dripproof, oil
immersedimmersedindoor
indoor
(see Notes 2
and 3)
A Type 11 enclosure is suitable for applicaLocations where acid or
fumes are present.
tions indoors where the equipment may be
subject to corrosive acid or fumes, as in chemical plants, planting rooms, and sewage
plants. The apparatus is immersed in oil.
2.2
.1.7
1.7
.
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60
60
RECOMMENDED
API
540
API RecoMMENDED PRACTICE
PRACTICE
540
Table
3-NEMA EnclosureTypes
Table 3-NEMA
EnclosureTypesfor
for AC
AC Motor
MotorControllers
Controllers (Continued)
(Continued)
of
NEMA Type
Typeof
T m Enclosure
Enclosure
12
12 Industrial
Industrial
U8euse-
dusttight
dusttightand
and
driptightdriptightindoor
indoor
Comparative
ComparativeCost
Cost
Combination
CombinationCircuit
Circuit
Breaker
Breaker Type
Type
Typical
TypicalApplication
Application
Sizc
1
Size
in
in Plants
Plants
Size 1 Size44
Characteristics
Characteristics
Where
Where Used
Used
A
AType
Type 12
12enclosure
enclosureisisprovided
provided with
withan
anoiloilresistant
thecase
caseand
and
resistantsynthetic
syntheticgasket
gasketbetween
betweenthe
the
thecover.
cover.The
The cover
coverisishinged
hinged to
to swing
swinghorihorizontally
zontallyand
and isis held
held ininplace
placewith
with captive
captiveclosclosing
inghardware;
hardware;aa screwdriver
screwdriveror
orwrench
wrenchmust
mustbe
be
used
used to
torelease
release the
the cover
coverfrom
fromthe
thehardware.
hardware.
There
There are
areno
no holes
holes through
through the
theenclosure
enclosurefor
for
mounting
mountingor
orfor
for mounting
mountingcontrols
controlswithin
withinthe
the
enclosure
enclosureand
andno
noconduit
conduitknockquts
knockoutsor
orconduit
conduit
openings.
openings.Mounting
Mounting feet
feetor
or other
other suitable
suitable
means
.
meansfor
for mounting
mounting are
areprovided.
provided.
Locations
Locations where
where oil
oil or
or
coolant
coolantmight
might enter
enter the
the
enclosure
enclosure through
throughmountmounting
ing holes
holes or
or unused
unused conconduit
duitopenings
openingsand
andwhere
whereitit
isis necessary
necessary to
to exclude
exclude
dust,
dust,fibers,
fibers,flyings,
flyings,and
and
lint.
lint.
Machine
Machine tool
tool drivedrivein
in shops;
shops;chemical
chemical
rooms
roomsin
in water
watertreattreatment
ment plants.
plants.
Indoor
Indoorlocations
locationssubject
subjectto
to
the
thecontaminants
contaminantslisted.
listed.
Indoor
Indoordusty
dusty control
control
areas
areasor
or where
where subsubject
ject to
to liquid
liquid spray.
spray.
1.2
1.2
1.2
1.2
When
When aaType
Type 12
12enclosure
enclosureisis specified
specifiedfor
for
equipment
equipmentconsisting
consisting of
of devices
deviceswhich
which
require
require ventilation
ventilation (electronic
(electronicdevices
devicesand
and
resistors),
resistors), such
suchdevices
devicesmay
may be
be mounted
mounted in
in aa
ventilated
ventilatedportion
portion of
of the
theenclosure
enclosureas
as long
longasas
they
they are
are capable
capable of
of operating
operatingsatisfactorily
satisfactorily
and
and without
withouthazard
hazard when
whenso
somounted.
mounted.
13
13 Oiltight
Oiltightand
and
dusttightdusttightindoor
indoor
A'lYpe
A Type 13
13enclosure,
enclosure,intended
intendedfor
for use
use
indoors,
as limit
limit
indoors,protects
protects pilot
pilot devices;
devices; such
suchas
switches,
switches,foot
footswitches,
switches,pushbuttons,
pushbuttons,selector
selector
switches,
switches,and
and pilot
pilot lights,
lights,against
againstlint;
lint; dust;
dust;
seepage;
seepage;external
externalcondensation;
condensation;and
and spraying
spraying
water,
oil,or
orcoolant.
coolant.A
AType
Type 13
13enclosure
enclosurehas
has
water,oil,
oil-resistant
oil-resistantgaskets,
gaskets,external
externalmounting
mounting
means,
means,no
no conduit
conduit knockouts
knockoutsor
or unsealed
unsealed
openings,
openings,and
andoiltight
oiltight conduit
conduitentry.
entry.
Notes:
Notes:
L1.MSHA
MSHA==Mine
MineSafety
Safetyand
andHealth
HealthAdministration.
Administration.
2.
2.Any
Any individual
individualstarter,
starter,circuit
circuit breaker,
breaker,fuse,
fuse, switch,
switch,fused
fused discondisconnecting
necting switch,
switch,or
orany
anycombination
combinationof
of these
theseitems
itemsmay
may be
beenclosed
enclosedin
in
any
8, and
any of
of the
the aforementioned
aforementionedenclosures.
enclosures.When
When NEMATypes
NEMA Types7,
7,8,
and
11
11enclosures
enclosures are
areapplied,
applied,aacombination
combination of
of enclosures
enclosuresmay
may be
be
required
required ifif the
theinstallation
installationisis outdoors
outdoorsor
oradditional
additionalprotection
protection feafeatures
turesother
otherthan
thanthe
thebasic
basic protection
protectionprovided
provided by
bythe
thespecific
specificNEMA
NEMA
type
type are
arerequired.
required.To
To standardize
standardizethe
the practice
practice in
inreferring
referring to
to equipequipment
ment known
known as
asexplosionproof
explosionproof(Types
(Types 77and
and 8),
S),apparatus
apparatusdesigned
designed
for
for use
usein
in Class
Class I,I,Group
GroupA-D
A-D locations,
locations, should
shouldbe
bedescribed
described in
inone
one
of
of the
thefollowing
followingways:
ways:
a.a.Control
Control listed
listedby
by aaNR'IL
NRTLfor
foruse
usein
inClass
ClassI,I,Group
Group (state
(statespespecific
cificgroup
groupletter)
letter)locations.
locations.
6.24
APPLICATION OF
6.24 APPLICATION
OF MOTOR
MOTORCONTROL
6.24.1
Squirrel Cage
6.24.1Squirrel
Cage Induction
InductionMotor
Motor
Because
Because of
of its
its simplicity
simplicity and
and adaptability
adaptabilityto
to full-voltage
full-voltage
starting,
starting, the
the squirrel-cage
squirrel-cageinduction
induction motor
motorisis widely
widely used
used in
in
constant-speed
constant-speed applications.
applications. Magnetic
Magnetic full-voltage
full-voltage starting
starting
with
with remote
remote or
or automatic
automaticcontrol
control isis customarily
customarily applied
applied for
for
motor
for this
this application
application isis diadiamotor starting.
starting. (The
(The wiring
wiring for
grammed
15.)Magnetic
Magnetic full-voltage
full-voltage starting
startingisis the
the
grammedin
in Figure
Figure 15.)
b.b. Control
Controldesigned
designedto
to conform
conform with
withthe
the manufacturer's
manufacturer's interpretation
interpretation
of
of the
the requirements
requirements of
of Underwriters
Underwriters Laboratories'
Laboratories' standards
standards or
orfrom
from its
its
testing
testingfacilities.
facilities.
c.c. Control
Control ofa
of a size
size and
and nature
naturefor
for which
whichthere
thereare
areno
noexisting
existing UnderUnderwriters
NRTLtesting
testingfacility.
facility.
writersLaboratories'
Laboratories' standards
standardsor
ortests
testsfrom
from aa NR'IL
3.3.When
When an
anenclosure
enclosurehas
has to
tomeet
meet the
therequirements
requirements of
of NEMA
NEMA'lYpe
Type 11,
11, .
the
on the
theconditions
conditionsof
ofexposure.
exposure.
thedesign
design will
willdepend
depend on
4.'NEMA
NEMA ICS
ICs 66 can
canprovide
provide more
more detailed
detailedinformation
information on
on enclosures
enclosures
and
and test
test requirements.
requirements.
4:
most
of motors
motors after
after the
the
most desirable
desirable and
and can
can prevent
prevent restart
restart of
return·
of
failed
voltage.
There
are
cases,
however,
where
return of failed voltage. There are cases, however, where
automatic
imperativebecause
becauseof
of critical
criticalprocess
process
automaticrestarting
restarting isisimperative
requirements.
If
automatic
restarting
is
necessary,
timerequirements. If automatic restarting is necessary, timedelay
delay relaying
relaying can
can be
be provided,
provided, and
and if
if several
several motors
motors are
are
involved,
involved, the
the motors
motors can
canbebe .automatically
automatically restarted
restarted in
in
sequence
sequenceto
to prevent
preventpossible
possible system
systemdisturbances.
disturbances.
Reduced-voltage
Reduced-voltage starting,
starting, either
either manual
manual or
or automatic,
automatic, isis
employed
to
reduce
the
starting
current
on
power
employed to reduce the starting current on power systems
systemsof
of
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STDmAPIlPETRO RP 540-ENGL
0732290
Ob15598 984 W
No furtherL999
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or distribution
permitted.
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
iNSTALLATlONS IN PETROLEUM PROCESSING PLANTS
PLANTS
61
61
limited capacity
capacity if the reduced-starting
reduced-starting torque
torque is adequate
adequate
connected equipment.
equipment. Reduced-voltage
Reduced-voltage starting
starting also
also
for the connected
is employed
employed when
whenthe driven load demands
demands smooth
smoothstarting.
starting.
applying
reduced-voltage starting are
Severalmethods
applying
reduced-voltage
Several
methodsofof
available:
available:
winding is brought out
outthrough
throughslip
slip rings and
and connected
connectedto a
winding
variable
resistor or regenerative
system. This arrangement
variableresistor
regenerativesystem.
arrangement
provides
selective speed
speedcontrol
controlunder
undervarying
varyingconditions
conditionsof
provides selective
load (see Figure 17).
17).
The primary control
controldevice
device for statting
wound-rotor
starting awound-rotor
motor is usually the same
used for a squirrel-cage
same as that used
squirrel-cage
a.
autotransformer method
methodoffers
offersvariations
variationsinin
starting
a. The autotransformer
starting
induction motor.
the
motor. The secondary
secondary device
device for regulating
regulatingthe
torque through
through selective
selective stalting
starting taps.
taps. It provides
provides maximum
maximum
torque
awound-rotor
motormotor consists
consists ofanan adjustable
adjustable
a wound-rotor
speedofof
starting torque
torquewith
withminimum
minimum
line current (see
(seeFigure
Figure16).
16).
starting
line
resistor or rheostat.
rheostat. It is general practice to interlock these
resistororor
reactor
method
offers
simplicity of
b. The series
seriesresistor
reactor
method
offers
simplicity
primary and secondary control devices so that the motor
primary and secondary control devices so that the motor
design
starter.
design and uses aamore
moreeconomical
economical
starter.
started except when
cannot be started
when the resistor is set
setininminiminic. Wye-delta
Wye-delta
starting
economical
method
mum-speed position.
position.
c.
starting is also an economical
method of
mum-speed
reduced-voltage
starting
torque
reduced-voltage starting
startingbut
butproduces
producesa lower
a lower
starting
torque
Application
Application of wound rotor motors
motors in
in petrochemical
petrochemicalenvienvithan the
theother
othermethods.
methods.
of the
ronments
because
ronments should
shouldbe
becat'efully
carefullyreviewed
reviewed
because
the sparksparkd.
d. The solid-state
solid-state reduced-voltage
reduced-voltagestarting
startingmethod
methodprovides
providesaa
ing nature
nature of
of the
and slip
slip rings.
ing
the brushes
brushes and
smooth,
stepless
acceleration with current-limit
control
smooth,
stepless
acceleration
current-limit
control
adjustable
betweenthe
the
limits of approximately
150% and
adjustablebetween
limits
approximately 150%
6.25MEANS
MEANS
DISCONNECTION
OFOF
DISCONNECTION
425% of motor full-load
full-loadcurrent.
current.
are discussed
Means of
ofdisconnection
disconnection
discussed in NFPA
NFPA 70.
70.
6.24.2Synchronous
Synchronous
Motor
Motor
6.26COORDINATION
COORDINATION
OF CONTROLLER
OFCONTROLLER
The synchronous
synchronous motor
motor isis applied
applied principally
principallyin the large
large
APPLICATIONS WITH
WITH FUSES
FUSES OR
ORCIRCUIT
CIRCUIT
horsepower
horsepower class,
class, greater
greater than
thanor equal
equal toto500
500 HP.
HP. Because
Because of
BREAKERS
BREAKERS ON
ON LOW-VOLTAGE
LOW-VOLTAGESYSTEMS
SYSTEMS
its limited
limited starting
startingcharacteristics,
characteristics,the
thesynchronous
synchronousmotor
motor is
generally
stalted
under
no-load
conditions
with
DC
field
generallystartedunderno-loadconditionswith
field
NormalOperation
Fault
Conditions
6.26.1 . Normal
Operationand
and
Fault
Conditions
excitation
excitation automatically
automaticallyapplied
appliedwhen the motor approaches
approaches
. A motor controller must be capable of starting
starting and stopstopsynchronous
be used
dur- dursynchronous speed.
speed.Variable
Variable field
fieldexcitation
excitationmay
may
be used
ping its ratedmotor
motor
horsepower
and inten'upting
motor
horsepower
andinterrupting
motor
ing normal
normal operation
operation to
to provide
provide power
power factor
factor correction
con-ectionand
and
locked-rotor
the the
controller
cannotcannot
interrupt
locked-rotor current.
current.Normally.
Normally,
controller
interrupt
should
should be specified
specified if required.
required.
from short circuits
circuits and grounds
fault currents resulting
resulting from
grounds so a
As isis the
andand
thecase for squirrel-cage
squirrel-cage induction
inductionmotors,
motors,fullfullcircuit breaker,
motor circuit
circuitprotector,
protector, or a set
set of fuses
breaker, motor
fuses isis
reduced-voltage
controllers
are available for starting;
reduced-voltagecontrollers
areavailable
starting; the
controller.The protective
devicesmust
aheadof the controller.
protective devices
must
installed ahead
selection
the local
selection depends
depends on the
local power source
source and operating
operating
have sufficient
sufficientcapacity
capacitytoto
interrupt the current safely
safelyand
and
interrupt
conditions.
conditions.There is aasimilarity
similarityin control
control except
exceptthat
thatthe outoutfast enough
enough to clear the fault
fault without damage
damagetotothe
the
must be fast
of-step
protectionautomatically
automatically
stops
the motor when the
of-stepprotection
stops
themotor
contactor
overcurrent
devices.
must
also carry
contactor andovercurrent
devices.
TheyThey
mustalso
carry
motor drops
dropsout of synchronism.
synchronism.
locked-rotor
to allow
accellocked-rotor current
currentlong
longenough
enough
allow the
themotor
motorto to
accelA controllerforafor
a synchronous
motor will generally
synchronous
motorwillgenerally
erate to rated speed without
withoutopening
opening the motor circuit
circuit and
and
include
in addition
include the
thefollowing
followingfunctions
functions
addition to the functions
functions of
should preferably
against
excessive
locked-rotor
time. time.
preferablyprotect
protect
against
excessive
locked-rotor
controllerfor a squirrel-cage
squirrel-cageinduction
induction
motor:
a controller
motor:
In addition,
to atominimum
in
addition, they should keep
keepmotor
motordamage
damage
a minimum
thethe
motor.
case of aafault
faultwithin
within
motor.
a.
against overcurrents
overcurrents in normal or
a. Protection
Protection of the field against
The complete
protection
package
normally
consists
of
completemotor
motor
protection
package
normally
consists
out-of-step
out-of-step operation.
operation.
disconnectdevice,
device,
fault-current
protection,
contactor,
a
timea disconnect
fault-current
protection,
a contactor,
timeAutomatic field
is responsive
b. Automatic
fieldapplication
applicationthat
that
responsive to the definite
definite
lag overcurrent
overcurrentprotection,
protection,and
and
associated
auxiliary
devices.
associated
auxiliary
devices.
current
in the
fieldfield
and and
stastatime, the
the relative
relativefrequency
frequencyofofthethe
current
in the
fault-current
protection
are often
disconnectand
and
fault-current
protection
are combined
often combined
tor, the power
power factor
factor of
ofthe
thecurrent
currenttotothe
thestator
statorwinding,
winding,andand The disconnect
in a circuit
circuit breaker.
breaker. Even
Eventhough
thoughsome
some
components
may
components
may
be be
variablesthat
that
may
be used
to obtain the desired
desired result.
result.
other variables
may
be used
combined,
must
be included.
protectivefeatures
features
must
be included.
combined, allallof these protective
shouldbebeprovided.
provided.
andDC meters should
Both AC and
'
6.24.3Wound-Rotor
Wound-Rotor Induction
Motor
InductionMotor
i
I
The wound-rotor
wound-rotorinduction
induction
motor
the operating
motor
meetsmeets
theoperating
and adjustdemands
demands of controlled
controlled stalting,
starting, in-rush
in-rush current, and
adjustable
suitable for a highable speeds
speedswith high starting
starting torque.
torque.It is suitable
loadwhere
where
critical
operations
closelyconconinertia load
critical
operations
may require closely
trolled acceleration.
acceleration. Starting
Startingfacilities
facilitiesare
aresimilar
similar to those of
trolled
the squirrel-cage
induction
motor,
except
that the motor
squirrel-cageinduction
motor,
except
thatthemotor
6.26.2 Fuse
Fuse
and
Circuit
Breaker
Considerations
and
Circuit
Breaker
Considerations
on on
fuses
and circuit
NFPA 70 provides general
generalinformation
information
fuses
breakers.
breakers.
6.26.2.1
FusesFuses
Dual element (time-delay)
(time-delay) fuses
fuses are better suited for
protection than are fuses
motor branch-circuit protection
fuses that open
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62
62
I
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
without
without delay;
delay; the
the time-delay
time-delay feature
feature avoids
avoids possible
possible fuse
fuse
opening
opening during
during the
the period of
of high
high motor
motor starting
starting current.
current.
This
This allows
allowsthe
the fuse
fuse to
to be
besized
sizedmore
more closely
closely to
to the
the motor's
motor's
rated
full-load
current.
rated full-load current.
Current-limiting
areare
alsoalso
commonly
usedfor
Cun-ent-limitingfuses
fuses
commonly
used
forthis
thisserservice
vicebecause
becauseof
ofthe
thefollowing:
following:
a.a. For
-cycle to
Forfaults,
faults,they
they operate
operatewithin
within1/2I/2-cycle
toreduce
reducethe
thedamdamage
agecaused
causedby
by short-circuit
short-circuitcurrent.
current.
b.b. The
The magnitude
magnitudeof
of the
the shOlt-circuit
short-circuitcurrent
currentisis actually
actuallylimlimited
short-circuit
current,
itedto
toless
lessthan
thanthe
theavailable
available
short-circuit
current,which
whichmay
may
allow
allow the
the use of
of smaller
smaller conductors
conductors in
in.branch
branch circuits.
circuits. The
The
fast
fast operation
operation of
of most
most fuses,
fuses, however,
however, makes
makes itit difficult
difficultand
and
often
impossible
to
coordinate
tbem
with
other
short-circuit
often impossible to coordinate them with other short-circuit
protective
protectivedevices.
devices.
c.c. Current-limiting
therefore,
an an
Current-limitingfuses
fusesare
arenot
not subject
subjecttotoaging;
aging;
therefore,
ultimate
is avoided
whenwhen
these devices
are
areused.
used.
ultimatefalse
falseoperation
operation
is avoided
these devices
6.28
VOLTAGE
LIMITATIONS
6.28VOLTAGE
LIMITATIONS
In
privately
owned industrial
In many
many cases,
cases, on
onaaprivately
owned
industrial supply
supply
system,
system, itit isis practical
practical to
to tolerate
tolerate voltage
voltage fluctuations
fluctuations somesomewhat
what in
ineXcess
excessof
of values
valuesthat
that generally
generallywould
wouldbe
be considered
considered
unacceptable
unacceptableon
on other
othersystems.
systems.When
When aalarge
largemotor
motorisis to
to be
be
installed
installed at
at aa point
point where
where severe
severe voltage
voltage dips
dips will
will result,
result, aa
check
check will
will determine
determine whether
whether the
the motor
motor terminal
terminal voltage
voltage
will
will be
be sufficient
sufficient during
during the
the starting
starting period
period to
to permit
permit the
the
motor
speedwithin
within
motor to
to bring
bring its
its load
load up
up to
tospeed
a a satisfactory
satisfactory
time,
time, and
and whether
whether the
the resulting
resulting voltage
voltage disturbance
disturbancewill
will be
be
acceptable,
of other
other electrical
electrical
acceptable, considering
consideringthe
the requirements
requirementsof
equipment
equipmentsupplied
suppliedby
by the
the system.
system.Where
Wherethe
the terminal
terminal voltvoltage
will
be
abnormally
low,
approaching
the
value
age will be abnormally low, approaching the valueatat which
which
the
the undervoltage
undervoltagedevice
devicein
in aa standard
standardcontroller
controllerisis designed
designed
to
operate,
it
is
recommended
that
the
to operate, it is recommended that the specification
specificationfor
for the
the
controller
include
the
anticipated
range
of
voltage
from
controller include the anticipated range of voltage from the
the
minimum
minimum during
during starting
starting to
to the
the maximum
maximum during
during normal
normal
operation.
operation.
6.26.2.2
Circuit
Breakers
6.26.2.2Circuit
Breakers
6.29
APPLICATION OF
6.29 APPLICATION
OFOUTDOOR
OUTDOOR AND
AND INDOOR
INDOOR
ItIt is
is essential
essentialto
to select
selectaacircuit
circuitbreaker
breakercapable
capableof
of closing
closing
TYPES
TYPES
into,
thethe
highest
faultfault
current
avail-availinto,carrying,
carrying,and
andinterrupting
interrupting
highest
current
6.29.1
Outdoor
able
6.29.1Outdoor
-Type-Type
ableat
atthe
thepoint
pointof
of installation.
installation.
ItIt isis common
commonpractice
practiceto
to install
installelectric
electricmotors
motorsand
anddriven
driven
equipment
outdoors
without
protection
from
the
equipmentoutdoorswithoutprotectionfromtheweather,weather,
unless
unless there
thereisissome
somegood
goodreason
reasonfor
for providing
providingaabuilding
buildingor
or
other
form
of
shelter.
Outdoor-type
controllers
may
be
used
other
form
of
shelter.
Outdoor-type
controllers
may
be
used
When
load
thatthat
Whenaamotor
motoris isto
tobe
be used
usedto
todrive
drivea ahigh-inertia
high-inertia
load
with
with these
thesemotors.
motors.The
Themain
mainconsideration
considerationin
in this
this application
application
requires
requires aa long
long time
time to
to accelerate
accelerate to
to nonnal
normal speed,
speed, a check
isis to
avoid
the
use
ofofbuildings
and
other
shelters
as
much
to
avoid
the
use
buildings
and
other
shelters
as
muchas
as
should
to determine
determine if
should be
be made to
if aa special
special form
form of
of overload
possible
so
that
the
possibility
of
an
accumulation
of
flammaso
that
the
possibility
of
an
accumulation
of
flammapossible
protection
protection will
willbeberequired.
required.This
This will
will usually
usuallybe
bethe
thecase
caseififa a
ble
orgases
gases isis reduced.
Enclosures for
ble vapors
vaporsor
reduced.Enclosures
for controllers
controllers
standard
standardprotective
protectivedevice,
device,set
setat
at the
the maximum
maximumcurrent
currentvalue
value installed outdoors must meet all service requirements of the
installed
outdoors
must
meet
all
service
requirements
of the
affording
affordingproper
properprotection
protectionfor
for the
the motor,
motor,trips
tripsthe
the motor
motoroff
off
location.
location.
the
period.
theline
lineduring
duringthe
thestarting
starting
period.
To
Toprovide
provideuninterrupted
uninterruptedstarting
startingand
andat
atthe
thesame
sametime
timepropro6.29.2
Indoor
-Type
6.29.2Indoor
-Type
vide
vide the
the desired
desired degree
degreeof
of protection
protection against
against sustained
sustainedhigh
high
Indoor-type
Indoor-typecontrollers
controllers are
are sometimes
sometimes llSed
used regardless
regardless of
of
starting
startingcurrents,
currents,ititmay
may be
be necessary,
necessary,in
in some
somecases,
cases,to
touse
usea a
the
location
of
the
associated
motors.
It
may
be·
more
ecothe location of the associated motors. It may be more ecothermal
built into
into the
the motor
motorstator
statorwinding.
winding.In
In
thermal device
devicethat
thatisis built
nomical
to
nomical
to use
use indoor
indoorequipment
equipmentin
in aabuilding
buildinglocated
locatedin
in an
an
other
cases,
it
may
be
necessary
to
use
long-time
inductionother cases, it may be necessary to use long-time inductionunclassified
area
than
to.provide
outdoor
controllers
that
are
unclassified
area
than
to.provide
outdoor
controllers
that
are
disk
are
diskor
orsolid-state
solid-staterelays
relaysthatthat
areadjustable
adjustabletotosuit
suitthe
thestarting
starting
suitable
..
suitablefor
forall
allconditions
conditionsof
of service
service.
conditions,
protective
conditions, or
or to
to supply
supply current to
to the
the overload protective
device
core
reactor
devicethrough
througha asaturable
saturable
core
reactoror
orcurrent
currenttransfonner
transformer
6.30
PUSHBUTTON
STATIONS
6.30PUSHBUTTON
STATIONS
with
characteristics suitable
suitable for
the
with characteristics
for limiting
limiting the
the current
current to the
6.30.1
Location
protective
6.30.1
Location
protective device
device during
during the
the starting
starting period;
period. If
If one
one of
of these
these
forms
forms of
of protection
protection will
will not
not suffice,
suffice, consideration
consideration should
shouldbe
be
If
If undervoltage
undervoltageprotection
protectionisis required,
required,the
the pushbutton
pushbuttonfor
for
given
givento
to other
other means
meansof
of providing
providingthe
the desired
desireddegree
degreeof
of proprooperating
the
controller
is
generally
of
the
momentary-conoperating the controller is generally of the momentary-contection.
thermally
compentection.If
If the
theambient
ambienttemperature
temperaturevaries,
varies,
thermally
compen- tact,
installed in
in sight
sightof
of and
and near
near the
the
tact, start-stop
start-stoptype
type and
and isis installed
sated
relays
may
be
used.
sated relays may be used.
motor
and
its
driven
equipment
and
in
a
position
that
motor and its driven equipment and in a position that will
will
A
A speed
speed sensor
sensoror
or switch
switchcoupled
coupled toto the
the motor
motor shaft
shaft can
can
facilitate
facilitate ease
ease and
and safety
safety of·
of operation.
operation. If
If aa pushbutton
pushbutton isis
also
system,particularly
with
also be
be integrated
integratedinto
into the
the control
control system,
particularly with
installed
on
or
near
a
controller
that
is
remote
installed onor near a controller that is remote from
from the
the
the
use
of
timing
relay(s).
Many
of
the
multifunction
protecmotor
controlled,
the
pushbutton
is
generally
of
the
the use of timing relay(s). Manyof the multifunction protecmotor controlled, the pushbutton is generally of the stopstoption
relays)available
available integrate
and·
type
tion relays
relays (solid-state
(solid-staterelays)
integrate this
thisand
type installed
installedonly
only for
for the
the purpose
purpose of
of stopping
stoppingthe
the motor
motor in
in
other
protective
features.
an
other protective features.
anemergency.
emergency.
6.27
OVERLOAD
PROTECTION:
6.27OVERLOAD
PROTECTION:
SPECIAL
SPECIALAPPLICATIONS
APPLICATIONS
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ELECTRICAL INSTALLATIONS IN
IN PETROLEUM
PETROLEUM PROCESSING PLANTS
63
6.30.2
6.30.2 Undervoltage
Undervoltage
6.31
Release Release
6.31
In installations
undervoltage release instead
installations whereundervoltage
instead of
provided, as in float-Operfloat-operundervoltage protection is to be provided,
ated
pumps,
pressure-operated
compressors,
and
other
ated pumps,pressure-operated compressors, and other pilotpilotoperated
operated equipment,
equipment, which function
function automatically
automatically on
onananononoff cycle, the pushbutton is generally of the maintained-conmaintained-contact type, wired in series
series with the pilot device.
device.
The following
references are helpful
following additional
additional references
helpful in preparing definitive
definitive specifications
specifications and correctly
correctly applying
applying motors
motors
and controllers:
controllers:
a.
b.
c.
C.
d.
d.
e.
e.
f.f.
ADDITIONAL REFERENCES
REFERENCES
AGMA 6019-E.
6019-E.
UL 674 and
andUL 698.
698.
MG 2.2.
NEMA ICS
ICs 1 and NEMA MG
API 541
541 data sheet guide.
guide.
546data sheet guide.
guide.
API 546
IEEE
E E E Std 242.
242.
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SECTION 7-LlGHTING
7-LIGHTING
SECTION
illuminance
PURPOSE
level:
7.3.77.1
7.1 PURPOSE
prescribed
illumi7.3.7 illuminanceamount
level: A presclibed amount of illuminance:
nance:
section serves
This section
serves as a guide
guide for the design
design of modern
modem
petroleum processing
processingplant
plantlighting
lighting facilities.
facilities. It advocates
advocates the
following
following principles:
principles:
a.
Initial is the amount
obtained when the
the
amount of illuminance
illuminance obtained
a. Znitial
luminaires
andclean
cleanand
and
when
the lamps
are first
luminaires are new and
when
the lamps
are first
energized.
energized.
b. In sewice
service or maintained is the average
average amount
amount of illuminance over
period
of time.
This is lower
overananextended
extended
period
of time.
lowerthan
thanthethe
initial illuminance
illuminance for
for several
several reasons
reasons noted
notedunder
underlight
lightloss
loss
factor.
factor.
a. Establishing
processing plant
Establishing recommended
recommended practices
practices for
for processing
lighting
lighting will ensure
ensure adequate
adequate and efficient lighting
lighting facilities
facilities
that contribute
and maintecontributeto the safe
safe and
andefficient
efficientoperation
operation
nance
nance of the
theplant.
plant.
b. Processing
lighting should not be considered
Processing plant lighting
considered just a
production;
necessary
costofofproduction;
necessary burden that only adds
adds to the cost
of safe
rather,
partpart
rather, it should
should be considered
considered ananintegral
integral
safe and effiefficient plant
plantoperation.
operation.
c. Lighting
Lightingdesign
designpractice
practice
should
with
should
be be kept up-to-date
up-to-date with
new developments
suchasas
high
intensity
discharge (HID)
(HID)
developmentssuch
high
intensity
discharge
lamps. Luminaires have
have been
been developed
developedthat
thatmake
makeeffective
effective
use of metallic additive and quartz
quartz light sources. High-pressuresodium
sodium
luminaires
are commonly
luminaires
arecommonly
usedwhere used where high
illuminances are
arerequired
requiredand where energy
energycost and reduced
reduced
illuminances
maintenance
maintenance cost are important
important considerations.
considerations.Applications
Applications
of these new developments,
developments, where suitable,
suitable, may offer the
most efficient
efficientlighting
lightinginstallation.
installation.
7.3.8 luminaire:
luminaire: Acomplete
completelighting
lighting
including
unitunit
including
the the
lamp,
lamp, globe,
globe, reflector,
reflector, refractor,
refractor,housing,
housing,and
andsupport
supportthat
thatis
integral
integral with
withthe
thehousing.
housing.
7.3.9 light
light loss
factor that represents the averloss factor:
factor: A
A'factor
age-to-initial
age-to-initial illuminance
illuminanceratio
ratioof a lighting
lighting system.
system.ItItreprerepresents the
the depreciation
depreciation and
and deterioration
deteriorationof a lighting
lighting system
system
sents
caused
caused by the following:
following:
a.
a. Loss of lamp
lamplumens
lumensas a result
resultof aging.
aging.
b. Decreaseinin lamp
lamp and luminaire
luminaireoutput
from
outputresulting
resulting
from
dust,
dirt,
insects,
and
chemical
changes
in
the
luminaire's
dust, dirt, insects, and chemical changes
luminaire's
reflecting surlace.
surface.
reflecting
c. Increased
Increased absorption of the light output
output of the luminaires
luminaires
by dust,
and chemical
chemical changes
changes in the room's
room's reflecting
reflecting
dust, dirt, and
surfaces.
surfaces.
d. Differences
Differencesbetween
actual and design
design lamp
lamp voltages.
voltages.
d.
between actual
7.2
SCOPE
SCOPE
The material
in this section is intendedto
toestablish
establishthe
the folmaterialin
lowing:
lowing:
7.3.10lux:
lux: The SI unitofof
illuminance. One lux is one
illuminance.
a. A general
general approach
approach to the practice
square meter.
meter.
practice and principles of good
lumen per
lumen
per square
lighting installation
installationand
andmaintenance.
maintenance.
b.
~~~i~
for
design of
of new
new processing
processingplmt
7.3.11
mounting
height:
distance
from
the
bottom
7.3.11
mounting
height: The distance
from
the bottom
b. Basic criteria for the
the design
plant
of
the
luminaire
to
the
surlace
used
as
a
reference.
lighting.
lighting.
reference.a
of the
as luminaire
used
surface
to the
c.
mostprocessing
processing plant
plant
Recommended illuminances
illuminances for
for most
factor:
c. Recommended
7.3.12reflection
reflection
factor: The ratio of the light reflected
reflected
areas.
by
the
body
light.
to
the
incident
areas.
by the body to the incident light.
d. A basis
basisfor
forestimating
estimatinglighting
lighting
power
requirements
in new
d.
power
requirements
in new
7.3.13
seeing or visual task:
The
processing
processing
design.
plant plant design.
visual
seeing
7.3.13
or
task
regarded
being
object
The object being regarded
and its background.
background.
7.3 DEFINITION OF
TERMS
DEFINITION
OFTERMS
7.3.1brightness:
The illuminance
illuminance of
of aa surface in
in any
any
7.3.1
brightness: The
direction.
given direction.
7.3.14
utilization:
The
received
flux
total flux receivedsurface
by
7.3.14
utilization: The
total
by aa surlace
divided
illuminating it.
dwided by the total flux
flux from
from the lamps
lampsilluminating
it.
7.4LIGHTING
LIGHTING
FACILITIES
FACILITIES
7.3.2brightness
brightness
ratio: The ratio of brightness
brightness of surratio:
faces.
faces.
