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Qatar Petrolium ES 2 03 0001 Rev B Electrical Engineering
Philosophy
Basic Electrical Engineering (Gujarat Technological University)
Studocu is not sponsored or endorsed by any college or university
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TECHNICAL DIRECTORATE
Technical Services Department
Engineering Standard ES.2.03.0001
Electrical Engineering Philosophy
-
Revision B
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CONTENTS
Introduction
Custodian
Purpose
Application
Standards, Codes and Regulations
Quality Management System
Certificates, Declarations and Test Reports
Electrical System Design Philosophy
General
Operational safety and reliability
Standardisationof equipmentand materials
Protection against explosionand fire hazards
Economicconsiderations
Power Supply Arrangement
Sources of power supply
Distribution philosophy
Single line diagrams and protection diagrams
Power system studies and protection studies
SAFety and Operability (SAFOP) study
Classificationof ElectricalLoads
Vital service
Essential service
Non-essential service
ElectricalLoad Schedule
Summationsand diversity factors
Sub-divisionof electrical load schedule
System Voltageand Frequency
Selection of voltage and frequency
Deviations in supply voltage and frequency
Deviations and variations in supply waveform
SystemPowerFactor
Power Supply Capacity
General
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Power supply units
Load shedding
Short Circuit Capacities
Neutral Earthing
HV systems
LV systems
Insulation System
Electrical Protection System
Power Management System
Basic requirements and DCS interfacing
Management functions
Control, Metering, Alarms and Indications
Design and Selection Philosophy for Electrical Equipment
General
Generators for Captive Power Plant
DieselEngine DrivenGenerators
Power Transformers
Switchgear
General
HV switchgear
LV switchgear
Configuration of switchboards
Operating philosophyof HV and LV switchboards
Spare cubicles
Choice of %pole and 4-pole LV circuit breaker
Ring-main units
Bus-bar Ducting
Neutral Earthing Resistor
AC UPS System
DC UPS System
Batteries
Capacitors
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Electric Motors
Cables and Wires
General
HV cables
LV cables
Earthing cables
Flexible cables
Wires
Cables with fire withstand capabilities
Cable accessories
Remote ControlUnit
Lighting Equipment
General
Plant lighting
Building lighting
Portable lamps
Electrical Heat Tracing
Electric Process Heaters
Heaters for Frost Heave Protection
Power and ConvenienceOutlets
General
Power outlets
Convenience outlets
NavigationalAids
Marine navigational aids
Air navigational aids
Obstacle markers and lights
Electric Motor Operated Valve Actuators
Variable Speed Drive Systems
Overhead Transmission Lines
Cathodic Protection System
Annunciation panel
Installation Design Philosophy
General
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Cabling and Wiring System
General
Undergroundcabling
Above groundcabling
Wires in conduits
Lighting System
General
Plant lighting
Emergency and escape lighting
Street, fence and open area lighting
Special lighting
Earthing and Bonding System
Earthing of equipment
Lightning and static electricity
Sub-station Design Philosophy
General
Indoor Sub-stations
Outdoor Sub-stations
Package Sub-stations
Drawings and Documents
Approval to Deviate
Revision History Log
Bibliography
APPENDICES
Appendix-A Selection of electrical equipment for hazardous areas
Appendix-B Details of protection requirements for different types of power system
components
Appendix-C Drawings and documents
Appendix-D Definitions
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1.O
Introduction
This Electrical Engineering Philosophydocument provides Qatar Petroleum (QP) guidelines
for the design, engineering and selection of electrical systems and equipment, in accordance
with latest international standardsand industrial installation practices. All partiesinvolved in
the engineering and design of a plant for QP shall use this document to achieve the standards
required by QP.
The following are themajor changesin the philosophydocument issued under earlier revision:
Editorial changes
Major revision in all sections
IEC numbering updated
ATEX requirementsadded
Requirements for SAFety and Operability (SAFOP) study added
Integration and rationalisationof various sections and sub-sections
References made throughout this document are numbered inside square brackets [ ] and are
included in the Bibliography (15.0).
Cross-references between sectionsand sub-sections withinthis document are numbered inside
round bracket( ).
Custodian
The custodian of this document is EE, who is responsible for the accuracy and quality of its
contents and for its future revisions, where these are required to reflect the industry trends or
changes to QP business practices.
Purpose
This philosophy document shall be used in the engineering and designof land-based plants
and offshore platforms& floating facilities located in the sea around Qatar.
Application
The electrical engineering philosophy described in this document shall be applied to the
engineering and design of QP electrical power systems and their components,and to the
technical and economical selectionof the most suitable electrical equipment for new as well as
existing plants.
5.0
Standards, Codesand Regulations
The principles used in this philosophy documentare, to a large extent, based on the IEC
(International ElectrotechnicalCommission)publications.
The selection and applicationof materials for the construction of equipment are described in
more detail in the respectiveQP Engineering Standards and the applicableIEC included in the
Bibliography (15.0).
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The design and engineering of the electrical installation shall meet all the Statutory
Requirements of the National and Local Regulations currently in force in the State of Qatar.
Also the requirements laiddown by Qatar General Organisationfor Standards and Metrology
(QGOSM) and Supreme Councilfor the Environmentand Natural Reserves(SCENR) shall be
met.
Electrical equipment andmaterials shallcomply with their relevant QPEngneering Standards,
respective Data Sheets and Project Specifications.
In the event of contradiction between various referenced engineering standards, data sheets
and National/ Local regulations, the followingshall be in order of precedence:
National/ Local Regulations
Electrical Engineering Philosophy(ES.2.03.0001Rev.B)
Data Sheets
Project Specifications
QP Engineering Standards
International Codeand Standards
In the event of contradiction between the requirements of various Engineering Standards
referenced in the Bibliography(15.0), the Engineering Standard issuedmore recently shall
prevail.
The SI systemof units shall be used. All documentationshall use the English language.
Electrical symbols shall conform to the QP Engineering Standardfor Draughting ES.D.-10 [I].
Where symbolsare not given in ES.D.-10 [I], those given in IEC 60617 [93] shall be used.
However, for protective relays and their systems the symbols and notation given by IEEE
C37.2 [I661 shall be used.
Quality Management System
The contractors, consultants and manufacturersof equipmentshall have a quality management
system based on a minimum standard of IS0 9000 [154], IS0 9001 [I551 and IS0 9004 [156].
The QAIQC documentation shall be reviewed and approvedby QP. The documentation shall
include the Quality Plan and Quality Control Systemincluding inspection & testing methods
and reporting recording formats.
Certificates, Declarationsand Test Reports
For all major electrical equipment like generators, motors, VSDS, switchgear, transformers
and UPS systems,the manufacturer shall submit Type TestReports of the equipment at the
tendering stage of an enquiry.
In addition to other Type Tests, short-circuit test reports especially for switchgear,
transformers, generators,bus-bar ducting and motors shall essentially be submitted.
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Furthermore, certificates or declarations in relation to the application of equipment in
hazardous areas shall be required accordingto the following rules:
For electrical equipment in Zone-0, Zone-1 and Zone-2, Certificate of Conformity shall be
obtained
For Type-n electrical equipmentin Zone-2, Declaration of Conformitymay be accepted
All equipment anddevices sourced from European manufacturers and installed inhazardous
areas shall be manufactured as per ATEX directives. The manufacturer of such equipment
shall ensure that these have ATEX recognised certificates against Essential Safety
Requirements listed in theATEX directives.
For details of tests to be performed on electrical equipment, requirementsfor witnessing of
testing and reports1documents to be submitted to QP, the necessary requirements arecovered
under respective equipment Engineering Standards.
8.0
Electrical System Design Philosophy
8.1
General
The design of the electrical installation shallbe based on the following:
Operational safety and reliability
Standardisationof equipment andmaterial
Protection against explosionsand fire hazards
Economic considerations
Other aspects like fail-safe features, provision for futureextension1modifications, suitability
for the environmentand inter-changeabilityof equipmentshall be duly considered.
8.1.1
Operational Safetyand Reliability
The design of the electrical installationshall be based on the provision of a safe and reliable
supply of electricity at all times. Safe conditions shall be ensured under all operating
conditions, including those associatedwith start-up andshutdown of plant and equipment,and
through the interveningshutdown periods.
The design ofelectrical systems and equipmentshall ensure that all operating and maintenance
activities can be performed safely. To fulfil these requirements, provisionsmay be required for
alternative supply sources and supply routes, spare and standby capacity, load shedding,
automatic changeover andautomatic restarting etc.
The simultaneousfailure of two pieces of equipmentshall not be cateredfor.
The insulating and dielectric materials usedin all electrical equipmentshall be non-toxic and
shall not contain compounds that are persistent and hazardous environmental contaminants,
such as poly-chlorinated biphenyls (PCBs).
Due consideration shall be gven to the phenomenon of zincembrittlement of stainless steel.
The necessary measuresshall be taken to prevent occurrence of this phenomenon.
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For temporary installations required for the erectionof permanent installations, the guidelines
given in this philosophy documentmust be adhered. Effort shall be made to cope with the
increased hazards generally associatedwith temporary installations.
For disposal of hazardous waste (e.g. transformer oil, used batteries etc.), recommendations
provided in QP Specification for Waste Management System SPC-ENV-001 [35] and QP
Guideline - Waste Management for Offshore Operations and Halul IslandGD-ENV-001 [36]
shall be followed.
8.1.2
Standardisationof Equipment andMaterials
Standardisationof materials and equipmentshall be aimed at as far as compatible with rational
design. Equipment, which will become obsolete in the near future,shall not be purchased nor
installed.
Electrical equipment of similar nature and incorporating similar or identicalcomponents and
of similar or identical construction (e.g. extension of existing switchgear) should be of the
same manufacture.
8.1.3
Protection against Explosionand Fire Hazards
All the area within the battery limitsshall be classified for the degree and extent of hazard
from flammable material.