7.4.1Recommended
Illumination
7.4.1
Recommended
Illumination
The data in Table 44 cover the minimum
minimum average
average maintained (in service),
service), horizontal lighting
lighting illuminance
illuminance requirerequirements of most processing
processing plant areas;
areas; however,
however, it must be
installations should be
clearly understood that lighting installations
designed to meet the conditions
conditions peculiar to the tasks of each
designed
area. For instance,
instance, Table 4 indicates
indicates a minimum illuminance
illuminance
of 5 (ftc) in service for operating
platforms on general prooperating platforms
process units. Obviously,
there are instruments
and control
Obviously, if
ifthere
instruments -and
control
valves
valves that must be operated
operated constantly,
constantly, the 5-ftc illumiillumi-
7.3.3 diffusion:
diffusion: The breaking
breaking up of a beam
beam of light and
a surface.
the spreading
spreading of its rays in many
manydirections
directionsbyby
a surface.
7.3.4
footcandle (ftc):
footcandle
(ftc): A unit of illuminance.
illuminance.
7.3.5 glare:
glare: The condition
condition in which brightness
brightness or the conbrightnessesinterleres
interferes
with
vision.
with
vision.
trast of brightnesses
"
7.3.6 illuminance:
illuminance: The density of
ofluminous
luminous flux
flux incident
incident
upon aasurface.
surface.
65
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!
,
66
API
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
540
lumen
lumen output;
output; however,
however, with
withthe
the advent
advent of
of metal
metal halide
halide and
and
high-pressure
vapor lamp
high-pressure sodium
sodium lamps,
lamps, the
the mercury
mercuryvapor
lamp is
is
considered
that
considered by
by many
many to
to be
be obsolete,
obsolete, except
except in
in existing
existing plants
plants
that platform
platform isis necessary.
necessary. In
In this
this sense,
sense, the
the data
data shown
shown in
in
having
Table
having sirnilar
similar lamps.
lamps. The
The mercury
mercury vapor
vapor lamp
lamp is
is considconsidTable44serve
serve only
only as
as aa guide
guide to
to good
good lighting
lighting practice.
practice.
ered
ered obsolete
obsolete because
because of
of its
its rapid
rapid lumen
lumen depreciation
depreciation and
and
Note:
Theseilluminances
illuminances are
are not
not intended
intended to
to be
be mandatory
mandatory by
by
Note:These
low
lumens-per-watt
(lmIW)
characteristics.
Also,
the
low
lumens-per-watt
(1mnV)
characteristics.
Also,
the
enactment
enactment into
into law;
law; they
they are
are aa recommended
recommended practice
practice to
to be
be considconsidwarm-up
and
restrike
may
vary
between
3
minutes
3
minutes
warm-up
period
and
restrike
may
vary
between
ered
ered in
in the
the design
design of
of new
newfacilities.
facilities.
and
minutes.As
As with
with other
other HID
HID lamps,
lamps, these
these ballasts
ballasts have
have
and 77 minutes.
a.a. Indicates vertical illuminance.
illuminance.
power
factors
in
the
40%
to
50%
range
unless
conected;
power factors in the 40% to 50% range unless corrected;
b.
local Coast
authority, or
b. Refer
Refer to local
Coast Guard,
Guard, port authority,
or governing
governing
capacitor
capacitor correction
correction results
results in
in power
power factors
factors in
in the
the 90%
90%
body
lights.
body for
for required
requirednavigational
navigational
lights.
range.
Efficacies
for
mercury
vapor
lamps
range
from
38 to
to
range. Efficacies for mercury vapor lamps range from 38
c.c. The
in petroleum
and and
chemical
plantsplants
is
The use
use of
ofmany
manyareas
areas
in petroleum
chemical
is63
63 Im/W,
l m , excluding
excluding ballast
ballast losses.
losses. Average
Average lamp
lamp life
life is
is
often
what
the
oftendifferent
differentfrom
from
what
thedesignation
designationmay
may infer.
infer.The
The areas
areas
24,000
24,000 hours,
hours, but
but itit isisrecommended
recommended that
that lamps
lamps be
be replaced
replaced
are
their
are generally
generallysmall,
small,
their occupancy
occupancyisis low
low(restricted
(restrictedto
to plant
plant
at
at 16,000
16,000hours
hours due
due to
to rapid
rapid lumen
lumen depreciation.
depreciation.
personnel)
andand
they
personnel)and
andinfrequent,
infrequent,
they are
are only
onlyoccupied
occupiedby
by perperMetal
Metal halide
halide lamps
lamps are
are similar
similar in
in construction
construction to
to mercury
mercury
sonnel
underunusual
unusual
sonnel trained toto conduct
conduct themselves
themselves safely under
vapor
vapor lamps.
lamps.The
The difference
differenceisis that
that metal
metalhalides
halidesare
are added
added toto
conditions.
conditions. For
Forthese
thesereasons,
reasons,illuminances
illuminancesmay
may be
be different
different
the
mercuryand
and
argon
tube. The
are
themercury
argon
in in the
the arc
arctube.
The efficacies
efficaciesare
from
recommended for other
other industries.
industries and for comcomfrom those
those recommended
improVed
improvedto
to the
therange
rangeof751mIW
of 75 lm/Wto
to 125
125ImIW,
I N , excluding
excludingbalbalmercial,
mercial,educational,
educational,or
or public
public areas.
areas.
last
loss. The
is usually
usually
last loss.
The color
color rendering isis quite
quite white
white and
and is
d.
d. Refer
Refer to
to local
local Federal
Federal Aviation
Aviation Administration
Administration regulations
phosphor-coated
mercury
superior
superiortotothethe
phosphor-coated
mercury
vaporvapor
lamp. lamp. The
The
for
andand
obstruction
lighting
and marking.
for required
requirednavigational
navigational
obstruction
lighting
and marking.warm-up
minutes to
to 44 minminwarm-up time
time for
for metal
metal halide lamps is
is 22 minutes
e.
and7.2B
7.2Binin API
API RP
RP 14F
14Ffor
for recomrecome. Refer
Refer to
to Tables
Tables 7.2A and
utes,
varies from
from 55 minutes
utes, and restrike time varies
minutes to
to 15
15 minutes,
minutes,
mended
for
mendedillumination
illuminationlevels
levels
foroffshore
offshoreproduction
productionplatforms.
platforms.
depending
factors
in
dependingon
on the
thetype.
type.Power
Power
factors
in the
the 90%
90% range
rangecan
can be
be
obtained.
3,000
3,000hours
hours toto20,000
20,000hours.
hours.
obtained.Lamp
Lamplife
lifevaries
variesfrom
from
7.4.2
Areas
7.4.2 Petroleum
PetroleumProcessing
Processing Plant Areas
Metal
depreciation
than
Metal halide
halidelamps
lampshave
havemore
morerapid
rapidlumen
lumen
depreciation
than
do
mercury
vapor
lamps,
and
have
high
surface
operating
temdo
mercury
vapor
lamps,
and
have
high
surface
operating
temAs
consider
when
As shown
shownin
in Table
Table 4,
4, the
the three
threebasic
basic areas
areasto to
consider
when
peratures
which
must
be
considered
before
application
in
clasperatures
which
must
be
considered
before
application
in
clasplanning
lighting
facilities are
areas,
nonprocess
planninglighting
facilities
are process
processareas,
nonprocess
sified
sified locations.
locations.The
Thelamp
lamplife
lifeand
andlumen
lumenoutput
outputare
areaffected
affected
areas,
areas, and
and buildings.
buildings.Buildings
Buildingspeculiar
peculiarto
to process
process and
and nonnonby
burning
position.
by burning position.
process
been
included
in
processareas
areashave
have
been
included
in Table
Table4.
4.
Currently,
Currently,most
most engineering
engineeringactivities
activitiesby
by lamp
lamp manufacturmanufacturThe
The three
three basic
basic areas
areas are
are broken
broken down
down into
into more
more specific
specific
ers
are
on
improvements
in
the
overall
efficiencies
ers
are
focused
on
improvements
in
the
overall
efficiencies
areas
or
activities.
Under
process
areas
and
the
more
specific
areas or activities. Under process areas and the more specific
and
life
of
the
metal
halide
lamps.
A
series
of
pulse
start
pulse
startmetal
metal
and
life
of
the
metal
halide
lamps.
A
series
areas
of
general
process
units,
minimum
lighting
requireareas of general process units, minimum lighting requirehalide
lamps
have
been
developed
with
features
halide
lamps
have
been
developed
with
of
improved
ments
are
given
for
areas
such
as
pump
rows,
heat
exchangments are given for areas such as pump rows, heat exchanglamp
lamp life,
life, lumen
lumen maintenance,
maintenance, and the
the use
use of
of more
more efficient
efficient
ers,
platforms.
ers, and
andoperating
operating
platforms.
ballast
lamps
have
wattages
ranging
fromfrom
150
ballast systems.
systems.These
These
lamps
have
wattages
ranging
150
W
to
400
W
with
efficacy
90
ImIW
to
110
ImIW;
lamp
life
of
W
to
400
W
with
efficacy
90
I
N
to
110
l
e
,
lamp
life
of
7.4.3
Types
7.4.3 Lamp
LampTypes
15,000
time
of 22of
minutes;
15,000to
to 30,000
30,000hours;
hours; improved
improvedwarm-up
warm-up
time
minutes;
The
The following
following types
types of
of lamps
lamps are
are commercially
commercially available
available
and
minutesto
to 44 minutes.
minutes.AA33%
33% improveimproveand restrike
restriketime
timeof
of 33 minutes
and
frequently
used
in
refinery
installations:
and frequently used in refinery installations:
ment
be
be seen
seenin
in these
these lamps.
lamps.
mentin
in lumen
lumen maintenance
maintenancecan
can
High-pressure
sodium lamps
efficaciesthat
that
range
High-pressuresodium
lamps have
haveefficacies
range
a.a. Incandescent,
halogen.
Incandescent,including
includingtungsten
tungstenand
and
halogen.
lmIW
to
140
ImIW,
depending
on
size.
The
color
from
77
from
77
lm/W
to
140
lm/W,
depending
on
size.
The
color
b.
b. Fluorescent.
Fluorescent.
high-pr~sure
rendition
is
a
distinct
orange.
Warm-up
time
for
rendition
is
a
distinct
orange.
Warm-up
time
for
high-pressure
c.
Mercuryvapor.
vapor.
c. Mercury
sodium
is
minutesto
to 44 minutes.
minutes. Restrike
Restriketime
time
is
sodiumlamps
lampsis
is from
from 33 minutes
d.
Metal
halide.
d. Metal halide.
less
than
11minute,
and
instant
restrike
devices
are
offered
for
minute,
and
instant
restrike
devices
are
offered
for
less
than
e.
e. High-pressure
High-pressuresodium.
sodium.
50-W
50-W to
to 150-W
150-W high-pressure
high-pressure sodium
sodium lamps.
lamps. Power
Power factors
factors
. range
Incandescent
Incandescent and
and fluorescent
fluorescent lamps,
lamps, including
including halogen
halogen
range from
from40%
40% to
to 99%
99% depending
dependingon
on the
the ballast
ballast type
typeand
and the
the
and
life
age
and tungsten,
tungsten, can
can be
be used
used in
in luminaires
luminaires with
with direct,
direct, semidisemidiage of
of the
thelamp.
lamp.Lamp
Lamp
lifeis
is 24,000
24,000hours.
hours.
reet,
IDD
rect, and
and general-diffuse
general-diffuse outputs,
outputs, while
while high-intensity disdisHID lighting
lighting may
may be
be supplemented
supplemented by
by incandescent
incandescent or
or
charge
lamps
can
be
used
in
luminaires
with
direct
and
fluorescent
lighting
which
would
provide
illumination
charge lamps can be usedin luminaires with direct and
fluorescent lighting which would provide illumination durdursemidirect
ingthe
semidirectoutputs.
outputs. Efficacies
Efficacies for
for incandescent
incandescent lamps
lamps range
range
ing the initial
initial warm-up
warm-up time
time and
and during
during the
the restrike
restrike time
time
from
4
to
24
lumens
per
watt
(lmlW)
and
for
fluorescent
after
an
extinction
caused
by
voltage
dips
in
the
from 4 to 24 lumens per watt ( l m and for fluorescent
10%to
to 60%
60%
after an extinction caused by voltage dips in the 10%
lamps
range,
75 to
to 80
80 (ImlW).
(lm/W).
lamps range
range from
from 75
range, depending
dependingon
on ballast
ballast type.
type. If
If required,
required, aa push-to-test
push-to-test
switch
Compared
Compared with
with incandescent
incandescent lamps,
lamps, mercury
mercury vapor
vapor
switch can
can be
be installed
installed with
with aa fixture
fixture that
that uses
uses the
the re-strike
re-strike
feature.
lamps
lamps offer
offer the
the advantages
advantagesof
of longer
longer average
averagelife
life and
and higher
higher
the testing
testing of
of the
the restrike
restrikedurdurfeature.This
This switch
switch will
will allow
allow the
nance
nance isis insufficient.
insufficient. Supplemental
Supplemental lighting
lighting on
on the
the immediimmedi-
ate
ate control
contro~area
area or
or aa general
general increase
increase in
in the
the illuminance
illuminance on
on
., ,
Copyrighted material licensed to IDOM.
STD.APJ.b.PETR0 RP 540-ENGL
1999.-orE
0732230
No further reproduction
distribution
permitted. ObJ15b03 073 : m ~
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ELECTRICAL
INSTALLATIONS IN
ELECTRICAL
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PIANTS
67
Table
4-lIluminancesCurrently
CurrentlyRecommended
Recommendedfor
for
Table 4-Illuminances
Petroleum,
Petroleum, Chemical,
Chemical, and
andPetrochemical
PetrochemicalPlants
Plants
Maintained
Horizontal Illuminance
(unless noted)
Area or Activity
Lux
Footcandles
Elevation
Location
Millimeters
Inches
Process Areas
General process units
Pump rows, valves, manifolds
Heat exchangers
Maintenance platforms
platforms
Operating platforms
Cooling towers (equipment areas)
areas)
Furnaces
Fumaces
Ladders and stairs
stairs (inactive)
Ladders and stairs
stairs (active)
Gauge glasses
Instruments (on process units)
Compressor houses
houses
Separators
General area
e
•
houses
Control rooms and houses
control house
Ordinary control
Instrument panel
Console
Back of panel
Central control house
Instrument panel
Console
Back of panel
Specialty process units
Electrolytic cell room
Electric furnace
Conveyors
Conveyors
Conveyor transfer points
Kilns (operating area)
Extruders and mixers
50
30
10
10
50
50
30
10
50
50a
5Oa
50a
5Oa
200
50
10
5
3
1
5
5
3
1
5
55aa
55aa
20
5
1
Ground
Ground
Floor
Floor
Ground
Ground
Floor
Floor
Eye level
Eye level
Floor
Top of
of bay
bay
Ground
300
30Oa
300a
300a
30P
100
100aa
30
3oa
30a
a
30
30a
lOa
1oa
Floor
500
5ooa
500a
5002
500a
lOoa
l0Oa
50
a
50a
50
a
50a
50
loa
102
Floor
50
50
20
50
50
200
5
5
255'
5
20
Floor
Floor
Surface
Surface
Floor
Floor
66
30
66
30
1700
760
760
66
30
30
1700
760
900
66
30
36
1100
1loo
45
Nonprocess Areas
Loading, unloading, and cooling water, pumphouses
Pump area
General control area
Control panel
50
150
200a
2w
5
15
20
20aa
Ground
Floor
Boiler and air
air compressor plants
Indoor equipment
Outdoor equipment
200
50
20
5
Floor
Ground
~~~~~~
~
~
~~~~~
~~~
~~~~~
~~~~
.
.STR..-.API./PET.RO
RP..
Copyrighted material licensed to IDOM.
540-EN.G.L
. I I .-073??90
No further reproduction or distribution
permitted.
4999.
.
Ob.15b09 ,.TO~¿L,,m.,
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68
API RECOMMENDED
RECOMMENDED PRACTICE 540
540
PRACTICE
API
4-llluminancesCurrently
CurrentlyRecommended
Recommendedforfor
Table 4-Illuminances
Petroleum, Chemical,
Petroleum,
Chemical, and
andPetrochemical
PetrochemicalPlants
Plants(Continued)
(Continued)
i
Maintained
llluminance
Horizontal Illuminance
(unless noted)
Area or Activity
Tank fields (where lighting is required)
Ladders and stairs
Gauging area
Manifold area
Loading racks
General area
Tank car
Tank trucks, loading point
Lux
Footcandles
55
10
55
0.5
1
0.5
50
100
100
100
100
10
10
20
20
150
150
50
50
a
50
50a
2
2
15
15
5
55aa
5
10
10
Elevation
Location
Millimeters
Inches
Floor
Ground
Floor
Ground
Point
Point
b
Tanker dock facilities
facilitiesb
Offshore production platformse
platformse
Electrical substations and switch yards
yardscC
Outdoor switch yards
General substation (outdoor)
(outdoor)
Substation operating
operating aisles
aisles
General substation (indoor)
(indoor)
Switch racks
Ground
Ground
Floor
Noor
Floor
Plant road lighting (where lighting is required)C
required)c
Frequent
Frequent use (trucking)
(trucking)
Infrequent
Infrequent use
0.2
44
22
0.4
0.2
Ground
Ground
e
Plant parking
parking lors
lotsC
1
0.1
o. 1
Ground
Ground
1200
1200
48
48
760
760
760
760
760
760
760
760
30
30
30
30
30
30
30
900
900
900
900
36
36
36
36
900
900
900
900
36
36
36
36
d
Aircraft
Aircraft obstruction
obstruction lighting
lightingd
C
Buildings
BuildingsC
Administration
Adminiswationbuildings
buildings and
and offices
offices
Prolonged
difficult
task
(drafting,
Prolonged difficult
(drafting, designing)
designing)
Difficult
Difficult task
task (accounting,
(accounting,business
business machines)
machines)
Normal
Normal office
office work
work (reading.
(reading, files,
files,mail
mail room)
room)
Reception
Reception areas,
areas,stairways,
stairways,washrooms
washrooms
Hallways
Hallways
Equipment
Equipment and
and service
servicerooms
rooms
Laboratories
Laboratories
Qualitative,
Qualitative,quantitative,
quantitative,and
and physical
physical test
test
Research,
Research, experimental
experimental
Pilot
Pilotplant,
plant, process,
process, and
and specialty
specialty 30
ASTM
ASTMequipment
equipment knock
knocktest
test
Glassware,
Glassware,washrooms
washrooms
Fume
Fumehoods
hoods
Stockrooms
Stockrooms
1000
o
l0
0
750
750
500
500
200
200
200
200
150
150
500
500
500
500
300
300
300
300
300
300
300
300
150
150
'
100
100
75
75
50
50
20
20
20
20
15
15
50
50
50
50
30
30
30
30
30
30
30
15
15
30
Floor
Floor
Floor
Floor
Floor
Floor
Floor
Floor
Floor
Floor
•
Copyrighted material licensed to IDOM.
No further reproduction
permitted.
1777 or distribution
I0732270
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
STD.API/PETRO RP
0635605 c l 4 4 ' * 1
540-ENGL
69
69
ELECTRICAL
INSTALLATIONS
PETROLEUM
ELECTRICAL
lNSTALLATlONS IN
IN PROCESSING
PETROLEUM PROCESSING PLANTS
PLANTS
Table
4-lIIuminances
Currently
Recommended for
Table 4-Illuminances
Currently
Recommended
for
Petroleum,
Plants
(Continued)
Petroleum,Chemical,
Chemical,and
andPetrochemical
Petrochemical
Plants
(Continued)
Maintained
Maintained
Horizontal
Horizontalll1uminance
Illuminance
(unless
(unless noted)
noted)
Area
Area or
orActivity
Activity
C
Warehouses
Warehousesand
and stockrooms
stockroomsC
Indoor
Indoorbulk
bulk storage
storage
Outdoor
bulk
Outdoor bulk storage
storage
Large
Largebin
bin storage
storage
Small
Smallbin
bin storage
storage
Small
Smallparts
parts storage
storage
Countertops
Countertops
Repair
Repair shope
shopC
Large
Large fabrication
fabrication
Bench
Bench and
and machine
machine work
work
Craneway,
Craneway,aisles
aisles
Small
Smallmachine
machine
Sheet
Sheet metal
metal
Electrical
Electrical
Instrument
Instrument
Lux
Lux
Footcandles
Footcandles
Location
Location
55
looa
1 ooa
loa
1oa
760
760
760
760
30
30
30
30
200a
20oa
20a
20a
30
30
760
760
1200
1200
30
30
48
48
760
760
30
30
760
760
30
30
30
30
30
30
30
30
20
20
50
50
Floor
Floor
15
15
30
30
Floor
Floor
200
200
200
200
300
300
20
20
20
20
100
100
10
10
10
10
Floor
Floor
Floor
Floor
50
50
10
10
15
15
55
Floor
Floor
Floor
Floor
Floor
Floor
Cafeteria
Cafeteria
Eating
Eating
Serving
Serving area
area
Food
Food preparation
preparation
General
General (halls)
(halls)
300
300
300
300
300
300
100
100
30
30
30
30
30
30
10
10
30
Floor
Floor
Garage
Garage and
andfirehouse
firehouse
Storage
Storage and
and minor
minorrepairs
repairs
100
100
10
10
Floor
Floor
700
700
70
70
C
Clock
Clock house
house and
and entrance
entrancegatehouse
gatehouseC
Card
Card rack
rack and
and clock
clockarea
area
Entrance
Entrance gate,
gate, inspection
inspection
General
General
c
. First
First aid
aidroom
roomc
Inches
Inches
Floor
Floor
Ground
Ground
200
200
500
500
150
150
300
300
c
Change
Change house
houseC
Locker
Lockerroom,
room, shower
shower
Lavatory
Lavatory
Millimeters
Millimeters
50
50
55
50
50
300
300
55
0.5
0.5
Elevation
Elevation
100
1O0
100
100
150
150
760
760
760
760
760
760
30
30
760
760
900
900
900
900
30
36
36
36
36
760
760
30
30
Note:
Note: These
These illuminances
illuminances are
arenot
not intended
intended to
to be
be mandatory
mandatoryby
by enactment
enactmentinto
into law;
law; they
they are
are aa recommended
recommended practice
practice to
to bebeconconsidered
sidered in
in the
the design
design of
of new
new facilities.
facilities.
aIndicates vertical
verticalilluminance.
illuminance.
bRefer
bReferto
to local
local Coast
Coast Guard,
Guard, port
port authority,
authority,or
or governing
governingbody
body for
forrequired
requiredriavigationallights.
navigational lights.
CThe
"The use
use of
of many
many areas
areas in
in petroleum
petroleum and
andchemical
chemical plants
plantsisis often
often different
differentfrom
from what
what the
thedesignation
designationmay
may infer.
infer.The
The areas
areas are
are
generally
areonly
only occupied
occupiedby
by personnel
personnel
generally small,
small,their
their occupancy
occupancyisis low
low (restricted
(restrictedto
to plant
plantpersonnel)
personnel) and
and infrequent,
infrequent, and
and they
they are
trained
trained to
toconduct
conduct themselves
themselvessafely
safely under
underunusual
unusual conditions.
conditions.For
For these
thesereasons,
reasons, illuminances
illuminancesmay
may be
be different
differentfrom
from those
those recrecommended
ommended for
for other
other industries
industries and
and for
for commercial,
commercial, educational,
educational, or
or public
public areas.
areas.
dRefer
dReferto
tolocal
local Federal
Federal Aviation
AviationAdministration
Administrationregulations
regulationsfor
forrequired
required navigational
navigational and
and obstruction
obstructionlighting
lighting and
and marking.
marking.
eRefer
toTables
Tables7.2A
7.2A and
and7.2B
7.2Bin
in API
API RP
RP 14F
14Ffor
forrecommended
recommended levels
levelsof
ofillumination
illumination for
foroffshore
offshoreproduction
productionplatforms.
platforms.
eReferto
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
70
70
API
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
540
ing
ing normal
normal operation
operation by
by interrupting
interrupting power
power to
to the
the fixture.
fixture.
This
This testing
testingmethod
method will
will ensure
ensure that
that the
the restrike
restrike wiH
will funcfunction
tion as
as intended
intendedafter
afteraa major
major voltage
voltagedip
dipor
orpower
powerfailure.
failure.
7.5
LUMINAIRES
7.5
LUMINAIRES
7.5.1
Selection
7.5.1
Selection
In
In choosing
choosing aaluminaire,
luminaire,aaseparate
separatestudy
studyshould
shouldbebemade
made
the
for
foreach
eachapplication.
application.Some
Someofof
thefactors
factorsinfluencing
influencingthe
thefinal
final
selection
selection are
are appearance,
appearance, efficiency,
efficiency,glare,
glare,density
densityof
of equipequipment,
frequencyofof operation,
requiredcolor
color
ment,frequency
operation, maintenance,
maintenance,required
rendition,
rendition,and
andarea
areaclassification.
classification.
7.5.2
Floodlighting
7.5.2
Floodlighting
Floodlights
area
lighting
at
cost.
They
Floodlightsprovide
provide
area
lighting
atan
aneconomical
economical
cost.
They
must
located at
atsuitable
suitablemounting
mountingheights
heightsand
and
with
unobmust be
be located
with
unobstructed
cancan
be
beon
onpipeways,
pipeways,vessel
vesselplatplatstructedbeam
beampaths.
paths.Mounting
Mounting
forms,
areare
forms,rigging
riggingstructures,
structures,and
andfloodlight
floodlightpoles.
poles.Floodlights
Floodlights
available
types, and
andwith
withbeam
beamspreads
spreadsfrom
from
available with
with most lamp types,
10"
10"to
to 18°
18"(NEMA
(NEMA1)1)to
togreater
greaterthan
than 130°
130"(NEMA
(NEMA7).
7).
7.5.3
Codes
and
Standards
7.5.3Codes
and
Standards
Local
Local codes,
codes, national
national codes,
codes, federal
federal standards,
standards, profesprofessional
sionalstandards,
standards,and
andmanufacturers'standards
manufacturers' standardsrelate
relateto
to spespecific
cificrequirements
requirementsthat
that must
must be
be met
met in
in the
the construction
constructionand
and
installation
installation of
of aa luminaire.
luminaire. Some
Some codes
codes and
and standards
standards deal
deal
with
fire and
and safety
with fire
safety (electrical,
(electrical, mechanical,
mechanical, and
and thermal);
thermal);
to
performance
and
construction
(materials
others
relate
others relate to performance and construction (materialsand
and
finishes).
of specificaspecificafinishes). Conformance
Conformanceto
to the
the appropriate
appropriate.set
set of
tion
tion isisoften
oftendetermined
determinedby
by certified
certifiedlaboratory
laboratorytests.
tests.CertifiCertifiis
often
denoted
by
an
identifying
labeL
. cation
cation is often denoted by an identifying label. Local
Local code
code
not
enforcement
enforcementauthorities
authoritiesmayor
may ormay
may
notrequire
requirecertification
certification
by
by an
an approved
approvedlaboratory.
laboratory.
7.5.3.1
National
Codes
7.5.3.1
National
Codes
NFPA
NFPA70,
70,the
the Canadian
CanadianElectrical
EZectricaZ Code
Code(CEC),
(CEC),and
andsimisimilar
codes
in
most
major
countries
state
specific
electrical
lar codes inmostmajorcountries
state specificelectrical
requirements
requirementswhich
whichmust
mustbe
be met
met by
by all
allelectrical
electricalequipment,
equipment,
including
luminaires.
including luminaires.
7.5.3.2
National
and
International
Standards
7.5.3.2 National
and
International
Standards
For
Forelectrical
electricalproducts,
products,UL,
UL,CSA,
CSA,and
andother
othersimilar
similarorganiorganiconzations
publish
minimum
safety
standards
that
are in
in conzations publish minimum safety standards that are
formance
with
electrical
codes.
Luminaires
approved
by
formance with electricalcodes.Luminairesapproved
by
these
organizations
will
meet
the
standards
that
ensure
that
these organizations will meet the standards that ensure that
they
toprovide
providesatsattheyare
areacceptable
acceptablefor
forinstallation
installationand
andare
areable
ableto
isfactory
service.
isfactory service.
from
industry,
inspection
and protecprised
prisedofofrepresentatives
representatives
from
industry,
inspection
and protection
agencies,
and manufacturers.
Confonuance
tionagencies,
andmanufacturers.
Conformance
tothese to these
standards
standardsisisnot
notnecessarily
necessarilyrequired,
required,but
butitit does
doesoffer
offer many
many
advantages
advantagesto
to the
the user
user when
whenconformance
conformanceisisspecified.
specified.StanStandards
dardsorganizations
organizationsinclude
includethe
theAmerican
AmericanSociety
Societyfor
forTesting
Testing
and
Materials
(ASTM),
Certified
Ballast Manufacturers
andMaterials
(ASTM),
Certified
BallastManufacturers
(CBM)17,
IEEE,
IES,
NEMA,
and
ANSI.
(CBM)17, IEEE, E S , NEMA, andANSI.
7.5.3.4
Manufacturers'Standards
7.5.3.4Manufacturers'
Standards
Since
Sincecodes
codes and
and standards
standards deal
deal primarily
primarily with·
with safety and
performance,
thespecifier
specifiershould
should be
of the
performance,the
be aware
awareof
the quality
quality
standards
standardsused
usedby
by the
themmmfacturer.
manufacturer.
7.5.4
Ballast
Considerations
7.5.4Ballast
Considerations
Lamp
be
when
Lampballasts
ballastsmust
must
be taken
takeninto
intoconsideration
consideration
when specspecifying
ifying luminaires
luminaires.for
for purchase.
purchase.For
For all
all lamp
lamp types
types requiring
requiring
ballasts,
ballasts, there
there are
are aa variety
variety of
of ballasts
ballasts available.
available.The
The design
design
engineer
engineer should
should consult
consult with
with the luminaire and lamp
lamp reprerepresentatives
to
get
more
details.
sentatives to get more details.
HID
HID luminaires
luminaires may
may be
be purchased
purchased with
with aa variety
variety of
of balballast
last types
types having
having aa range
range of
of power
power factors
factors and
and costs;
costs: but
but
with
with the
the introduction
introduction of
of the
the high-pressure
high-pressure sodium
sodhm lamp,
lamp, aa
new
new ballast
ballastconsideration
considerationhas
has been
been introduced.
introduced.Unlike
Unlikeother
other
HID
HID lamps,
lamps, the
the high-pressure
high-pressure sodium
sodium lamp
lamp isis one
one .with
with
dynamic
dynamiccharacteristics
characteristicsover
overits
itslife.
life.By
By carefully
carefullyspecifying
specifying
high-pressure
high-pressure sodium
sodium luminaire
luminaire ballast-types,
ballast-types, the
the design
design
engineer
can
achieve
a
good
power
factor
over
the
engineer can achieve a good power factor over thelife
lifeof
of the
the
lamp.
The
design
engineer's
considerations
when
selecting
lamp. The design engineer's considerations when selecting
the
the type
type of
of ballast
ballast to
to be
be used
used are
are energy
energy efficiency
efficiency(losses),
(losses),
lamp
life,
lumen
output,
wiring
and
circuitry
lamp life, lumen output, wiring and circuitry(number
(numberof
offixfixtures
turesper
percircuit),
circuit),and
anddip
dip tolerance
tolerance(ability
(abilityto
tosustain
sustainthe
thearc
arc
during
duringaavoltage
voltagedip).
dip).
Remote
to
Remotemounted
mountedballasts
ballastsareareavailable
available
to use
use with
withmercury
mercury
vapor,
metal
halide
or
high-pressure
sodium
lighting
vapor, metal halide or high-pressure sodium lightingfixtures.
fixtures.
The
can be
bemounted
mountedaway
awayfrom
fromthe
the
The distance
distancethat
that the
the ballast can
lamp
is
based
on
the
type
of
lamp,
wattage,
ballast-to-Iamp
lamp is based on the type of lamp, wattage, ballast-to-lamp
wire
In general,
general,balbalwire size,
size,and
andwhether
whetheran
anignitor
ignitorisisinvolved.
involved.In
lasts
andand
metal
lastsfor
formercury
mercuryvapor
vapor
metalhalide
halidelamps
lampsdo
do not
notrequire
require
newer,
ignitor,
high-pressure sodium
sodiumand
and the
the newer,
ignitor, but
but ballasts
ballasts for high-pressure
low-wattage
low-wattagemetal
metalhalide
halidelamps
lampsrequire
requirean
anignitor
ignitorfor
forstarting.
starting.
The
consult
with
the ballast
and
The design
designengineer
engineershould
should
consult
with
the ballast
and lumiluminaire
determinethe
theproper
properballast-to-lamp
ballast-to-Iamp
naire representatives
representatives to determine
size
distance
distanceand
andthe
theminimum
minimumwire
wire
s i srequired.
required.
7.5.5
Application
in Classified
Locations
7.5.5Application
inClassified
Locations
7.5.3.3
Industry
Standards
7.5.3.3Industry
Standards
Some
Somelocations
locationsmay
may be
beexposed
exposedto
to the·
therelease
releaseof
of flammable
flammable
gases,
gases, vapors,
vapors,or
or dnsts.
dusts.NFPA
NFPA 70
70requires
requiresthat
thatthese
theselocations
locations
be
sets forth
forth rules
rules for
for luminaires
luminairesthat
that may
may be
be
be classified
classified and sets
Industry
Industrystandards
standardsare
arepublished
published by
by various
variousorganizations
organizations
that
generally
utilize
national
technical'
committees
thatgenerallyutilizenationaltechnical'committees
com- com-
17Certified
BallastManufacturers,
Manufacturers,355
355Lexington
LexingtonAvenue,
Avenue,17th
17thFloor,
Floor,
17CertifiedBallast
NewYork,NewYork
New York, New York10017-6603.
10017-6603.
Copyrighted material licensed to IDOM.
STD.API/PETRO RP
No further L999
reproduction1111
or distribution
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ELECTRICAL
lNSTALLATlONS
IN
PETROLEUM PROCESSING PLANTS
ELECTRICAL
INSTALLATIONS
IN PETROLEUM
71
71
installed ininthese
These
luminaires
mustmust
be approved
for
theseareas.
areas.
These
luminaires
be approved
forTable
Table >Temperature
Marking
IdentificationNumbers
Numbers
S-Temperature
Marking Identification
zone,
and group
theythey
are to
the class,
class,division
division
zone,
groupininwhich
which
arebetoused.
be used.
Maximum Temperature
Temperature
Identification, as required by NFPA 70, is provided
Identification,
provided for
Identification
Identification
each approved
approved luminaire
luminaire as applicable,
applicable, showing
showing its class,
class,
OF
°C
"C
Number
"F
Number
group,
and operating
operatingtemperature
temperaturerange
range (see Table
5). The
group, and
Table 5).
I,
temperature rating
a luminaire
approved
a luminaire
approved for a Class
Class I,
450
temperature
ratingofof
842
Tl
T1
Division 11 location (explosionproof)
(explosionproof) is based on the
the hottest
hottest
300
572
T2
spot on the exterior surface of the luminaire,
the
luminaire, generally the
280
536
T2A
I, Division
Division 2 lumiglobe.
globe. The temperature
temperature rating
rating of a Class
Class I,
260 .
T2B
500
(enclosed and
andgasketed)
gasketed)is based on the hottest
hottest spot
spoton
naire (enclosed
the interior
generally the lamp
interior of the luminaire,
luminaire, generally
lamp wall.
wall. The
230
446
T2C
maximum
temperature of
of the luminaire
must be
maximum allowable temperature
luminaire must
215
419
T2D
below the ignition
ofthe
the group of gases in the
ignition temperature
temperature of
200
T3
392
classified
classified area.
area.
In zone applications,
theluminaires
luminaires
must be rated and
and
applications,the
must
approved
zone designation
designationwhere
where they are
approved for the specific
specific zone
installed.
installed.
180
356
T3A
T3A
165
165
329
T3B
160
160
320
T3C
7.6LIGHT
LIGHT
QUALITY
QUALITY
135
135
275
T4
7.6.1
Design
Considerations
7.6.1
Design
Considerations
120
248
T4A
100
100
212
T5
85
185
185
T6
Lighting
qualityisas
isimportant
as important as asufficient
sufficient
Lighting of good quality
quantity
brightness
ratios,
diffuquantity of lighting.
lighting. Glare,
Glare,uniformity,
uniformity,
brightness
ratios,
difision,
reflectionfactor,
factor,color,
color,
surrounding
sion,reflection
andand
surrounding
colorcolor
aretheare the
major considerations
Another
considerationswhen designing
designingquality
qualitylighting.
lighting.
Another
consideration
fixtures
consideration isis that
that lighting
lightinginstallations
installationsusing
usingHID fixtures
should be designed
designed to avoid stroboscopic
stroboscopiceffect
effect
7.6.2
GlareGlare
Glare can be controlled
by careful manipucontrolledtotosome
someextent
extent
manipulation
factors: the
the brightness
brightness of the
lation of the following design factors:
source, and the brightness
brightnessratio
ratio
source,
source, the position of the source,
the
viewed
objects
their surroundings.
The
betweenthe
viewed
objects
andtheirand
surroundings.
The
the visual
visual task and its near surroundsurroundbrightness ratio
ratiobetween
between
ings should be no
nomore
more than 3:1,
thebrightness
brightnessratio
ratio
3: 1, and the
taskand
anditsits far surroundings
should be
be
between the visual task
surroundings should
limited to 10:
10:1.
l.
7.6.3
1
Reflection
Reflection
In buildings where
require
wheretasks
tasksthat
that
require lighting
lighting are critical
critical or
prolonged,special
special
attention
reflection
factors
prolonged,
attention
to to the properreflection
factors
to the colors of walls,
walls, the ceilings,
must be paid
paidto
ceilings, the
thefurniture,
furniture,
and the equipment.
process units, reflection
reflection is extremely
equipment. In process
extremely
important and
significantly
andwill
willcontribute
contribute
significantly
to the overall
overall light
light
level.
ofreflective
reflective surface,
level. The amount of
surface, such as aluminum
aluminum
insulation
sheathing, should be considered in the light-level
insulation sheathing,
light-level
calculations.
calculations.
Rendition
7.6.4Color
Color
Rendition
With the application
application of HID lighting,
lighting, color shift becomes
an important consideration.
consideration. Color shift occurs when an
Note: The temperature
temperature marking
markingspecified
specifiedin the table
tableshall not
exceed the
theignition temperature
temperature of the specific gas
gasororvapor to be
be
encountered.
ignition
temperatures
of
encountered. For
Forinformation
informationregarding
regarding
ignition
temperatures
gases and
and vapors,
vapors, see
seeNFPA
NFPA325M.
a a light
object is viewedinin natural light and thenunder
under
source,
source, such as high-pressure
high-pressure sodium lighting.
lighting. High-presHigh-pressure sodium lighting
lighting is an
an economical
economical source
source because of its
high efficacy,
efficacy, but it has the greatest problem with color
shift;
shift; mercury vapor
vaporand metal halide lighting
lighting provide good
color rendition.
rendition.
Background colors
colors are critical
critical with high-pressure
high-pressure sodium
sodium
lighting.
lighting. Safety
Safety.colors
colorsthat
that identify
identify aa first
first aid
aid station
station or fire
fire
protection equipment
equipment can become obscure
high-presprotection
obscure under high-pressure sodium
paints are
are available
available that minisodium lighting.
lighting. Special
Special paints
mize color distortion
andshould
should be considered
distortion and
considered for use in
areas
colors.
areas which
whichrequire
requiresafety
safety
colors.
7.7ILLUMINANCE
ILLUMINANCE
Although the fundamental
illumination is to
Although
fundamental purpose of illumination
task, particular
provide enough light with which to see the task,
attention
attention must be
be given
givento the type of task requiring
requiring illumiillumination.
Prolonged, difficult
nation. Prolonged,
difficult tasks, such as drafting
drafting or
accounting,
accounting, require the highest illuminance.
illuminance. Some
Some critical
critical
tasks
illumination
need
tasks requiring
requiring than
illumination levels
need much
much higher
higher levels than
the minimum
minimum values
shown inin Table 4. In general,
values shown
general, excepexceptionally
tionally high illuminance
illuminance is needed only in relatively
relatively small
small
areas,
supplementary lighting
areas, where supplementary
lighting equipment
equipment should be
used.
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further
5YO-ENGL reproduction or distribution permitted.
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1111 0732290 Oh>ShOt!- h 5 3
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72
72
540
.m
API
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
7.8
INSTALLATION
INITIAL
VALUES
7.8INSTALLATION
INITIAL
VALUES
1201240
120/240V,
V,Single-Phase,
Single-phase, Four-Wire
Four-Wire
7.8.1
Light Loss
Loss Factor
Factor
7.8.1Light
To
Toprovide
providea adesign
designbasis
basisfor
for new
new lighting
lightinginstallations,
installations,ini-iniof
illuminance
have
been
included
in
Table
These
tial
values
tial values of illuminance have been included
in4.
4.Table
These
values
are
higher
than
the
in-service
or
maintained
values
values are higher than the in-service or maintained values by
by
an
light
lossloss
factor.
an amount
amountequal
equalto
to aa representative
representativetotal
total
light
factor.
-L
7.9
LIGHTING
SYSTEM
POWER
SUPPLY
7.9LIGHTING
SYSTEM
POWER
SUPPLY
The
The choice
choiceof
of aa voltage
voltageand
and distribution
distributionsystem
systemfor
for aa lightlighting
area to
supplied and
andthe
the
ing installation
installation depends
depends on
on the
the area
to be
be supplied
desired
considered most
most desirable
desirable
desired lighting
lighting load.
load. The
The supply considered
will
varythroughout
throughout
a processing plant
will, to
will vary
a processing
plant and
andwill,
to some
some
distribution
system
and the
extent,
extent,depend
depend on
onthe
thepO\ver
power
distribution
system
and
the voltvoltage.
be considered
considered ininthe
the selection
selectionof
of aa lightlightage. Some
Somepoints
points to
to be
ing
aredepicted
depictedin
in Figure
Figure 18.
18.
ing system
systempower
power supply
supplyare
The
The effect
effectof
of voltage
voltagedips
dips and
and flicker
flickeron
on aa lighting
lightingsystem
system
should
should be
be considered
considered when
when choosing
choosing aa power
power supply
supply system
system
for
of utilization
utilization equipment,
equipment, such
such as
as
for lighting.
lighting. Certain
Certain types
types of
motors,
highinitial
initial inrush
motors, have
have aa high
inlush current
current when
when turned
turned on
on
and
and impose
impose aa heavy load at
at aa low
low power
power factor
factor for
for aa very
very
short
flowing to
short time.
time. This
This sudden
sudden increase
increase in
in the
the current
current flowing
to
the
the load
load causes
causes aa momentary
momenlary increase
increase in
in the
the voltage
voltage drop
drop
along
along the
the distribution
distribution system,
system, and
and aa corresponding
corresponding reducreduction
the voltage
voltage at
at the
the utilization
utilization equipment.
equipment.A
A small
small dip
dip
tion in
in the
of
of 1/4%-1/2%
l/d%-l/z% will
will cause
cause aa noticeable
noticeable reduction
reduction in
in the
the light
light
output
output of
of an
an incandescent
incandescentlamp
lamp and
and aaless
less noticeable
noticeablereducreduction
HID type
type lamps.
lamps.
tion in
in the
the light
light output
outputof
of HID
When
on and
and off
offrapidly
rapidly as
as in
in the
the case
caseof
of
When loads
loads are
are turned
turnedon
resistance
welders,
or
fluctuate
rapidly
as
in
the
case
resistance welders, or fluctuate rapidly as in the case of
of arc
arc
furnaces,
the light
light output
output is
is called
called
furnaces, the
the rapid
rapid fluctuations
fluctuations in
in the
flicker.
The
effect
of
flicker
depends
on
lighting
intensity
flicker. The effect of flicker depends on lighting intensity
and
and working
working conditions.
conditions.Flicker
Flicker isis more
more of
of aa problem
problem with
with
240 V
120 v
1
Use:
Short feeder runs.
runs.
Use: Short
Small
Small loads.
loads.
7.8.2
Initial
Allowances
7.8.2Initial
Allowances
In
designing aa lighting
installation,the
thelight
light loss
Indesigning
lightinginstallation,
loss factor
factor
must
must be
be taken
taken into
into account.
account. This
This factor
factor allows
allowsfor
forall
all condiconditions
of
of
tions that
that decrease
decrease the
the output
output of
of aa luminaire
luminaireover
overa period
a period
time.
time. The
The two
two major
majorconditions
conditionsare
arelamp
lamp lumen
lumen depreciation
depreciation
(LLD)
(LLD) and
and lurninaire
luminaire dht
dirt depreciation
depreciation (LDD);
(LDD); WD
LDD is
is light
light
loss
loss from
from the
the accumulation
accumulationofofdust,
dust,grease,
grease, and
and other
other foreign
foreign
matter
surfaces.
the lurninaire
luminaireand
andreflecting
reflecting
surfaces.
matter on
onthe
A
lighting
design
is
based
on
the
maintained
A lighting design is based on the maintainedillumination,
illumination,
which
must take
output of
of the
which must
take into
into account
account the
the decreased
decreased output
the
as
it
ages
and
the
decreased
output
of
the
·luminaire
lamp
lamp as it ages and the decreased output of the luminaire
between
between cleanings.
cleanings. For
For this
this reason,
reason, the
the initial
initialilluminance
illuminanceisis
considerably
This initial
initial illuminance,
illuminance, rather
ratherthan
than the
the
considerably higher.
higher.This
maintained
maintainedilluminance,
illuminance,isisthe
the figure
figure to
to be
be used
used when
when checkchecking
ing new
new installations
installationsfor
forcorrectness
correctnessof
of light
light output
output design.
design.
V
480
The
LLD value
value isis the
thevalue
value published
published by
by the
the lamp
lamp manumanuThe LLD
facturer.
facturer.The
The LDD
LDD value
value isis aafunction
functionof
of the
the in-service
in-servicecondiconditions
tions and
and the
the type
typeof
of luminaire
luminaire selected.
selected.Values
Valuesfor
forluminaire
luminaire
dirt
0.70 to
to 0.97.
0.97.
dirt depreciation
depreciationtypically
typicallyrange
range from
from0.70
1'21200Vv
""'
-
208Y/120
208Yll20 V,
V,Three-Phase,
Three-phase, Four-Wire
Four-Wire
t
208 V
208 V
t
208 V
120V
f
120 V
120V
Use:
Use: Large fractional horsepower motor
motor loads.
loads.
Medium
Mediumfeeder
feederruns.
runs.
Relatively
Relativelysmall
smallloads.
loads.
Some
Some need
need for
forthree~phase
three-phasepower.
power.
Numerous
Numerous 120·V
120-Vloads.
loads.
480YI277
48OYl277 V,
V,Three-Phase,
Three-phase, Four-Wire
Four-Wire
V
t
480 V
480
t
480 V
t
480 VV
480
1277 V
J
277
277 VV
277
277 Vv
1
1
1
Use:
Use: Fluorescent and
and high-intensity-discharge
high-intensity-dischargelighting
lighting
(any
to
V).
(anyincandescent
incandescentlighting
lighting
to be
be served
servedatat120
120
V).
Large
lighting
!oad.
Largepower
powerload
loadVS.vs.
lighting
load.
Large
Large load
load (power
(power and
andlighting).
lighting). .
Long
Longfeeder
feederruns.
runs.
Figure
System Power
Power Supply
Supply
Figure 18-Lighting
1&-Lighting System
Considerations
Considerations
incandescent
incandescent lighting
lighting than
than with
with fluorescent
fluorescent and
and HID
HID type
type
lamps.
lamps. When
When flicker
flicker continues
continues over
over an
an appreciable
appreciable period,
period,
voltiige
voltage variations
variations as
as low
low as
as 1/l/2%
may be
be objectionable.
objectionable.
2 % may
When
objectionable
flicker
occurs,
either
the
When objectionable flicker occurs, either the load
load causing
causing
be
reduced
or
eliminated,
or
the
flicker
should
the flicker should be reduced or eliminated, or the
the capacity
capacity
of
of the
the supply
supplysystem
system should
shouldbe
be increased
increasedto
to reduce
reduce the
the voltvoltage
age drop
drop caused
caused by
by the
the fluctuating
fluctuating load.
load. In
In large
large plants,
plants,
flicker-producing
flicker-producing equipment
equipment should
should be
be segregated
segregated on
on sepaseparate
soas
as not
not to
to disturb
disturb flicker-senflicker-senrate transformers
transformersand
and feeders
feeders so
sitive
sitiveequipment.
equipment.
7.10
LIGHTING
7.10 EMERGENCY
EMERGENCYLIGHTING
7.10.1
Requirements
7.10.1
Requirements
In
In the
the event
event of
of aa power
powerfailure,
failure, operating
operating personnel
personnel nornormally
mally have
haveplanned
planned operating
operating or
or shut.,.down
shut-down procedures
procedures that
that
.’
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73
ELECTRICAL INSTALLATIONS
lNSTALL4TlONS IN PETROLEUM
PETROLEUM PROCESSING PLANTS
PLANTS
ELECTRICAL
must be
be followed.
followed.Should
Shouldpower
powerfail,
fail, an emergency
emergencylighting
lighting
system must
must provide
provide sufficient
sufficient illumination
illumination to enable these
efficiently with
with aaminimum
minimum of
procedures to be performed efficiently
time.
lost time.
7.1 1 DESIGNCONSIDERATIONS
7.11
CONSIDERATIONS
Efficiency
7.11.1
7.11.1Efficiency
Locations
Locations
7.10.2
Emergency lighting shall
shall be provided in control
control houses of
all types,
types,atcritical
at critical instruments,
substainstruments, in large
large electrical substations, at
atsafety
safetyshowers
showersand
and other safety
equipment, and
and inin
safety equipment,
lightingshould
should be prolaboratories.
laboratories. In general,
general, emergency lighting
the ability to see
vided in
inall
alllocations
locationswhere
where
see during an emeremernecessary. Local,
and state
require
gency isisnecessary.
Local, city, and
state codes
codes may require
special areas
areas where
where personnel work
emergency lighting
lighting for special
work;
these
these codes should
shouldbebechecked.
checked.
7.10.3
beswitched
switchedononas required.
arrangementlimits
limits the
may be
required. This arrangement
drain on the
thebattery
lighting is needed.
drain
battery to the periods
periods when lighting
Escalation of
ofenergy
energy costs requires the consideration
consideration of
while not
notreducing
reducingthe effectiveeffectivemethods for reducing costs while
lighting system. These methods
ness of the lighting
methods can
can consist of
the following:
following:
a.
Automaticlight
light
switching by photocell or clock-based
a.Automatic
switching
timers.
timers.
b. Use of
andand
structures.
ofswitches
switchesatattowers
towers
structures.
c.
c. High-efficiency
High-efficiency lamps
lampsand
andballasts.
ballasts.
d.
d. Optimum
Optimum use
useof floodlights.
floodlights.
Power
Power Supplies
Supplies
7.11.2Maintenance
7.11.2
Maintenance
lighting power
powersupplies
supplies may be
beas follows:
follows:
Emergency lighting
either diesel or
or gas.
gas.
a. Engine-generator
Engine-generator sets using either
b. A
turbine-generator using
usingeither
either steam or
orgas.
gas.
b.
A turbine-generator
c.
whereavailable,
available,providing
providing 125
c. Station batteries, where
125 V direct
direct
current.
d.
Battery-operated self-contained
self-contained floodlights;
floodlights; the most ecod. Battery-operated
nomical for
forgeneral
generallighting.
lighting.
e.
e. Battery-operated fluorescent
fluorescent fixtures.
fixtures.
In each case,
case,ififthe primary power
powersupply
supplyis lost,
lost, automatic
automatic
either energizes
energizes the emergency lights
transfers
operation either
lights or transfers
the lighting load from
emergency
from the primary circuit to the emergency
power supply.
supply.
In unattended areas
areas such as substations,
substations, some lights
lights may
be put permanently on a DC source,
source, such as the substation
substation
batteries,
batteries, or on another source designed just for
for emergency
emergency
use. These lights
lights are controlled by a switch adjacent to the
AC light switch.
switch. If
If there is a power
failure, the DC lights
lights
power failure,
The effectiveness of
,ofaalighting
lightinginstallation
installation is based
based on
on and
and
proportional to the adequacy of
ofits
itsmaintenance,
maintenance, so maintemustbe considered in the initial
initialdesign
designofofthe processnance must
ing plant
plant lighting.
replacementand
and
lighting. Accessibility for lamp replacement
reflector cleaning
cleaning should be considered when
whendetermining
determiningthe
of aaluminaire.
luminaire.
location of
ELECTRIC
POWER
7.12ESTIMATING
ESTIMATING
ELECTRIC
POWER
REQUIREMENTS
REQUIREMENTS
estimatedwatts
wattsload
load
lighting a parparFor calculating the estimated
for lighting
2/ftc
ticular
W/ft2/ftc
ticular processing plant area,
area, Table 6 provides aa W/ft
constant
luminaire,
constant for each different
different type of lamp and luminaire,
outdoor. Using these constants,
constants, select the footfootindoor and outdoor.
level by the square
illuminancedesired,
desired, multiply this level
candle illuminance
footage
footage of the area being considered,
considered, and then multiply by
the constant.
will give
give the estimated lighting
constant. This will
lighting load for
area.
the area.
Table
Table 6-Constants
6-Constants for Estimating
Estimating Lighting
Lighting Loads
Loads
Location
e Type Lamp Area Service
Location
Indoor
Service Area
Lamp Type
Type
of Lighting
Wlft2Iftc
W/ft2/ftc
General, all
alltypes
typesof areas
areas
Incandescent
Incandescent 0.176 diffuseGeneral
General diffuse
0.176
Indoor and
andoutdoor
outdoor
General,
General, all
all types of
ofareas
areas
Incandescent
Incandescent
0.143
Indoor
General, all
areas
alltypes
typesof areas
Fluorescent
Fluorescent
Indoor
General,
General, all
alltypes
typesof areas
areas
Fluorescent
Fluorescent
0.067
Semidirect
Semidirect
0.067
Indoor and
andoutdoor
outdoor
General,
areas
General, all
alltypes
typesof 0.061
areas
Fluorescent or
ormercury
mercury
Direct
0.061
Outdoor
Process
Process unit,
unit,small
smallparking
parking
lot, protective
protectivelighting
lighting
High-pressure
floodlights
Direct floodlights
Direct
High-pressuresodium 0.167
0.167
Outdoor
High-pressure
Outdoor
Loading
railroad
yard
docks,
floodlights
sodium
Direct
0.077
Loading docks, railroad yard
lighting
lighting
High-pressure sodium
Direct floodlights
0.077
High-pressure
floodlights
Direct
sodium sodium
Direct floodlights
0.080
Outdoor
general
Large
Outdoor
Large general area
Direct
semidirect
or
0.143or semidirect
0.077 diffuseGeneral
General diffuse
0.077
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74
74
API
API RECOMMENDED
RECOMMENDED PRACTICE
PRACTICE 540
540
~~
7.13 ILLUMINANCE
METERS
ILLUMINANCEMETERS
____
~~
~
~~
_____
~
~
~
~~~~
give lower-than-true
lower-than-truevalues
valuesunless
unless
correction
procedures
correction
procedures
me are
used. This
is
the
cosine
effect
or
angle-of-incidence
effect.
This is the cosine effect angle-of-incidence effect.The
Portable,
Portable, light-sensitive-cell
light-sensitive-cellmeters
metersare
are simple
simple and
and conveconvewinerror may be
as 25%
25% when the
the light
light isisfrom
fromside
side
winbe as
as much
much as
nient
precision
instruments.
Under
the the
nient to
to use,
use, but
butthey
theyarearenotnot
precision
instruments.
Under
only.
Most·
presentday
daymeters
meters
have
a diffusing
cover
dows
dows
only.
Most
present
have
a
diffusing
cover
most favorable
favorable conditions,
conditions.measurements
measurementsmade
made in the field
field
plate
plate or some
some other device
device to
to ensure
ensure that
that light
lightfrom
fromall direcdirecshould
5%.
should not be expected
expected totohave
have an
an accuracy
accuracygreater
greaterthan
than5%.
tions
is
properly
evaluated.
A
well-corrected
cell
has
nearly
aa
tions
is
properly
evaluated.
well-corrected
cell
has
nearly
All
light-sensitive cells
cells have
All light-sensitive
have certain
certain inherent
inherent characteristics
characteristics
true
cosine
response
at
all
angles
of
incidence.
When
using
an
true
cosine
response
at
all
angles
When
using
that should
shouldbe recognized.
recognized.
uncorrected
uncorrected cell.
cell,direct
d i r e c t light from
from a single
single source
sourcecan be meaMeters
Meters without
without color correction
correction can accurately
accurately read only
by
holding
the
cell
perpendicular
to
the
light source
sured
holding
the
cell
perpendicular
the
sourceand
and
they are
the
are calibrated
calibrated (usually
(usually
the type of illumination
illumination for
forwhich
which
multiplying
the
reading
by
the
cosine
of
the
angle
of
incidence.
multiplying
the
reading
the
cosine
the
angle
incidence.
light
lamp
at a color
of 7,700
light from
from aafilament
filament
lamp
colortemperature
temperature
7,700 K).
K).
All light-sensitive
are subject
subject to fatigue.
fatigue. Meter indilight-sensitivecells
cells are
Most meters
with
a color-correcting
filter that
meters are made
madewith
acolor-correcting
filterthat
cation drops
drops Slowly
slowly for
for several
several minutes
minutes until
until a constant
constant
changes
changes cell
cellresponse
response to
to aareasonably
reasonablyclose
close approximation
approximationof
value
value is
is reached.
reached. The
The effect
effect is noticeable
noticeable at high footcandle
footcandle
the
whichwill
will be sufficiently
the standard
standard eye
eye response
response curve, which
sufficiently
values.
values. Prior
Prior to
to measurement,
measurement, all
all recorded meters
meters should
should be
purposes.
accurate
accurate for
forordinary
ordinary
purposes.
Meters
are
usually
calibrated
with
light
perpendicular
to
the
given
as
long
an
adaptation
period
as
necessary
before
valas
necessary
before
valgiven
as
long
an
adaptation
Meters are usually calibrated with light perpendicular to the
cell
surface;
light
from
oblique
angles
or
diffused
light
will
ues
are
recorded.
cell surface; light from oblique angles
diffused
will
are recorded.
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SECTION 8-WIRING
8-WIRING
SECTION
8.1
PURPOSE
8.1 PURPOSE
noted,
otherwise
Unless
instrumentation
circuits.
the
into the instrumentation circuits. Unless otherwise noted,
spacing should
shouldbebeper API RP 552 or IEEE
spacing
E E E 518.
5 18.
section isis intended
intended as a guide for providing safe
safe and
This section
. reliable wiring
for the petroleum processing
wiringsystems
systems
processingindustry.
industry.
SYSTEMS
8.4CONDUIT
CONDUIT SYSTEMS
8.2
8.4.1
SCOPE
This section covers the basjc requirements for the design
and installation of wiring systems using electrical raceways
trays. (For general
general guidelines
guidelinesconcerning
concerningoverhead
overhead
and cable trays.
distribution
methods,
most
electrical
4.1 1.) Because
Becausemost
electrical
distributionmethods,
see see 4.11.)
installations within
within aa processing
processing plant
plant are
are in classified
classified localocainstallations
tions and
mainly
to wiring
tions
and are
areoutdoors,
outdoors,this
thissection
sectionpertains
pertains
mainly
to wiring
practices for
forthose
thoselocations.
locations.
GENERAL
8.3
GENERAL
electricalinstallations
should
meetorexceed
8.3.1 All electrical
installations
should
meet or exceed
ANSI/IEEE C2
and
NFPA 70 requirements;
requirements; ANSVIEEE
C2 requirements;
requirements: and
federal,
federal, state,
state,and local requirements.
requirements.
8.3.2 All raceways
raceways and
andcable
cable trays
and
trays should
should be selected and
installed in accordance
as as
defined
accordance with
withthe
thearea
areaclassification
classification
defined
in API RP 500 or 505 and with
with the requirements
requirements of NFPA 70
for the area classification.
classification.
General
8.4.1.1 Conduit and associated fittings and boxes should be
specifically manufactured for electrical installations.
8.4.1.2 The gasket
gasket material
conduit fittings
fittings and boxes
8.4.1.2
material for
for conduit
boxes
should
to the process
plasticthat
thatis isresistant
resistant
process
should be
beneoprene
neopreneor a plastic
solids,
solids, liquids,
liquids,and gases to which ititmay
maybebeexposed.
exposed.
8.4.1.3 Conduits
Conduits should beswabbed
clean
8.4.1.3
swabbed
clean prior tothe
the
installation
installation of wire
wireand
andcable.
cable.
Commercialpulling
compounds
compatible
8.4.1.4 Commercial
pulling
compounds
compatible with
thewire
wire or cable
being pulled
pulled
the jacket and insulation
insulation of the
cable being
should be
pulling
compound
should
beused.
used.Excess
Excess
pulling
compound
should
be removed
removed
before
before the
theconduit
conduitsealing
sealing compound
compound is poured in the seal-fitseal-fit.
tingaround
theconductors.
ting
around
the conductors.
8.4.1.5
8.4.1 -5 Temporary
Temporary openings
openings in
in conduits
conduits should
shouldbe plugged
or capped to prevent
prevent moisture
from
moistureand
andforeign
foreignmatter
matter
from enterduringthetheconstruction
construction
phase
ing during
phase
of a job.
8.4.1.6 Conduit
8.3.3 The
The wiring
in the
Conduit fittings
fittings and pull,
pull, splice,
splice, and junction boxes
8.3.3
wiring methods
methods used
used in
theoperating,
operating,utility,
utility,and
and
should
be
sized
using
dimensions
and
volume in
other similar
petroleum
processing
plants
are: besizedusingdimensionsandvolume
similar areas
areasofof
petroleum
processing
plants
are:should
in accordance
accordance
with NFPA 70.
a.
a. Electrical
Electrical conductors
conductorsenclosed
enclosedin conduit.
conduit.
b.
Cable-Type
by NFPA 70.
b.Cable-Type
MC MC and Type TC as definedby
8.4.2 Rigid
Rigid Metal
Metal Conduit
Conduit
8.4.2
Generally, the use of busways
electrical
8.3.4 Generally,
busways is limited to electrical
rooms or
buildings, substations,
Or buildings,
substations,repair
rep&shops,
shops,and
andother
Other simiSimilar locations.
locations.
8.3.5 The useofof
wireways
should be restrictedtotoshort
short
wireways
should
runs, where
where many electrical
conductors may.be
,ge collected.
electricalconductors
collected.
Electrical conductors
starter
racks
conductorsmay be collected
collectedononmotor
motor
starter
racks
and at entrances
to
relay
or
control
cabinets
in
electrical
entrances
control cabinets electrical and
and
rooms.
instrument rooms.
8.3.6 The use of electrical
electrical metallic tubing
tubingand
andintermediate
intermediate
restricted to indoor,
indoor, dry,
dry, unclassified
metal conduit
conduitshould
shouldbe restricted
metal
locations, such
suchas offices
offices and
andlaboratories,
laboratories,where
where
installalocations,
the installawouldnot
notbe subject to mechanical
mechanical damage.
damage.
tion would
~
I
I
8.4.2.1 The
The type
q p e of
of rigid
rigidmetal
conduit
tobeinstalled
8.4.2.1
metal
conduit
to be installed
should be
on the type
beselected
selectedbased
based
typeof exposure
exposure to which the
the
conduit is to be subjected and,
on past plant
and,when
whenapplicable,
applicable,
plant
experience.
experience.
8.4.2.2
conduit system
8.4.2.2 The rigid metal conduit
system selected should be
composed of
ofat least one of the following
following types:
types:
a.
a. Hot-dipped galvanized steel conduit,
conduit, conduit elbows,
elbows, and
and
couplings used
used with
with ferrous
ferrous fittings
fittings and enclosures
enclosures having
having aa
couplings
protective coating
finish. Where suitable
suitable
protective
coatingof
of zinc and an outer finish.
for the
the environment,
environment, aluminum
aluminum fittings
fittings and
andenclosures
enclosures may
be substituted
substituted for
foruse
usewith
withthe steel conduit.
conduit. Hot-dipped
Hot-dipped galgalvanized
C80.l .
vanized steel
steelconduit
conduitshould
should conform to ANSI C80.1.
aluminum
alloyconduit
conduit, conduit
b. Corrosion-resistant
Corrosion-resistant
aluminum
alloy
conduit,
elbows,
couplings,fittings,
fittings, and enclosures
elbows,couplings,
enclosures containing
containing not
more than 0.4%
0.4% copper.
copper. Aluminum
Aluminum conduit
conduit should conform
conform
(30.5.
to ANSI C80.5.
8.3.7 The mechanical
mechanical continuity
continuity ofall
allraceways
raceways
andand
the the
electrical
maintained
electrical continuity
continuity of
of metal
metalraceways
racewaysshould
should
be maintained
additionalgrounding
electrical system.
system. An additional
throughout the
the electrical
grounding
conductor installed
power
circuit
should
be considinstalledwith
witheach
each
power
circuit
should
be considered.
8.4.2.3
ered.
8.4.2.3
metal Rigid
Rigid metal conduit
conduit should
should be
be cut
cut square
square and
and
reamed before
beforethreading.
threading.
Spacings
between
instrumentation
circuits
and
8.3.8 Spacings
between
instrumentation
circuits and
power,
lighting,and
and
control circuits
andcable
cable
8.4.2.4
bendshould
should be madewith
witha a
8.4.2.4 A rigid metal conduit bend
power,lighting,
control
circuits in raceways
racewaysand
notless
less
than the requirements
trays should
should be maintained to
toprevent
preventintroduction
introduction of noise radiusradius ofnot
than
requirements found
found in NFPA 70.
75
75
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76
76
API
API REcOMMENDED
RECOMMENDEDPRACTICE
PRACTICE540
540
The
than
the the
minimum
bending
radius
Theradius
radiusmust
mustbebegreater
greater
than
minimum
bending
radius
of
should be
of the
the cable.
cable. AA field
field bend should
be made
made with
with equipment
equipment
specifically
made so
specifically intended
intended for
for the
the purpose
purpose and made
so that
that the
the
conduit
conduit isisnot
not injured
injured and
and the
the internal
internaldiameter
diameterisis not
not effeceffectively
tivelyreduced.
reduced.
8.4.6
Abovegrade
Installations
8.4.6Abovegrade
Installations
8.4.6.1
8.4.6.1 General
General
Rigid
Rigid metal
metalconduit,
conduit,or
orcables
cablesin
in cable
cabletray
trayare
areconsidered
considered
the
normal
wiring
methods
for
all
outdoor
above-grade
the normal wiring methods for
all outdoor above-gradeinstalinstallations
and
for
all
indoor
installations
subject to
8.4.2.5
should
lations and for all indoor installations subject
to moisture,
moisture,
8.4.2.5 Threaded
Threadedrigid
rigidmetal
metalconduit
conduitand
andfittings
fittings
shouldbe
be
andand
mechanical
damage.
used
areare
generally
preferred
for for .chemical
.chemicalfluids
fluidsand
andsolids,
solids,
mechanical
damage.
used for
foroutdoor
outdoorinstallations
installationsand
and
generally
preferred
indoor
In
indoorinstallations.
installations.
In Class
ClassI,I, Division
Division 22locations
locationsand
and wet
wet locations,
locations,conduit
conduit.
connections
to
equipment
subject
to
vibration
or
movement
connections to equipment subject to vibration or movement
8.4.2.6
8.4.2.6 Threaded
Threadedconduit
conduitjoints
joints should
should be
be coated
coated with
with an
an
should
conshouldbe
be made
made with
withapproved
approvedliquidtight
liquidtightflexible
flexiblemetal
metal
conapproved
electrically
conductive
sealant
and
corrosion
inhibiapproved electrically conductive sealant and corrosion
inhibiduit
exceeding 915
rom
(36
in.)
in
length
and
withan
an
duit
not
exceeding
915
mm
(36
in.)
in
length
and
with
tor
that
is
not
harmful
to
the
conductor
insulation.
Aluminum
tor that isnot harmful to the conductor insulation. Aluminum
equipment
equipmentgrounding
groundingconductor.
conductor.
conduit joints should be coated with anti-seizing compounds
conduit joints should be coated with anti-seizing compounds
specifically
foruseuse
aluminum.
Threaded joints
specificallymadefor
withwith
aluminum.
Threaded
joints
should
shouldbe
be made
made with
with at
at least
least three
three fully
fully engaged
engaged threads,
threads,or
or
five
threads
for
fivefully
fullyengaged
engaged
threads
forexplosionproof
explosionproofconnections.
connections.
8.4.2.7
are not
8.4.2.7 Rnnning
Running conduit
conduit-threads
,threadsare
not acceptable.
acceptable. The
The
threads
shall
have
a
taper
of3/4-in.lft.
threads shall have taper
a of 3/4-in./ft.