For proper selection of electrical equipment for areas where flammable gas or vapour risks
may arise, Area ClassificationDrawings shall be prepared based on the IP Model Code of Safe
Practice - Part 15, Area ClassificationCode for Petroleum Installations[143].
The Area Classification Drawingshall be subject to approval by QP.
For installations having presence of flammabledust, area classification and selection of
electrical equipmentshall be as per IEC 61241 [135].
For the construction and installation of electrical equipment in hazardous area, all relevant
parts of IEC 60079 [48] shall be complied.
Following shall be consideredfor proper selection of electrical equipment for use in hazardous
area:
0
Presence of flammable gases/ vapour andl or flammable dust
Area classification interms of Zones
Apparatus group
Temperature classification
Ingress protection
Electrical sub-stationsshall be located in non-hazardousareas.
Where it is impractical to install electrical equipment in non-hazardous areas, an appropriate
selection of types of protection can be specified for the different Zones classified accordingto
the likelihoodof an explosive atmospherebeing present.
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Although many types of protection are available, the final selection for the electrical
equipment shall be as perAppendix-A.
The specificationor procurementof equipment complying withother standards, differentfrom
the above, will be subject to approval fromQP.
Any process plantlunit having Zone-2 hazardousarea as well as non-hazardous area withinits
extent, Zone-2 equipment shall be installed consideringthe interchangeability of equipment
and their spares. The criteria shall be applicable to equipment like motors, lighting fixtures,
RCUs and power & convenience sockets.
Electrical equipment installed in non-hazardous areas within process units shall be industrial
type while those installed outside processunits shall be industrial/ domestic type dependingon
the type of installation.
Economic Considerations
Due regard should be given to the selection and utilisation of efficient electrical equipment in
order to reduce energy consumption. Theuse of high efficiency and highpower factor electric
drives, use of VSDS for speed control, selection of low loss transformers etc. should be
evaluated during the detaildesign stage of the project.
Power Supply Arrangement
Sources of Power Supply
While designing the electrical supply and distribution systems, the following alternatives for
the electrical supply shall be considered:
0
Captive power generation (i.e. own generation)
Power supply fromKAHRAMAA
Combinationof these
The selection of power supply sources shallbe based on all possible factors like availabilityof
power from KAHRAMAA, continuity of supply, flexibility of operation, operational costs,
reliability of power supply from available sources, total loadand concentration of individual
loads.
For power supply from KAHRAMAA, close co-ordination will be required with
KAHRAMAA to finalise all parameters of intake power and due consideration should be
gwen to the expectedfuture planned increase in loads.
Distribution Philosophy
Generating units for captive power generation and intake sub-stationsfor power supplyfrom
KAHRAMAAshall normally be in an electrically centralised locationand the distribution
system shall be arranged radially.
The distribution system and the interlocking schemes shall be based on the Secondary
Selective Distribution Philosophy and the requirements of QP Engineering Standard for
Secondary SelectiveSystem ~~2.14.0060 [20] shall be complied while designing the system.
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Ring distribution system shall onlybe considered for those applications where the loads are
small in nature and are at large distances from the power source or are at large distances from
each other. Selectionof the ring distribution systemshall be based on actual economics.
Each distribution system should havereliability at least comparable with its supply system. It
shall incorporate sufficient standby capacityto enable maintenance work,tests and inspection
checks to be carried out.
The main sources and feeders of power shall be duplicated in such a manner that if one of
them is tripped or is out of service, the remaining units will take care of the total power.
New plants should be designed with sufficient spare capacity in the captive generationand
KAHRAMAAfeeders to render load shedding unnecessary under normal operation of the
plant.
8.2.3
Single Line Diagrams andProtection Diagrams
The conceptual designand philosophy of the electrical distribution systemshall be represented
by means of a Single Line Diagram.
Every installation shall be designed on the basis of conceptualised Single LineDiagram. This
diagram may be a new document or a modification of an existing document. The following
information shall be shown on the Single Line Diagram:
All sources of electric power
The main supply voltageand distribution system interconnectionsat each voltage level
System capacities,equipment ratings and impedances, winding configurationand earthing
arrangements
Vector diagrams forall voltage levels
Relevant information that basically describes the design and operating philosophy
to be
adopted for the system, e.g. arrangement of main and stand-by circuits, normal switch
positions, switch interlocking and circuitchangeover facilities, synchronising facilities,
power factor correction facilities, anticipated future loadsor circuit extensions,etc.
Location of earth switches,CTs, VTs and measuring instruments
Cable type, sizeand tag numbers
Motor kW ratings
For large installations, the Single Line Diagram can be sub-divided into several Single Line
Diagrams so that all aspectsare shown moreclearly and easily.
Nominal system voltage(s), frequency and the positive phase sequence shall be indicated on
the Single Line Diagram. The phase sequence shall be specified in alphabetical orderL1, L2,
L3 or U, V, W, each phase reaching its maximumin time sequence in that order.
The Single Line Diagram shallbe kept up to date throughout the lifetimeof the plant.
A protection diagram in the form of a Single LineDiagram shall be prepared for the complete
electricity supplyand distribution system. The drawing shall indicatethe type and locationof
all protective devices and associatedCTs and VTs that are to be provided.
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The Single Line Diagramsand ProtectionDiagrams shall be subject to approval by QP.
8.2.4
Power System Studiesand Protection Studies
Power System Studies and Protection Studies shall be performed at different stages of a
project and shall be performed as per QP Engineering Standard for Power System Studies
ES.2.14.0095[28].
The Power SystemStudies and Protection studiesshall be performed in supportof the design
and procurement of equipment withcorrect specifications. Thesestudies may comprise ofthe
following depending on the type, size and complexity of the electrical generation and
distribution system:
Load flow studies
Fault level studies
Motor start-up studies
Transient stability studies
Power factor studies
Harmonicspenetration studies
Power system reliabilityand availability studies
Relay settings/ protection studies
inter-connections, requirements pertainingto the KAHRAMAAsystem
For
shall be considered withinthe scope of these studies.
The scope of the studies shall depend on the stage of the project at which these studies are
performed andshall be accordinglydefined.
All studies for QP power systems shall use the latest version of CYME suite of software
programs created by CYMEInternationalInc. PowerEngineering Software.
The reports for Power SystemStudies and Protection Studies shall be subject to approval by
QP-
8.2.5
SAFety and Operability (SAFOP) Study
In order to ensure full range of safety, operability and operatortask analysis, the safety and
operability studyshall be performed in the early stages and final stages of the electrical system
design. The modalities of carrying out these studies should be finalised in consultationwith
EE in the early stageof the project.
The method for the study is to systematically questionengmeering design and operabilityof
the system to identify any possible limitations and lack of flexibility and assess the
consequences on the operabilityand safety of the system as well as safety of the operator.
This study shall consist of the following:
SAFAN (SAFetyANalysis) will examine hazards present in construction, commissioning
and operation of electrical installation and consider them in relation to the safety of
personnel who are to operate, work or be in the vicinity of the equipment
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SYSOP (SYStem Operability) study will review the overall electrical system design
examining control systems,main equipment of plant andtheir auxiliaries and consider
any limitationsfound andtheir effect on the system operability
OPTAN (Operator Task ANalysis) will look at the probable tasks to be undertaken by
both the control room and the field operator duringnormal and abnormal conditions.It
will also review the instructionsand measures built-into prevent humanerror.
The study shall be conducted by an independent agency not involved in the design of the
electrical system and should be attended by all involved in the design of the system including
the end-user andEE representative.
Classification of Electrical Loads
Electrical loads shall be classified asperforming a service, which is of the following types:
Vital (i.e. critical)
Essential (i.e. emergency)
Nonessential (i.e. normal)
8.3.1
Vital Service
Vital service is a service which, when failing in operation or when failing if called upon, can
cause an unsafe condition of the installation, jeopardise life or cause major damage to the
installation. This appliesto life support systems on offshore platforms, emergency andescape
lighting,DCS, ESD etc.
Depending on the service conditions, the electrical supplyto the vital service may have to be
non-interruptible. Since the faultless functioning of equipment cannot be guaranteed,
duplication of sources of power supply and redundancyof equipmentshall be built up.
8.3.2
Essential Service
Essential service is a service which, when failing in operation or whenfailing if called upon,
can affect the continuity of operation, the quality or the quantity of product. Therefore the
economics of partial or complete duplication of the energy source,of the lines of supply or of
the equipment or the introductionof automatic restarting facilities or of changeover facilities
or provision of standby energy source shall be evaluated in relation to the consequences of
service interruptionsmentioned above.The examples are power supply to process equipment
by means of a duplicate supply systemwith changeover facility,power supply to plant lighting
etc.
8.3.3
Non-essentialService
Non-essential service is a service that is neither vital nor essential and therefore does not
require any specialmeasures for safeguarding it. Theexample is normal lightingetc.
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8.4
Electrical Load Schedule
8.4.1
Summations andDiversity Factors
Summary of electrical loads called the Electrical Load Schedule shall be prepared as earlyin a
project as possible in the format Utility Data Sheet - Electrical included inES.D.-10 [I]. The
Electrical Load Schedule will form the basis for provision of the necessary electrical
distribution system capacity.
The following shall be included in the Electrical Load Schedule:
The installed electrical loads
Category of load i.e. continuous (all loads required continuously for normal operation
running all the time), intermittent(all loads required for intermittent operationand running
occasionally)or standby (all loads required in emergencies only)
Rated active power in kW (shaft output), rated power factor, rated current, rated efficiency
Absorbed active power in kW
Reactive power in kvar
The continuous (Sum C), intermittent (Sum I) and standby (Sum S) loads shall be summated
separately.
A diversity factor shall be applied to each of these summationsso that the Total Plant Running
Load (TPRL) andthe Total PlantPeak Load (TPPL)can be calculated.
The recommended diversity factors are 1.0 for (Sum C), 0.3 for (Sum I) and 0.1 for (Sum S).
Adequate care needs to be given to the requirementthat 0.3 x (Sum I) shall not be less than the
largest single intermittentload. For non-processloads like offices, workshops lighting etc., a
typical diversity factorof 0.9 shall be applied to (Sum C) of such loads.
The TPRZ,shall be the sum of 1.0 x (Sum C) and0.3 x (Sum I). The TPPL shall be the sum of
1.Ox (Sum C), 0.3 x (Sum I) and 0.1 x (Sum S)
The diversity factor may vary (specially for extensions of existing plants) and must be
finalised in the early stage of the project. For extension of existing plants, the TPRZ,and TPPL
shall be checked against the actualmeasured values.
8.4.2
Sub-divisionof Electrical Load Schedule
A separate schedule shall be prepared for eachHV and LV switchboard. Each separate
schedule will thereforebe a sub-divisionof the complete Electrical Load Schedule. Each subdivision shall clearly show the following information:
Summations of the load fed from the particular switchboard, excluding feedsto and
received from other switchboards
Active and reactive power fed individually to other switchboards, including losses in
feeder transformer ifused
Total active and reactive power received from the source, e.g. up-stream switchboard,
generator, transformer intake
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All loads to be automatically restarted after a voltage dipshall be clearly identified. Also, all
loads to be shed as part of load shedding scheme shall be clearly identified.
The Electrical Load Schedule shall be updated regularly throughout the design stage of the
project.
8.5
System Voltage and Frequency
8.5.1
Selection of Voltage and Frequency
The various voltages shallbe decided basedon the following factors:
KAHRAMAAsupply voltageat battery limits
Size and locationof loads
Future margm and expansions
Short circuit levels
Availability of switchgearfor continuous and short circuit ratings
Keeping the number of different voltage levelsto a minimum
Economic considerations
Voltage levelsof existing installations
The system voltages shall be selected from IEC 60038 [38]. For existing installation, the
selected voltage shallbe subjected to compatibility.The frequency for all installationsshall be
50 Hz.
The LV voltage and frequencyat PS4 (North field) Station is 440 V, 60 Hz 3-phase, 3-wire
and for lighting 380VI 220 V, 60 Hz 3-phase, 4-wire.
On 50 Hz systems, the nominal LV power supply voltage for new plants shall be 4001230V
three phase andneutral. This voltage should also be consideredfor extension to existing plants
requiring new LV distribution systems.
The existing systems of 4151240 V shall be rationalised to 4001230 V. The approach to
achieve this shall be as follows:
For new projects1new plants (Green field), new equipment like transformers,motors etc.
are to be provided. The transformer no load secondary voltage shall be 417 V to give 400
V at the LV bus. The tap changer range shall be *5% in steps of 2.5%. The LV motors
shall have voltage rating of 400 V*10%.
For upgrade projects (Brown field), where the existing electrical system is only upgraded
and system voltages are not altered, the transformer noload secondary voltageis 433 V to
give 415 V at the LV bus. The tap changer range is *5% in steps of 2.5% and the LV
motors have voltage rating of 415 Vrt6%. For such cases, new LV motors of 400 V rating
shall be specified to be suitable for continuous operationfor a voltage variationof *lo%.
For upgrade projects (Brown field), where new transformers and associated LV
Switchboards areto be provided, thetransformer no load secondary voltageshall be 417 V
to give 400 V at the LV bus and the LV motors shall have voltage ratingof 400 VilO%.
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Voltage up to 1000 V ac shall be termed as Low Voltage i.e. LV and voltage exceeding the
limits of lowvoltage shallbe termed as High Voltagei.e. HV.
8.5.2
Deviations in SupplyVoltage and Frequency
During normal system operation, the voltage at consumerterminals shall not deviate from the
rated equipment voltage by more than *5% and the frequency shall not deviate from the rated
frequency by more than *2% under steady-state conditions. The combined voltage and
frequency deviations shall liewithin Zone-Aas described in IEC 60034 [37]. All loads shall
be balanced such that the negativephase sequence componentsof voltage and current, at any
point in the system,shall not exceedthe values quoted in IEC 60034 [37].
During starting or re-accelerationof a motor, either individually or in agroup, the voltage dip
at the motor terminals shall not vary more than 20% from rated voltagewhen started direct on
line under the worst operating scenario i.e. largest motor started with minimum number of
power sources and minimumfault level.
Transient voltage variations occurringat switchgearbus bars during starting or re-acceleration
of a motor or group of motors shall be such as to maintain a minimum of 90%voltage on
switchgearbus-bars for HV motors and 92.5%for LV motors.
The following criteria shall apply with respectto transient voltage depressions or interruptions
such as those arising as a consequenceof system short circuits or disturbances from the grid
intake supplies:
Voltage depressions resultingin consumerterminal voltages down to 80% of rated voltage
shall not affect plant operations
Voltage depressions resulting in consumer terminal voltages below 80% of rated
equipment voltage for a duration of not more than 0.2 seconds shall, on a voltage
restoration, result in the instantaneousre-energsation of consumers performing an
essential service
Voltage depressions resulting in consumer terminal voltages below 80% of rated
equipment voltage for a duration between 0.2 and 0.4 seconds shall, on a voltage
restoration, resultin a sequential re-energisationof selected consumers
The above shall be achieved within the constraints imposed by the electrical system andas
feasible with regardto process requirements, safetyand economic factors.
Under steady state conditions, the maximum voltage drop in various sections of electrical
system shall be limited to the following:
Cables1bus-bar ducting between transformer and switchboard
:
0.5%
Cables1bus-bar ducting between generatorand switchboard
:
0.5%
Cables between HV switchboardand HV motor
3%
Cables between LV switchboardand LV motor
5%
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Cables between LV switchboardand Lighting Panel
1%
Cables between Lighting Panel andfarthest Lighting Point
4%
DC UPS outgoingfeeders (for electrical controls)
5%
DC UPS outgoing feeders (for Instrumentation)
2%(*)
AC UPS outgoing feeders (for Instrumentation)
5%(*)
(*) To be finalised in consultation with InstrumentationDepartment
8.5.3
Deviations and Variations in Supply Waveform
All equipment shall be suitable to operate satisfactorily for the total harmonic voltage
distortion of 5% in the supply voltage.
Electrical loads having non-linear characteristics, such as to produce voltage and current
waveform distortion of a magnitude detrimentalto the lifetime or performance of system,
electrical equipment, shall not be utilised unless appropriate measures are taken to render
harmless the effect of such distortionse.g. by filtering or phase displacement, etc.
Total harmonic voltage distortionat any point in the system shall, in any event,not exceed 3%
(Individual odd harmonic<2% and individual even harmonic4.5%).
For installations having submarine cables used to transmit power to or from offshore
platforms, a study shall be carried out to find out the possibility of resonances occurring
specially at low order harmonics leading to over voltages and over currents.Means shall be
provided to mitigate the problem of resonance and to avoid the voltage distortionat the load or
the supply. Based on the study, the necessary protective measuresshall be adopted. However,
these will be project specific.
This study shall be subject to approvalby QP.
Equipment having special requirements with respect to variation in voltage level and
waveform shall be provided witha power supply that is adequately stabilised or filtered.
System Power Factor
The overall systempower factor, inclusive of reactive power losses in transformers and other
distribution system equipment, shallnot be less than 0.9 lagging at rated load. KAHRAMAA
may specify a minimum powerfactor and would needto be maintained. The requirements for
power factor correctionshall be decided at an early stage of the project.
Static Capacitor Banks (HV and1 or LV) shall be provided to improve the power factor.
Automatic control of Capacitor Banks shall be provided where these are provided for a group
of motors/ loads. The location of capacitorbanks mustbe given very careful considerationand
shall not be applied in piece-meal manner.
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The installations where capacitorsare added for power factor improvement, a study shallbe
carried out to analyse their impact on increase in striking voltage transientsat switchgear,
resonances due to presence of non-linear loads and transformerthird harmonics.
This study shall be subject to approvalby QP.
Use of synchronous motors helps in achieving better power factor but their use shall be
decided based on economic considerations.
8.7
Power Supply Capacity
8.7.1
General
For new plants, the capacityof the electrical distribution systemshall be capable of supplying
continuously 125%of the peak load. While sizing equipment like generatorsand transformers,
direct on line starting and auto-reaccelerationof motors shall be duly considered. Futureplant
load, if any, shall be duly taken care in the peak load calculations.
This 25% spare capacity is kept to cater for the possibilityof future de-bottleneckingof the
plant and to accommodate changestaking place during project design thatmay involve minor
adjustments in electrical loads.This factor of 25% may get reduced to 10% when the plant is
ready to start.
The provision of stand-bycapacity shall be considered in relationto safety, reliability and the
continuity of plant operation.
8.7.2
Power SupplyUnits
The number of power supply generator or power transformer units to be installed and their
individual ratings depend on many factors, e.g. maintenance requirements, economic size,
future load development pattern, unit reliability etc. Sufficient stand-by capacity shall be
incorporatedto fulfil the requirement ofthe peak load continuously, even if the largestsupply
unit trips or is out of service for maintenance purposes.
For plants having only captive generating units, thenumber of units n+2 or n+l (where n is the
number of generating sets requiredto supply the peak load) shall be decided by the nature of
process and acceptance of load shedding scheme for non-essential loads. To the extent
possible, sufficientspare capacity shall be built-upto avoid load shedding.
The availability of further stand-by supply capacity to cater for unit failures during
maintenance or repair periods shall be provided where the aggregate maintenanceor repair
time warrants this. Where no such capacity is provided, nor it is practically possibleto provide
(specially for an existing plant), then automaticload shedding schemesshall be implemented.
Each circuit of the radial power distribution system shall be rated to cater for the peak load
requirements on continuous basis so asto facilitate the isolationof individual circuits for the
purpose of testing, maintenanceand faulty conditions.
For ring distribution, thering-main cable shall be rated to cater for the peak load requirements
continuouslyon the basis that the ring is open at one end.