8.4.3
Intermediate
Metal
Conduit
8.4.3Intermediate
Metal
Conduit
8.4.3.1
The applicable
applicablerequirements
requirements in
in 8.4.2
8.4.2 pertaining
pertaining to
8.4.3.1 The
rigid
apply
to
rigid metal
metalconduit
conduitalso
also
apply
tointermediate
intermediatemetal
metalconduit.
conduit.
8.4.3.2
intermediate metal
systemshould
should
8.4.3.2 The
Theintermediate
metal conduit
conduitsystem
bebe
composed
should
conform
to
composedof
ofgalvanized
galvanizedsteel
steelandand
should
conform
toUL
UL 1242.
1242.
8.4.4
Rigid
Nonmetallic
Conduit
8.4.4Rigid
Nonmetallic
Conduit
Conduit
beinstalled
installed
directly
adjacent
Conduit unions
unions should
shouldbe
directly
adjacent
to to
equipment,
such
as
motors
and
motor
starters,
subject
to
equipment, such as motorsandmotorstarters,subject
to
replacement
replacementor
or removal
removal for
forrepairs.
repairs.This
This allows
allowsmalfunctionmalfunctioning
ingmotors
motorsand
and motor
motorstarters
startersto
to be
be removed
removedwithout
withoutdisturbdisturb. ing
supply
conductors.
Conduit
ing the
the conduit
conduit and
andsupply
conductors.
Conduit
unions. unions.
provided
provided at
at explosionproof
explosionproofenclosures
enclosuresshould
shouldalso
alsobebeexploexplosionproof
and
should
be
located
between
the
conduit
seal
sionproof and should be located between
the conduit sealfitfittings
and
the
enclosures.
tings andthe enclosures.
Expansion
Expansionjoints
joints should
shouldbe
be provided
provided in
in long
longconduit
conduitruns
runs
that
compensatefor
for thermal
that are
are required
required to compensate
thermal expansion
expansion and
contraction.
contraction.
Conduit
Conduitofof1/2-in.
l/Z-in.size
sizemay
maybe
beused
usedfor
forcontrol
controlpanel,
panel,shortshortrun
ofof
%-in.
run instrumentation,
instrumentation,and
andtelephone
telephonewiring.
wiring.Conduit
Conduit
3/4-in.
size
power, and
size should
should be
be the
the minimum
minimum used for
for lighting,
lighting, power,
and
motor-control
wiring.
motor-control wiring.
8.4.4.1
nonmetallic
conduit to
8.4.4.1 The
The type
type of
of rigid
rigid
nonmetallic
conduit
to be
be
installed
should
be
selected
based
on
cable-pulling
resistance,
installed shouldbe selected basedon cable-pulling resistance,
ConduitSystems
Systems in
8.4.6.2 Conduit
inWet
Wet and
and Corrosive
Corrosive
construction
conduit
exposure.
RigidRigid
nonmeconstructiontechniques,
techniques,andand
conduit
exposure.
nonme- 8.4.6.2
Areas
not
be
used
in
Class
I,
aboveground
tallic
conduit
should
Areas
tallic conduit should not be used in Class I, aboveground
installations.
installations.
Precautions
to
Precautionsshould
shouldbebetaken
taken
to prevent
preventgalvanic
galvanicand
andatmoatmo8.4.4.2
nonmetallic
conduit
system selected
spheric,
corrosion
when
metal
conduit
is
installed
in
areas
8.4.4.2 The
The rigid
rigidnonmetallic
conduit
systemselected
spheric .corrosion when metal conduit is installed in areas
of
(Schedule
40
should
shouldbebecomposed
composed
ofthermoplastic
thermoplasticconduit
conduit
(Schedule
40or
or
where
wherecontinuous
continuousmoisture
moisturemay
maybe
be present.
present.In
In locations
locationssuch
such
Schedule
SO), conduit
conduitelbows,
elbows,couplings,
couplings,and
andsimilar
similarfittings
fittings as
Schedule80),
ascooling
coolingtowers,
towers,where
whereexcessive
excessivemoisture
moistureisisexpected,
expected,corcorof
polyvinylchloride
chloride or
Lightofpolyvinyl
or high-density
high-deqsity polyethylene. LightrosIon-resistant
conduit
materials
(aluminum
and plasticrosion-resistantconduit
materials
(aluminum
andplasticwall
wall plastic
plasticconduit
conduitshould
shouldbebeinstalled
installedonly.
onlywith
witha aconcrete
concrete
coated,
conduit)
should
be considered.
coated,rigid
rigidsteel
steel
conduit)
should
be considered.
encasement,
and
it
should
be
used
only
when
encasement, and it should be used only when the
the insulation
Plastic-coated
rigid
steel
conduit
systems
Plastic-coated rigid steel conduit systems should
should also
also be
be
temperature
cable to
temperaturelimitation
limitation of
of the cable
to be
be installed
installed does
does not
not
considered
or
consideredfor
for use
use in
in areas
areaswhere
wherecorrosive
corrosivevapors
vapors
orliquids
liquids
exceed
limit
exceedthe
thetemperature
temperature
limitfor
forwhich
whichthe
theconduit
conduitisislabeled.
labeled. may be prevalent. Galvanized conduit, couplings, and elbows
may be prevalent. Galvanized conduit, couplings, and elbows
be
made
with
an
approved
bending
A.
field
bend
should
Afieldbendshould
be madewith an approvedbending
with
PVC
with
PVCcoating
coatingbonded
bonded to
to the
the metal
metal may
maybebeused
usedfor
for such
such
boxbox.
..
means,
means,preferably
preferablya heat
a heat
. systems.
systems.Careful
Carefulattention
attentionshould
shouldbebegiven
givento
to the
theinstallation
installation
methods
methods to·
to maintain
maintain the
the integrity
integrity of
of the
the protective
protectivecoating.
coating.
8.4.5
Liquidtight
Flexible
Metal
Conduit
8.4.5 Liquidtight
Flexible
Metal
Conduit
Workers
should
use
only
roll-type
benders
and strap
Workers should use
only
roll-type
benders
and
strap
metal conduit
8.4.5.1
8.4.5.1 Liquidtight
Liquidtightflexible
flexiblemetal
conduit should
shouldhave an
an
wrenches
wrenchesso
so that
that the
the plastic
plastic coating
coatingdoes
does not
not abrade
abradeor
or tear.
tear.
integral
conductor, when
integral grounding
grounding conductor,
when available,
available, and
and an
an outer
outer
All
All exposed conduit
conduit threads
threads at
at the
the terminations
terminations should be
be
liquidtight,
nonmetallic,sunlight-resistant
sunlight-resistant jacket.
In some·
some
liquidtight,nonmetallic,
jacket. In
thoroughly
sealant.
thoroughlycoated
coatedor
orcovered
coveredwith
withplastic
plastic
sealant.
cases,
cases, an
an external
external bonding
bonding jumper
jumper may
may be
be required
required to
to meet
meet
Epoxy-coated
metalfittings
fittings
enclosures
having
Epoxy-coatedmetal
andand
enclosures
having
cast cast
NFPA
70requirements.
requirements.
NFPA70
metal
covers,
plastic-coated
metal
fittings,
or
suitable
metal covers, plastic-coated metal fittings,or suitableplastic
plastic
enclosures
where plastic-coated
plastic-coatedrigid
rigid
8.4.5.2
flexible
metal
conduit should be
enclosures should
should be
be considered where
8.4.5.2 Liquidtight
Liquidtight
flexible
metal
conduit
should
be
installed
fittings
approved
for
steel
to
installedwith
withtermination
termination
fittings
approved
forthe
thepwpose.
purpose.
oraluminum
aluminumconduit
conduitsystems
systemsareare
tobe
beinstalled.
installed.
steelor
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L999 orW0732290.
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ELECTRICAL
INSTALLATIONS IN PETROLEUM
PETROLEUM PROCESSING PLANTS
PLANTS
ELECTRICAL
INSTALLATIONS
8.4.6.3Conduit
Conduit
Drainage
Drainage
Provisions for
for drainage
drainage should
should be installed
installed in the vertical
Provisions
drops of
oflong,
long, outside, above-grade
above-gradeconduit
conduitruns
runsat the points
points
drops
at whichthe
the
conduits
buildings,
switchgear,
conduits
enterenter
buildings,
switchgear,
control control
panels,
lightingpanelboards,
panelboards, and other similar
enclosures.
panels,lighting
similarenclosures.
Long, outside,
runs
thatthat are extended
extended
Long,
outside,above-grade
above-gradeconduit
conduit
runs
below grade should
ver-vershould be provided with
with drain
drainfittings
fittingsininthethe
tical drops directly
directly above
above grade.
grade. In areas
areas of high humidity
rapidly
changing
temperatures,
drain
requirements
and rapidly
changing
temperatures,
drain requirements
should be reviewed
reviewed and
andenforced.
enforced.
should
8.4.6.4Conduit
Conduit
Routing
Routing
Exposed conduit
installed
parallel
with with
or at light
conduitshould
shouldbe be
installed
parallel
right
angles to walls,
walls,columns,
angles
columns, and beams. Adequate
Adequateclearances
clearances
ali
from high-temperature
high-temperature surfaces
surfacesshould
shouldbe
beestablished
establishedfor
forall
from
conduit runs.
runs. Clearances
Clearances of 152
152 mm (6
(6 in.) from
from sUliaces
sufaces
45°C to 65°C (113°F
(113°F to 149°F);
149°F); and 305
305 mm (12
(12 in.)
in.) from
surfaces greater
greater than
than65°C
65°C (l49°F)
surfaces
(149°F) are recommended. Where
Where
necessary totoroute
routeconduit
conduitclose
close to high-temperature
high-temperaturesursurit is necessary
faces, a high-reflectance
installed
faces,
high-reflectance thermal
thermal barrier should be installed
between the conduit and
andthe
thesurface.
surface.•
Generally,
Generally, conduits
conduits should
should be routed
rouied to allow
allow pull boxes,
junction boxes,
boxes, and
andfittings
fittingstotobe accessed from
from platforms
platformsor
structures
structures without
withoutthe use of scaffolding.
scaffolding.
Wherever
possible, conduit
conduit routing
routing should
should be maintained
maintained
Wherever possible,
at a specified
specified minimum
minimumhorizontal
holizontaldistance
distance from
high-firefrom high-firedistance of 7.6
7.6 m (25 ft)
ft) is often considered
considered
risk equipment.
equipment.A distance
lisk
to be
must be operbeadequate.
adequate.Conduits
Conduits containing
containing wiling
wiringthat
that
operable during
fireproofed
when
the conduits
are
during a fire
fireshould
shouldbebe
fireproofed
when
the conduits
installed
closer than the specified
minimum distance
installed closer
specifiedminimum
&stance from
high-fire-lisk
high-fire-risk areas.
areas.
Conduits
be spaced
away from continuConduits and
andfittings
fittingsshould
should
be
continually
ally moist
moistsurfaces.
surfaces.
ofconduit
conduit runs are
Where
portions of
are exposed
exposed to temperatemperaWhere portions
tures in excess
excess of the design ambient temperature
temperature or where
conduits
cable
conduits have
have been fireproofed,
fireproofed, additional
additional derating
derating of cable
ampacity may
may be
berequired.
required.
8.4.6.5Conduit
Conduit
Supports
Supports
i
I
shall be properly fastened
fastened and
and
All rigid metal conduit runs shall
supported
at
the
intervals
specified
in
NFPA
70.
Standard
supported
intervals specified
70. Standard
conduit clamps
clamps and mUltiple
multiple conduit
conduit hangers
hangers are acceptable
acceptable
conduit
supports for mostinstallations.
One-hole
malleable iron
supports
installations.
One-hole malleable
clamps,
clamps, or other adequate
adequatemethods,
methods,are recommended
recommended to support conduits
conduits installed on
structures subject to
on pipeways
pipeways or structures
vibration
movement.Conduit
supports should be
vibration or movement.
Conduit supports
befabrifabricated from a matelial
from a matelial
materialor should have
havea aplating
plating
material
that minimizes
minimizesgalvanic
galvanicaction.
action.
Conduits
Conduits for main feeders
feeders and long parallel
parallel runs of conduit
conduit
for
any
service
should
not
be
directly
supported
from
for any service
should
not
be directly supported
from overoverhead piping.
Conduits also should
supported
Conduits
should not be directly
supported
from
piping.
from insulated
insulated piping.
77
be be
installed
as close as practicable
practicable
Conduit SUppOlts
suppoltsshould
should
installed
vertical drops
drops in horizontal
horizontal conduit
conduit runs
runsthat
thatsupport
supportpenpento vertical
dant-mountedlighting
fixtures.
Also, liquidtight
liquidtightflexible
dant-mounted
lighting
fixtures. Also,
flexible
metal conduit
areare
conduit should
should be
be supported
supportedonly
onlywith
withdevices
devicesthat
that
used in
instandard
standardtrade
trade
practice
accorpractice
andand that are in stIict
strict accordance
of NFPA
dance with
withthe
therequirements
requirements
NFPA 70.
70.
8.4.6.6Conduit
Conduit
Terminations
Terminations
Conduits
Conduits that
that enter
enter switchgear,
switchgear,motor
motorcontrol
controlcenters,
centers,and
and
similar
below
should
project
at leastat25least
similar installations
installationsfrom
from
below
should
project
mm 25
(1 in.)
in.) above
otherwise be termi(1
above the
thefinished
finishedfloor
floororor shall otherwise
terminated totoprovide
thethe
addition
of conduit
provideforfor
addition
conduit fittings.
fittings.
Spareconduits
belocated
nearest
totheaccess
Spare
conduitsshould
should
be located
nearest
to the access
openings
installations.Spare
Spareconconopenings to facilitate
facilitate future
future cable
cable installations.
duits
terminating
within
buildings
and outside
enclosures
duitsterminating
within
buildings
andoutside
enclosures
should
should have
haveaacoupling
couplingflush
flush
with the floor
floor and
andplugged
pluggedwith
with
recessedsquare-head
square-headplug.
plug.
a recessed
Spare low-voltage
low-voltage conduits that originate
originate at buildings
buildings
housing electrical
electrical facilities
facilities and that
that are routed underground
to structures
structures or columns
columns for future
future extension
extension overhead
should be capped above
abovegrade.
grade. These conduits
conduits should
should be
limited in number at a structure
structure or column and should
should be
spaced
spaced at the location to permit the future
future installation
installation of
staggered
staggered pulled boxes that orily
only minimally project beyond
the structure.
structure.
It is preferred
entrances
be be
provided
preferred that
thatthreaded
threadedconduit
conduit
entrances
provided
as integral
parts
of
sheet
metal
enclosures
if
conduits
are
integral parts
metal enclosures conduits areto be
terminated
at
these
enclosures
(both for outdoor enclosures
enclosures
terminated these
(both
and,
if
the
area
is
continually
damp,
indoor
enclosures).
and,
continually damp,
enclosures). If
are threaded
threaded entrances
entranceshave not been
beenprovided,
provided, field-welded
field-welded hubs
hubs
or approved
fittings
thatthat
are watertight
approved screwtight
screwtightconduit
conduithub
hub
fittings
are watertight
and provide aapositive
ground
are are
acceptable.
positive
ground
acceptable.
Generally, allallconduits
conduits
terminating
originating in Class
Class I
Generally,
terminating
or originating
locations
locations should
shouldbe terminated in threaded conduit
conduitentrances.
entrances.
When this requirement
requirement may be impractical
impractical for
for Class
ClassI, Division 2 indoor installations,
installations, locknut-bushing
locknut-bushingand
anddouble-lockdouble-locknut terminations
terminations with bonding jumpers and proper
properfittings
fittings
may be substituted.
applies to all
substituted. This means ofof bonding applies
intervening
boxes,
and enclosures
intervening raceways,
raceways,fittings,
fittings,
boxes,
enclosures between
between
thethe
point
of grounding
the classified
classifiedlocation
locationand
and
point
grounding of the elecelectrical service
service equipment.
equipment.
tIical
Conduit bushings
bushings should
shouldbe used where
where conduits
conduitsat boxes
or other enclosures
terminated
enclosuresareare
terminated
unless the box or enclosure
enclosure
design
design provides
providesan equivalent
equivalent protection.
protection.
8.4.6.7Conduit
Conduit
Seals
Seals
Explosionproof
sealfittings
fittings
located in compliance
with
Explosionproofseal
located
compliancewith
conduit
systems
in classified
beprovided
providedin in
conduit
systems
in classified
NFPA 70 should be
locations to minimize
minimize the passage through
locations
through the conduit
conduit of
gases, vapors,
vapors, and
and flames
flames from
from one portion of the electrical
gases,
electIical
installation to another.
installation
with
a compound
Seal
fittingsshall
shall be pouredwith
Sealfittings
acompound
recom-recommended by
by the
thefitting
fittingmanufacturer.
manufacturer. The sealing
sealing compound
STD API(P.TTR.0 R P
Copyrighted material licensed to IDOM.
-53-O-EN.GL..
3999 or distribution permitted.
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78
1ED PRACTICE 540
API RECOMMEND
and fiber dam used in the fittings should not be affected by
the surrounding atmospheres
or liquids and should not have a
melting point below 93°C (199OF). Combination explosionproof drain-seal fittings may be used in classified locations
where conduit drainage is required.
All conduits entering process control houses above grade
atpetroleumprocessing
plants should be provided with
explosionproof seal fittings outside the building walls. All
conduits originating at manholes within petroleumprocessing plants should be provided with explosionproof seal fittings at the points of entry to buildingsand electrical
equipment enclosures.
Conduits that dependon single-seal diaphragms or tubes
to
prevent process liquids or gases from entering their electrical
conduit systemsshouldbeprovidedwithsealfittings
for
blocking passage of the fluids and with a means of venting
the fluids to the atmosphere.This includes conduits routedto
canned pumps and to devices used for flow, pressure, and
analysis measurement.
Underground conduit runs that
are completely within a nonclassified location, and enter buildings below grade, should
be
sealed at their terminations with a mastic or expanded-foam
compound. The compound should be impervious to liquids
thatmaybeintheground.Endsofshortconduitsleeves
through building walls, used
for the entrance of cables, should
be sealed with mastic or expanded-foam compound.
8.4.7UndergroundInstallations
8.4.7.1WiringMethods
Generally,hot-dippedgalvanizedrigidsteelconduitor
rigidnonmetallicconduitthat
is encased in concrete (per
NFPA 70, 5014) should be used for underground conduit
systems. Concrete-encased, rigid aluminum conduit should
only be installed underground at those locations where prior
performance has proven satisfactory and where it conforms
with local codes and regulations. (Special requirements for
the concrete envelope used with an aluminum conduit
are
found in 8.4.7.4.)
Rigid metal conduit shouldbe used for underground installations whenever an extra-high-strength installation, such as
in an equipment foundation,
is required, andit is preferred for
underground installations where only one or two relatively
short runs of conduit are to be installed.
Subject to local practices and site conditions, the use of
underground, galvanized rigid steel conduit without continuous concreteencasementmaybeconsideredforcertain
installations. Normally, the underground conduit should be
provided with additional corrosion protection, such as a factory-applied plastic coating, a bitumastic coating, or a tape
wrap. On low-investment installations where this protection
may be omitted from underground conduit, additional protection should be provided at the grade line where the conduits
emerge above grade.
In certain applications, specifically approved direct burial
cable may be used.
8.4.7.2ConduitSize
A minimum sizefor a conduitfor installation underground
should be established. A 1-in. minimum size for a conduit is
recommended;however,a3/4-in.conduitinstalledunderground to a single, isolated device, such as a motor control
station or an instrument, is usually acceptable. A minimum
size for an underground conduitfor main distribution andfor
bulk cable routing between distribution centers shouldbealso
established.
The initial sizing of underground conduits for main distributionfeedersshouldtake
into considerationthepossible
replacement of the conductors with a larger size to accommodate a future increase in load.
8.4.7.3ConduitBankConfigurations
Conduit bank configurations should contain sufficient conduits for the present installation plus spare conduits for
future
use.
Consideration should be given to conduit bank configurations that will provide effective heat radiation when theduct
banks contain power cablesfor mains and major feeders.The
effect of certain duct bank configurations on cable ampacity
is reflected in the ampacity tables
of NFPA 70. Special calculationsarerequiredtodeterminetheampacityofcables
installed in duct bank configurations thatare not covered by
NFF'A 70. Consideration shouldalso be given to conduit bank
configurations and entry locations that provide the best racking conditions at manholes.
A specifiedminimumseparationshould
be established
between the outside surfaces of conduits in conduit banks.
8.4.7.4ConcreteEnvelope
The concreteenvelopesurrounding
the rigidconduits
should have a specified thickness on the top, bottom,
and
sides, Where reinforced conduit bank sections are required,
the thickness of the concrete envelope should be increased
accordingly.Whereconduitscometograde,
the envelope
should be extended at least 76 millimeters (3 inches) above
grade and should
be sloped for water runoff.
Red-pigmentedconcretecontainingat
least 5.9kg/m3
(10 lb/yd3yard) ofred iron oxide should be used
for the envelope. The concrete should be a 17.25-mE'a (2,500-psi) mixture having a coarse aggregate not exceeding19 mm (3/4-in.)
in size. The concrete should havelowa chloride content when
aluminum conduitis encased.
8.4.7.5 Underground Conduit Bank Routing
The location of all underground conduit bank runs should
be selected with consideration for future structural installa-
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
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ELECTRICAL
INSTALLATIONS IN
IN PETROLEUM
PETROLEUM PROCESSING
PROCESSINGPLANTS
PLANTS
ELECTRICAL
INSTALLATIONS
tions
area.Generally,
Generally,
underground
condlJit
tions in
in the
thearea.
underground
conduit
runs runs for
for
main
bank
runsruns
should
be routed
parmain feeders
feedersand
andallallconduit
conduit
bank
should
be routed
allel
should
notnot
cross
allel to
to plant
plantcoordinates
coordinatesand
androadways
roadwaysand
and
should
cross
congested
manufacturing or paved areas.
congestedmanufacturing
areas. Conduit
Conduit banks
banks
should
or in areas
shouldnot be installed
installed under
underfoundations
foundations
areas of excesexcessive
sive vibration.
vibration.
Sections
steel conduit
conduitbanks
banksspanning
spanningunder
underrailroads
railroads
Sections of steel
and
roadways,
crossing
disturbed soil,
crossingopen
open
androadways,
crossing
disturbed
soil, and
andcrossing
trenches,
such as
and water
watermains,
mains,may
may
require
trenches, such
as for
for sewers
sewers and
require
steel
reinforcement for
considerations.Where
Wheresoil
soil
steelreinforcement
for loading
loadingconsiderations.
conditions
footings may be required to
conditions are
are poor,
poor, anchors
anchors or footings
support
support and hold aaconduit
conduitbank
bank run,
run,especially
especiallyon slopes.
slopes.
be be
Where
bank
runsruns
should
Where possible,
possible,underground
undergroundconduit
conduit
bank
should
routed
routed in aa straight line
line between
between terminations.
terminations. Unavoidable
Unavoidable
bends should
radius
shouldbe
bemade
madewith
witha large
a large
radius and,
and, wherever
whereverpospossible,
near aa termination
sible, should
shouldbe located
located'near
telminationpoint.
point.
The
the concrete envelope
envelopeshould
shouldbe located
located aaspecispeciThe top
top of
ofthe
fied
minimum
depth
below
grade,
provided
the
bottom
fiedminimum depth
grade,providedthebottom is
is
below
the
frost
line.
This
depth
should be increased
below the frost line. This depth should
increased under
roadways
roadways and
and further
further increased
increased under
under the
thebase
base of the
the rail
rail at
railroads.
Underground conduit
conduit bank runs
installed in sysrailroads. Underground
runs installed
systems
manholes should
shouldslope
slopetoward
towardthe
themanholes
manholesforfor
tems using manholes
drainage
drainage purposes.
purposes.
To
vertiTo facilitate
facilitate maintenance,
maintenance,an
an adequate
adequatehorizontal
horizontaland
and
vertical
between
underground
con-concal separation
separationshould
shouldbebeprovided
provided
between
underground
duits
duits or conduit
conduit banks
banks and
and foreign
foreign structures,
structures, such
such as
as water
water
mains,
sewers,and
and gas
Where feasible,
feasible,underground
underground
mains, sewers,
gas lines.
lines. Where
conduits
and conduit
should be routed
abovesewer
sewer
conduits and
conduit banks
banks should
routed above
lines
may
A minminlines and other
other piping
pipingthat
that
may contain
containhydrocarbons.
hydrocarbons.A
imum
separation
between
communication conduits
imumseparation
between
communication
conduits and
and
power
also
be established.
power conduits
conduitsshould
should
also
established.
Care
Care should
shouldbe taken
taken to
to avoid
avoid installing
installingconduit
conduitand
andcable
cable
banks near
this can not
not be
be
near or above
above hot
hot process
processlines.
lines.When
Whenthis
avoided,
heatingeffect
effectofof
avoided, the heating
thethe source
source should
should be considconsidered.
alsoalso
be
ered. This
Thiscaution
cautionshould
should
be considered
considered for
fordirect
direct buried
cables.
cables.
Rigid
onlyonly
be extended
Rigid nonmetallic
nonmetallicconduits
conduitsshould
should
extended above
above
grade
switchgear
or similar
grade as
as stub-ups
stub-ups within
withinmetal-enclosed
metal-enclosed
switchgear
similar
enclosures
locations.
Where
above-grade
enclosures in nonclassified
nonclassifiedlocations.
Where
above-grade
extensions
rigid
extensions are
are to
to be rigid metal conduits, underground rigid
nonmetallic
be provided
with adapters,
nonmetallic conduits
conduits should
shouldbeprovided
withadapters,
enabling
metal conduits.
conduits.Adapters
Adaptersshould
should
enabling connection
connection to
to the metal
be installed
below
grade
within
the
concrete
envelope.
installed below
within the concrete envelope. The
The
adapters
reduce
the conduits.
conduits.
adapters should
shouldnotnot
reduce the
the size
size ofofthe
Note:
onmanhole
manhole and above-grade
Note: For considerations on
above-grade pull
pull point
locations,
practicesassociated
associated with conduits
locations, and installation
installationpractices
conduits and
and
conduit
conduit bank systems,
systems, see
see8.9.
8.9.
I
,
I
l
1
I
l
8.5
ELECTRICAL
METALLlCllJBING
8.5ELECTRICAL
METALLIC
TUBING
79
79
8.5.2 Compression-type
fittings are
arerecommended
recommended
Compression-typefittings
forfor use
in electrical
systems.
electricalmetallic
metallictubing
tubing
systems.
8.5.3 Electrical
tubing shall
shallbe
besecurely
securelysupported
supported
Electrical metallic tubing
at
least
every
3
m
(10
ft)
and
within
920
mm
(36
in.)
at least every 3 m (10 ft) and within 920
(36 in.) of each
each
outlet
box,
junction
box,
cabinet,
and
fitting.
outlet box, junction box, cabinet, and fitting.
8.6
BUSWAYS
BUSWAYS
8.6.1
shouldnot
notbebe
used
infollowing
the following
8.6.1 Busways
Buswaysshould
used
inthe
loca- locations:
tions:
a.
excessivevibravibraa. InIn locations
locations subject
subject to physical
physical damage, excessive
tion,
tion, or corrosive
corrosive vapors.
vapors.
b.
b. In
In locations
locations subject
subject to
to dust,
dust, unless
unlessthe
thebusways
buswaysare
aretotally
totally
enclosed.
enclosed.
c.
In Class
Class I,I, Division
c. In
Division 11 locations.
locations.
d.
thebusways
buswaysare
are
d. In Class
Class I,I, Division
Division 22 locations,
locations, unless the
enclosed
enclosed and
andgasketed.
gasketed.
e.
locations
above classified
e. In nonclassified
nonclassifiedlocations
aboveclassified
locations, locations,
unless
totally
enclosed.
unless the
thebusways
buswaysareare
totally
enclosed.
f.f. Above
Above highly
highly flammable
flammable materials
materials or areas
areas where
where personpersonnel
are are
totally
enclosed.
nel may
may congregate,
congregate, unless
unlessthethebusways
busways
totally
enclosed.
g.
locations or in
locations, unless
unless
g. In
In outdoor locations
in wet or damp
damp locations,
the
for
the busways
busways are
areapproved
approved
for the
the purpose.
purpose.
8.6.2 To
busway
To provide
provide aalow-resistance
low-resistancefault
fault return path, busway
enclosures
and bonded
bonded
enclosures should
should be securely
securely fastened
fastened in
in place and
and
with NFPA
70.
and grounded
groundedininconformance
conformance
NFPA 70.
8.6.3 Where
ground-faultcurrents
currents may be available
Where high
highground-fault
available
on large-capacity
busways
of
solidly
grounded
electrical
syslarge-capacity busways solidly groundedelectrical systems,
tem, consideration
consideration should
should be
be given
givento
to providing
providing an
an internal
internal
grounding
grounding bus
bus or,
or,if it is not
not provided,
provided,to
to installing
installing an
an exterexternally
mountedcontinuous
continuousgrounding
grounding
conductor
bonded to
to
nally mounted
conductor
bonded
each
each separate
separatesection
section of the
the busway enclosure
enclosure and
andto
to ground.
ground.
8.6.4 All boltedbusway
busway joints
be
made up and
joints should
shouldbe
made
and
torqued
in
strict
conformance
with
the
manufacturer's
torqued in strict
conformance
with
the
manufacturer's
instructions.
instructions.
8.6.5.
clearance
should be provided
around
8.6.5. Sufficient
Sufficient
clearance
should
provided
around
busways
forfor
busways to ensure
ensure efficient
efficient operation
operationand
andadequate
adequatespace
space
installing
installing and maintaining
maintainingthe
the busway fittings
fittingsand
andaccessories.
accessories.
8.6.6 Space
should be provided
Space heaters
heaters
should
provided
outdoor
in in outdoor
busways.
busways.
8.7
WIREWAYS
WIREWAYS
8.7.1
8.7.1
Usage
Usage
The
tubing(EMT)
(EMT)
should
The use ofof electrical
electrical metallic
metallictubing
should
be be
restricted
8.3.6.
restricted in accordance
accordance with
with8.3.6.
8.7.1.1 Wireways
should
used
where they are
Wirewaysshould
onlyonly
beusedbe
where
theyare
exposed
theywill
willnotnot
be subjected to
exposed and
and where
where they
be subjected
to physical
physical
damage
excessively corrosive
corrosiveconditions.
conditions.
damage or excessively
8.5.1
conduit
8.5.1 Applicable
Applicable requirements
requirements of 8.4 pertaining
pertaining to conduit
systems
to
systemsalso
alsoapply
apply
to electrical
electrical metallic
metallictubing.
tubing.
8.7.1.2 Industrial-quality
inindoor
indoor
Industrial-quality wireways
wireways may
may be used in
and
and outdoor
outdoorlocations.
locations.
Copyrighted material licensed to IDOM.
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80
80
API
PRACTICE
540
API RECOMMENDED
RECOMMENDED
PRACTICE
540
8.7.2
Construction
8.7.2
Construction
wirewaycovers
coversand
and
bodies
8.7.2.1
Minimum thickness of
of wireway
bodies
8.7.2.1 Minimum
should
dry locations,
locations,ininoutoutshouldbe
be established
establishedfor
forinstallations
installationsinindry
door
locationswhere
wherecorrosive
corrosiveconditions
conditions
door locations,
locations, and
and in locations
may
may exist.
exist.
8.8.2.4
bolts,and
and other
hardware for
8.8.2.4 Nuts,
Nuts,bolts,
other small
smalljoininghardware
for
cable
cable tray
tray systems should be
be corrosion-resistant
corrosion-resistantand
and should
should
preferably
preferablybe
be fabricated
fabricatedof
of stainless
stainlesssteeL
steel.
8.8.3
Routing
8.8.3
Routing
should be
8.8.3.1
Cable trays should
be supported
supported at all
all turns
turns and at
at
8.8.3.1 Cable
8.7.2.2
enameled
over a corrosion8.7.2.2 Generally,
Generally,anan
enameled
finishfinish
overacorrosionspacing
intervals
recommended
by
the
manufacturer.
spacing
intervals
recommended
by
the
manufacturer.
resistant
surface isisacceptable
acceptable for
resistant phosphated surface
for steel
steel wireway
wireway
construction.
For
extremely
damp
areas,
aluminum
construcexposureand
andaccessibility
accessibilityshould
should
construction. For extremely damp areas, aluminum
construc- 8.8.3.2
8.8.3.2 Cable
Cable tray exposure
be be in
in
tion
steel construction
constructionwith
withanan
enamaccordance
tion or
or hot-dip
hot-dip galvanized steel
enamaccordancewith
withNFPA
NFPA 70.
70.
eled
eled finish
finishshould
shouldbebeused.
used.
8.8.4
Cable
Arrangement
8.8.4Cable
Arrangement
8.7.2.3
wireways for
damp-area
8.7.2.3 Weatherproof
Weatherproofwireways
for outdoor
outdoor ordamp-area
use
with
bolted
covers
and gaskets.
Wrre- Wire- The
use should
shouldbebeprovided
provided
with
bolted
covers
and gaskets.
arrangementand
andnumber
number of
power, instruThe arrangement
of lighting,
lighting, power,
instmways
for
indoor,
dry
use
may
have
hinged
covers.
ways for indoor, dry use may have hinged covers.
mentation
controlcables
cables to
installed inincable
cable
trays
mentation and control
to be
be installed
trays
should
bebein
strict
accordance
with
NFPA
70.
70.
should
in
strict
accordance
with
NFPA
8.7.2.4
8.7.2.4 Wireways
Wirewaysshould
shouldnot
not contain knockouts.
8.7.3
Installation
8.7.3
Installation
Sections
Sections of
of wireways
wireways should
should be
be joined
joined together
together and supported
alignported in
in aamanner
mannerthat
thatensures
ensurescontinued
continuedrigidity
rigidityand
and
alignment
withoutsacrificing
sacrificing
of conductor
installation
or
mentwithout
easeease
ofconductor
installation
or
replacement.
.
replacement.
8~8.5
Grounding
8.8.5
Grounding
Cable
Cable trays
traysshould
shouldbe
be bonded
bonded and
and effectively
effectively grounded
grounded in
in
accordance
circuit
for
70to
to provide
providea acontinuous
continuous
circuit
for
accordance with
with NFPA
NFPA70
fault
Mllterials for
fault current·
current. Materials
for grounding
grounding should
should be compatible
with
with those
thoseused
usedfor
forthe
the tray
trayfabrication.
fabrication.
8.8
CABLE
TRAVS
8.8CABLE
TRAYS
8.9
MANHOLESAND
ANDABOVE-GRADE
ABOVE-GRADE
PULL POINTS
8.9 MANHOLES
PULL
POINTS
8.8.1
Usage
8.8.1
Usage
8.9.1
General
8.9.1
General
trays may
accordance
with
8.8.1.1
Cabletrays
may be
be installed
installedininaccordance
with
8.8.1.1 Cable
NFPA
in in
classified
and and
unclas70both
both indoors
indoorsand
andoutdoors
outdoors
classified
unclasNFPA 70
sified
regarding cable
cabletray
tray
sified locations.
locations. Additional information regarding
applications
availablefrom
from the
the Cable
Cable Tray
Tray
applicationsand
andinstallation
installationisis available
Institute.
IS
..
Institute.18
inmajor
majorunderunder8.9.1.1
Manholes should be
be installed
installed only in
8.9.1.1 Manholes
ground
ground conduit
conduitbanks
bankswhere
whereitit isis necessary
necessary to
to pull
pull or
or splice
splice
cable.
cable.The
Thepreferred
preferred location
locationfor
for these
these manholes
manholesisis in
in unclasunclassified
sifiedlocations.
locations.
8.8.1.2
cable
trays
8.8.1.2 The
The type
type of
of cabie
cable to
to be
be installed
installedinincable
trays
should
applicablerequirements
requirements
should be
be in
in conformance
conformance with applicable
of of
NFPA
70 and
and rated
ratedfor
for cable
cable tray
tray use.
use. Installations
Installations typically
typically
NFPA 70
use
TC,TC,
andand
MC
MC cable.
cable.
use multiconductor
multiconductortype
typelTC,
ITC,
. 8.8.2
Construction
8.8.2
Construction
orventilated-trough
ventilated-trough
trays
should
8.8.2.1
Open-ladderor
trays
should
be be
8.8.2.1 Open-ladder
used
used for
for cable
cabletray
traysystems.
systems.
8.8.2.2
removablecovers
coversoror
enclosures
should
8.8.2.2 Protective
Protectiveremovable
enclosures
should
be
where
the cables
may
be considered
consideredon
oncable
cabletrays
trays
where
the cables
may be
besubject
subject
to
or liquids.
to damage
damage from
fromobjects
objects
or liquids.
8.8.2.3
trays,
separators,
fittings,
and mounting
8.8.2.3 Cable
Cabletrays,
separators,
fittings,and
mounting
hardware
should
be
fabricated
of
hot-dip
galvanized
hardware should be fabricated of hot-dip galvanizedsteel
steelor
or
corrosion-resistant
alloy
aluminum
containing
not
more
thanthan
corrosion-resistant alloy aluminum containing not more
0.4%
0.4%copper.
copper. Where
Where severe
severecorrosion
corrosionconditions
conditionsexist,
exist,cable
cable
tray
systems
fabricated
of
flame-retardant
nonmetallic
tray systems fabricated of flame-retardant nonmetallic matematerials
rialsshould
shouldbe
be considered.
considered.
18Cable
%able Tray
Tray Institute,
Institute, 4101
4101Lake
Lake Boone
Boone Trail,
Trail, Suite
Suite201,
201, Raleigh,
Raleigh,
North
North Carolina
Carolina 27607.
27607.
8.9.1.2
undergroundconduits
conduits or
bankruns,
runs,
8.9.1.2 For
Forunderground
or conduit
conduitbank
above-grade
be
above-gradepull
pullpoints
pointsshould
should
be installed
installedwhere
whereitit isis necesnecessary
cables
in any
classified
location.
Abovesary totopull
pullororsplice
splice
cables
in any
classified
location.
Abovegrade
grade pull
pullpoints
pointsare
are preferred
preferred at
at locations
locationswithin
withinprocess
processor
or
other
operatingareas,
areas,regardless
regardless of
areaclassification,
classification,
other operating
of the
the area
where
necessary toto pull
pullor
or splice
spliceconductors
conductorsororcable
cablein
in
where itit isis necessary
underground
power
circuits
.
undergroundruns
runsfor
forcontrol,
control,lighting,
lighting,and
and
power
circuits.
8.9.1.3
andspacing
spacing of
above8.9.1.3 The
The location and
of manholes
manholes and abovegrade
and the
therouting
routingofofinterconnecting
interconnectingunderundergrade pull points and
ground
or
attention.
groundconduit
conduitbanks
banks
or conduits
conduitsrequire
requirecareful
careful
attention.
8.9.1.4
basic
criterion for
8.9.1.4 The
Thebasic
criterion
for achieving
achieving the
the maximum
maximum
spacing
of
manholes
or
above-grade
pull
points
spacing of manholes or above-gradepullpointsis is not
not to
to
exceed
the
maximum
cableor
wire-pulling
tensions
exceed the maximumcable- or wire-pullingtensions and
and
sidewall
Thesemaximum
maximumtensions
tensionsand
and
pressures
sidewall pressures. These
pressures
are
contingent
on
the
following:
are contingent on the following:
a.
a. Conductor
Conductor material.
material.
b.
Size
b. Sizeof
of the
thecable
cableor
or wire.
wire.
c.
a single
conduit.
or wires
wiresinstalled
installedinin
a single
conduit.
c. Number of
of cables
cablesor
d.
sheath.
d. TYpe
Typeof
ofinsulation,
insulation,shielding,
shielding,and
and
sheath.
e.e. Size
Sizeand
andtype
type of
of conduit.
conduit.
f.f. Number
and
radius
Number and radiusof
of bends.
bends.
Copyrighted material licensed to IDOM.
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONS IN PETROLEUM
PETROLEUM PROCESSING
PROCESSING PLANTS
PLANTS
g. Quality of
bank
alignment.
of the
theconduit
conduitand
andduct
duct
bank
alignment.
Lubrication for
h. Lubrication
for pulling
pullingpurposes.
purposes.
8.9.1.5 Calculations
substantiating
the proposed
Calculationssubstantiating
theproposed
under- undergrounddesign
design
medium-voltage
and high-voltage
forfor
largelarge
medium-voltage
andhigh-voltage
cablesystems
systems
should be prepared.
prepared. The calculations
and
should
calculationsand
installation
shouldbebe
in accordance
installationshould
inaccordance
with with IEEE 576. The
cablemanufacturer’s
recommended
cablepulling
cable
manufacturer's
recommended
cable factors
pulling factors
should
should be included
included with
withthe
thecalculations.
calculations.
8.9.1.6 The underground
underground system
not require
system should not
require spedesigned equipment
equipment or generally
generally unavailable sizes
sizes of
cially designed
accessory
accessory equipment
equipment for pulling
pulling or installing
installing cables without
damage.
damage.
8.9.1.7
be per8.9.1-7 For circuit
circuitidentification,
identification,conductors
conductorsshould
should
manently
points
housing
mUltiple
circuits.
manently tagged
taggedatatpull
pull
points
housing
multiple
circuits.
8.9.2
Manholes
Manholes
8.9.2.1
Manholes should
shouldbe installed
installed in
inor along
along roadways;
roadways;
8.9.2.1 Manholes
installation of manholes
manholes in
in manufacturing
manufacturingareas
areasand
andininareas
areas
installation
having high
highwater
water tables
andmanholes
manholes
tables should
should be avoided;
avoided; and
should not be installed
locations.
installedininclassified
classified
locations.
8.9.2.2
8.9.2.2 Manholes
Manholes should
should have established
established minimum
minimum inside
inside
dimensions.
dimensions.
8.9.2.3
sizing
manholes,
consideration
8.9.2.3 When
Whensizing
manholes,
consideration
shouldshould be
given to the following
followingfactors:
factors:
a.
a. Wall space required
requiredfor making up
up splices.
splices.
distance of straight sections
for supporting
supporting splices
splices
b. Linear distance
sections for
and cables.
cables.
c. Space
Space required for bending and
and training
trainingcables
cablesfor offsets
offsets
and differences
in horizontal
differences ininduct
ductelevations,
elevations,and
andchanges
changes
horizontal
direction.
direction.
wall space
space required for
forracking
rackingcable
cable
splices.
d. Vertical wall
andand
splices.
e. Working
Working area
arearequired
requiredfor cable pulling
pullingand
andsplicing.
splicing.
f.
Number of ducts
f. Number
ducts entering
entering manholes
manholesand their elevation.
elevation.
8.9.2.4
should have
established,
minimum
8.9.2.4 Manholes
Manholesshould
haveanan
established,
minimum
covers and roof construction
construction
diameter top opening,
opening, and
and the covers
should be
be designed
designed for the expected
expected surface
surface loading.
loading.Where
Where
feasible,
feasible, the elevation
elevation of
of the top opening
opening should
shouldbe sufficient
sufficient
to minimize
minimize the
theentry
entryof surface
surface water.
I
~
81
81
floor
towardthe
the sump.
should
floor should be sloped toward
sump. Manholes
Manholes should
also
also be
beprovided
providedwith pulling irons,
irons,cable racks,
racks, and
andladders.
ladders.
Pull Points
Points
8.9.3Above-Grade
Above-Grade Pull
practicable, pull pointsforunderground
for underground
8.9.3.1 Where
Wherepracticable,
conduit runs
runsshould
shouldbebe
grouped
installed in protected
grouped
andand
installed
areas,
such as
pipewaycolumns
columns or similar structural
structural
as along pipeway
areas, such
supports.
points
are are
exposed
supports. Where
Wherepull
pull
points
exposed
to damage
damage by mobile
equipment,
should be protected by concrete-filled
concrete-filledsteel
steel
equipment, they should
stanchionsset
setin concrete.
concrete.
pipe stanchions
Wire and cable
cable pull points
points should
shouldnot
notbe installed at locaaccess, maintenance,
maintenance,and
andother operations.
operations. Pull
Pull
tions used for access,
and junction boxes
should
be installed
only at locations
boxesshould
beinstalled
onlyatlocations
accessible.
where they
theywill
willbebepermanently
permanently
accessible.
8.9.3.2 Generally,
Generally, aaseparate
separatepull box
box fitting
fitting should
should be promotor supply
supplycircuit.
circuit. Where
the
vided for each motor
Where applicable,
applicable, the
andassociated
associatedcontrol
controlleads
leads
a low-voltage
motor
power and
of aoflow-voltage
motor
may use
use a common
commonbox
boxor fitting.
fitting.
8.9.3.3 Whereseparate
separate
pull boxes are notpracticable,
practicable,
pullboxes
multi-purpose pull
pullboxes
boxes may be used
usedprovided
provided
multi-purpose
thatthat
they they
forfor
different
services.
have the
themeans
means for isolating
isolatingconductors
conductors
different
services.
8.9.3.4 Pull points should consist
consist of approved
metal
approved sheet metal
boxes or castmetal
metal
boxes
and fittings.
Nonmetallic
pullboxes
boxes
andfittings.
Nonmetallic
whereapproved
approved
the purpose,
an acceptable
boxes,where
forfor
thepurpose,
areanare
acceptable
alternative
corrosive
locations.
alternative ininhighly
highly
corrosive
locations.
Minimum thickness of
should
Minimum
ofsheet
sheetmetal
metalpull
pullboxes
boxes
should be
established. The minimum
minimum thickness
thicknesswill
willdepend on whether
whether
established.
the boxes
boxes are
are installed
installedinindry
drylocations,
locations,outdoor
outdoor locations,
locations, or
locations
exist.
locations where
wherecorrosive
corrosiveconditions
conditions
exist. The thickness
thickness will
will
further
material
further depend
dependononthethe
material
used for the fabrication
fabrication (either
(either
aluminum
heavier sheet-metal
sheet-metalrequirerequirealuminum or steel)
steel) and on the heavier
ment necessary
in large
boxes.
necessaryforforrigidity
rigidity
in large
boxes.
Sheet
steelboxes
boxes for outdoor
andcontinuously
continuously
Sheet steel
outdoor locations and
damp indoor
should
havehave
a hot-dip
galvanized
finish. finish.
indoorlocations
locations
should
a hot-dip
galvanized
Gasketed cover joints should
should be provided; joints that are
Gasketed
shielded
water
flowing
directly
shielded from
fromrain
rainand
and
water
flowing
directly across
across them are
preferred.
preferred.
8.9.3.5
andfittings
fittings
used as pull points
points for under8.9.3.5 Boxes and
used
underground conduit runs should be supported by steel
steel members
set in concrete.
concrete.
8.9.2.5.
shouldhave
haveprovisions
provisions for the installainstalla8.9.2.5 Manholes
Manholes should
tion
of anticipated
anticipated future
future conduits.
conduits.
tion of
AND
CABLE
8.10WIRE
WIRE
AND
CABLE
facilitate future
future cable
cableinstallations,
8.9.2.6 To facilitate
installations, the initial
cable routing
manholes should
routing in ducts
ducts and manholes
should reflect
reflect the
the need
need
for good
good access
accessto spare
spare and
andproposed
proposedducts.
ducts.
8.10.1.1
selection of the wire
wire and
and cable
cable to be installed
8.1 0.1.I The selection
should
should be based on the following:
following:
8.9.2.7 Usingprecast
manholes
mayprovide
significant
8.9.2.7
precast
manholes
may provide
significant
savings.
cost savings.
8.9.2.8 Manholes
preferaManholes should
should be provided with
with sumps,
sumps, preferably located in
in one comer
corner of the manhole; and the manhole
manhole
8.10.1
General
General
a. Conductor
Conductor material.
material.
b. Voltage
grounding
Voltagelevel
leveland
and
grounding of the system in which the
the
andcable will be
beapplied.
applied.
wire and
c. Atmospheric
Atmospheric conditions,
andand
type of
of
conditions,ambient
ambienttemperature,
temperature,
physical
exposure.
physical exposure.
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
82
82
l
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
d.
d. Availability of
of the
the wire
wire and
and cable.
cable.
Electrical Code
e.
NFPA
e. NFPA 70
70 National
National
Electrical
Code requirements.
requirements.
f.f. Available
Availabletypes
typesofofcable
cableterminators.
terminators.
g.
g. Method
Method of installation.
installation.
h.
h. Quality
Quality and
and degree
degree of importance
importanceof service.
service.
i.i. Classification
wire
and
cable
willwill
Classificationof
ofthe
thearea
areaininwhich
whichthethe
wire
and
cable
be
be installed.
installed.
j.j. Type
used.
Type of
of wiring
wiring method
methodtotobebe
used.
k.
Possibility
of
exposure
to
chemicals
k. Possibility of exposure to chemicals that
that may be harmful
harmful
to
materials
used
in
a
particular
cable
construction.
to materials used a particularcable construction.
1.1. Materials
handling and
anddisposal
disposal
Materials that may require
require special handling
due
due to
to environmental
environmentalregulations.
regulations.
8.10.1.2
8.1 0.1.2 The
The construction
construction and
and testing
testing of rubberrubber- and
and thermoplastic-insulated
wire and
comply
moplastic-insulatedwire
and cable
cable should
shouldcomply
withwith
NEMA
and we
WC5,
5, respectively.
respectively.
NEMA we
WC 33 and
8.10.1.3 The
The construction
constructionand
andtesting
testingof
of cross-linked
cross-linkedpolypolyethylene-insulated
wire and cable
comply
ethylene-insulated
wire
cable should
should
comply
with with
NEMA
..
NEMA we
WC 77 and
andABle
AEICess
CS5.
8.10.1.4 The
constructionand
and
testing of ethylene-propyTheconstruction
testing
ethylene-propylene-rubber-insulated
wire and cable
comply
lene-rubber-insulatedwire
cable should
shouldcomply
withwith
NEMA
and ABIC
AEIC eS6.
CS6.
NEMA we
WC 88 and
8.10.1.5 The
construction and
Theconstruction
and testing
testing of impregnatedimpregnatedpaper-insulated,
paper-insulated, lead-covered
lead-coveredcable,
cable, solid
solid type,
type, should
should be
be in
in
accordance
CS 1.
1.
accordancewith
withABle
AEIC
CS
8.10.1.6 Generally,
copperconductor
conductorshould
should be used for
Generally,copper
for
all
low-voltage wiring
mecIium- and
and
all low-voltage
wiring and
and is
is preferred for all medium. high-voltage
Aluminum conductors
conductors may
maybe
beconsidconsidhigh-voltage wiring.
wiring. Aluminum
ered
high-voltage distribution
distributionfeeders
feedersthat
that
ered for
for mediummedium- and high-voltage
are
terminatedwith
withcompression
compression
connectors and in encloencloare terminated
connectors
sures
sures specifically
specifically approved
approvedforforthe
the purpose.
purpose.
8.10.2
8.10.2 Conductors
Conductors
minimum
conductor
8.10.2.1
8.10.2.1 The
Theminimum
conductor
size size for
for 120-Y,
120-V, 1201
120/
208Y-V, and
1201240V
lighting
and
receptacle
circuits
and 120/240-V lighting receptacle circuitsshould
should
be 4-mm
copper.
[No. 12
12American
American WIre
WireGauge
Gauge(AWG)]
(AWG)]
copper.
4 - m 22 [No.
Note:
The metric
sizesshown
shown in these
paragraphsare
aretrade
trade
Note:The
metric wire sizes
these paragraphs
AWG
sizes
sizes and
and are
are not mathematical
mathematicalequivalents
equivalentstotothethe
AWG sizes.
sizes.
8.10.2.2
8.1 0.2.2 The
The minimum
minimum conductor
conductor size
size for
for single-.
single- or
or mulmul2
tiple-conductor
tiple-conductor general
general control
control wiring
wiring should
should be 2.5-mm
2.5-mm2
(No.
(No.14
14AWG)
AWG) copper.
copper. The
Theminimum
minimum conductor
conductorsize
size in
in mulmulticonductor
ticonductor cables
cables for
for low-energy
low-energy control
control wiring
wiring should
should be
be
2
1.5-mm
(No.
16
AWG)
stranded
copper.
Voltage
drop
and
1.5-mm2 (No. 16 AWG) stranded copper. Voltage drop and
pulling
selecting the
pulling stresses
stresses should
should be considered
considered when
whenselecting
the
conductor
size.
conductor size.
8.10.2.3 For supervisory
supervisory control
control wiring,
wiring, the conductor
conductor
should
be
sized
to
meet
the
requirements
should be sized meet the requirements of the
the connected
connected
equipment
in accordance
accordance with
with the
the manufacturer's
manufacturer's recequipment and
and in
ommendations.
ommendations.
8.10.2.4 The
conductor size
The mmlmum
minimumconductor
size for
for low-voltage
low-voltage
2 (No.
power
power wiring
wiringshould
shouldbe4-mm
be 4-mm2
(No. 12
12AWG)
AWG) copper.
copper.
8.10.2.5 For
andhigh-voltage
high-voltage cable,
miniFor mediummedium-and
cable, the
themini2 (No.6
mum
mum conductor
conductorsize
size should
should be
be16-mm
16-mm2
(No. 6 AWG)
AWG) copper·
copper
2 (No.4 AWG) aluminum.
or
or 25cmm
25-mm2
(No. 4 AWG) aluminum.
8.10.2.6
8.1 0.2.6 Depending
Depending on
on the
the interrupting
interruptingtime
time of
of the
thecircuitcircuitbe
capable
of
protective
devices;
wire
and
cable
should
withprotective devices; wire and
cable should be capable of withstanding
availableshort-circuit
short-circuit
current
without
standing the.
the system
systemavailable
current
without
suffering
sufferingdamage.
damage.
8.10.2.7 Stranded
faciliStranded conductors are
are generally
generally used
used to
to facilitate
vibration
damage.
Solid
tate installation
installation and
andresist
resist
vibration
damage.
Solid conductors
conductors
may
may be
be used
used for
for wiring
wiringitems
itemssuch
suchas
as general-purpose
general-purpose recepreceptacles
and
lighting
circuits.
tacles and lighting circuits.
8.10.3
8.1 0.3 Insulation
Insulation
8.10.3.1
8.1 0.3.1 The
The following
following types
types of insulation
insulation forlow-voltage
for low-voltage
wire
wire and
andcable
cable are
are commonly
commonly used
usedininpetroleum
petroleumfacilities:
facilities:
a.
THW, THWN,
a. Thermoplastic
Thermoplastic (NFPA
(NFPA 70,
70, Types
TypesTHW,
THWN, and
and
THHN)
at
75°C
conductor
temperature.
THHN) at75OC conductor temperature.
Note:
not recommended
recommended for
foruse
useon
on DC
DC
Note: Thermoplastic
Thermoplastic insulation
insulation is not
circuits
310-13
circuitsin wet
wet locations.
locations.See
SeeNFPA
NFPA 70,
70,3
10-13for
for more
more information.
information.
b.
b. Ethylene-propylene-rubber
Ethylene-propylene-rubber (NFPA
(NFPA 70,
70, RHW
RHW at
at 75°C
75°C
conductor
conductor temperature
temperature and
and RHW-2
RHW-2 at
at 90°C
90°C conductor
conductor
temperature).
temperature).
c.
Cross-linked
polyethylene
(NFPA 70,
70, Type
Type XHHW
XHHW at
at
c.Cross-linked
polyethylene
(NFPA
75°C
XHHW-2
75°C conductor
conductor temperature
temperatureandand
XHHW-2 at
at 90°C
90°C conductor
conductor
temperatw'e
).
temperature).
8.10.3.1.1 The
usedinsulation
insulation is
The commonly
commonlyused
is the
the thermothermo2 (No.
setting
setting type
typeon
on larger
larger conductors
conductors(l6-mm
(1
6-mm2
(No. 66AWG)
AWG) copcop2
per or
25-mm
(No.
4
AWG)
aluminum)
and
above.
or 25-mm2 (No. 4 AWG) aluminum)andabove.
usedonon
Thermoplastic
typeinsulation
insulation is
Thermoplastic type
is more
more commonly
commonly used
smaller
smallerconductor
conductorsizes.
sizes.
8.10.3.1.2
8.1 0.3.12 For single
single conductors
conductors installed
installedininconduit
conduit addiadditional
tional insulation
insulationor jackets
jackets should
should be considered
considered such
suchas
as used
on
on RHW
RHW and
and RHW-2.
RHW-2.
8.10.3.2 The
insulation for
The following
following types
types ofinsulation
for mediummediumvoltage
voltage wire
wireand
andcable
cable (5
(5 kV,
kv, 15
15kV,
kv, and
and 35
35 kV
k v and
and 90°C
90°C and
and
in
petro10SoC
conductor
temperature)
are
commonly
used
105°C conductor temperature) are commonly used in petroleum
leum processing
processing plants:
plants:
a.
a. Paper-insulated
Paper-insulatedlead-covered.
lead-covered.
b. Ethylene-propylene-rubber
MV-90 or
Ethylene-propylene-rubber(NFPA
(NFPA 70,
70, Type
TypeMV-90
or
MV-I05).
MV-105).
c.
Cross-linked polyethylene
(NFFA 70,
70,Type
Type MV-90).
MV-90).
c. Cross-linked
polyethylene(NFPA
Note:
of insulations
insulations should
should
Note: The
The effect
effect of treeing
treeing on
on different
different types of
be
be considered.
considered.
Copyrighted material licensed to IDOM.
STD.API/PETRO RP 540-ENGL
11999 or distribution
I0732290
No further reproduction
permitted. Oh1rShL9.. 4-39-m
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ELECTRICAL
INSTALLATIONS
IN
PROCESSING
ELECTRICAL
INSTALLATIONS
IN PETROLEUM
PETROLEUM
P R O C E S ~ ~ NPLANTS
PLANTS
G
8.10.4
Shielding
Shielding
8.10.7
shieldingshould
should be considered
8.10.4.1 Insulation
Insulationshielding
considered for
for all
solid-dielectricinsulated
to to be operated
operatedabove
above
solid-dielectric
insulatedconductors
conductors
Shielding should
should also
also be considered
considered when
when in prox2,000 V. Shielding
imity to high-voltage
high-voltage installations.
installations.
8.10.7.1
General
8.10.7.1
General
8.10.4.2 Solid
dielectric
insulated
cable
to be operated
Soliddielectric
insulated
cableto
beoperated
above 2,000 V requires
requiresinsulation
however,
above
insulationshieldmg;
shielding;
however, by
exception,
V-8,000
2,001 V-8,000
exception, nonshielded
nonshieldedcable
cablewith a rating
rating of 2,001
applied, provided
providedinsulation
insulation and jacket requireV may be applied,
ments conform
70.
ments
conformto NFPA 70.
8.10.4.3
several,
recognized
cable shielding
8.10.4.3 There
There areseveral,
recognized
cableshielding
methods available
methods
available in standard
standard cable
cable construction.
construction. The availavailable
current
and and
fault fault
clearing
time oftime
the system
able ground
groundfault
fault
current
clearing
system
in which
shouldbe taken into considerconsiderwhichcable is to be installed should
ation
ation when selecting
selecting the insulation
insulation shielding.
shelding.
8.10.5
8.10.5 Armor
8.1 0.5.1 Certain
Certain cable
cable constructions
constructions employ
employ armor
armorjacket8.10.5.1
ing above
applied,
several
typestypes
of conconabovethe
theinsulation.
insulation.When
When
applied,
several
struction
available.
struction and
andmaterials
materialsareare
available.
~. .
8.10.5.2 Cable
Cable armorshould
normally
be be of acorrosion8.10.5.2
should
normally
con'osionresistant
resistant metal
metalor hot-dipped galvanized
galvanizedsteel.
steel.
8.10.6Jacket
8.10.6
Jacket
Armored cable that will
installed underground
will be installed
underground
8.10.6.1 Armored
corrosive or outdoor locations
locationsshould
shouldbe provided with
with
or in corrosive
to protect
protect the
thearmor
armor from
jacketing over the armor to
from damage
damage
deterioration.
and deterioration.
8.10.6.2
cable
with
a rating of 600 V thatisis
8.10.6.2 Armored
Armoredcable
with
arating
installed in wet locations
locations should
shouldhave
haveananoverall
overall
jacket under
installed
the armor,
is impervious
armor, unless
unlessthe
thearmor
armor
impervious to liquids.
liquids.
8.10.6.3 Armored cable with a rating
ratingabove
above 600
600 V should
armor, unless
have an overall
overall jacket under the armor,
unless the armor is
liquids.
impervious to liquids.
impervious
:
I
I
~
8.10.6.4
8.1 0.6.4 Cables
Cables rated at 5,001
5,001 V-8,OOOV
V-8,000 V that do not have
insulation
metallic sheaths,
insulation shielding,
shielding, metallic
sheaths, or armor should have
single
single conductors
conductors with jackets resistant to ozone,
ozone, electric
electric
discharge, and surlace
surface tracking
tracking and shall
shall conform
conform to NFPA
discharge,
70. These jackets for multiconductor
multiconductor cables should be common coverings
over
the
assembled
coverings
assembled single-conductor
single-conductorcables.
cables.
8.10.6.5 Outer jackets on cables
cables that are exposed
exposed outdoors must
be sunlight-resistant.
sunlight-resistant. The
The selection
selection between
doors
muSt be
between aa
thermosetting
jacket
and
a
thermoplastic
jacket
should be
thermosetting jacket and a thermoplastic jacket should
be
basedonon the environment
environment inwhich
which the cable will be
installed.
installed.
83
InstallationRequirements
Installation
Requirements
wire
and
cable installations
shall be in
8.10.7.1.1
8.10.7.1.1 Allwire
andcable
installations
shall
accordance
withthethe
requirements
local
accordancewith
requirements
of of NFPA 70 andlocal
codes
codes and regulations.
regulations. Details
Detailson proper installation,
installation,splicing,
splicing,
and testing
testingare provided in IEEE 576.
8.10.7.1.2
8.1 0.7.1.2 The radii of
of cable bends should
shouldequal
equalor exceed
manufacturer. For rubthe minimum values specified by the manufacturer.
rubber,
thermoplastic, cross-linked
cross-linked polyethylene,
polyethylene, and
andethyleneethyleneber, thermoplastic,
propylene-rubber insulated
propylene-rubber
insulatedcable,
cable, the minimum
minimumbending
bendingradii
radii
specified
in
WC 3, WC 5,
5, WC 7, and WC 8 and in
specified in NEMA we
usedwhen
when the manufacturer's
not
NFPA 70 may be used
manufacturer’s data is not
available.
available.
8.10.7.1.3 Wireand
and
sidewall
8.10.7.1.3
and cable pulling
pullingtensions
tensions
and
sidewall
pressures should not
maximum values specified
pressures
not exceed
exceed the maximum
specified
manufacturer. The manufacturer's
manufacturer’s limitations
limitationson
onpullpullby the manufacturer.
ingcable
cable at low ambienttemperatures
temperatures
should
also
be
shouldalsobe
enforced.
enforced.
8.10.7.1.4
satisfactorymediummedium-and
and
high-volt8.1 0.7.1.4 To obtain satisfactory
high-voltage
cable splices
following prerequiprerequiage cable
splices and tenninations,
teminations, the following
sites
sites should
shouldbe met:
met:
a. All work should
should be done by qualified
qualified personnel.
personnel.
a.
b. Only
Only the highest quality
used.
quality materials
materialsshould
shouldbebe
used.
c. The manufacturer’s
manufacturer's instructions
instructionsshould be
befollowed.
followed.
d.Provisions
Provisionsshould
should be taken to preventthe
theintrusion
intrusion of
moisture.
moisture.
e. Cleanliness
Cleanliness of tools,
e.
tools, materials,
materials,work
workspace,
space,and
andsplicer’s
splicer's
clothing
clothing should
shouldbe maintained.
maintained.
f. Splices
Splices and
and terminations
terminations should
should be made only at ambient
ambient
temperatures
temperatures above
abovethe minimum temperature
temperaturerecommended
recommended
by the manufacturer
manufacturerfor handling
handling the
thenecessary
necessarymaterials.
materials.
g.
splicesand
andterminations
terminationsshould
should
made
g. All permanent
permanent splices
be be
made
with compression
compressionconnectors.
connectors.
8.10.7.1.5
wire and
and cable
cable
8.1 0.7.1.5 Taps and splices
splices of low-voltage wire
should conform
conformwith
withthe following
following specific
specificrequirements:
requirements:
should
a. Wire
WIre connectors
connectors consisting
consistingof insulator
insulator caps
capsand springs
springs or
set-screw inserts
andand
splices
in lightlightinserts may be used only
onlyforfortaps
taps
splices
ing and convenience-receptacle
branch-circuit
wiring.
These
convenience-receptacle branch-circuit wiring. These
connectors
to prevent the entry
connectors should
shouldbebetaped
taped
entryof moisture.
moisture.
b. Pigtail-type
Pigtail-type taps and splices
splices should
should be made only above
above
grade
grade in appropriate
appropriate boxes or conduit fittings
fittings that are
accessible.
accessible.
c.Where
Where practical,
conductorsshould
should
be installed
practical, powerconductors
beinstalled
without
terminating
points.
Where
splicessplices
are
without splices
splicesbetween
between
terminating
points.
Where
are
unavoidable,
splicesusing
using
two-way
comunavoidable, straight
straight (in-line)
(in-line)splices
two-way
comare preferred;
however, where
whereenclosure
enclosure
pression connectors
preferred; however,
connectors are
splices
size limitations
limitations prohibit
prohibitabovegrade
abovegradestraight
straightsplices,
splices, splices
using bolted
boltedconnectors
connectors are usually acceptable.
acceptable.
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~
84
84
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
d.d. Splices
conductorsshould
should be
in an
an
Splicesof
of power
power conductors
be made
made only
only in
approved
manner.
approved manner.
e.e. Where
conductors
areare
to
Wheremore
morethan·two
than twocontrol
control
conductors
tobe
bejoined,
joined,
the
connection should
shouldnormally
normally be
only atat terminal
theconnection
be made
madeonly
terminal
boards
preferably
located
on equipment
or
boardsthat
thatar~are
preferably
located
on equipment
orpanels.
panels.All
All
connections
so
connectionsshould
shouldbe
be accessible
accessibleand
andshould
shouldbebeidentified
identified
so
that
thatindividual
individualconductors
conductorsmay
maybe
bechecked.
checked.
8.10.7.2
8.10.7.2 Wire
Wireand
andCable
Cablein
inRaceway
RacewaySystems
Systems
In
raceway systems,
systems,the
thefollowing
followingrequirements
requirements
In raceway
forfor wire
wire
and
cable
should
be
fulfilled:
and cable should be fulfilled:
a.a. The
conduit
and
Themaximum
maximumallowable
allowablepercentage
percentagethat
that
conduit
andtubtubing
may
be
filled
by
wire
and
cable
shall
be
as
specified
ing may be filled by wire and cable shall be as specifiedin
in
NFPA
70.
NFPA70.
b.b. MediumMedium-and
andhigh-voltage
high-voltagecables
cablesininmanholes,
manholes,cableways,
cableways,
8.10.7.1.6
Where
conductors
for
control
wiring
and
instrupull
boxes,
trays,
and
splice
boxes
should
ifif
8.10.7.1.6 Where conductorsfor control wiring and instrupull boxes, trays, andsplice boxes shouldbebeflameproofed
flameproofed
mentation
power
supply
wiring
are
to
be
connected
to
bindthere
is
a
possibility
that
a
cable
failure
may
damage
other
mentation power supply wiringare to be connected to bindthere is a possibility that cable failure may damage other
ing-screw
thethe
conductors
should
cables.
ing-screwtenninal
terminalboards,
boards,
conductors
shouldbe
beprovided
provided
cables.
with
c.c. Cables
manholes;pull
pull boxes,
withpressure
pressureterminals.
terminals.
Cables and
and splices
splices in
inmanholes;
boxes, and
and splice
splice
boxes
should
be arranged and
visual
boxesshould
bearranged
and supported
supported to
to allow
allowvisual
8.10.7.1.7
circuits
8.10.7.1.7 Circuit
Circuit separation
separation for
for different
differentcircuits
and and
inspection,
inspection,and
and to
to prevent
prevent excessive
excessivetension
tensionand
andpressure
pressureon
on
classes
with
thethe
foHowing
specific
classesof
ofservice
serviceshould
shouldconform
conform
with
following
specific the
thecable
cablesheath
sheathand
andinsulation.
insulation.
requirements:
requirements:
d.d. The
Theseparation
separationof
ofphase
phaseconductors
conductorsin
inindividual
individualducts
ductsand
and
conduits
should
be
avoided.
conduks
should
be
avoided.
a.a. Where
is used
Wheresingle-conductor
single-conductorwiring
wiring
used
is for
forsupply
supplyand
andconcone.e. Control
manholes
should
be fiameproofed,
and
Controlcable
cablein in
manholes
should
be flameproofed,
andprepre-.
trol
motor,
all conductors
may
trolofofa low-voltage
a low-voltage
motor,
all conductors
maybe
beinstalled
installedin in
cautions
should
be
taken
to
minimize
inductive
voltage
effects.