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The maximum rating of power transformers shall be decided such that the rated current of
their low voltage winding does not exceed 2000 A when feeding HV switchboard and 2500 A
when feeding LV switchboard. Higher ratings shall only be considered in case of significant
cost saving. Such cases shall be brought to the notice of EE and necessary approvalshall be
obtained.
8.7.3
Load Shedding
Load shedding shall be based on high speed tripping of low priority (non-essential) loads.
Various loads or group of loads shall be selected for load shedding and be placed in the
tripping sequence. The sequenceshall trip the lowest priority loads and thenthe higher priority
loads after a time delay. This process shall be repeated until the electrical system is safe and
stable.
The priority sequence and choice of loads for shedding shall be determined in consultation
with Process Department.
For installations where captivepower plant is operating in parallel withKAHRAMAAsupply,
bulk load shedding facility may be required depending on the magnitudeof power imported
from KAHRAMAA.
Short Circuit Capacities
All equipment shall be capable of withstanding the effects of short circuit currents (initial
symmetrical short circuit current and peak short circuit current) and consequential voltage
arising in the eventof equipmentfailure or equipmentfaults.
Each short circuit interrupting device shallbe designed to have rated breaking capacityequal
to or higher than the maximumvalue of short circuit current calculatedat its location.
For calculation of maximumvalue of short circuit ratings including the short circuitmaking
and brealung capacity of circuit breakers, parallel operation of all power supplies and
contributions frommotors shall be duly considered.
For power intake switchboards, closeco-ordination will be required with KAHBMAA and
due considerationshall be given to the expected futureplanned increase in short circuitlevel.
Short circuit rating of generator switchgearshall be calculated taking into consideration the
maximum numberof generators simultaneouslyin operation includingfuture expansions.
All switchgear and bus-bar ducting shall withstand themaximum fault current for a minimum
period of one second.
Sizing of high voltage cables shall be based on the short circuit withstand capacity for a
duration dictatedby the protection system.
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8.9
Neutral Earthing
8.9.1
HV Systems
For HV systems with voltagenot exceeding 33 kV, the neutrals of following shall be earthed
through a current limiting resistor called a Neutral Earthing Resistor
(NER):
Generators directlyconnectedto HV switchboards
Generator transformers
Incomingtransformer feeders fromKAHRAMAA
Transformers connectedto HV switchboard
Unit transformerfor HV motor
The rating of each NER shall be such as to limit the earth fault current supplied by the
equipment to which it is connected to a value as low as practical and which can be reliably
detected by earth fault relays in the circuit. Generally theearth fault current shall not exceed
50% of transformer or generator full load current.
Where generators are connected in parallel to the same switchboard and each is earthed
through its own NER, then each NER shall be rated to allow the circulationof zero sequence
harmonic currents to flow continuously. Data shall be obtained from the generator
manufacturer for the estimated level of these circulating currents originating from the
generator. If the circulating currentis such as to exceed the thermal rating of the NER, then
the generatorsshall be earthed via one NER only. Each generatorshall then be provided with a
suitable switching deviceto facilitate connectionof any generatorto the single NER.
In some situations the construction of a high resistance, low current, NER may not be
sufficiently robust and manufacturersmay be unable to provide a robust design.In this case a
two-winding distribution transformer should be used in combination with an NER in its
secondary winding. The secondary voltage can then be selectedin the LV range, thereby
enabling a low resistance, high current, NER to be chosen.
The NER and the transformershall be rated to withstand the respective earthfault current for a
duration of not less than 10sec.
8.9.2
LV Systems
LV electrical system neutralsat each source of supply shall be solidly earthed by means of
dedicated earth electrodes,which have a direct, low impedance connectionto the installation
main earth grid. The system of earthing shall be designated as 'TN-S', as defined in IEC
60364 [73], unless otherwise specifiedby QP.
For fixed LV equipment, the earth loop impedance shall be low enough to cause circuit
disconnection in less thanone second, when a bolted fault of negligible impedanceis applied.
A.C.UPS system shall have their neutrals solidly earthedand DC UPS system for electrical
loads and critical lighting shallbe unearthed.
Earthing of DC UPS system for telecom, fire alarmand plant communication systems shall be
as required by the respectiveequipmentmanufacturer.
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8.10
InsulationSystem
The insulation of electrical facilities shall be designed considering the highest system voltage,
system neutral earthing,over voltages resulting dueto faults and switching1lightning surges
and the insulation co-ordinationshall be carried out as per IEC 60071 [44].
A study shall be performed forthe insulation co-ordination betweenthe electrical equipment
and protective devices.
The study shall be subject to approvalby QP.
Surge arresters shallbe provided wherenecessary.
8.11
Electrical ProtectionSystem
The electrical systemshall be equipped withreliable automatic protections.
QP Engineering Standards for HV Switchgear andControlgear for indoors ES.2.14.0010 [8]
and LV Switchgear and Controlgear ES.2.14.0015 [9] give details of the selection and
specification of switching and protective devices, control circuits and associated auxiliary
equipment.
The details of protection of different equipment, feedersand various types of circuits are given
in Appendix-B.Specific project requirementsmay call for slight changesto these detailed.
The type and characteristicsof protective devices shallbe selected accordingto the application
and shall be compatible with thoseof existing system.
However, for new installations microprocessor based numerical protection system in
combination withPower Management Systemshall be considered.
Protective relays shallhave one or more of the following basic requirements:
Fully solid state
Multi-functionwhere appropriate
Intelligent and dynamic (e.g. self-adjusting characteristicsfor thermal imaging)
Fully compatible with DCS and data networking using 'industry standard'methods and
configurations
Separate lockout relays
The automatic protective systems shall be designed to achieve selective isolation of faulted
equipment without delay, which shall be within a time corresponding to the short-circuit
current withstand capabilityof equipment, system stable operating limits and the maximum
fault clearancetimes.
Adequate and selective phase short-circuit and earth fault protection shall be provided. Due
regard shall be givento the magnitude of short-circuit currents and methodof system earthing.
Limited duration overcurrents arising from single or group motor starting and reacceleration
shall be permitted. Automatic control systems such as load transfer, motor restarting
arrangements andprotective systemsto initiate load shedding, may be required for a particular
plant.
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Protective relay settings shall be based on a study of the fault conditions for which the
protective system has been designed and incorporated. Protective relay systems shall be
selective and the settings shall be co-ordinated so that back-up protection is provided in the
event of protective systemor switching device failure.
The minimum generation or supply capacity conditionsshall be at least representativeof those
that arise duringnormal operation of the process units, productionfacilities and their utilities.
The protection of distribution systems during the more extreme conditions, such as those
occurring at the time of starting up generating plant and utilities, may be catered for by
appropriate adjustmentsof protection relaytime settings.
Where relevant, the dynamic performance of the electrical system shall be analysed to verify
the adequacy of the protection system provided, by ensuring successful recovery of the
electrical system to a stable operating state following the clearanceof a short circuit. The
study shall be repeated for the application of a short circuit at various critical locations in the
power system. In particular, systems incorporating on-site generation as themain means of
power supply, shall be studied to establish the extent to which re-energisation of essential
service loads may be applied. The protection of the interconnectionswith KAHRAMAAshall
be mutually agreed betweenQP and KAHRAMAA.
The relay settings shallbe self-contained within therelay so that they can only be changed at
the relay, and not by a remote means. Forintelligent relays, accessto the settings shall be via
the software and a MMI using a password or similar securemethod.
The software for intelligent protective relays shall beuser friendly, menu driven, and capable
of being used by an operator having little experience in softwareprogramming.
8.12
Power ManagementSystem
A dedicated Power Management Systemfor the electrical generation and distributionsystem
shall be considered where centralised supervision, control and meteringis required. This
system shall comply with the requirements of QP Engineering Standard for Power
ManagementSystemES.2.14.0065[211.
For a new project involving power generation and1 or KAHRAMAA interconnection, the
associated power generation and distribution system shall be managed by the Power
Management System (PMS). For upgradeprojects, the requirementof PMS shall be based on
the operational requirements andeconomics.
8.12.1
Basic Requirementsand DCS Interfacing
The PMS shall be a continuouslyon-line computer-basedsystem of the DCS type. Itshall not
be an integral part of the overall DCS network system and the operation of the power system
shall be kept independentof other DCS type of operations.
An important function of the PMS will be the high speedload shedding needed when oneor
more generators or KAHRAMAAfeeders trip. This essentialfeature will require the PMS to
be constantly monitoring the power generation and distribution network, to be making
complex real time calculations and accurately, and to be in a state of readiness to start the load
shedding process within afew milli-secondsof receiving the initiating signal from the tripped
source.
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The PMS should be connected to the overall DCS system simply for the purpose of
'delivering' informationto the DCS network for the purposes of event recording, trending,
reporting and the like. It shall not receive control functions from the DCS. A hierarchy in
terms of informationnetworks shall therefore be established at an early stage of a new project.
This will enable the PMS to function as required, with themaximum availability, when the
connection to the DCS is out of service. The transmission of signals to and from the PMS
needs to be fast and can be through oneor combinationof the following:
Hard-wired for simple signals thatare only a short distance away fromthe PMS
Standardised signalling techniques for anew plant where networkingand fibre optics are
common
For long distances e.g. submarine power cables to platforms, over-head transmission
lines, use of fibre optics as integralparts of the cables or line conductors
8.12.2
ManagementFunctions
The main PMS functions that should be considered are:
VDU display of the main generation and distribution in single-line page-by-pageformat,
at a MMIin the central controlroom
Display of load flows and voltage profiles
Schedulingof generators and KAHRAMAAfeeders
Load shedding
Inhibiting the start of large motors
Load sharing between the generatorsand KAHRAMAAfeeders, if used
Frequency and voltagemaintenance ofgenerators
Automatic synchronisingof generators
Monitoring and alarmingperformance
Fault level surveillancein special cases
Intelligent interlockingfor special cases
The choice of these functionsshall be specific to a particular project. Notall projects need the
same functions. The PMS functions shallbe identified at an early stage of the project.