2
be
taken
to
minimize
inductive
voltage
effects.
cautions
should
the
supply
conductors
thesame
sameconduit,
conduit,provided
providedthethe
supply
conductorsare
are25
25mm
mm2
(No.4
AWG)
or
smaller.
Unless
special
multiple-conductor
(No. 4 AWG) or smaller. Unless special multiple-conductor
8.10.7.3
Metal-Clad
and
Metal-Sheathed
Cable
8.10.7.3Metal-Clad
and
Metal-Sheathed
Cable
cable
used
for
cableisisused,
used,separate
separateconduits
conduitsshould
shouldbebe
used
forthe
thesupply
supply
Systems
Systems
and
when
andcontrol
controlconductors
conductors
whenthe
thesupply
supplyconductors
conductorsare
arelarger
larger
2.
than
25mm
Specific
for for
the
than 25 mm2.
Specificrequirements
requirements
theinstallation
installationof
ofapproved
approvedmetalmetalclad
above
grade
b.b. Single-conductor
asfollows:
follows:
,,.
cladand
andmetal-sheathed
metal-sheathedcablesabove
grade
areare as
Single-conductorwiring
wiringfor
formore
more than
than one
onemotor
motorshould
should
not
be
installed
in
a
common
raceway.
Separate
multiple-connot be installed in a common raceway.
Separate multiple-cona.a. Metal-clad cables
cables specifically
specificallyapproved
approvedas
as type
type HL
HL may
may
ductor
ductorcables
cablesfor
foreach
eachmotor
motormay
may be
be installed
installedininaacommon
common
be
installed
in
Class
I,
Division
1
as
well
as
Division
locabe installed in Class I, Division 1 as well as Division22 locaraceway,
raceway,subject
subjecttotoengineering
engineeringapproval.
approval.
tions
must
be
tionsand
andnonclassified
nonclassifiedareas.
areas.Cables
Cables
must
betenninated
terminatedwith
with
c.'
c.' For
For each
each motor
motor operating
operating above
above 600
600 V,
V, the
the motor
motor supply
supply
fittings
(terminations
or
glands)
approved
fittings(terminations
or glands)approved for
for the
the .area
area
and
shall
be installed
in
andcontrol
controlconductors
conductors
shall
be installed
inseparate
separateraceways.
raceways.
classification.
classification.
d.d. Conductors
may
b.b. Cables
Conductorsfor
forone
one or
or more
more lighting
lighting branch
branch circuits may
600 VV should
should be
be installed
installed inin cable
cable
Cables rated
rated above
above 600
be
or tubing.
trays.
berun
runin
incommon
commonconduit
conduit
or tubing.
trays.
c.c.When
When
planning cable·
consideration
should
e.e. Power
system control,
instrument, alarm,
alarm, and
planning
cable routes,
routes,consideration
should
be be
Powersystem
control, metering,
metering,instrument,
and
given
to
the
possibility
of
interference
with
piping
and
other
to
the
possibility
of
interference
with
piping
and
other
given
relaying
circuits
associated
with
a
particular
piece
of
electrirelaying circuits associated with a particular
piece of electriequipment,
and
to
the
possibility
of
cable
damage
that
may
equipment,
and
to
the
possibility
of
cable
damage
that
may
cal
equipment,
such
as
a
transformer
or
motor,
may
be
routed
cal equipment, suchas a transformeror motor, may berouted
occur
through
normal
facility
operations
such
as
traffic.
mainoccur
through
normal
facility
operations
such
as
traffic,
mainin
a
common
raceway
or
cable,
provided
that
all
of
the
conin a common raceway or cable, provided that all of the contenance,
of corrosive
materials.
tenance,and
andrelease
release
of corrosive
materials.
ductors
ductorshave
havean
aninsulation
insulationvoltage
voltagerating
ratingequal
equalto
tothe
thehighest
highest
d.
Cables
should
be
run
between
terniinating
pointsinin one
d.
Cables
should
be
run
terminating
points
one
system
noise
interference
systemvoltage
voltagelevel,
level,and
andthat
that
noise
interferencebetween
betweencircircontinuous
length
wherever
practicable.
Where
splices
cannot
continuous
length
wherever
practicable.
Where
splices
cannot
cuits
a problem.
cuitswill
willnot
notbebe
a problem.
be
avoided, they
should
be
enclosed in
accessible
splice
be
avoided,
they
should
be
enclosed
in
accessible
splice
f.f. Generally,
Generally,substation
substationcontrol
controlcircuits
circuitsassociated
associatedwith
withaasinsinboxes
boxesor
orfittings.
fittings.
gle
power
source
may
be
routed
in
a
common
raceway
gle power source may be routed in a common raceway or
or
e.e. A
minimum
separation
A
minimum
separation between power cables
cables and
and comcomcable.
cable.Station
Stationcontrol
controlcircuits
circuitsassociated
associatedwith
withprimary-selecprimary-selecmunication·and
instrumentation
cables
should
be
established
munication and instrumentationcables should be established
tive,
secondary-selective, or
substationsthat
that
tive,secondary-selective,
or spot-network
spot-networksubstations
and
for
..
andmaintained
maintained
forall
allcable
cableruns
runs(see
(see8.3,8)
8.3.8).
have
havealternate
alternatepower
powersources
sourcesshould
shouldbe
be separated
separatedaccording
according
f.f. A
minimum
spacing
should
be
maintained
A minimum spacing should be maintainedbetween
betweencables
cables
to
ItItisis also
totheir
theirrelated
relatedpower
powersource.
source.
alsopreferable
preferablethat
thatdifferdifferand
high-temperature
surfaces.
Where
necessary
to
route
and
high-temperature
surfaces.
Where
necessary
to
route
ential
entialrelay
relaycircuits
circuitsbe
bekept
keptseparate
separatefrom
fromthe
theother
othercircuits.
circuits.
cables
thermal
bar-barcablesclose
closeto
tosuch
suchsurfaces,
surfaces,a ahigh-reflectance
high-reflectance
thermal
g.g. Normally,
telephone
circuits
should
be
routed
in
Normally, telephone circuits should be routed in separate
separate
rier
should
be
installed
between
the
cables
and
the
surface.
rier should be installed between
the cables andthe surface.
raceways.
engineering
approval,
telephone
and sigraceways.Subject
Subjecttoto
engineering
approval,
telephone
and
sig- .
g.g. Where
outdoor
boxes
andand
Wherepracticable,
practicable,cables
cablesshould
shouldenter
enter
outdoor
boxes
nal
65
nalcircuits
circuitsoperating
operatingbelow
below
65VV may
may be
berouted
routedininthe
thesame
same
equipment
enclosures
from
the
bottom
or
the
sides
to
prevent
equipment enclosures from the bottom
or the sides to prevent
raceway
racewayor
orcable
cablesupport
support.
the
Cables
theentrance
entranceof
ofwater
waterinto
intothe
theenclosures.
enclosures.
Cablesentering
enteringoutouth.h. Special
caution
should
be
taken
to
ensure
that
the
operatdoor
boxes
or
enclosures
from
the
top
should
be
Special caution should be taken to ensure that the operatprovided
door boxes or enclosures from the top should be provided
ing
temperature of
terminating
devices,
with
designed
to
ingtemperature
of the
the cables,
cables,terminating
devices,
and and
withtel1l1inators
terminatorsspecifically
specifically
designed
toprevent
preventthe
theentrance
entrance
tel1l1inations
be
consistent.
of
ofwater.
water.
terminations be consistent.
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
INSTALLATIONSIN
INPETROLEUM
PETROLEUM PROCESSING
PROCESSINGPLANTS
PLANTS
85
85
h.
approval,
h. Subject
Subjecttotoengineering
engineering
approval,cables
cablesmay
may be
beinstalled
installedin
in
Class
ClassI,I,Division
Division22locations.
locations.
8.11.1.2
operatorsand
and junction
8.11.1.2 For
For motor operators
junction boxes
boxes the
the folfollowing
lowingmethods
methodsare
arecommonly
commonlyused:
used:
8.11
FIREPROOFING
8.11FIREPROOFING
a.a.
b.b.
c.c.
8.11.1
General
8.11.1General
8.11.1.1
fireproofing
of
critical and
equipment, and
When
fireproofing
of
critical
equipment,
8.11.1.1 When
associated
systems, is
associated wiring systems,
is required
required (such
(such as
as emergency
emergency
block
block valves),
valves),special
specialcare
careshould
shouldbe
be taken
takenininthe
theselection
selectionof
of
suitable
application.
In In
general,
the the
installasuitablematerials
materialsfor
forthethe
application.
general,
installation
for for
the operation
of critical
equipment
for
tionshould
shouldprovide
provide
the operation
of critical
equipment
15
to ato1,lOO°C
(2,OOO°F)
15minutes
minutesexposed
exposed
1,lOO"C
a
(2,000"F)fire.
fire.
Intumescent
method).
Intumescentepoxy
epoxycoating
coating(prefelTed
(prefen-ed
method),
Fireproofed
Fireproofedboxes.
boxes.
Fire
Fireblankets.
blankets.
8.11.1.3
wiring
methods
are commonly
8.11.1.3 The
The following
followingwiring
methods
arecommonly
used:
used:
a.a. Fire-rated cable
cableassemblies
assemblies(preferred
(preferredmethod).
method).
b.
Insulation
over
conduit
systems.
b. Insulation over conduit systems.
for
c.c. Fire
Fireblankets
blanketsover
overconduit
conduitsystems.
systems.
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SECTION 9-POWER
9-POWER SYSTEMS
SYSTEMS FOR INSTRUMENTATION
INSTRUMENTATION AND
ANDPROCESS
PROCESSCONTROL
CONTROL
SECTION
9.1
PURPOSE
9.1 PURPOSE
9.4DESIGN
DESIGN
CONSIDERATIONS
CONSIDERATIONS
This section reviews
reviews requirements
requirementsfor the continuous
continuous supsupelectric power
powerto a plant's
plant’s instrumentation
instrumentation and
andprocess
process
ply of electric
requirements are essential
essential for the
control systems.
systems. The requirements
the safe
safe
operation
operation of the facility
facility and
and for
for the
the manufacture
manufacture of ongrade
products.
field,
andand
the the
products. Instrumentation
Instrumentationisisa arapidly
rapidlyevolving
evolving
field,
power system
systemsupporting
Supp0l1ingthethe
instrumentation
must
provide
instrumentation
must
provide
electric
electric power of
of sufficient
sufficientquantity,
quantity,quality,
quality,and
andreliability
reliabilityto
situationswhich
whichmight lead to
to unsafe
unsafe operating
operatingconconprevent situations
of offgrade
ditions,
the the
production
ditions, equipment
equipment failure,
failure,or or
production
offgrade prodprodproperlydesign
andand select asatisfactory
power
ucts. To properly
design
satisfactory
power
system,
essentialtoto
understand the importance
system, ititisisessential
understand
importance of,
of, the
function
all of
ofthe
thecompocompofunction of, and the relationship
relationship between all
facility's control,
nents which are part of the facility’s
control, shutdown,
shutdown, and
and
monitoring
monitoring systems.
systems.
Each type
control
system
has basic
type of
ofinstmmentation
instrumentationand
and
control
system
requirements in terms of the following
requirements
following that
that must
must be
be considconsidered when designing
system.
designing the
theoverall
overallpower
power
system.
9.4.1Load
Characteristics
9.4.1
Load
Characteristics
9.4.1.1
General
General
controlpower
powersystem
systemserves
serves
the control
control
The process control
all all
of the
and measuring
measuring devices
devicesin addition
addition to the interlock,
interlock, alarm,
alarm, and
safety
safety shutdown
shutdown systems.
systems.These
These can be grouped into control
and noncontrol
noncontrol circuits
circuits or loops. Typically,
Typically, the
the control
control loops
loops
of
the
flow,
pressure,
temperature,
and
level
controlconsist
consist
flow, pressure, temperature, and level controllers
well as the associated
controlvalve,
valve,interlock,
interlock,
lers as
aswell
associatedcontrol
andand
safety
systems. The noncontrol
loops contain
safety shutdown systems.
noncontrol loops
contain the
indicating
indicating and
and recording
recording instruments,
instruments,annunciator
annunciatorand
andalarm
alarm
SCOPE
9.2
SCOPE
panels, and
panels,
and gas stream
stream analyzers.
analyzers. Careful
Carefulconsideration
considerationmust
must
device,
and the
be given
givento the type of control
controlan<;l
andmeasuring
measuring
device,
section covers
forfor
designing
This section
coversthe
thebasic
basicrequirements
requirements
designing
service of each control
controland
device,
andmeasuring
measuring
device, so that its
service
and selecting
instrumentation
andand
process
selectingpower
powersystems
systemsforfor
instrumentation
process
power
The typical
typical load
power supply
supplyrequirement
requirementisismet.
met.
load charactercharactercontrol
control facilities.
facilities. It is intended
intended to establish the
thefollowing:
following:
istics of the
described in
istics
the three types of
of control
control systems
systems are
are described
fordesigning
andselecting
a. Basic criterianecessary
necessary
for designing
and aselecting a
9.4.1.2
9.4.1.2 through
through9.4.1.4.
9.4.1.4.
power system.
system.
b. Recommended
Recommended power
powersystems
systemsfor typical control
controlsystems.
systems.
Pneumatic Analog Control
9.4.1.2 Pneumatic
ControlSystems
Systems
In a process
analog
processplant that largely
largelyemploys
employsa pneumatic
a pneumatic
analog
control
control system
system for process control,
control, indicating,
indicating,and
andrecording
recording
To design
a satisfactory
power
system,
designand
andproperly
properlyselect
select
a satisfactory
power
system, instruments
from a relatively
relatively simple
simple
instruments can usually be supplied
supplied from
it will be necessary
necessary to define
define what
whatcriteria
criteriamust
mustbebeaddressed
addressed power supply
distribution system
system with a reliability level
level
supply and distribution
in the selection
of the power
criteselection and
anddesign
design
powersystem.
system. Typical
Typical criteconsistent
required control
control functions.
functions. For
For the most
consistent with the required
ria to be addressed
addressed are as follows:
follows:
part, instruments
instruments requiring
requiring the
the electric
electric power supply will be
limited
indicators and recorders,
limited to mUltipoint
multipoint temperature
temperature indicators
a.
a. Momentary
Momentary interruptions
interruptionsin the supply
supply to the plant
plant electri~
electrisolenoid
alarm
andand
trip cirsolenoid valves,
valves,temperature
temperatureand
andpressure
pressure
alarm
cal system.
system.
cuits,
cuits, and annunciator
annunciator panels.
panels. Although
Although a stabilized voltage
b. Extended outages
plant
electrical
outagesofofthethe
plant
electrical system.
system.
source
supply
for
source is required for some
some instruments,
instruments, the
thepower
power
supply
c.
conditions, such as harmonics,
voltage regularegulac. Transient
Transient conditions,
harmonics, voltage
majorpart of the system
system will not
notrequire
requireclosely
closely
regulated
the major
regulated
tion, and
andfrequency
frequencystability,
stability,that
thatareare
incompatible
with
incompatible
with
the the
voltage,
frequency,and
andharmonic
harmonic
characteristics.
Particular
voltage, frequency,
characteristics.
Particular
instrumentation and propower quality requirements of the instrumentation
applications
detectors
fuel solenoids
applications like flame
flamedetectors
andand
fuelsolenoids
may may
cess control
controlsystem.
system.
require
require continuous
continuous electric
electric (uninterruptible)
(uninterruptible)power.
d.
theinstrumentation
instrumentation or process
d. Internal
Internal requirements
requirements ofthe
process
control systems.
systems.
control
9.4.1.3
Analog Control
ControlSystems
Systems
9.4.1.3 Electronic Analog
e.
e. The need for isolation
isolation or
orremoval
removalof major electrical
electricalcomcomponents for
maintenance
without
unacceptable
loadunacceptable load
ponents
maintenance
without
A process
process plant
plantemploying
employinganan
electronic
analog control
electronic
analog
control
interruptions.
system
supply
whose
per- persystem will
willrequire
require a highly
highlyreliable
reliablepower
power
supply
whose
intermptions.
ventilation, air conditioning,
and
missible
voltage, frequency
frequencyregulation,
regulation,and,
and,
f. The loss
loss of heating,
heating,ventilation,
conditioning,and
missible voltage,
in in some
some cases,
cases,
harmonic
bythe
theparticular
particular
instrupressurization.
pressurization.
harmonic content will be dictated
dictated by
instruments used.
g.
Emergency lighting.
lighting.
supply capacity
capacity will
willbe
besubstantially
substantiallylarger
larger
g. Emergency
ments
used. This supply
pneumatic system.
Interaction between the power system and
than the
thesupply
supplyfor the pneumatic
system.
h. Interaction
and the
the instrument
instrument
air
Because
air supply.
supply.
Because control
control systems
systems must
must be kept in operation
operation during
during
plantemergencies,
emergencies,
power
supply for the elecprocess plant
thethe
power
supply
elecMethods of grounding
grounding and/or
systems
withwith
i. Methods
andlorisolation
isolationofof
systems
tronic
separate
tronic analog
analogcontrQI
contrd system
system will normally
normallyrequire
requiresome
some form
form
separate remote
remote (isolated)
(isolated)power supplies
supplies that will have
haveinterinterof backup,
connected
backup, such
suchas standby
standby generators
generatorsor batteries
batteries with
withinvertinvertconnected signal
signalwiring.
wiring.
9.3BASIC
BASIC
DESIGN
CRITERIA
DESIGN
CRITERIA
87
87
P
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88
I
RECOMMENDED PRACTICE
PRACTICE 540
API RECOMMENDED
(if AC powered), or batteries (if
(if the systems require
ers (if
require DC
backup maintains
supply
only). The backup
maintainsa apower
power
supply
to critical instruinstrucontrol circuits during total power failures
ments and control
failures which
which
supply.
affect the
thenormal
normalelectric
electricpower
power
supply.
9.4.1.4Digital
Digital
Systems
Systems
be limited to a value
valuesuch
suchas 4 milliseconds (ms).
(ms).To maintain
a critical load, a power supply
supply independent
independent of
ofnormal
normalplant
plant
power supply
supply interruptions
interruptionsisisrequired.
required.AC loads are supplied
typically from aa rectifier-battery-inverter
rectifier-battery-inverter (UPS)
(UPS) combination
combination
. while DC loads are
are supplied
supplied from
from aabattery-supplied
battery-suppliedbus.
bus.In
some cases,
cases,rotary
rotaryno-break
no-break
generators
are used.
generators
Transfer from
fromnormal
normaltotostandby
standbysupply
supply
require
solidwillwill
require
solidstateswitches
which
have
essentially
zero
switching
time.
switches which have essentially zero switching
Typical
examplesare flame
scannersininboiler
boiler
safety
systems;
Typical examples
flame scanners
safety
systems;
fuel
valves; and
and centrifugal
centrifugal comcomfuel system solenoid shutdown
shutdown valves;
pressor shutdown
shutdown circuits,
circuits,ififthey are designed to shut down
when de-energized.
de-energized.
process control computers and microprocessormicroprocessorDigitalprocess
instrumentation are now widely
based instrumentation
widelyused
usedinin
direct control,
supervisory, and
and monitoring functions.
functions. These systems can
supervisory,
10 kVA to as
as
require power supply capacities ranging from 10
much as 300 kVA in large plants. The electric power supply
usually must meet closely regulated voltage, frequency,
frequency, and
hmmonics
limits
for
the
connected
load,
and
the purchased
connected
hamonics
9.4.2.3
9.4.2.3 Semicritical
Semicritical
requires some conutility or plant generation supply usually requires
A semicritical
ditioning to meet the requirements
requirements of the load.
load.
semicritical load is any load that must operate during
ditioning
emergency conditions but can
can operate satisfactorily
satisfactorily through
frequently proDigital control
control system power supplies are frequently
interruptions. For a semicritical
semicritical load, an independent
short interruptions.
two isolated, redundant,
redundant, power input ports. The
vided with two
power supply available
failures is required.
available during power failures
sources should be separated as much as pracpower supply sources
A semicritical
semicritical load may be
be broken
brokendown
down into a load
load for
tical from the facility main
main power
power source(s) to obtain maxiwhich interruptions
reliability.
interruptions up to
to 0.2 sec are permitted and a load
mum reliability.
interruptions as long as 20 sec may be permitted.
for which interruptions
Uninterrupted power
Uninterrupted
powermay be required to
to provide
provide continucontinunonconThe typical control loop is in
in the
the0.2-sec
0.2-secgroup; the nonconfailllre.
ous control and
andmonitoring
monitoringduring
duringa power
a power
failure.
The deci(temperature, indicator,
indicator, and annunciator systems)
systems)
trol loop (temperature,
sion totoinstall
Uninterruptible Power
install an Unintermptible
PowerSupply
Supply(UPS)
(WS) should
20-sec
group. Faster transfer from normal
normal to
is inthe
the
20-sec group.
be based on the effects
effects to the facility
facility resulting
resultingfrom
froma apower
power
standby
supply,
using
electromechanical (contactor)
(contactor)
standby
supply, using electromechanical
failure.
manufacturer of
failure. Each manufacturer
ofthethecontrol
control and monitoring
monitoring syssysswitches with approximately
approximatelyaa100-ms
switching time,
switches
100-ms switching
time, is
tems will
power
tolerances and requirements
requirements
willprovide
providedetailed
detailed
power
tolerakes
for
the
0.2-sec
group;
plant
supply
required
group;
normal
power
of
these
requirefor this equipment.
equipment. Careful
consideration
Carehl consideration these requiredelayed
transfer
until
the
start-up
of
the
standby
generators
start-up
the
standby
generators
ments
is
essential
to
providing
a
proper
electric
power
supply
ments is essential to providing a proper electric power supply
suffices for the 20-sec group.
group.
suffices
and distribution
distributionsystem.
system.
9.4.2 Reliability
Grading
ReliabilityGrading
9.4.2.4
9.4.2.4 Noncritical
Noncritical
9.4.2.1
General
General
thatmay be dropped
dropped without
A noncritical
noncritical load is any load that
affecting safe
safe and
and orderly
orderly emergency
emergencyoperations.
operations.The power
affecting
system during
duringnormal
normaloperating
operatingconditions
conditions
must
have
system
must
have
aa,high
degree of
of reliability.
reliability.Tank
Tankgauging
gaugingsystems
systemsand
andquality
qualityanaanadegree
lyzers
lyzers are
areexamples.
examples.
Reliability
be keyed
keyed to the ability
ability to operate
Reliability grading
grading can be
operate
during
Economic
during power
powersupply
supplyinterruptions.
interruptions.
Economic design
design requires
req@es
that control loops be
be graded
graded both
bothwith
withrespect
respecttotoreliability
reliability
requirements
undernormal
normal and emergency
conditionsand
and
requirements under
emergency conditions
with
with respect
respect totopermissible
permissiblevoltage
voltageand frequency
frequency regulation
regulation
9.4.3 Quality
Grading
QualityGrading
and harmonic
limits.
harmoniccontent
content
limits.
.‘Quality
Quality grading
according to the
grading groups
groups loads
loads according
the stringency
stringency
Permissible
are
illustrate critical,
critical,
Permissible interruption
interruptiontimes
times
are used to illustrate
of
the
control
devices'
requirements,
ensuring
that
realistic
control
devices’
requirements,
ensuring
realistic
semicritical,
loads, the three
categoriesofof
semicritical, and noncritical
noncriticalloads,
threecategories
are
supply
fluctuaand
not
excessive
limits
and
not
excessive
limits
are
placed
on
power
supply
fluctualoads
supply
andand
distridistriloads requiring
requiringdifferent
differentdegrees
degreesofofpower
power
supply
tions.
Exact
limits
on
supply
fluctuations
must
coordinated
tions.
Exact
limits
on
supply
fluctuations
must
be
coordinated
bution
interruption
times,
how-howbution system
systemreliability.
reliability.Permissible
Permissible
interruption
times,
each equipment
equipmentsupplier.
supplier.Typical
Typicalhigh
highquality
qualitylimits
limits
areare
ever,
to
ever, will
willvary
varyaccording
according
to control
control equipment
equipmentcharacteristics.
characteristics. with each
as
follows:
as
follows:
For instance,
of aofdelayed
dropout
provi- proviinstance,it is
is possible
possible that
thatuseuse
a delayed
dropout
sion
sion ininaacontrol
controlloop
loop may
may shift
shift the
the control
control loop
loop from
froma acriticritiAC loads:
loads:
a. For AC
a.
cal
semicritical category.
category. The
three categories
categories of loads
cal to
to a semicritical
The three
1.
l. Voltage
Voltageregulation:
regulation:±2 2%.
are
are described
described in 9.4.2.2
9.4.2.2 through
through 9.4.2.4.
2. Frequency
f 1 Hz for
for 50/60
50/60Hz systems.
systems.
2.
Frequency regulation: ±
3. Total
Total harmonic
harmonicdistortion:
distortion:3%
3% maximum.
maximum.
3.
9.4.2.2 Critical
Critical
DC load~:
loads:
b. For DC
l. Voltage
Voltageregulation:
A
load
1.
regulation: ± 11%.
%.
A critical
critical load
loadis any
is any
load which
which cannot
cannot be interrupted
intempted even
even
may
momentarily
2. Voltage
112% maximum.
maximum.
2.
Voltage ripple: 1/2%
momentarily or has
has aa permissible
permissibleinterrupting
interruptingtime
timethat
that
may
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ELECTRICAL
INSTALLATIONS IN PETROLEUM PROCESSING PLANTS
89
9.5ELECTRICPOWERSYSTEMS
power system can sewe as the alternate source. By applying
the reliability and quality grading characteristics, the capacity
9.5.1
General
and degree of redundancy that must be provided in indepenThe acceptability ofthe normal process plant power supply dent generation can be heldantoeconomic minimum. Important factorsin supply sizing are the amount of in-rush current
as the insuument supplywill be determinedby the reliability
expected and the supply in-rush response characteristic.The
and quality requirements of the loads served.
An independent
power supply must be provided when the normal supply does memory and data preservation requirements, self-protection
features, and limits of process computers also have a major
not meet the load requirements.
The length of timethe particeffect on power supply requirements.
ular load must function during abnormal or emergency electric power supply conditions must also be considered. Loads
can bedivided into categories that will determine the required 9.5.3TypicalPowerSupplies
supplyperiod
capacity of thestandbypowersupply. A
Specialequipmentdesignandapplicationproblems
are
may be adequate for some loads; an 8-hr supply period may
encountered where automatic transfer
or parallel operation of
be adequate for others; and still others may require longer
powersupplies is used.Thereare many combinations of
periods. Capacitiesfor periods of 2 min to 3 hr are common
rotating and static generation power supplies and plant power
for rectifier-battery-inverter (UPS) systems.Whenlonger
supplies that may be used. The operating conditions which
periods are required, or load requirements exceed 20 kVA,
must be met and the unique characteristics
of the combination
standby generatorsmay be more economical.
which is selected should be understood thoroughly before a
final design isestablished..
9.5.2InstrumentationandControlSystem
Typical one-line diagramsof power supplies are illustrated
Requirements
in Figures 19, 20, and 21. Each facility will require a unique
design; however, the concepts noted in the following sections
9.5.2.1PneumaticAnalogControlSystems
can be applied to most supplies.
Generally, the pneumatic analog control system can be satisfactorilysupplied from thenormalplantpowersystem,
9.5.3.1 Rectifier-Battery-Inverter System[suchas
assuming that this system has normal and alternate supplies
an Uninterruptible Power Supply (UPS)]
that are reasonably independent of each other. This independence should be maintained in providing normal and alternate Many features areavailablewiththerectifier-batterysupplies to the main distribution bus of the process control
inverter system. When specifying the system, the following
power system. Wherethe plant has only a simple radial elecfeatures shouldbe considered:
trical distributionsystem, some provisionfor an alternate supa. The type ofbatterysystem,consideringtheability
to
ply to the process control system main bus
should be made.
maintain and testthe condition of the batteries.
In all cases,particular attention must bepaid to the requireb. The ventilation of the batteries, if required.
ments of critical devices and circuits; examples
of these critic. The ampere-hour ( A h )capacity of the battery bank.
cal devicesand circuits areboilerplantcontrol,safety
devices, and associated circuits; compressor control and shut- d. The seismic requirements forthe battery rack.
down circuits; and critical motor-operated valves which must e. Rectifier input voltage, phase, and frequency.
function after a total power failure. Special provisions,. such
f. The required inverter output voltage, phase, and frequency.
as standby generator sets or rectifier-battery-inverter (UPS)
g. The inverter capacity, considering the largest load to be
combinations, may be required.
started, especially ifit has high in-rush currents.
h. The ambient temperature and humidity range in which
9.5.2.2 Electronic Analog and Digital Control
the system will operate. Will the loss of heating, ventilation,
Systems
and air conditioning be detrimental to the system?
i.
The space required to house the complete rectifier-batteryThe electronic analog control and digital computer moniinverter
system.
toring and control systems impose more stringent demands
II
I
I
on the power supply. Independent normal and alternate supplies to main AC and DC distributionbuses are required.In
most
plants, it will be necessary to provide an independent
generation supplyeither in the form of a generatoror a rectifier-battery-inverter (UPS) combination.
Where
quality
requirements are necessary, the independent generation supply serves as the normal supply. Particular attention mustbe
paid to determining to what extent the supply from the plant
Some questions to consider when specifying the rectifierbattery-inverter system areas follows:
a. Where will the alternate supply originate? It should be a
veryreliablecircuit(s)from
the plant powersystem or
another standby power supply.
b. Will the inverterautomaticallyreturn
to theprimary
source after power is restored?
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90
90
API
PRACTICE
API RECOMMENDED
RECOMMENDED
PRACTICE540
540
Plant
standby
generator
advised
of load
that would
be
advisedof
ofthe
theexact
exacttype
type
of load
that would
besupplied
suppliedfrom
from
the
thesystem.
system.
g.g. Will
Willmaintenance
maintenancebypass
bypassswitches
switchesbe
berequited
requiredto
tofacilitate
facilitate
maintenance
and
load
testing
of
the
rectifier,
battery,
maintenance and load testingof the rectifier, battery,inverter
inverter
system?
system?
9.5.3.2
9.5.3.2 Generators
Generators
As
questions
to
Aswith
withthe
thefeatures
featuresand
and
questions
toconsider
considerfor
forthe
therectirectifier-battery-invelter
system,
there
are
many
concepts
confier-battery-inverter system, there are many concepts totoconsider
powersystem
systemusing
usingin-plant
in-plantgeneration.
generation.
siderwhen
whendesigning
designing aa power
Some
of
the
more
prominent
considerations
are
as
follows:
Some of the more prominent considerations as
arefollows:
To
Toinstrument
instrumentpower
power
conditioning
conditioningand
and
distribution
distributionequipment
equipment
Other
Otherloads
loads
Figure
Figure 19-Typical
19-Typical Instrument
InstrumentPower
PowerSupplies:
Supplies:
Standby
Requiredfor
forInstrument
InstrumentPower
Power
StandbyGeneratorNot
GeneratorNotRequired
Plant
power
source
1
~
Standby
generator
-4)."~)
(
I
I
~
~
:amIOWPlant IOWvoltage
bus
vollag.
b"
To
Toinstrument
instrumentpower
power
conditioning
conditioningand
and
di~ribution
distributionequipment
equipment
Figure
Instrument
PowerSupply:
Supply:
Figure 20-Typical
20-Typical Instrument
Power
Standby
forfor
Instrument
Power
StandbyGenerator
GeneratorRequired
Required
instrument
Power
c.c. IsIsaamanual
output
manualmake-before-break
make-before-break
outputmaintenance
maintenanceswitch
switch
required?
required?
d.d. Will
such
as
Willsome
someform
formof
ofadditional
additionalpower
powerconditioning,
conditioning,
such
as
aalow-noise
transformer,
be
required?
If
it
is
required,
the
syslow-noise transformer,
be required? If it is required, the system
be advised
of
temvendor
vendorshould
should
be advised
ofthe
therequirement.
requirement.
e.e. What
be used?
used?
What form
form of
of load
loadovercurrent
overcurrentprotection
protection will
will be
There
theinverter
inverteroutput
outputbreaker
breaker
Theremust
mustbe
becoordination
coordinationwith
withthe
or
orfuses.
fuses.
f.f. Has
advised
of
Hasthe
thevendor
vendorbeen
been
advised
ofthe
theload
loadsupplied
suppliedfrom
fromthe
the
system?
Whenselecting
selecting
the system, the
mustbebe
system?When
thesystem,
the vendor
vendormust
'.
a.a. Type
Type of
ofprime
primemover
moverfor
forthe
thegenerator
generator(gas
(gasturbine,
turbine,steam
steam
turbine,
electric
motor;
or
gas
or
diesel
engine).
turbine, electric motor; or gas or diesel engine).
b.b. Size
Sizeof
ofthe
thegenerator,
generator,taking
takinginto
intoaccount
accountthe
thelargest
largestload
load
to
inrush
currents
tobe
bestarted
startedespecially
especiallyif high
if high
inrush
currentsare
areinvolved.
involved.
c.c. Recommendations
emerRecommendations of
of IEEE
IEEE Std
Std 446
446 concerning
concerningemergency
systems.
gencyand
andstandby
standbypower
power
systems.
d.d. Recommendations
emergency
Recommendationsof
of NFPA
NFF'A 110
110concerning
concerning emergency
and
standby
power
systems.
and standby powersystems.
e.e. Operation
Operationof
ofthe
thegenerator.
generator.Will
Willthe
thegenerator
generatorrun
runcontinucontinuously
or
will
there
be
provisions
for
manual
or
ously or will there be provisions for manual or automatic
automatic
start?
mode,
start?IfIfthe
thegenerator
generatorisistotobe
beoperated
operatedininstandby
standby
mode,then
then
aaregular
testing
program
must
be
developed.
regular testing program must be developed.
f.f. Paralleling
equipment toto operate
Parallelingof
of the
theequipment
operate inin synchronism
synchronism
with
another
generator or
plant
power
withanother
generator
or with
with the
the normal
normalplant
power
system.
system.
g.g.Study
Studyofof
governor
characteristics
forturbine
steam· turbine
thethe
governor
characteristics
forsteam
prime
movers.
prime movers.
h.h. Location
that
safe
Locationof
ofthe
thegenerator,
generator,ensuring
ensuring
that
safeoperation
operationcan
can
occur
during
hazardous
conditions.
occur during hazardous conditions.
i.i. Need
Needfor
foreither
eitherelectronic
electronicor
orelectromechanical
electromechanicalswitching
switching
to
Thisisisdetermined
determined
toconnect
connectto
tothe
thenormal
normalelectrical
electricalsupply.
supply.This
by
bythe
thereliability
reliabilitygrading.
grading.
j.j. Need
for
some
form
Need for some formof
ofload
loadpower
powerconditioning.
conditioning.
k.k.Amount
of
flywheel
effect
required
Amount of flywheel effect required inin aa rotating
rotating set
set toto
maintain
voltage
and
frequency
during
transfer.
maintain voltage and frequency during transfer,
9.6
9.6 DISTRIBUTION
DISTRIBUTIONSYSTEM
SYSTEM
9.6.1
9.6.1 General
General
The
investmentinin
suitable
power
supply
The design
design of
of and
andinvestment
suitable
power
supply
sourceS
can
be
nullified
by
the
failure
to
specify
the
details
sources can be nullified by the failure
to specify the detailsofof
the
distribution
system
and
its
equipment.
the distribution system and its equipment.All
Allequipment
equipmentand
and
circuits
from
the
main
distribution
buses
to
the
individual
circuitsfrom the maindistributionbusestotheindividual
instrument's
circuit must
mustbe
beconsidered
considered in
in the
the
instrument's power
power supply
supply circuit
distribution
system
design
and
installation.