Other details like configuration, inputs, outputs, displays, indications andalarms shall be as
detailed out in QP Engineering Standard for Power ManagementSystem ES.2.14.0065 [21].
All equipmenthaving interfacewith the PMS system shall have communication capabilities.
8.13
Control, Metering, Alarms and Indications
Adequate controls, metering, alarms and indications for checking and monitoring of power
system, as required for proper control and operation of the electrical installation shall be
provided. Metering shall be provided to keep a record of powerconsumption andmeasurement
of current, voltage,power, frequency,power factor etc.
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QP Engineering Standards forHV Switchgear and Controlgear for indoors ES.2.14.0010 [8]
and LV Switchgear and Controlgear ES.2.14.0015[9] give full details of these requirements
for each type of incomer and outgoing feeders.
Equipment specific requirements are alsocovered in QP Engineering Standards for HV Gas
Turbine Driven Synchronous Generators ES.2.14.0001 [3], Diesel Engine Driven Generators
ES.2.14.0002 [4], HV Induction & Synchronous Motors ES.2.14.0030 [13], Electric Motor
Operated Valve Actuators ES.2.14.0036 [15], AC UPS Systems ES.2.14.0040 [16], DC UPS
Systems ES.2.14.0044[17] and Variable Speed DriveSystem ES.2.14.0050 [19].
Gnd intake circuits which are required to operate in parallel with captive generators shall be
provided with synchronising facilities, check synchronising relay and dead-bus override.
These controls shall be locatedwhere control of the frequency and voltageof the generators
can be exercised.
Each motor circuit shall be provided with aremote ammeter andprovision of power supply for
motor anticondensation heater.
Switching counters shall be provided on all HV motor and transformer feeders. Runninghour
meters shall be provided for generators and HV motors.
Electricity consumption metering shall be revenue class of metering. Maximum demand
indicators shall be provided for KAHRAMAAsupplies having contractual restrictions. The
control and metering requirementsfor interconnectionswith KAHRAMAA shall be mutually
agreed betweenQP and KAHRAMAA.
Current transformers (CTs) and voltage transformers (VTs) shall have the characteristics
adequate and suitable for the associated protectionand metering.
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Design and Selection Philosophy for Electrical Equipment
9.1
General
All electrical equipment shall be new and shall be manufactured with state of the art
technology.The equipment shall not be proto-type or from a new product line that is not proven
earlier in the oil & gas and petrochemical industry. The equipmentshall be designed for a
service life of at least 20 years.
All electrical equipment shallbe suitable for the site and environmental conditionsas specified
in the respectiveequipment DataSheets and Project Specifications.
Where necessary, special attentionshall be paid to the selection and installation of electrical
equipment suitable for seismic conditions.
All electrical equipment shallbe designed andsized to operate at the specified designambient
temperature. For batteries, minimum design ambienttemperature shall be considered while for
electrical heat tracing,minimum ambienttemperature shall be considered.
The outdoor equipment shall be protected with suitable sun-shelter and the ingress protection
for the equipment enclosure shall be minimum IP-55 as per IEC 60529 [87]. Sheds with open
sides shall be considered as outdoor installations.
The indoor equipment shall be installed in rooms having HVAC systems. The ingress
protection for the equipment enclosure shall be minimum IP-42 as per IEC 60529 [87].
However, the indoor equipment shall be designed for satisfactory continuous operationeven if
HVAC system fails.
The atmospherethroughout all QP installations shall be consideredto be corrosive, as normally
associated with oil and gas processing plants, refineries, chemical plants,LNG plants, offshore
platforms, industrial sites and the like. In addition, for offshore and coastal locations, the
atmosphereshall be considered as salt laden with presence ofH2S.
High humidity is experienced in all areas and condensationwill occur on all equipment during
some period of their lifetime and therefore all components, nuts, bolts and washers etc. shallbe
of corrosion resistant material and shall be tropicalised. Anti-condensation heatersshall be
provided in all electrical equipment like switchgear, UPS systems, motors, generators etc. as
specified in their respective Engineering Standards.
Equipment like main generators, emergency generators, VSDS, AC UPS system, DC UPS
system, batteries and switchboards shall be installed in non-hazardous areas. Only in
exceptional cases, these can be installed in hazardous areas in specially designed
rooms
meeting the requirements specifiedunder Sub-stationDesign Philosophy (11.0).
For 3-phase systems, the line terminals shall be denoted byL1, L2, L3 or U, V, W. Neutral
terminal shall be denoted by N. The colour coding shall be Red, Yellow, Blue and Black
respectively.
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Generatorsfor CaptivePower Plant
The generator, generator controlpanel and auxiliaries shall comply with QP Engineering
Standard for HV Gas Turbine Driven Synchronous Generators ES.2.14.0001[3]. The
generators shall be procured as a complete packagealong with the gas turbines.
The kVA rating of the generator shall be such that it does not limit the output of prime mover
over the specified operating temperaturerange. The generator shall be sized to have at least
10% spare capacityfor future.
The generator rated power factor shall be 0.8 lag, unless otherwise specified in the Generator
Data Sheet.
Generators shall be air-cooled. Use of water-cooledgenerators shall be subject to approval by
QP.
The rating, type, characteristicand other technical parametersof the generators shall be based
on the mode of operation i.e. island mode or parallel operation with other generators or
parallel operationwith KAHRAMAAfeeders or any combinationof these.
Based on the application, the overload capacity, impact loading capacity, activeand reactive
power sharing, speed variations, response time, reactance andinertia etc. shall be decided and
indicated in the Data Sheet.
The generators shallbe provided withthe following controls:
Manual and automatic synchronisingwith a check synchronisingrelay and a dead bus-bar
override
Manual andautomatic voltage control
Reactive power sharing among various generators
Power factor control to keep the generator power factor constant when operating in
parallel with KAHRAMAA supply
Speed control with droop characteristicwhen operating in parallel with KAHRAMAA
supply
Isochronouscontrol in island operation
Details of controls, metering, alarmsand indications are given in QP Engineering Standard for
HV Gas Turbine Driven SynchronousGenerators ES.2.14.0001[3].
Each generator set shall be provided with its own LV auxiliary switchboard for supply and
control of all its motor driven auxiliaries. This switchboardshall be treated as emergency
switchboard and shall be provided with a normal feeder and a feeder from emergency diesel
engine driven generator.
For installations having captivepower generation only, generatingsets shall be provided with
black-start facility. The number of generating sets provided with black-start facility shall be
based on the configurationof the power plant.
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9.3
Diesel Engine Driven Generators
The Diesel Engine Driven Generators shall be procured as a self-contained completepackage
along with Diesel Engine andshall be subject to any of the following applications:
Standby or EmergencyOperation
With Black Start Facility
Base Load PowerGeneration
These Generators shall comply with the requirementsof QP Engineering Standard forDiesel
Engme Driven Generators ES.2.14.0002 [4] and shall be complete with AVR, Generator
Control Panel and Generator Breaker. The Generator Control Panel shall contain AVR
controls, metering, indications, annunciations and protective relaysfor the generator. The
generating set shall be hooked-upto the switchboard through theincomer circuit breaker in the
switchboard. Additional local breaker near to the generator shall be provided in those cases
where the generating set is located away from the switchboardto which it is hooked-up and
local isolationis essential.
Necessary hardware for AMF facility shall also be provided for Standby1 Emergency
Generators.
Generators of sizes up to 1000 kVA shall have voltage rating of 400 V. Above 1000 kVA, the
generators shall be HV.
Generators shall be air-cooled.Use of water-cooled generatorsshall be subject to approval by
QP.
The emergency generators shall feed the following loads:
Electrical loads essentialfor safe shutdownof the plant
Emergencylighting
Plant instruments, as applicable
Communication equipment
Fire and gas detection system
UPS systems (AC & DC)
Fire fightingequipment
Loads critical for personnel safety
Helicopter landing area perimeter andobstacle lighting
ESD system
DCS system
The generators shall be sized to have at least 10%spare capacity for future and the declared
output of the generator at maximum operating temperature shall be net of auxiliaries. Motor
starting requirementsand UPS loadsshall be duly consideredfor sizing of generators.
Facility shall be provided to enable full load test of the emergency generators duringnormal
plant operation. Necessary synchronisingfacilities shall be provided where parallel operation
is envisaged.
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9.4
PowerTransformers
The transformers shall comply with the requirements specified inQP Engineering Standards
for Liquid Filled Power Transformers ES.2.14.0020 [ll] and Dry-Type Power Transformers
ES.2.14.0022[12].
The transformers for outdoor use shall be oil filled type. Sealed type transformers shall be
specified for ratings less than 5 MVA. Transformers 5MVA and above shall be provided with
membranetype split conservator.
For increased fire risk locationsand indoor installations and where transformers arean integral
part of a switchboard, a VSDS line-up of cubicles or a large UPS, dry-type transformer shall
be used. Their maximumrating shouldbe up to 2.5 MVA.
The transformer rated duty shallbe selected as at least 100% of the nominal continuous
running kVA as calculated in the ElectricalLoad Schedule for the short-term situation.Short
term in this context relates to the time duration of the project engineering and a fewyears after
the plant is commissioned.In the case of doubly fed switchboards each transformer shallbe
sized on the assumption thatit is taking the entire load on the switchboard, i.e. one feeder is
out of service and the bus-bar section circuitbreaker isclosed.
It is also necessaryto cater for long-term plantextension requirements.At least a 25% margin
shall be added to the rated duty to obtain the highest rated duty for continuous running. This
margin shall be obtained from forced air-coolingby attaching fans at a later stage. The fan
fixings shall be incorporated in the initial purchasingof the transformers. The cables,bus-bar
ducting and switchgear in theprimary and secondary circuits of the transformer shall be sized
initially for the currents correspondingto the highest rated duty. The overload settingsof the
protection relays in these circuits shallbe initially set to match the rated duty, and only
increased when the fans are added.
In accordance with IEC 60076 [47], the transformer kVA rating refers to maximum secondary
current and to no-load voltage, not systemvoltage.
On load tap changers shall be provided on intake transformers fedfrom KAHRAMAA.
Transformers equipped with amanual or automatic on-load tap changer shall have a separate
switching compartment so that the oil can be independently sampled and filtered during
operation. All tappings shall be on the highest voltage winding.
The automatic on-load tap changers of transformers working in parallel shall each have
selective facilities for independent,master andslave operation.
The percentage impedance of the transformers shall be as per IEC 60076 [47], unless
otherwise a different value is specified from the considerations of short circuit and voltage
drop duringmotor start up.
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9.5
Switchgear
9.5.1
General
Switchgear shall be of the compartmentalised metal clad type designto minimise any risk of
developing a short-circuitor the propagation of a short-circuit and to ensure personnel and
operational safety during all operating conditions, inspections, maintenance, the connection
of
main, control and auxiliary cables and the equippingand commissioningof spare panels whilst
the switchgearis live and in operation.
All switchboard components e.g. circuit breakers,main horizontal & vertical bus bars, bus bar
joints, bus bar supports etc. shall be designedto withstand the maximum expected short circuit
level for a minimum time of1 sec.
All switchgear and associated equipment fed from generators and transformersshall be rated
at least 125%of the rating of maximum number ofgenerators and/or transformers (ONAF)
simultaneously feeding it includingfuture expansions. The bus-section circuit breaker shall
have rating equalto that of the rating of the largest incomer circuit breaker.
The control circuit and auxiliary circuit voltage supplies forHV and LV switchgearshall be as
per QP Engmeering StandardsES.2.14.0010 [8]and ES.2.14.0015 [9] respectively.
9.5.2
HV Switchgear
HV switchgear shall be in accordance with the requirements of QP Engineering Standard
ES.2.14.0010 [8].
The breakers shall be SF6(Sulphur Hexafluoride)or Vacuum.
GIs switchgear is now being offered at 36 kV and may becomeattractive where primary substations are required in remote areas where no maintenanceis required and spaceis a premium
and costs become competitive.
Contactorsused in motor starters shall have AC3 utilisation categoryas per IEC 60947 11223.
HV switchgear and controlgear shallbe of withdrawabletype.
9.5.3
LV Switchgear
LV switchgear shall be in accordance with the requirementsof QP Engineering Standard
ES.2.14.0015[9].
Components of LV switchgear shall be standardised as much as possible and selected in
accordance with the current ratings.
Back-to-back design or double front design of LV switchgear shall not be provided unless
floor space is severely restricted.
All LV switchgear incomers shall be provided with breakers1 isolators. The choice of
incomingisolation shall be as per Data Sheet.
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LV switchgear and controlgear shallbe of withdrawabletype.
9.5.4
Configurationof Switchboards
For all switchboards, the number of sections shall be two and each bus-section shall be
provided with 100% rated incomingcircuit. Only in very special cases, switchgearwith three
sections shall be provided and each bus-section shall be provided with 50% rated incoming
circuit.
For interruptible, maintained supplies to vital services, a separate switchboard should be
provided. The normal feeder to this switchboardshall be derived from the mains power system
and the standby circuit from an emergency diesel generating set. An automatic changeover
system shall be provided tochangeoverto the standby circuit incase of mains failure.
Duplicate (double) bus-bar arrangements are occasionally required for the principal high
voltage switchboards in a plant,e.g. main generation switchboards or intake stations. Theiruse
shall be justified on the basis of requirementsof very high availability.
However, use ofswitchboardswith duplicate (double)bus-bars shall be subject to approval by
QP.
For nonessential loads, switchgear withone bus-section with 100% rated incoming circuit can
be considered.
9.5.5
Operating Philosophyof HV and LV Switchboards
The requirements for controlsand interlocks will influence the physicalsize of some circuit
breaker and contactor cubicles. This must be taken into account in the sizing and layout of
switchgear as awhole unit andin the interchangeabilityof individual units, traysand trucks.
In the majority of plants, the normal operating position of switchboard incoming and bussection circuit breakers shallbe as follows:
For the upstream HV switchboards the bus-section circuit breakers shall be operated
normally closed on switchboards at intake stations, generation stations and distribution
stations.
For downstream HV and LV switchboards the bus-section circuit breakers shall be
operated normally open,except on switchboards, which are the only sourceof supply i.e.
at LV generator switchboards. Theincoming circuit breakers shall be operated normally
closed. An auto-changeover schemeshall be employed to close the bus-section circuit
breaker automatically restoring the loss of supply to the section, which has lost supply
from its feeder. Facility formomentary paralleling1synchronisation,as applicable, shallbe
provided for the incoming feeders for changeoverschemes.
When a section of bus bars or a feeder transformer is being taken out of service, the normal
operation of the bus-section circuitbreakers shall be a manual function, carried out locally at
the switchboardfor the purposes of maintenance.
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The configuration of intake, power plant and distribution switchboards shall permit one
section of the switchboard to be taken out of service while still maintaining the normal plant
operations.
9.5.6
Spare Cubicles
HV switchboards shall have at leasttwo spare outgoing cubicles on eachbusbar section. The
type and rating of the spare cubicles shall be decided based on the type and rating of feeders
provided in the HV Switchgear.All spare cubiclesmust be fully equipped.
LV switchboards shall have spare cubicles, etc., for the possible future installation of
additional outgoing circuits equivalentto approximately 30% of the number of circuits
initially utilised, with a minimum of one circuit of each size and type of consumer (e.g.
outgoing static feeder, outgoingmotor feeder).
All spare cubiclesmust be fully equipped.
9.5.7
Choice of 3-pole and 4-poleLV Circuit Breaker
The neutral circuit of each transformer and generatorincomer shall be connected to the earth
bus-bar by bolted links so that the connection is physically located on thebusbar side of the
neutral earthing facility. This isolating facility shall be either a bolted link or one
of the poles
of a 4-pole circuit breaker. All earth links shall be labelled 'neutral earth link'. Provision shall
be made for the installation of CTs on each incomingneutral connection, both beforeand after
the point where it is earthed, and on the connectionsto the earth busbar.
Where morethan one transformer1 generator areinvolved, all incoming andbus-section circuit
breakers in the LV Switchboard shallhave 4-poleto control the phases and neutral.
Alternative configurations,in which the connection point is different from that described
above, may be offered to QP by the manufacturerfor discussion and approvalin writing.
9.5.8
Ring-mainUnits
A ring-main shall be designed strictly as one simple ring. The simple ring shall not have any
interconnectors to other sources outsidethe ring. The ring shall only be supplied at its two
"ends".
Ring-main units (RMU) shall be specially designed for the purpose, and each such unit shall
only consist of two incomer switches and one outgoing circuit breaker.Two outgoing circuits
from one ring-main unit are notacceptable.
The ring-mainshall normally be fed from both ends with a RMU near to the middle of the ring
kept normally open. All switching operations shallbe manual.
The ring-main units shall be located inside the sub-station. In exceptional cases where the
ring-main unit is required to be located outdoor, suitable sun-shade and fence shallbe
provided.
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The maximum number ofring-main unitsin one ring system shall be such that the protection
discrimination can be achieved. Directional and non-directional time graded protection
shall
be provided. The unitshall also incorporatetransformerearth switch.
Remote indications for ring-rnain unitswitching status shallonly be provided if essential from
operationalpoint of view.
Bus-bar Ducting
Bus-bar ducting shall complywith the requirementsof QP Engineering Standard ES.2.14.0019
POI.
The continuous and short-circuit ratingof bus-barducting shall be same as that of switchgear,
transformers and generatorsto which theseare connected.
For LV systems where the current rating exceeds 1600Amp, interconnection of equipment
shall be through bus-bar ducting insteadof cables.
In HV systems, decision of using bus-bar ducting shall be based onthe number of cables used
for interconnectionof equipment. Wherethe number of cables requiredis more than three (3),
bus-bar ducting shallbe used.
Neutral Earthing Resistor
The neutral earthing resistor shallcomply with the requirements of QP Engineering Standard
ES.2.14.0085[27].
The NER shall be housed in a sheet metal enclosureand shall be naturally ventilated.
The resistance elements shall be made of stainless steel alloyin a grid formation.
NER shall be rated to withstandthe specified faultcurrent for minimum 10 seconds.
9.8
AC UPS System
AC UPS system shall be provided for continuous process loads and instrumentation system
requiring unintermptiblemaintainedAC supply. Followingloads shall be connectedto the AC
UPS system:
DCS system
ESD system
Fire and gas system
Local panelsfor criticalpackages
Analyser room instruments
Metering stationinstruments
Annunciation panel
AC UPS systemshall complywith the requirementsof QP EngineeringStandard ES.2.14.0040
[la
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The configuration of UPS System,e.g. redundant, stand-by redundant, parallel redundant, will
depend upon the function of its consumers.For all configurationsof the UPS System,2 Nos.
50% rated back-up battery banks shall be provided. The UPS system shall also be provided
with stabilisedstatic and maintenance bypass.
AC UPS system shall be sized to take care of the crest factor of the load current.
10% marginin capacity shallbe kept for future requirements.
AC Distribution Board shall have at least 10% spare outgoing feeders for future use. The
largest outgoing feeder load shall not exceed25% of the AC UPS System rating.
DC UPS System
DC UPS system shall be provided tofeed the following:
Switchgear control
Critical lightingand navigational aids
DC motors, if applicable
Telephone system
Fire alarm system
Communication equipment
Solenoidvalves
Telecom
SCADA
The DC UPS system shall comply with the requirements of QP Engneering Standard
ES.2.14.0044 [17].
The DC UPS system shall comprise of 2 Nos. 100% rated rectifier1charger units and 2 Nos.
50% rated back-up battery banks.
10% marginin the capacity shallbe kept for future requirements.