The
distribution
distributionsystemdesignandinstallation.Thedistribution
system
mustbe
becompatible
compatible
with
the reliability
and quality
systemmust
with
thereliability
andquality
requirements
of
the
loads
served
and
must
maintain
thethe
levels
requirements of the loads served and must maintain
levels
that
have
been
provided
in
the
power
supply.
The
basic
system
that have been provided
in the power supply. The basic system
design
by
division
and circuit
and equipdesignshould,
should,
bymeans
meansofload
of load
division
and circuit
and equipment
redundancy,
ensure
that
any
short
circuit
or
overload
trip trip
ment redundancy, ensure that any short circuit or overload
affects·
an
acceptable
minimum
number
of
instrument
loads.
minimum number of instrument loads.
affects an acceptable
Copyrighted material licensed to IDOM.
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91
ELECTRICAL
INSTALLATIONS
PETROLEUM
ELECTRICAL
INSTALLATIONSIN
INPLANTS
PROCESSING
PETROLEUMPROCESSING PLANTS
,v
Supply
Supplyfeeders
vfeeders
4
____ JI____ _
t
"
"
"
"
"
"
1I
1I
II
Line
II
conditioning
Line conditioning
I
(see
Note
5)
I
Note
(see
1I ____
__5)
, ___ ..1I
I
-I
Rectifier
Rectifier
(see
(see Note
Note1)
1)
- - - - - - _ _ , _ _ _
1_____ 1.. _ _ _ _ •
I""""-"
I
II
Line
conditioning
II
Line
conditioning
:___________
(see
II
I
(see
NoteNote 2)
2)
1
I""--""-I
Battery
Battety system
system
(see
(see Note
Note1)
1)
111111-~l~l~l"
Inverter
Inverter
(see
(see Note
Note 1)
1)
Normal
Normal Solid-state switch
supply
supply
Solid-state switch
(see
3)
(see Note
Note3)
1-_ _ _ _--1 Alternative
Alternative
supply
supply
n
Maintenance
Maintenancebypass
bypass
(optional)
(optional)
I- - - - - - ----'"" - - - - - - - - - II
Line
1I
Line conditioning
conditioning
I
"
"
"
"
"
"
"
"
"
"
1II _ _ _ _
_ _ _(see
_ _Note
_ _2)
_
Note
(see
2) _ _ _ _ _ _ ..1II
~---------
---------,
1
1
I
1
1
11- ___________________ II
r-------- -------"I"""-
I
II
I
l - f 1 7 ]o
II
"
I
I
-"J+ I
II
II
II
II ________________
I
~
~
~
-
Panelboard
PanelboardBB
(see
(see Note
Note5)
5)
Panelboard
Panelboard A
A
(see
(see Note
Note4)
4)
Notes:
Notes:
1.
may
be used
in lieuinoflieu
the rectifier-hattery-inverter
1.A
A rotary-uninterruptible
rotary-unintermptible or
ornormally
normallyoperating
operatinggenerator(s)
generatods)
may
be used
of the rectifier-battery-inverter
combination.
combination.
2.
as low-noise,
isolation,
or a constant-voltage
transformer,
may be required
2. Some
Someform
formofofline
line conditioning,
conditioning,such
such
as low-noise,
isolation,
or a constant-voltage
transformer,
may be required
for
for some
someloads.
loads.
3.
aa momentary
be used
for supply
switching.
3. Ifloads
If loadscan
cantolerate
tolerate
momentaryloss
loss of
of supply,
supply, an
an electromechanical
electromechanicalswitch
switchmay
may
be used
for supply
switching.
4.
be be
selected
to coordinate
with upstream
devices.devices.
4. Fuses
Fusesor
or circuit
circuitbreakers
breakersshould
should
selected
to coordinate
with upstream
5.
power
inputs
to Des
input
5. Panelboard
Panelboard"B"
" B may
maybe
berequired
requiredtotoprovide
provideseparate
separate
power
inputs
DCS
to power
powersupplies
supplieswith
withseparate
separate
input
ports.
maymay
be replaced
with awith
UPSlbattery
backup
requirements
are justified.
ports.The
Theline
lineconditioner
conditioner
be replaced
Upsbattery
a
backupsystem
systemif reliability
if reliability
requirements
are justified.
Figure
Switching
Figure 21-Typical
21-Typical Instrument
InstrumentPower
PowerSupply
Supplywith
withSupply
Supply
Switching
I
I
1I
IJI
~
~
~
-
.
..
.
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92
92
PRACTICE 540
API RECOMMENDED
RECOMMENDED
540
9.6.2Design
Design
Requirements
Requirements
9.7.2Power
PowerWiring
Wiring
Power supply
supplyand
and
distribution
system
wiring for instmdistribution
system
wiring
instruRequirements
be speciRequirements for the following
following components
componentsmust
must
be speciment and control
control system
system power shall
shall comply
comply with
with NFPA 70.
fied in the distribution
distribution system
systemdesign:
design:
Section
practice should
Section 8 of this recommended
recommended practice
should also
also be cona. Feeders
from the supply
sources to the main
maininstrument
instmment
Feeders from
supply sources
sulted
applicable power wiring
wiring used
used
sulted for the various types
types of applicable
power
power panelbmird.
panelboàrd.
processingplants.
plants.
in petroleum processing
Feederstotomain
loadload
panelboards,
branch
panelboards,
b. Feeders
main
panel boards,
branch
panelboards,
and instmment
instrument and
andcontrol
controlpanels.
panels.
Considerations
9.7.3Special
Special
Considerations
c.
Panelboards, including
breakers
and fuses.
c. Panelboards,
includingcircuit
circuit
breakers
fuses. The fuses
fuses
acceptable
for power wiring
Wiring methods
methodswhich
whichareare
acceptable
wiringmay
may
required to
to coordinate
coordinate with
with the
the upstream
upstreamdevices
devices(see
(see
may be required
be
used.
Attention
must
be
paid
special
requirements
which
used.
Attention
must
be
paid
to
special
requirements
which
Figure 21). To avoid
transfer-to-bypass and
andpossible
possiblevoltage
voltage
avoid transfer-to-bypass
are a result
circuit function.
function.For instance,
instance, special
special attenattenresult of the circuit
depression
CC or J fuses,
depression during
duringfaults,
faults,Classes
Classes
fuses, with
withasaslow an
should
be
paid
to
the
routing
of
safety
control
and
tion
should
be
paid
to
the
routing
of
safety
control
shutampere
as possible to serve the load,
load, are recommended
ampere rating
rating as
circuits. These
Thesecircuits
circuits
should
fromnormal
normal
be segregated from
should
for the distribution
circuit
overcurrentprotection.
distributionpanel
panelbranch
branch
circuit
overcurrent protection. down circuits.
circuit mutes
routes to prevent aa single
single accident
accidentfrom
fromdisabling
disablingboth
both
Note: This will allow the UPS
U P S source to clear the fault rather than
than
circuits.
circuits. Fireproofing
Fireproofingof
ofexposed
exposedcomponents
componentsof these circuits
circuits
transferring to bypass to clear the fault.
and use of wire insulation
insulation rated
rated for
for high
hightemperature
temperaturemay
maybebe
necessary to preserve
necessary
preserve the
the circuit
circuit integrity
integrity for
for aa specified
specified time
time
d.
d. Transfer switches.
switches.
To To
facilitate
the fast
of branch
period during
duringa afire.
fire.
facilitate
theclearing
fast clearing
of cirbranch circuit
faults
by
current-limiting
fuses,
the
branch
circuit
wiring
faults
current-limiting
fuses,
the
branch
circuit
wiring
9.6.3 Criteria
Criteria
System
Design
forfor
System
Design
need to be oversized
oversized totoreduce
reducethe
thetotal
totalcircuit
circuit
resistance
may heed
resistance
The following
followingare some criteria
criteriafor system
system design:
design:
(and subsequently
subsequently increase
increasethe fault
fault current available
available totomake
make
the
fuses
operate
in
current-limiting
region).
fuses
operate
their
current-limiting
region).
a.
panelboards
a. Normal and alternate feeders
feeders to distribution
distribution panelboards
should be provided as required by
by reliability
reliabilityrequirements.
requirements.
b. Particular
Particular attention
attention should
should be
be given
given to distribution
distribution panelpanelboard load assignments.
each process
processunit
unit or
assignments. The loads
loads on each
section should
should be split so
so that aadistribution
distribution
major process section
busbus
failure
of of
the the
control
loops.
failure cannot
cannotaffect
affectallall
control
loops.
c.
Mainand
and
important
branch
panelboards should have at
c. Main
important
branch
panelboards
least two
or separate
twoseparated
separatedor isolated
isolated bus
bussections,
sections,
separate panelpanel'boards should
shouldbe used.
'boards
Circuit protection and disconnect means
means for each control
control
d. Circuit
loop
supply
should
be
provided.
loop supply should provided.
e. All
All overcurrent
overcurrent and short-circuit
short-circuit protective
protectivedevices
devicesshould
should
be coordinated
device closest
closest to fault opens
opens first.
first.
coordinatedso that the device
f. The system
system should
should be able
able to transfer
transferbetween
f.
betweensources
sources
supply.
without loss of supply.
g. Individual
Individual pieces
equipment
should
be redundant
to to
g.
piecesofof
equipment
should
be redundant
lessen the probability of a total
totalsystem
system failure.
failure.
METHODS
9.7WIRING
WIRING
METHODS
9.7.1
General
9.7.1
General
actual circuit requirements
individual instmments
instruments
The actual
requirements for individual
of instrument
instrument being served,
determined by the type of
served,
will be determined
and are a part of the instmment
instrument system
systemdesign.
design.
9.8
SYSTEM
AND GROUNDING
EQUIPMENT GROUNDING
AND
EQUIPMENT
Normal system
supplesystem and
and equipment
equipmentgrounding
groundingmust
must be supplemented and modified
modified by
byany
anyspecial
specialrequirements
requirementsimposed
imposedbyby
distribthe instrument
instmment and
and computer
computer loads.
loads. Manufacturers
Manufacturers of distributed control system
systemcomputers
computersand
andprogrammable
programmablecontrollers
controllers
supply
manuals which may specify any
supply facilities'
facilities' requirement
requirementmanuals
special
requirements for their equipment.
equipment. Electrical
Electricalsafety
safety is
special requirements
essential
essential in the power system
system grounding
grounding design;
design; therefore,
therefore, the
the
requirements of NFPA
be satisfied.
groundingmust
must
satisfied. (Sec(Secrequirements
NFPA70 for grounding
tion 5 provides information
information on specific
specific grounding
groundingpractices
practicesin
process
plants.)
The
grounding
of
a
power
system
for
process plants.) The grounding of
system fora adistribdistributed control
careful
start of a
careful planning from
fromthethe
controlsystem
systemrequires
requires
be developed for
detailed grounding
groundingdiagram
diagramshould
should
project. A detailed
each project
withwith
all ofall
projectand
andreviewed
reviewed
the equipment
theofequipment
vendors.vendors.
9.9CONSIDERATIONS
CONSIDERATIONS FOR CLASSIFIED
CLASSIFIED
LOCATIONS
LOCATIONS
application and wiring methods
methods for the power
Equipment application
supply
system
must
comply with
supply source
source and distribution
distributionsystem
must
comply
NFPA 70 requirements
requirements applicable
applicableto the particular
particular classified
classified
location. Generally,
operate
at
equipment and
andwiring
wiringwill
will
operate
Generally,this equipment
energy
energy levels
levelswhich
whichcan cause ignition.
ignition.
P.
~
STD.API/PETRO RP
~
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1779
0732290
44% H.
SECTION
SECTION 10-SPECIAL
IO-SPECIAL EQUIPMENT
EQUIPMENT
10.1
PURPOSE
10.1 PURPOSE
,
have
have elected
electedto
to furnish
furnishor
or lease
leasetheir
theirown
own instruments,
instruments,
switch-switchboards,
equipment.
boards, and
andconnecting
connecting
equipment.
This
electrical
equipment
and
This section
sectioncovers
coversspecial
special
electrical
equipment
and instalinstalTelephone
Telephone instruments
instruments used
used in
in Division
Division 11 locations
locations must
notnot
covered
lations
lations encountered
encounteredin
in aa processing
processingplant
plantthat
thatareare
covered
be
of
explosionproof
construction.
In
Division
beof explosionproof construction. Division 22 locations,
locations,
in
in other
othersections
sectionsof
of this
this publication.
publication.
standard
have
beenbeen
tested
and approved
for for
standardtelephones
telephoneswhich
which
have
tested
and approved
of
explosionproof
conDivision
2
locations
or
telephones
Division 2 locations or telephones ofexplosionproofcon10.2
SCOPE
10.2
SCOPE
struction
structionmay
may be
be used.
used.In
In nonclassified
nonclassifiedlocations,
locations,instruments
instruments
of standard
standardconstruction
constructionmay
may be
be used.
used.
This
such
instalThis section
sectionisis limited
limited totoa abrief
briefdescription
descriptionofof
such
instal- of
Telephone
is usually
located
in a telelations.
installations
is not
Telephoneswitching
switchingequipment
equipment
is usually
located
in a telelations.The
The need
need for
foror
or the
the extent
extentofofsuch
such
installations
not
is
defined
phone
thethe
phone room
room in
in an
an office
officeor
or other
otherservice
servicebuilding
buildingoutside
outside
defined ininthis
thissection.
section.
process
process area.
area. Distribution
Distributionof
of telephone
telephone circuits
circuitswithin
withinbuildbuildings
is
usually
accomplished
with
multiconductor
cablesinin
ings is usually accomplished
multiconductor cables
10.3
GENERAL
10.3
GENERAL
conduit
in
conduitor
or underfloor
underfloorducts;
ducts;or
or with
withplastic-sheathed
plastic-sheathedcables
cables
in
Many
systemsand
andpieces
pieces of
processing
Many systems
of equipment
equipment in aaprocessing
ceiling
spaces
and
walls.
Outdoors,
the
telephone
distribution
ceiling spaces and walls. Outdoors, the telephone
hstribution
plant
is is
somewhat
different
or has
plant need
needelectrical
electricalservice
servicethat
that
somewhat
different
has
or
system
mayconsist
consist of
conduit or
of multiconductor
multiconductor cable ininconduit
or
system may
requirements
requirements other
other than
than those
those generally
generally provided
provided for
for by
by the
the
underground
ducts,
directcable,
burial cable, or
undergroundducts,
directburial
or aerial
aerial cable
cable
usual
usual power
powerand
andlighting
lightingservice.
service.TheSe
Theseinclude
includecommunicacommunicaattached
and
attachedto
to poles
polescarrying
carryingpower
power
and lighting
lightingfeeders.
feeders.Wiring
Wiring
tion
andsignaling
signalingsystems,
systems,
Supervisory Control
tion and
Supervisory
Control And
And Data
Data
methods
methodsmust
mustbe
be suitable
suitablefor
forthe
the electrical
electricalarea
areaclassification.
classification.
Acquisition
special
lighting
systems,
and
Acquisition(SCADA)
(SCADA)Systems,
Systems,
special
lighting
systems,
and
Corrosion
protectionrequirements,
requirements,
reliability
requireCorrosionprotection
andand
reliability
requireheat
tracing.Consideration
Consideration
betothe
given
to the special
heattracing.
mustmust
begiven
special
ments
be be
considered
in selecting
wiringwiring
methods.
mentsshould
shouldalso
also
considered
in selecting
methods.
requirements
this equipment.
equipment.
requirementsofofthis
Sound-powered
units
andand
Sound-poweredtelephones
telephonesare
are used
usedon
onoperating
operating
units
in
in other
other classified
classified areas.
areas.The
Theinstmments
instrumentsare
arevoice-operated
voice-operated
10.4
COMMUNICATION
SYSTEMS
10.4COMMUNICATION
SYSTEMS
and
require
no
electric
power
to
operate.
Associated
with
and require noelectric power to operate.Associatedwith
these
sound-powered
telephones
is
usually
some
type
of
these sound-powered telephones is usually some type ofsigsigRadio
Systems
10.4.1
10.4.1
Radio
Systems
naling
naling system which
which requires
requires electric
electric power.
power. The
The voice
voice and
Fixed
equipment is
extensively in
Fixed radio equipment
is used
used extensively
in processing
processing
signaling
signaling system
systemshould
shouldnot
not be
be installed
installedininthethesame
same raceway
raceway
plants
for
communication
between
other
fixed
equipment,
plants for communicationbetweenotherfixedequipment,
unless
unless the
the signaling
signalingcircuit
circuitisisintrinsically
intrinsicallysafe.
safe.
portable
The
portable equipment,
equipment,and
andmobile
mobileequipment.
equipment.
The fixed
fixed equipequipBells,
relays
Bells,horns,
horns, howlers,
howlers,and
and
relaysassociated
associatedwith
withcommunicommuniin
operation
or
maintenance
centers
ment
is
typically
located
ment is typically located in operation or maintenance
centers cation
be be
suitable
for
cation equipment
equipmentmust
must
suitable
for the
the electrical
electrical area
areaclasclasand
and is
is used
used for
for dispatching,
dispatching, security,
security, and
and process-unit
process-unit comcomsification
they
are are
installed.
sificationininwhich
which
they
installed.
munication.
munication.
Portable
Portable radio
radio equipment
equipment is
is available
available in
in two
two forms,
forms, the
the
10.4.3
Public
Address
Systems
10.4.3Public
Address
Systems
hand-held,
hand-held, two-way
two-way communication
communication device
device and
and the
the beltbeltPublic
addresssystems
systems are
used for
mounted,
Publicaddress
are commonly
commonlyused
for public
public
mounted, call-pager
call-pager system.
system. The
The call-pager
call-pager unit
unit alerts
alerts its
its
address
in procarrier,
addresspurposes
purposesas
as well
well asasfor
for paging
paging plant
plantpersonnel
personnel
in procarrier, who,
who, in
in turn,
turn, uses
uses aatelephone
telephone to
to communicate
communicatewith
with
cess
the
In some
some cases,
cases, they
they are
are used
used for
for addressing
addressing and
cess units. In
the caller.
caller.Some
Some call-pager
call-pagerunits
units allow
allow aamore
more detailed
detailedmesmespaging
saging
paging entire
entireplants.
plants. They
Theyare
areoften
often used
used ininconjunction
conjunctionwith
with
sagingcapability.
capability.Portable
Portableradio
radio equipment
equipmentthat
that will
willbe
be used
used
sirens
in
sirensor
or howlers
howlers to
to convey
convey emergency
emergency warning
warning information
information
in classified
classified locations
locations must
must be
be approved
approved for
for use
use in
in such
such
to
should be
locations.
to plant
plant personnel. Caution should
be exercised
exercisedin
in applying
applying
locations.
this
type
of
equipment
in
classified
areas
(see
NFPA70).
this
type
of
equipment
in
classified
areas
(see
N”A
70).
Mobile
vehicles used
used for
Mobile radio
radio equipment
equipment isis provided in vehicles
for
deliveries,
fire protection,
protection, and
deliveries, maintenance,
maintenance, security,
security, and fire
and isis
also
management.
10.5
SUPERVISORY
CONTROL
AND
DATA
alsoprovided
providedin
in vehicles
vehicles used
usedbybyfacility
facility
management.
10.5 SUPERVISORY
CONTROL
AND
DATA
ACQUISITION
ACQUISITION EQUIPMENT
EQUIPMENT(SCADA)
(SCADA)
10.4.2
Telephone Systems
Telephone
10.4.2
Systems
Supervisory
Supervisory control
controland
anddata
data acquisition
acquisition (SCADA)
(SCADA)equipequipment
plant
utility
Most
ment may
maybe
be used
used for
formonitoring
monitoringand
andcontrolling
controlling
plant
utility
Most processing
processing plants
plants are
are served
served by
by the
the local
local telephone
telephone
systems
cooling water,
water, and
andsteam
steamsystems).
systems).
utility,
install
systems (e.g.,
(e.g., electrical, cooling
utility, which
whichmay
mayfurnish
furnishand
and
install all
all wire,
wire, cable,
cable,terminal
terminal
blocks,
batteries,
battery
chargers,
is usually
usually located
locatedininan
an
The user
user interface
interfacefor
for this
this equipment
equipmentis
blocks, instruments,
instruments,switchboards,
switchboards,
batteries,
battery
chargers, The
operations
center. Through
and
this equipment,
equipment, circuit
circuit
operations control
controlcenter.
Through this
and other
other miscellaneous
miscellaneousequipment.
equipment.It Itis the
is
the responsibility
responsibilityofof
breaker
the
plant to
andinstall
install all
the processing
processing plant
to furnish
furnish and
all conduit
conduit and
and
breaker positions
positions (open
(open or
or closed),
closed), pump
pump status
status (mnning
(running or
or
not
parameters (e.g.,
flow, pressure,
and
junction
not mnning),
running), system
systemparameters
(e.g..flow,
pressure,and
In recent
recent years,
years,many
many facilities
facilities
junctionboxes
boxes for
forthe
the system.
system.In
93
93
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94
94
PRACTICE
RECOMMENDED
API
API RECOMMENDED PRACTICE 540
540
load),
load), and
and substation
substationbuilding
buildingpressurization
pressurizationsystems
systemscan
canbebe
monitored
remotely.
monitoredand
andcontrolled
controlled
remotely.
10.6
10.6 CLOSED-CIRCUITTELEVISION
CLOSED-CIRCUIT TELEVISION(CCTV)
(CCTV)
Applications
televisionare
are
numerous.
Applications for
for closed-circuit
closed-circuittelevision
numerous.
Monitoring
boards
andand
metering,
as
Monitoringof
ofprocess
processcontrol
control
boards
metering,
aswell
wellas
as
monitoring
monitoringflare,
flare,boiler,
boiler,and
and furnace
furnace flarne
flamepatterns,
patterns, isis comcommon.
mon.The
The largest
largestapplication
applicationof
of television
televisionequipment
equipmentininproprocess
cessfacilities,
facilities,however,
however,isisfor
forsecurity.
security.In
Inthis
thisapplication,
application,ititisis
used
rail-railusedfor
formonitoring
monitoringoperations
operationsatatpersonnel,
personnel,vehicle,
vehicle,and
and
and
storage
areas.
Video
recording
road
gates,
warehouses
road gates, warehouses and storage areas. Video recording
equipment
equipmentisis often
often used
used in
in conjunction
conjunction with
with the
the CCTV
CCTV syssystem
when
historical
records
are
required.
tem when historicalrecords are required.
10.7
LIGHTING
10.7 OBSTRUCTION
OBSTRUCTION AND WARNING LIGHTING
For
or
For tall
tallstructures
structuresand
andstacks,
stacks,special
specialobstruction
obstruction
or warnwarnbe
required
by
the
Federal
Aviation
Adminising
lights
may
ing lights may be required by the Federal Aviation Adminisjurisdiction.
tration
trationor
orother
otherauthority
authorityhaving
having
jurisdiction.
10.8
LIGHTING
10.8 NAVIGATION
NAVIGATIONLIGHTING
Piers
and
similar
structures
extending
Piersand
similar
structures
extendinginto
navigableinto navigable
waters
must
be
furnished
with
watersmust
be furnished with obstruction
obstruction lighting
lighting as
as
required
by
regulations
of
the
U.S.
Coast
Guard
U S . CoastGuard or
or other
other
required byregulationsofthe
authOlity
jurisdiction.
authorityhaving
having
jurisdiction.
10.9
10.9 FIRE
FIREALARM
ALARMSYSTEMS
A
A fire
fire alarm
alarm system
system isis normally
normallymaintained
maintainedwithin
withinaaproprocessing
plant.
Some
systems
are
elaborate
while
cessing plant.
systems are elaborate while others
others are
are
relatively
RP 2001
2001 discusses
discusses fire
firealarm
alarmrequirerequirerelatively simple.
simple. API
API RP
ments,
the NFPA
Fire Protection
Protection Handbook
Handbook discusses
discusses
ments, and the
NFPA Fire
alarm
alarmfacilities.
facilities.
10.10
HEAT TRACING
10.10 ELECTRIC
ELECTRICHEATTRACING
Electric-heat
areare
usedused
for
Electric-heattracing
tracingsystems
systems
formaintaining
maintainingproprocess
cesspiping
piping or
orvessel
vesseltemperatures
temperaturesand
andfor
for freeze
freezeprevention.
prevention.
of steam-heat
tracing
Electric
heattracing
tracing isis used
inlieu
lieu
Electricheat
usedin
ofsteam-heat
tracing
where
determinedto
to be
be more
moreeconomical
economicalororwhere
wherepreprewhere itit isis determined
cise
cisetemperature
temperaturecontrol
controlisisrequired.
required.
Several
Several types
types of
of electric
electric heat
heat tracing
tracing systems
systems are
are availavailable.
able.These
These include
includeelectrical-resistance
electrical-resistanceheat
heattracing
tracingas
as well
well
as
asimpedance,
impedance,induction,
induction,and
andskin
skineffect
effectsystems.
systems.ElectricalElectricalresistance
resistance heat
heat tracing
tracing isis typically
typically used
used for
for applications
applicationson
on
process
process units.
units. Impedance,
Impedance, induction,
induction, or
or skin-effect
skin-effect electric
electric
heat
heat tracing
tracing isis typically
typically applied
applied on
on long
long pipelines
pipelinesto
to offsite
offsite
locations
locations or
or between
between. facilities.
facilities. IEEE
IEEE Std
Std 515
515 provides
provides
design
design guidance
guidance for
for electrical-resistance
electrical-resistance heat
heat tracing
tracing syssystems.
IEEE 844
844 provides
provides similar
similar guidance
guidance for
for impedance,
impedance,
tems. IEEE
induction,
induction,and
and skin
skineffect
effectsystems.
systems.
Electric-heat
tracing
systems
typically
powered
Electric-heattracingsystemsareare
typically
powered
from from
field
distribution
panelboards
fed
from
dry-type
transformers.
field distribution panelboardsfed from dry-type transformers.
Each
Each panelboard
panelboardcircuit
circuitisis used,
used,within
withinits
itscapllcity,
capacity,to
to serve
serveaa
continuous
if required.
continuoussection
sectionof
ofpiping,
piping,associated
associatedvalves
valvesand,
and,
if required,
process
Power
circuit
conductors
must be
suitprocessinstrumentation.
instrumentation.
Power
circuit
conductors
be
must
suitbe be
exposed.
abJe
ablefor
forthe
thetempera~s
temperaturesto
towhich
whichthey
theywill
will
exposed.
System
disconnect and
arrangementsshould
should
Systemdisconnect
and grounding
groundingarrangements
NEC
Article 427
meet
427 requirements.
requirements. For
For electrical-resiselectrical-resismeetNEC
Article
tance-type
tance-type heat
heat tracing systems,
systems,this
this includes
includes aa requirement
requirement
that
all
heat-tracing
circuits
be
provided
with
either
ground
that heat-tracing circuits be
with either ground
an
fault
protection
or,
for
industrial
establishments,
alarm
faultprotectionor, for industhl establishments, an alalm
indication
indicationof
of aa ground
groundfault.
fault.
All
must be
All components
components of
of electric-heat
electric-heat tracing
tracing systems must
be
suitable
for
the
area
classification
in
which
they
will
suitable for the area classification in which theywill
be be
installed.
installed.
10.11
10.11 CATHODIC
CATHODICPROTECTION
PROTECTIONSYSTEMS
Cathodic
Cathodicprotection
protectionsystems
systemsare
are used
usedto
to provide
provideCOITosion
corrosion
protection
for
underground
piping,
tanks,
protection for undergroundpiping, tanks, or
or other
other metal
metal
structures
andand
offshore
facil-facilstructuresthat
thatare
arein
incontact
contactwith
withthe
theearth,
earth,
offshore
ities.
either
ities.Cathodic
Cathodicprotection··
protectionsystems
systemsareare
eithersacrificial
sacrificialanode
anode
or
impressed
CUlrent
type.
Cathodic
protection
sUl'Veys are
are
or impressed current type. Cathodic protection surveys
to
determine
the
type
of
system
to
typically
performed
typically
to determine the type of system to be
be
used.
used.
Sacrificial
source.
Sacrificialanode
anode systems
systems do
do not
not require
require aa power source.
Impressed
Impressedcurrent
currentsystems
systemsrequire
requireaaDC
DC power
powersource
sourcethat
that isis
supplied
suppliedfrom
fromaa field
field transfOlmer/rectifier
transformer/rectifierassembly.
assembly.AmmeAmmeters
of the
flow
tersare
areoften
oftenprovided
providedto
toallow
allowmonitoring
monitoring
of current
the
currentflow
in
circuits.
inimpressed
impressedcurrent
current
circuits.
Design
protectionsystems
systemsis prois proDesign guidance for
for cathodic
cathodic protection
vided
RP 651
65 l and
and NACE
NACE RP
RP 0169.
0169.In
In the
the design
design of
of
vided by
by API
API RP
cathodic
cathodicprotection
protectionsystems,
systems,consideration
considerationmust
mustbe
be given
given to
to
the
thatthat
such
nearby
theadverse
adverseimpact
impact
suchsystems
systemsmay
may have
haveononany
any
nearby
electrical-grounding
electrical-groundinggrid
grid systems.
systems.For
Foroffshore
offshoreinstallations,
installations,
design
guidanceisis
given
RP 0176
0176 and
and NACE
NACE
designguidance
given
by by NACE
NACE RP
RP0675.
RP 0675.
Cathodic
Cathodicprotection
protection system
system components
componentsmust
must be
be suitable
suitable
for
the
area
classification
in
which
they
are
installed.
'Transfor the area classificationin which they are installed.Transformer/rectifier
thatthat
are installed
in classified
loca- locaformer/rectifierassemblies
assemblies
are installed
in classified
to
be
oil-immersed.
tions
are
often
designed
tions are often designed
to be oil-immersed.
10.12
ANDPRECIPITATORS
PRECIPITATORS
10.12 OESALTERS
DESALTERSAND
desalters are
areused
used to
10.12.1
10.12.1 Electrostatic
Electrostaticdesalters
to reduce
reduce the
the salt
salt
of
corand
andsolids
solidscontents
contents
ofcrude
crudeoils.
oils.This
Thisreduces
reducesfouling
foulingandand
corsurfaces,
rosion
salt
rosionresulting
resultingfrom
from
saltdeposition
depositionononheat
heattransfer
transfer
surfaces,
and
by decomposition
of the
lYpiandacids
acidsformed
formed
by decomposition
theofchloride
chloridesalts.
salts.
Typical
the
cal solids
solidswhich
whichare
areremoved
removedfrom
from
the crude
crudeoil
oilinclude
includefine
fine
sand,
clay
and
soil
particles,
irbn
oxide,
and
other
contamisand, clay and soil particles, iron oxide,
other contaminants
picked
up during
crude
nantswhich
whichcan
canbebe
picked
up during
crudeoil
oilproduction
productionand
and
The
desalting
process
can
also
improve
transportation.
also improvecatalyst
catalyst
transportation.The desalting process can
life
downstreamprocesses
processes
by partially·
rejecting
life in
indownstream
bypartially
rejecting
certaincertain
metals
that
can
cause
catalyst
deactivation.
metals that can cause catalyst deactivation.
Desalting
Desaltingisis performed
performedby
by mixing
mixingcrude
crude oil
oil with
withwater
wateratat
from
90°C
to
150°C.
The
salts
are
dissolved
temperatures
temperatúres from 90°C to 150°C. The salts are dissolvedin
in
the
the wash
wash water
water and
and the
the oil
oil and
and water
water phases
phases are
are then
then sepaseparated
rated in
in aa settling
settling vessel.
vessel.AA high-potential
high-potentialelectrical
electrical field
fieldisis
Copyrighted material licensed to IDOM.
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ELECTRICAL
INSTALLATIONS
ELECTRICAL
lNSTALLATlONSIN
IN PETROLEUM
PETROLEUMPROCESSING
PROCESSING PLANTS
PLANTS
applied
applied across
across the
the settling
settling vessel
vessel to
to facilitate
facilitatethe
the coalescing
coalescing
of
of the
the salt
salt water
water droplets.
droplets. Either
Either AC
AC or
or DC
DC fields
fields may
may be
be
used,
with potentials
16,000V
V to
to 35,000
35,000 V.
V.
used, with
potentials ranging
ranging from
from 16,000
Energy
Energy consumption
consumptionisis typically
typically0.05
0.05 kWh
kWh to
to 0.15
O. 15kWh
kWh per
per
barrel
barrel offeed.
of feed.
In
In some
some cases,
cases,both
bothAC
AC and
and DC
DC fields
fields are
areused
usedto
to provide
provide
high
high dewatering
dewatering efficiency.
efficiency.The
The AC
AC field
field isis applied
applied near
near the
the
oil/water
the the
DC
applied
oivwaterinterface;
interface;andand
DC field
fieldin
in the
theoil
oilphase
phaseisis applied
above
abovethe
the interface.
interface. Efficiencies
Efficienciesofofup
uptoto99%
99%water
water removal
removal
in
single stage
stage are
are claimed
claimed for
for the
the dual-field
dual-field process.
process. The
The
in aa single
dual-field
water
sepadual-fieldelectrostatic
electrostaticprocess
processprovides
providesefficient
efficient
water
separation
temperatures,resulting
resultingin ainhigher
a higher
overall
ration at
at lower
lowertemperatures,
overall
energy
energyefficiency
efficiencythan
thanfor
for single
singlefield
fielddesigns.
designs.
10.12.2
10.12.2 Electrostatic
Electrostaticprecipitators
precipitatorsare
are used
used to
to remove
remove solid
solid
a DC
particles
streams an
anapplication
applicationofof
particles from
from flue
flue gas
gas air
air streams
a DC
field.