DC Distribution Boardshall have at least 10%spare outgoing feedersfor future use.
9.10
Batteries
Batteries shall be of adequate capacityto meet the back-up requirements for the required duty
cycle and to take care of future load margin of 10%.
While sizing the batteries, temperature correction factor and ageing factor shall be duly
considered.
For both AC UPS and DC UPS system,Ni-Cd batteries shall be specified.
However, for very special cases wherespace is a constraint, valve regulatedlead-acid (VRLA)
batteries with absorbed electrolyte in a microporous structure can be specified. In such
installations, close controlof worlung temperature is essential.
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The battery autonomytimes shall be as per QP Philosophy for Fire and Safety QP-PHL-S-001
[34]. Batteries feeding switchgear controls shallhave an autonomy time of 60 minutes.
9.11
Capacitors
The capacitors describedhereunder are those to be used for power factor correction and may
be used for both HV and LV applications.
The capacitors and associated equipment shall comply with the requirements of QP
Engmeering Standard for HV Capacitors ES.2.14.0080 [25] and LV Capacitors ES.2.14.0081
[261.
Capacitors shall be of the low-loss, metal enclosed and hermetically sealed type.LV
capacitors shall be of self-healing type and comply with IEC 60831 [log] while HV
Capacitors shall comply with IEC 60871 [I 141.The capacitors shall be protected with internal
fuses.
The capacitor bank along with series reactors, if provided,shall provide minimum net kvar at
rated voltage. However, the insulation system shall be designed to withstand continuousover
voltage of 110% of rated voltage.
Attention shall be paid to the capacitor inrush currents and in particular to the possibility of
very high inrush currents when being paralleled with capacitors already energised.The
inductance of interconnecting cables and additional series inductances shall be considered in
the assessmentof the inrush currents.
Consideration shall be given to the relatively long discharge times(from operating voltage
down to less than 75 V) allowed in the relevant IEC i.e. 3 minute for LV capacitors and 10
minutes for HV capacitors. Shortertimes shall be specified where necessary.
An interlock system shall be provided to avoid re-energising the capacitor bank when the
residual voltageis above 10% ofthe system voltage.
9.12
Electric Motors
9.12.1
Squirrel cage inductionmotors shall be specified on account of their robust constructionand
lower capital cost. Synchronous motors of samerating of squirrel cage induction motors are
more efficient but have higher capital cost. For applications wherepower factor compensation
is beneficial and cost permits, synchronousmotors may be used.
9.12.2
The LV induction motors shall comply with the requirements of QP Engineering Standard
ES.2.14.0035 1141 and HV induction and synchronous motors shall comply with the
requirementsof QP Engineering StandardES.2.14.0030[13].
9.12.3
All motors shall be rated for continuous dutyexcept for cranes1 hoists1engine starting which
may be rated for the envisagedduty cycle.
9.12.4
All motors shall be designed for Direct On Line starting unless otherwise other methods of
reduced voltage starting are specifically mentioned.
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9.12.5
Recommended powerratings of electric motors in relation to system voltages are:
Motor Rating (kW)
System Voltage (V)
Above 3000
11000
In some cases, it would be economical to supply one or two large motors at lower voltage
rather than having additionalHV switchboard and transformer. Also the installationof LV
motors of higher rating than the above mentioned ratings may be justifiable when, for
example, the additional installationof an HV system would be uneconomical.
All such applications shall be duly supportedby voltage drop calculations andrun up time
calculations of the motor.
9.12.6
Motors shall be provided with anti-condensation heater.In case, the manufacturer does not
provide anti-condensation heater (formotors 15kW and less), the manufacturermust provide
an undertaking that there will not be any detrimental effect onthe life of the motor due to
condensation.
9.12.7
Integrated Motor Control System(IMCS) which are micro-processor controlledmotor starters
and with additional drive monitoring & protection features and self-diagnostic &
communicationfacility shall be consideredfor new installations.
9.12.8
Use of DC motorsshall be limited to those applications wheresafety of equipment is involved
e.g. motors for emergency lubeoil pumps shall be on DC supply to cool the bearings on failure
of AC supply.
9.13
Cables and Wires
9.13.1
General
Construction of cables is defined in detail in the QP Engineering Standard for Electrical
Power, Control Cables and CableGlands ES.2.14.0070 [22]. All power, lighting, controland
earthing cablesshall have copperconductors.
Multi-core cables shall be given preference to single core cables. However, singlecore cables
may be used for practical and economicreasons.
Dedicated cables shall be provided for protection, controls, indications and alarms for
individual equipment.
Separate cablesshall be used for each of the following:
CT secondary circuits
VT secondary circuits
Interlock1intertrip circuits
Differential circuits
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Fibre optic cablesor fibre optic cores in compositecables can be used for the transmissionof
signals and data.
The power andlighting cables shall be sized basedon maximum continuous current,voltage
drop, system earthing and short circuit withstandcriteria. The de-rating dueto ambient air
temperature, ground temperature, grouping
and proximity of cables with each other, thermal
resistivityof soil, depth of laying etc.shall be considered.
Cables for capacitorbanks shall be sized for minimum 135% of the rated capacitor current.
All power and control cables shall be in continuous lengths without anysplices or
intermediatejoints except for long feeders. The cables usedfor lighting shall have appropriate
junction boxes with adequately sized terminals. Cable
joints in hazardous area shall not be
permitted.
9.13.2
HV Cables
Three core HV cables shall be cross-linked polyethylene (XLPE)insulated, single galvanised
steel wire annoured and PVC oversheathed. These cables shall have a minimum cross
sectional area of 25 mm2 and maximum cross sectional area of 240 mm2. Use of cables of
higher size, only in special cases, shallbe subject to approval of QP.
Single core HV cables shall be cross-linked polyethyleneinsulated, screened, aluminium
armouredand PVCoversheathed.Unarmouredcables canbe used for short lengths only.
9.13.3
LV Cables
Multi-core power, lighting and control cables shall be cross-linked polyethylene insulated,
single galvanisedsteel wire armouredand PVCoversheathed.
Maximum cross section area shall be 240 d.
For power, lighting and control cables, the
minimumcross section shallbe 2.5 mrn2.
For multi-corecontrol cables,20% of total cores or min. 1 core shall be kept spare.
9.13.4
Earthing Cables
Earthing cables for both abovegroundand underground shall be PVC sheathed, coloured
yellowlgreen.
9.13.5
Flexible Cables
Flexible cables for voltagesup to 450 V to earth shall be heavy duty neoprene rubber
insulated, PVC sheathed. The flexible cables shall be used for welding sets, portable
equipment,hand tools, hand lamps, winches andhoists etc.
9.13.6
Wires
Wires shall be PVC insulatedin accordancewith IEC 60227 1593.
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Wires laid in conduits shall have minimum cross section area of 2.5 mrn2except for wiring
between a switch and a lighting fixture,minimum cross-section of 1.5 mm2may be used. For
control wiring withinpanels, minimumcross section of 1 mm2may be used.
Wiring colours shall beas follows:
Blue for neutral
Brown for phase
Black for switched phase
Green/ Yellow for earth
Wiring in conduits shall not be used in hazardous area.
Cables with Fire Withstand Capabilities
Cables required to continue in operation for a specified time during a fire e.g. cables for
emergency shutdownsystems shall have increased fire withstand capabilities. Thesecables
shall not emit halogen and smoke emission
shall be limited. The method of test to demonstrate
this capability shall be asper IEC 60331 [70].
Use of mineral insulated cablesas fire resistant cablesis not acceptable.
Cable Accessories
Cable glands shall be selected to suit the type of cable and termination bod enclosure and
shall be of appropriate type of protection for the hazardous area. Effective earth continuity
shall be ensured between the cable armour and the gland plate or the internal earth terminal.
All LV terminations shallbe through cable lugs.
HV terminations shall be through heat shnkable type termination kits. However,for HV
motors and generators, the terminations shallbe through Elastimoldl Bi-mold plug and socket
connectors.
Remote ControlUnit
Each motor shall be provided with a Remote Control Unit(RCU) in the field near the motor
for starting and stopping purpose. Sun-sheltershall be providedto protect the outdoorRCUs.
Based on the control requirements, theRCU shall be provided with start/ stop push button,
ammeter, auto/ manual andlocal/ remote selector switches, etc.
Motors installed at elevated platforms shall be provided with additional RCU at ground level
for stoppingthe motor.
Lighting Equipment
General
Industrial fluorescent lightingin 'white' colour shall, in general, be used for illumination.
Where special requirements regarding colour distinction exist, theseshall be met.
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Incandescent lightingshall be applied for the purpose of decorative lighting.
High-pressure dischargelamps may be used for practical and economic reasons in the case of
lighting of tall buildings (e.g. compressor shed, etc.) or large areas.Such lighting shall alsobe
supplemented with fluorescent lighting fixtures for immediate use on failure of AC supply
installed at strategc locations.
Flood lighting shall be used for the open areas aroundthe process and production plants.Highpressure dischargelamps shall be used for flood lighting.Care shall be taken to avoid shadows
in the working areas.
Low-pressure sodium lamps shall not be used, as they constitute a fire hazard in the event of
breakage.
All outdoor lightingshall be controlled by means of photoelectric cell withmanual overriding
control. Controlcircuit shall be fail-safe.
9.15.2
Plant Lighting
Plant lightingshall comprise of following:
Normal lighting
Emergencylighting
Escape] Critical lighting
Normal and emergency lightingshall be fed by AC supply while escape1critical lighting shall
be fed from self-contained batteries.
For both Zone-1 and Zone-2 hazardousareas, the preferred form of illumination shall be
fluorescent lamps with type of protection Ex-e.
If high-pressure dischargelamp fittings are needed in hazardous areas then they shall be of the
Ex-d type only. An isolating switch shall be included inside the fitting to prevent the light
fitting from being energisedwhen it is not fully assembled.
For standardisation purposes, the same type Ex-d or Ex-e lighting fixtures should be used
whether classified Zone-1 orZone-2.