Typically,precipitators
precipitators
are located
inplants,
power plants,
field.Typically,
arelocated
inpower
incinerators,
units.
incinerators,and
and fluid
fluidcatalytic
catalyticcracking
cracking
units.
10.13
10.13 PORTABLE
PORTABLE EQUIPMENT
EQUIPMENT
Much
in processMuchofofthe
the portable
portableor
ormobile
mobileequipment
equipmentused
used
in processing
electric
ingplants
plantsrequires
requires
electricpower.
power. Some
Someexamples
examplesof
of portable
portable
equipment
power
equipmentrequiring
requiringelectric
electric
power are
are as
asfollows:
follows:
95
95
a.a. Welding
Weldingmachines.
machines.
b.
b. Motor-driven poliable
portable pumps.
pumps.
c.
c. Motor-driven
Motor-drivenportable
poltablecompressors.
compressors.
d.
Power
tools.
d. Power tools.
e.
e. Extension
Extensionand
and hand
hand lamps.
lamps.
f.f. Annealing
machines.
Annealingmachines.
g.
g. Test
Test instruments.
instruments.
h.
h. Tool
Tool trailers.
trailers.
i.i. Storehouse
trailers.
Storehousetrailers.
j.j. Office
trailers.
Officetrailers.
k.
k. Meter
Meter testing
testingrigs.
rigs.
This
600 V
V or
or less,
less, single-phase
single-phase or
or
This equipment
equipment operates
operatesatat600
three-phase
areinstalled
installed
three-phase as
as required.
required. Permanent receptacles are
the installawhen
use of
when periodic
periodic'use
of portable
portableequipment
equipmentjustifies
justifies
the installation.
Otherwise,
temporary
wiring
used for supplying
tion.Otherwise,
temporary
wiring
isusedforissupplying
power.
given
to grounding
porpower. Particular
Particularattention
attentionshould
shouldbebe
given
to grounding
portable
equipment
for
personnel
protection.
(Section
5
provides
5 provides
table equipment for personnel protection. (Section
further
of this
thissubject.)
subject.)
furtherdiscussion
discussionof
~~
.
STD.API/PETRO RP
~
.
Copyrighted material licensed to IDOM.
SL10-ENGL
ObLSb3L
No further reproduction or distribution permitted.
L999
m
0732290
T36 I
I
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
SECTION
SECTION 11-INHERENT
Il-INHERENT ELECTRICAL
ELECTRICALSAFETY
SAFETY
11.1
11.1 GENERAL
GENERAL
11.1.1
advan11.1.1 The
The electrical
electrical engineer who
who intends
intends to
to take
take advantage
electIical safety by design
tage of incorporating electrical
design in
in his work
needs
first totoobtain
obtainknowledge
knowledge
about
the requirements for
needs first
about
the requirements
for
working
safely
in
an
atmosphere
influenced
by
the
presence
working safely in an atmosphere influenced by the presence
of electricity.
electricity.
11.2.1.2
OSHA 29
11.2.1.2OSHA
29 CFR
CFR 1926
1926
Subpart
Subpart K-Electrical
K-Electrical Standards
Standardsfor
for Construction
Construction
11.1.2
pIincipal hazards
hazards of
working around
aroundelectrical
electtical
11.1.2 The
The principal
of working
equipment
equipment are
are electrical
electricalshock
shock and
andelecttical
electricalarc
arc flash.
flash. While
While
an electrical
electrical
shock
hazard
involves
or approach
approach so
so
an
shock
hazardcontact,
involves contact, or
close
close that
that the
the intervening
interveningair
airgap
gap breaks
breaks down
down and
and becomes
becomes
conductive,
conconductive,the
theelectrical
electrical arc
arc flash
flash hazard can extend a considerable
considerabledistance
distancefrom
from the
the exposed
exposedenergized
energizedelecttical
electrical
conductor
ductor or
or circuit
circuit part.
part.
I
related
related maintenance requirements.
1910.381
futuresafety
safety
1910.381 through 1910.398-Reserved
1910.398-Reserved for
for future
requirements
requirementsfor
for special
specialequipment.
equipment.
1910.399-Definitions
applicable to
1910.399-Definitions applicable
to each
each division.
division.
requirements.
maintenance
11.2.1.3
112.1.3 NFPA
NFPA 70
70 National
National Electrical Code
Code
The
ElectricalCode
Code deals
the
The National
NationalElectrical
deals primatily
primarily with
withthe
minimum
installation requirements
requirements for
minimum design and installation
for electrical
electrical
equipment.
thatelectrical
electtical
facilities
OSHA has
has determined
determinedthat
facilities
equipment. OSHA
installed
are
installedin
in accordance
accordance with
withthetheNEC
NEC
are safe
safe until
untilthe
theequipequipment
ment isiscompromised
compromisedby deterioration,
deterioration,or
or until
until an
an unsafe
unsafe act
act
or
or aa combination
combinationof
of unsafe
unsafe acts
actsoccur.
occur.
11.1.3
11.1.3 The
The most
most effective
effective protection against electrical hazards
ards can
canbe
be achieved
achieved by
by distance
distance and/or
andor by
by enclosure.
enclosure.Where
Where
exposed
energized electrical
electticalconductors
conductors or
exposed energized
or circuit
circuit parts
parts are
are
present,
present, the
the assigned
assigned employee
employee must
must possess
possess knowledge
knowledge of,
of,
and
safe
work
practices~
and must
mustemploy,
employ,electrical
electrical
safe
work
practices.
11.2.1.4
11.2.1.4 NFPA
NFPA 70E
70E Electrical
Electrical Safety
Safety Requirements
Requirementsfor the
the
Employee
Employee Workplace
Workplace
This
This document
documentdeals
deals primarily
primarily with
with the
the minimum
minimum requirerequirements
for
protecting
employees
working
in
and
around
ments for protecting employees workingin
around elecelecttical
equipment.
OSHA
recognizes
the
benefits
of
OSHA recognizes
the
benefits
of aa
trical
equipment.
consensus
consensusstandard
standardfor
for safe
safe work
work practices
practicesin
in general
general industry
industry
and
has
encouraged
the
NFPA
to
pursue
the
full
and has encouragedthe NFPA to pursue the fulldevelopment
development
of
of NFPA
NFPA 70E.
70E. NFPA
NFPA 70E
70E attempts
attempts to
to develop
develop specifics by
by
which
in Subpart
OSHA performance
performance statements in
Subpart SS can
can be
be
which OSHA
ac{;omplished.
accomplished.
11.2
REFERENCES
11.2
REFERENCES
~
11.2.1
11.2.1 The
The principal
principalsources
sourcesof
of guidance
guidancefor
for electrical
electricalsafe
safe
work
safe
workpractices
practicesand
and
safeelectIical
electricalfacilities
facilitiesare:
are:
~
11.2.1.1
.2.1.1
11
OSHA
OSHA 29
29 CFR
CFR 1910
1910
a.
a. Subpart
SubpartI-Personal
I-Personal Protective
ProtectiveEquipment
Equipment
1910.
137-Electtical protective
1910.137-E1ectrica1
protectiveequipment.
equipment.
b.
b. Subpart
SubpartJ-General
J-General Environmental
EnvironmentalControls
Controls
1910.
145--Specifications for
1910.145-Specifications
for accident
accident prevention
preventionsigns
signs
and
and tags.
tags.
191O.147-The
1910.147-The control
control of
of hazardous
hazardous energy
energy(lockout
(lockout
tagout).
tagout).
c.c. Subpart
SubpartR-Special
R-Special Industries
Industries
1910.269-Electrical
power generation, transmission
1910.269-Electrical power
transmission and
and
distribution.
distribution.
d.
d. Subpart
Subpart S-Electrical
S-Electrical
1910.30l-"Introduction':-This
elec1910.301-“Introduction’~-This subpart
subpart addresses electrical
safety
requirements
that
are
necessary
for
the
practical
tricalsafetyrequirementsthatarenecessary
for the practical
safeguarding
safeguardingof
of employees
employees in
in their
their workplaces.
workplaces.
Sections
1910.302
through
1910.399
contain
five major
Sections1910.302
through
1910.399
contain
fivemajor
divisions:
gized
divisions:
:
I
I
I
11.2.1.5
11.2.1.5 ANSJlIEEE
ANSIAEEE C2
C2 National
National Electrical
Electrical Safety
Safety Code
Code
The
with
The National
National Electrical
Electrical Safety Code
Code deals
deals primarily with
the
minimum design,
design,installation,
installation,and
andmaintenance
maintenance
requirethe minimum
requirements
ments related
related to
to overhead
overhead power
power lines,
lines, control
control and
and telecomtelecommunications
OSHA recognizes
recognizes the
thebenefits
benefitsof
of aa
municationsinstallations.
installations.OSHA
consensus
indusconsensus standard
standard for
for safe
safe work
work practices
practices in
in special industries
tries and
andhas
has encouraged
encouragedthe
theIEEE
E E E to
to pursue
pursue regular
regularrevisions
revisions
of
specifANSIAEEEC2.
C2.ANSJlIEEE
ANSVIEEEC2
C2 attempts
attemptstotodevelop
develop
specifof ANSIIIEEE
ics
Subpart
R can
OSHA performance
performancestatements
statementsin in
Subpart
R can
ics by
bywhich
whichOSHA
be
measured.
be measured.
.3 SPECIFICS
SPECIFICS
11.3
1910.302 through 191O.33O-Contain design safety stan1910’302through 1910*330”Contain
safety
dards
dards for
for electrical
electricalsystems.
systems.
1910.302 through 191O.308---Contain design safety stan1910’302 &Ough 1910’308rontain
safety
struction
dards
utilization
dards for
for electric
electric
utilization
systems. systems.
1910.309
1910.309through
through191O.330-Reserved
1910.330-Reserved for
for possible
possiblefuture
future
use
use for
for design
design safety
safetystandards
standardsfor
for other
otherelectrical
electricalsystems.
systems.
1910.331.
safety-related
1910.331. through
through 191O.36O--Contain
1910.360-Contain
safety-related
work
practices.
work practices.
1910.361
1910.361 through
through 1910.380-Reserved
1910.38O”Reserved for
for future
future safetysafety97
97
11.3.1
ener11.3.1 Distance
Distance from
from potential
potential sources
sources of
of exposed
exposedenergized electrical
conductors
and
circuit
parts
can
be
achieved
electricaland
conductors
circuit parts can be achieved
by
means.
Qualified persons
permitted to
by various
variousmeans.
Qualified
persons are
arepermitted
to
approach
much
closer
than
are
unqualified
persons.
Qualified
approach
much
closer
than
are
unqualified
persons.
Qualified
persons
familiar
with
OSHA definition
definition are
are"Ones
“Ones
familiar
with the
the conconpersons by
byOSHA
struction and
operation
of
the
electrical
equipment
and operation
theof
electrical equipment and
and the
the
electtical
withwith
the work
beingbeing
performed:'
electricalhazards
hazardsinvolved
involved
the work
performed.”
11.3.1.1
11.3.1-1 Unqualified
Unqualified persons
persons around
around voltages
voltages to
to ground
ground
of
V or
of 50
50 kkV
or less
less must
must maintain
maintain aa distance
distance of 305
305 em
cm (lOft).
(10 ft).
For
For voltages
voltages to
to ground
ground over
over 50
50 kV,
kv, use
use 305
305 cm
cm (10
(10 ft)
ft) plus
plus
10
10cm
cm (4
(4 in.)
in.) for
for every
every kV
k v over
over 50
50 kV.
kv.
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98
98
API
PRACTICE 540
PRACTICE
API RECOMMENDED
RECOMMENDED
540
11.3.1.2 Qualified
personsmust
mustnot
not
approach closer than
Qualified persons
approach
the distances
S,
S, Table S-5.
distances shown
shownininSubpart
Subpart
11.3.1.3 Examples
Examples of distance
distance are: the clear working
working
space
space requirements
requirements of Subpart
Subpart S,
S, Table
Table S-1;
S-1; that tobebe
achieved
control room breaker operation
operation for
for
achieved by use of control
remotely opening
opening or closing
closing switching
switching devices;
devices; that
achieved
bus with
withcontrol switches
switches located
located
achieved by use of mimic bus
remote from
the
front
of metal enclosed or metal clad
fromthe
front
ofmetal
switchgear;
umbilical cords
cords
switchgear; or that to be achieved
achievedby use of umbilical
having
having control
control switches
switches for
for opening
opening or closing
closing the switching
switching
device
device on the far end.
end.
11.3.2 Enclosures
varyingdegrees
degrees of integrity.
The
Enclosures have
havevarying
integrity.The
enclosures' principal
principalfunctions
functions are
theelectrical
electrical
are to protect the
conductors
elements
and from
conductors or circuit parts
partsfrom
fromthethe
elements
from physical damage,
damage,as
as well as
as to isolate
isolate the electrical
electricalconductors
conductorsand
by corcircuit
circuit parts from
from people.
people. Detelioration
Deteriorationofofenclosures
enclosures
rosion,
mechanical damage
damage can
can lead to exposure
exposure
rosion, neglect,
neglect, or mechanical
of electrical
or circuit
electricalconductors
conductors
circuit parts.
parts.
11.3.2.1
enc1osure~when:
properly applied
11.3.2.1 Examples
Examples ofenclosure-when'
properly
and maintained
maintained can be counted
counted on to contain
contain the explosive
explosive
force
force of an electrical
electrical arc
arc or divert its
its effect
effect in an innocuous
direction-are:
direction-are: explosionproof
explosionproof enclosures
enclosures that contain
contain the
explosive
explosive forces;
forces; or those
those of arc-resistant
arc-resistant construction
construction that
through specially
direct theenergy
energy of the explosion
explosion
through
specially
designed vents in the top or ends of the equipment
equipment to nonocnonoccupied locations.
locations.
Copyrighted material licensed to IDOM.
ST$.API/PETRO RP 540-ENGL.Lq99
I
No further reproduction or distribution
permitted.
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APPENDIX
APPENDIX A-INFORMATIVE
A-INFORMATIVE
INHERENT
SAFETY
INHERENT SAFETYCONSIDERATIONS
CONSIDERATIONS
Appendix
additional items
items that
that
q.q. Provision
all energy
energy isolating
isolatingdevices,
devices,includincludAppendix A
A isis intended
intended to
to provide
provide additional
Provision to
to padlock all
may
ing
in
may need
needto
to be
be addressed
addressedininthe
thesafe
safeapplication
applicationof
of electrical
elecbical
ingfuse
fuseblocks
blocks
in off-position.
off-position.
equipment
A suggested
suggested
equipmentinto
into petroleum
petroleum processing
processing facilities,
facilities:A
r.r. Use
Use of
of voltage-rated
voltage-ratedboots
boots over
over switchgear bus joints
joints in
in
approach
asdiscussion
discussion
topics when
approach isis to
to use
use these
these items
itemsas
topics
when
place
placeof
of electrical
electricaltaping
tapingto
tofacilitate
facilitatemaintenance.
maintenance.
defining
Communicadefiningthe
thedesign
designscope
scopewith
withthe
theproject
projectteam.
team.
Communica- s.s. Use
of“transparent
"transparentinspection
inspectionwindows”
windows"
in switchgear,
Use of
in switchgesu;
tion
between
the
user,
Engineering
&
Construction
Service
tion
the user, Engineering & ConstructionService
switches,
motor
control
centers,
and
transformers
allow
switches,
control centers, and transformers toallow
(E&CS),
(E&CS),and
and vendor
vendor isis strongly
strongly urged
urgedto
to evaluate
evaluatethe
thedesirdesirinspection
or
monitoring
of
required
components
and
inspection or monitoring
of
required
components
and
ability,
necessity
of each
item.item.
It is It
recognized
ability,capability
capabilityand
and
necessity
of each
is recognized functions.
functions.
that
or
thatnonodesign
designcould
could
or would
would incorporate
incorporateallallof
of these
theseitems.
items.
t.t. Use
CT secondary,
secondary,open-circuit
open-circuitprotectors.
protectors.
Useof
of CT
u.
Segregation of
u. Segregation
of electrical
electrical components
componentswith
with different
different voltvoltA.1
MotorControl
Control
A.l Switchgear
Switchgear and Motor
ages
enclosures,
cabinets,
etc. etc.
agesinincommon
common
enclosures,
cabinets,
Centers
Centers
v.v. Moisture
inhibitors in
Moistureinhibitors
in switchgear,
switchgear, instruments, junction
junction
boxes,
enclosures,
etc.
boxes, enclosures,etc.
Consider
in the
design:
Considerusing
usingthe
thefollowing
followingfeatures
features
in the
design:
w.
primary
and secondary
breakers
of a
W. Interlocking
Interlocking of
ofprimary
andsecondary
breakersof
a
a.a. Arc
Arc Resistant
ResistantSwitchgear
Switchgearfor
forall
all metal-clad
metal-cladapplications.
applications.
power
prevent
back-feed
through the
power transformer
transformer
prevent
to to back-feed
through
the
b.b. Use
ofcurrent-limiting
cunent-limiting fuses
480 V
V and
and 600
600 VV
Use of
fuses for
for all
all 480
transformer.
transformer.
devices.
devices.
x.
(on
x. Provisions
Provisions to
to manually
manually trip
trip breakers
breakers(on
lossloss of
of trip
trip
c.c. Equipment
Equipmentselection
selectionand
and sizing
sizing to
to minimize/reduce
minimize/reduceflash
flash
power)
thethe
opening
of
power)without
withoutrequiring
requiring
opening
of the
theenclosure
enclosuredoors.
doors.
protection
protectionboundary.
boundary.
y.y. Interlocking
Interlockingto
toprevent
prevent any
anyundelTating
unden-atingbecause
becauseofofsystem
system
d.d. Remote
Remoteclose/open
close/openof
ofswitchgear
switchgearbreakers.
breakers.
configuration,
or
out-of-synch
closures
at
locations
where
configuration, or out-of-synchclosures at locationswhere
e.e. Remote
Remote racking-in
racking-in of
ofswitchgear
switchgearbreakers.
breakers.
synch
an
synchcheck
checkrelays
relaysare
arenot
notprovided
providedand
and
an out-of-synch
out-of-synchconconf.f. Secondary
Secondaryselective
selectiveswitchgear
switchgearsystems:
systems:Use
Useof
of aa second
second
dition
can
occur.
dition can occur.
tie-breaker
the tie-breaker
tie-breakertotoensure
ensurecomplete
complete
tie-breaker in
in series
series with the
z.z. Interlocking
switches(with
(with no.
no or
or inadeinadeInterlocking of
of all
all isolating switches
de-energization
isolation.
de-energizationand
and
isolation.
quate
rating) with
withinterrupting
interruptingdevices
devicessuitable
suitable
quate interrupting rating)
g.
g. Secondary
Secondaryselective
selectiveswitchgear
switchgearsystems:
systems:Use
Useof
of aa second
second
for
ensure
forfault
faultinterruption
interruptionto to
ensurede-energized
de-energizedoperation.
operation.
tie-breaker
in
parallel
with
the
tie-breaker
to
facilitate
tie-breaker in parallel with the tie-breaker tofacilitateon-line
on-line
aa.
aa. Interlocking to
to prevent
preventaccess
accessto
to live
live parts.
parts.
testing
testingof
of the
the secondary
secondaryselective
selectivesystem
systemoperation.
operation.
bb.
bb. Interlocking
Interlockingto
to prevent
prevent closing
closing of
of breakers
breakers or
or starters
startersifif
h.
h. Local
Local back-up trip
trip provisions
provisionsonly
only of
of breakers
breakers normally
trip
power
is
not
available.
trip poweris not available.
closed/opened
location.
closedopenedfrom
froma aremote
remote
location.
cc.
cc. Indication
Indicationof
of overload
overloadtrips
tripson
on all
allmotor
motorstarters.
starters.
i.i. CT
CTshorting
shortingteD"Dinals
terminalstotobebelocated
locatednear
nearrelay
relay wiring
wiringterterdd.
Covers
for
all
teD"Dinals
containing
potential
50
dd. Covers for all terminals containing potential sources
sources 50
minals
access and
andautomatic
automatic
minals for
for quick/easy
quicweasyaccess
and shorting;
shorting;and
V
and
above.
V
and
above.
shorting
provisions
whenever
relays
with
current
inputs
are
shorting provisions whenever relays with current inputs are
ee.
failure of
ee. Utilization
Utilization of
of single7phase
single-phaserelays to
to prevent
preventfailure
of
removed.
removed.
breaker
tripping
of
three-phase
relay
failure
at
the
breaker
tripping
because
of
three-phase
relay
failure
at
the
j.j. Use
Use of
of insulated
insulatedbuses
busesand
andbus
busends
ends in
in bus
bus ducts,
ducts, switchswitchtime
timeofofa fault.
fault.
a
gear,
center,
and
gear,motor
motorcontrol
control
center,
and switchracks.
switchracks.
ff.
ff. Utilization
Utilizationofoflock-out
lock-outrelays
relaysto
to prevent
preventclosing
closingof
of breakbreakk.
k. Use
Use of
of "finger
“fingersafe"
safe”fuse-holders:
fuse-holders:the
thefuses
fusesare
are contained
contained
ers/starters
operation.
ers/startersafter
afteraaprotective
protectivedevice
device
operation.
in
removable carrier
carrierwith
withmarkable
markable
labels. Finger
Finger safe
safe isis
in a removable
labels.
gg.
defined
fuse
relays
vs
gg. Utilization
Utilizationofofsingle-phase
single-phase
relays
vsthree-phase
three-phaserelays
relaysto
to
definedas
aswhere
wherelive
liveparts
partsare
areinaccessible
inaccessiblewhether
whether
fuseisisin,
in,
or
out,
or
in-between.
allow
safe
testing
and
calibration
of
relays
while
the
or out, or in-between.
allow safe testing and calibration of relays while the equipequipment
1.1. Use
mentisisenergized.
energized.
Useof
offinger
fingersafe
safeteD"Dinals
terminalsin
in 120/208/240
120/208/240V
V power
powerpanpanels,
panels,
DCSIPLC
hh.
els,relay
relaycontrol
control
panels,
DCSPLCcontrol
controlsystems,
systems,metering
metering
hh. Utilization
Utilization of
of independent
independent current
currenttransformers
transformersand
andcircirand
control
room
cuits/wiring
relaying.
andinstrument
instrumentpanels,
panels,
control
roomteD"Dination
terminationpanels,
panels,etc.
etc.
cuitdwiringfor
forprimary
primary and
andback-up
back-up
relaying.
m.
"built-in"
transducers.
m. Use
Useofofequipment
equipmentwith
with
“built-in”
transducers.
ii.
ii. Installation
Installationof
of surface
surfacemounted
mounted flexitest
flexitestswitches
switches on
on the
the
n.
Use
of
"encapsulated"
equipment.
switchgear
during
testing
(blades
n. Use of “encapsulated” equipment.
switchgearto
to prevent
preventrelay
relaytrips
trips
during
testing
(bladesof
of sursurface-mounted
not
..
o.
face-mountedswitches
switchesshall
shall
notbe
be energized
energizedwhen
whenopen)
open).
o. Lockable,
Lockable,hinged-type
hinged-typerear
reardoors
doorsat
at switchgear
switchgearbreakers.
breakers.
jj.
Criticalalarms
alarms
to attended
an attended
location or
jj. Conveying
Conveying all critical
to an
location
or
control
controlroom.
room.
p.
where itit isis
p. Lockable
Lockable front
front doors
doors atat switchgear
switchgear breakers
breakers where
unfeasible
to
place
a
lock
on
the
switchgear
breakers.
unfeasible to place alock on the switchgear breakers.
99
99
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100
1O0
API
PRACTICE
RECOMMENDED
API RECOMMENDED
A.2
Groundingand
and
A.2 Electrical
ElectricalSystemGrounding
Ground
Detection
GroundFault
Fault
Detection
following:
theConsider
Considerthe following:
PRACTICE
540
540
e.e.Procedures
Procedures for
restoration of
transfer of
formanual
manualrestoration
ofand
andtransfer
ofbuses
buses
in secondary selective substations on the switchgear doors.
secondary
in selective
substations
on the switchgesu. doors.
f.f. Caution
switchgear work:
Cautionfor
for switchgear
work caution
cautiontags
tags toto be
be located
located
transformers
(PTs)/fuses/etc.
nearpower
powertransformers (PTs)/fuses/etc.
near
a.a. Existing
Existing 480
480 VV and
and 600
600 VV ungrounded
ungrounded wye
wye systems:
systems:
Examples:
Examples:
Install
high-resistance
grounding
systems
to
enable
quick
to enablequick
Installhigh-resistancegroundingsystems
1.1. Removing
RemovingPT
PTfuses
fuseswill
willcause
causetransfer
transferof
ofbuses.
buses.
alann,
of
alarm,detection,
detection,and
andisolation
isolation
ofground
groundfaults
faultsininmotor
motorconconof
!::tuses.
2.2. Removing
PT
will
cause
transfer
Removing PT will cause transfer of buses.
..
trol
trolcenters
centersand
andswitchracks
switchracks.
3.3. Removing
RemovingPT
PTfuses
fusesmay
mayshutdown
shutdownlarge
largedrivers.
drivers.
b.b. Existing
deltasystems:
systems:
Existing 480
480 VV and
and 600
600 VV ungrounded
ungroundeddelta
4.4. Removing
voltage
relay
may
shutdown
large
driver.
Removing
voltage
relay
may
shutdown
large
driver.
Install
ground,
andand
Installgrounding
groundingtransformers
transfomerstotocreate
createa asystem
system
ground,
5.5 . Removing
protection
relay(s)
may
shutdown
switchRemovingprotectionrelay(s) may shutdownswitchhigh-resistance
groundingsystems
systems
alann,
high-resistancegrounding
to to enable
enable quick
quickalarm,
gear
breaker(
s).
gear
breaker(s).
detection,
motor
control
cen- cendetection,and
andisolation
isolationof
ofground
groundfaults
faultsin in
motor
control
6.6. Removing
etc.etc.
Removingrelay
relaymay
mayshutdown
shutdownswitchgear
switchgearbus,
bus,
ters
tersand
andswitchracks.
switchracks.
g.g. Caution
onstored
stored
energy equipment:
Caution for
for work
workon
energy
equipment:Caution
Caution
c.c. Ground-fault
Use
zero
Ground-faultalann
alarmand
anddetection:
detection:
Use
zerosequence
sequenceCTs
CTs
tags
to
be
located
on
electrical
and
mechanical
stored
energy
to
be
located
on
electrical
and
mechanical
stored
energy
tags
ininstarters
startersand
andbreakers
breakersforforquick
quickalann,
alam,detection,
detection,and
andisolaisolaequipment.
equipment.
tion
faults inin 480
control
480 VV and
and 600
600 VV motor
motorcontrol
tion of
of ground
groundfaults
centers
and
switchracks
with
high-resistance
grounding.
Examples:
centers and switchracks with high-resistance grounding. .
Examples:
d.d. Auto/manual
Auto/manualgrounding
grounding of
of 1,000
1,000VV and
and above,
above,feeders,
feeders,
1.1. Discharge
capacitors prior
work on
Dischargecapacitors
prior toto start
start of
of
work
.on
capacitor
etc.,' when
capacitorbanks,
banks, motors,
motors, etc.,
when switchgear
switchgearbreakers
breakers or
or
capacitors.
capacitors.
motor
motorstarters
startenare
arewithdrawn.
withdrawn.IfIf grounding
groundingisisprovided,
provided,propro2.2. Discharge
prior
power
Dischargepower
powercables
cables
priortotostart
startof
ofwork
workonon
power
vide
interlock
with
main
switching
device.
vide interlock with main switching device.
cables.
cables.
3.3. Discharge
to
Dischargemotors
motorsprior
prior
tostart
startof
ofwork
workon
onmotors.
motors.
A.3
A.3 Substations
Substations
work on
4.4. Discharge
generators prior
Dischargegenerators
prior toto start
start of
of
work
on
generators.
generators.
Consider
Considerthe
thefollowing:
following:
5,5: Discharge
to
Dischargesprings
springsprior
prior
tostart
startof
ofwork
workon
onbreakers.
breakers.
a.a. Fire
transfonners.
Firewall
wallbetween
betweenpower
power
transformers.
h.h. All
substation
and
outdoor
equipment
labeling
All substation and outdoor equipment labelingtotoinclude
include
b.b. Use
interrupter
(GFCI)
receptacles.
Useof
ofground
groundfault
faultcircuit
circuit
interrupter
(GFCI)
receptacles. the
fonowing:
the following:
c.c. Use
Use of
of insulating
insulatingmats
matsin
in substations
substationsand
andmotor
motorcontrol
control
1.l. Equipment
name.
Equipmentnumber
numberand
and
name.
centers.
centers.
2.2. Source
Sourceof
ofincoming
incomingpower
powersupply.
supply.
d.d. Use
around
outdoor
pad-padUseof
ofconcrete
concreteor
ormetal
metalpost
postbarriers
barriers
around
outdoor
3.3. Areallist
AreaAistofofpower
powerusers,
users,etc.
etc.
mount
other
electrical
equipment.
mounttransfonners
transformersandand
other
electrical
equipment.
1.i. Labeling
forequipment
equipment
with
multiple
incoming
Labelingfor
with
multiple
incoming
power power
e.e. Use
bank
totocontain
Useoftoe-waU
of toe-wallaround
aroundbattery
battery
bank
containbattery
battery.
sources
to
be
as
follows:
sources to be as follows:
liquid
liquidininthe
theevent
eventof
ofbattery
batteryleaks.
leaks.
1.l. Equipment
name.
Equipmentnumber
numberand
and
name.
f.f. Use
bank toto prevent
Use of
of plexiglass
plexiglass barrier
barrier atat the
the battery
battery bank
prevent
ofofincoming
power
supply.
2.2. Sources
Sources
incoming
power
supply.
unqualified
getting
close
to
unqualifiedpersons
personsfrom
from
getting
close
tothe
theexposed
exposedbattery
battery
3.
Areallist
of
power
users,
etc.
3.
AreaAist
of
power
users,
etc.
tenninals.
terminals.
4;4. Any
required
for
Anyspecial
specialprocedures
procedures
required
forthe
theisolation
isolationof
ofthe
the
g.g. Use
Use of
of on-line
on-line monitoring
monitoring of
of dissolved
dissolved gas
gas in
in transtransmultiple
incoming
power
sources.
multiple incoming power sources.
former
formeroil.
oil.
j.j. Caution-for
Caution-forremote
remoteenergizationlstart
energizatiodstartof
ofequipment:
equipment:
1.
Label
switchgear
breakers,
generators,
motors,
etc.;etc.;
1.
Label
switchgear
breakers,
generators,
motors,
A.4
Marking
A.4 Labeling
LabelingandMarking
ififthese
are
designed
for
remote
start
orenergization.
start or energization.
these are designed for remote
Consider
2.2. Use
Considerthe
thefollowing:
following:
Useof
ofaudible
audiblesignals
signalsatatequipment
equipmentprior
priortototheir
theirenerenergizationlstart.
gizatiodstart.
a.a. Mark
flash protection
protectionboundary
boundary
personal
pr~tective
Mark flash
andand
personal
protective
equipment
(PPE)
requirements
on
each
switchgear,
equipment
(PPE)
requirements
each
onswitchgear,
A.5
A.5 Miscellaneous
Miscellaneous
switchrack,
motorcontrol
controlcenter,
center,
work,
switchrack,motor
etc.etc. for
for energized
energizedwork,
work
within
flash
protection
boundary,
etc.
work within flash protection boundary,
etc.
Consider
Considerthe
thefollowing:
following:
b.b. Labeling/marking
Labelinglmarkingof
of instrument
instrumentrelays/meters,
relaydmeters,all
all should
should
a.a. Fireproofing
in fire
hazard
area.area.
be
Fireproofingofofcables/conduits
cables/conduits
in fire
hazard
be labeled/marked
labeledmarked both
both on
onfront
frontand
andrear
rearof
ofthe
the switchgear
switchgear
b.
Fireproofing
of
motor-operated
valves
in
fire
hazard
doors
to.eliminate
errors
when
troubleshooting.
b. Fireproofing of motor-operated valves
in fire hazardarea.
area.
doors to eliminate errors when troubleshooting.
c.
Use
of
fluorescent
yellow
plastic
covers
c.c. Mimic
one-line
diagram
on
the
front
panel
of
uninterruptc. Use of fluorescent yellow plastic coverson
onpole
poleline
lineguy
guy
Mimic one-line diagram onthe front panelof uninterruptwires
traffic
ible
wirestotoalert
alert
trafficininthe
thearea
area.
(UPS).
iblepower
powersupply
supply(UPS).
d.d. UPS
manual-bypass procedures
procedures
d.d. All
source breakers
breakers for
U P S shut-down,
shut-down,start-up,
start-up, and
and manual-bypass
All incoming
incoming and
and alternate
àlternate power
power source
for aa
on
the the
UPS.UPS.
UPS
onthe
thefront
frontpanel
panelof of
U P Sshould
shouldbe
belockable
lockabletype.
type.
material licensed to IDOM.
STD.API/PETRO RP 5 9 O - E NCopyrighted
G L 1777
W 0 7 3 2 2 9 0 Ob15720 O31 B
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
ELECTRICAL
IN
ELECTRICALINSTALLATIONS
INSTALLATIONS
PETROLEUM
IN PETROLEUM PROCESSING PLANTS
e. If UPSbreakers
breakers
switches
are outside
locatedthe
outside the
andand
switches
arelocated
inverterarea,
area,
isolated
safely
easilyisolated
andand
safely
the the UPS can be easily
worked on.
on.
f. Provide
with capaProvide electric
electric heat tracing
tracing control systems
systems with
capaheaters and
bility to routinely monitor the integrity
integrity of the heaters
control system.
system.
g. Use of pocket-size
pocket-size continuous-monitoring
continuous-monitoringtype
typegas detecdetecWork Permit."
Permit.”
tors in place of
of"Hot
“Hot
A.S
A.6
101
1o1
Documentation
Documentation
Consider
Consider the
thefollowing:
following:
Single line diagrams.
diagrams.
a. Single
b. Control
Control schematics.
schematics.
b.
c. Protective
Protective device
devicesettings
settingsand
andequipment
equipmentparameters.
parameters.
c.
d.
troubled. Equipment operating
operating maintenance,
maintenance, testing,
testing, and troubleshooting.
shooting.
e. Procedures
Procedures and
andapplicable
applicabledata.
data.
e.
f.
f. Area classification
classificationdrawings.
drawings.
Copyrighted material licensed to IDOM.
No further reproduction or distribution permitted.
Printed / viewed by: [jonathan.cruz@idom.com] @ 2023-10-03
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