9.15.3
Building Lighting
Lighting fittings in closed buildings,which are classified as non-hazardous areas, such as
offices, control rooms, sub-stations,shall be fluorescent bi-pin, switch-start type, industrialor
domestic type.
9.15.4
Portable Lamps
Hand-held lampsshall be rated for maximum50V AC supply.
For power supply to portable hand lamps,single-phasedouble-wound portable safety isolating
transformers having a secondaryno-load voltage of not more than 50 V, shall be provided.
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Standard rating of this transformer shall be 250 VA. The primary side of the transformer shall
be provided with a suitable length of flexible cable and a plug for connection to a convenience
outlet.
Accumulator type hand lamps, suitable for Zone-1 hazardous area, provided with wall
mounted bracket type battery charger shall be kept inside the sub-stations. These shall be
located near the entrances.
Hand torches shall be provided for all locations where operating personnel are present (control
room, fire station, security house etc.). These shall be plug-in type complete with fixed
chargmg units and rechargeable batteries and the complete unit shall be suitable for Zone-1
use. The number of hand torches shall be based on the number of personnel per shiR of
operation.
9.16
Electrical Heat Tracing
Electrical heat tracing systems shall comply with the requirements of QP Engineering
Standard for ElectricalHeat Tracing ES.2.14.0004 [6].
The system shall be ordered as a packaged unitincluding design, supplyof tracers and cables,
installation at site and all necessary control auxiliaries.
In all cases where electric heating is applied, each circuit shall be fitted with earth leakage
protection device.
9.17
Electric ProcessHeaters
Electric process heaters shall comply with the requirements of QP Engineering Standard for
Electrical Process HeatersES.2.14.0005[7].
The heaters shall be either contactor controlled havingonloff facility or thyristor controlled as
per process requirements. For thyristor-controlled heaters, power of each heater shall be
controlled by firing of thyristors accordingto zero-crossover mode i.e. where the voltage or
current is zero.
Over-temperatureprotection for the heatersand the thyristor control panel, heater protection
for low flow/ low level andearth leakage protection device inthe power supply circuit shallbe
provided.
9.18
Heatersfor Frost HeaveProtection
For frost heave protection of tank bases and walls, self-regulating type heater tape installed in
non-corrosive material conduitsshall be provided. Thesystem shall be ordered as a packaged
unit including design, supplyof tracers and cables, installationat site and all necessary control
auxiliaries.
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Power and ConvenienceOutlets
General
For maintenance purposes, an adequate number of 3-phase power outlets for movable
equipment and single-phase convenience outlets for the supply of portable tools and hand
lamps shall be provided at suitable locations. Moreover, convenience outlets for portable
igniting equipment ofboilers and furnaces shall be provided in the vicinity of the burners. The
outlets shall be standardised for each rating throughout the plant and shall have an earth
connection incorporated. The outlets installed inplant areas shall comply with IEC 60309
[681.
Plugs shall not be interchangeable with sockets of different voltages or current ratingsnor
shall it be possible to insert an industrial type plug intoan outlet suitable of Zone-11Zone-:!
hazardous areas.
All power and convenient outlets shall be protected by means of short circuit protective
devices and current operated earth leakage protective devicesi.e. residual current circuit
breakers (RCCB). The RCCB operating current shall be 30 mA for circuits less than 125 A
rating and 300 mA for circuits equal to or greater than 125 A rating.The operating time shall
not exceed 30 rnsec.
Power Outlets
Power outlets shall have a standard supply voltage equalto the LV motor supply voltage
selected for the plant. These outlets shallbe rated for at least 100 A and be suitable for
outdoor installation. They shallbe located in a safe area alongthe battery limits, spaced in
such a way that, with the aid of extension cables feedingmovable secondary supply boards, all
points can be served conveniently.The power outlets shall be connected in such away as to
retain the same phase sequence, ensuring that the correct directionof rotation of movable
equipment isobtained from all outlets.
Adequate number of power outlets shall be provided at suitable locations to ensure
accessibility with a 50 m lengthof flexible cable to any point in the process area and around
transformers in a sub-station.
Convenience Outlets
Convenience outlets shallhave a single-phase supply voltage equalto the voltage selected for
normal lighting.
For industrial areas the outlets shallbe rated for 16 A suitable for outdoor installation and
shall conform to the hazardous area classification. These shall have necessary mechanical
interlocks and earthing facility.
Adequate numberof convenience outlets for hand lamps and portabletools shall be provided
at suitable locationsto ensure accessibilitywith a 15 m length of flexible cableto all manholes
of process equipmentand any other important areas in the process unit.
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9.20
Navigational Aids
Marine and air navigational aids are required for all QP mobile and fixed offshore
installations. These shall comply to the requirements of QP Engineering Standard for
NavigationalAids ES.2.14.0003[5].
9.20.1
Marine NavigationalAids
All offshore installationsshall be provided with the following navigational aidsto assist ships
and aircrafts in the surrounding area:
Main lights
Secondary lights
Subsidiary lights
Fog signals
Secondary fog signals
Underdeck illuminationof legs, risers and conductors
The lights and fog signals shall be provided with independent back-up DC UPS Supply
System.
An alarm for the failure of main lights and fog signals shall be provided in the Central Control
Room (CCR) to gwe a warning to the operator. These alarms shall also be provided for
satellite platforms, structuresand unmannedinstallations.
9.20.2
Air Navigational Aids
The helicopter landing area on all offshore platforms and structuresshall be provided with
alternate yellow and blue lights, which are visible ornni directionally above the landingarea
level. The lights shall not be below the level of the deck and shall not exceed a heightof 0.125
metres abovethe deck. The lights shallbe spaced at interval of 3 m. round the perimeter.
9.20.3
Obstacle Markers and Lights
Tall structures, stacks,columns andtall vessels etc. shall be provided with obstaclelights andl
or markers as per the guidelinesof ICAO [179].
The obstacle lights shall beprovided on the top most level of the structure. Where it is not
practical e.g. at the top of the flare tower, these lightsshall be provided at lower level with
suitable heat shields based on radiation calculations.
For offshore installations, obstacle lights shallbe installed at suitable locations to provide the
helicopter pilot with visual information onthe proximity and height of objects which exceed
the height of landing area and are close to landing area.
Obstacle lights shall be connectedto emergency powersupply.
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9.21
Electric Motor Operated Valve Actuators
The valves to be actuated with electricmotor shall be identified by Process Department.
The electric motor operated valve actuators shall comply with the requirements of QP
Engmeering Standard ES.2.14.0036 [15]. These shall be provided with integral starters. The
necessary local1 remote selector switches, start/ stop switches or push buttons, torque limit
switches etc. shall be provided on the actuator for local andremote control dependingon the
mode of selection. Failure of the torque limit switches shall not cause any damage to the
actuator motor.
9.22
Variable Speed Drive Systems
The variable speed drive systems shall comply with requirementsof QP Engineering Standard
ES.2.14.0050[19].
The application of variable speed drive system shall be considered where there is a
requirement of speedvariation as per the process. Flexibility of operation and increased
efficiency will be theadded advantage withvariable speed drive systems.
It shall be the responsibility of the VSDS manufacturer to offer the most suitable system to
match the following requirements:
The kW rating of the motor
The power systemto which it will be connected
VSDS produces significant harmonic voltage and current distortioninto the connected power
system, and therefore they shall be provided with carefully designedfilters that will greatly
attenuate selectedharmonic numberse.g. 5,7, 11, and 13.
The manufacturer shall be given the full details of the relevant parts of the connected QP
power system, so that he can carry out detailed studies into the interactionof the VSDS with
existing equipment in the vicinity of its connection. The manufacturershall pay particular
attention to the possibility that resonancesmay occur in the system due to cable capacitance
and power factor correction capacitors. The filtersshall perform correctly for the specified
frequency variation in thepower system.
Each variable speed dnve system, including the driven equipment,shall have for its electrical
auxiliaries its own distribution panel. This panel shall be fed via transformation or conversion
equipment from the same supply source and system side as the main unit to obtain optimum
availabilityof the total variablespeed dnve system.
9.23
Overhead Transmission Lines
The design of overhead transmission line and specificationof equipment associated with
overhead transmission lines shall meet the requirements of QP Engineering Standard
ES.2.14.0071[23].
Conductors, insulators, supportsand other equipment shall be designed to provide adequate
protection against the adverse effectsof prevailing site conditions e.g. temperature, wind,
lightning and polluting atmosphere etc.
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The design and installation of overhead lines is described in detail in QP EngineeringStandard
ES.2.06.0001 [2] with respect to clearances above ground, choice of materials, tensioning,
span, pole spacing etc.
HV overhead lines shall have ACSR (aluminium-conductor steel-reinforced) conductors
complyingto IEC 61089 [I321 on steel pole or lattice steel structure.
Insulators shallbe porcelain or glass with a smooth profile and an absolute minimum creepage
of 40 mrnlkV.
All steel components including fasteners shall be hot dip galvanised after fabrication in
accordance with IS0 1461 [146].
Each individual overhead line circuit shall eitherbe adequately spaced apart or strung on to
separate poles for the purpose of carrying out maintenance on one circuit whilst the otheris
live.
Overhead lines should not be routed parallel to pipelines for long distances.Where this cannot
be avoided, and depending on voltage levels, sufficient distanceshall be maintained to avoid
electrical interference between overheadlines and pipelines. For distance betweenoverhead
lines and pipelines, refer QP Engineering Standard for Onshore Pipeline Construction
ES.5.14.0051[32].
All connected equipment shall be protected against effects of lightning by means of earth
wires and surge arrestors at each end of the line. At road crossings, where overhead line
crosses the roadvia under groundcables, each sideof the overhead line shall be provided with
surge arresters. Surge arresters shallcomply withIEC 60099 [50].
The current rating of surge arresters shall be selected to suit the system short circuit rating and
the voltage rating shall be determined as part of the insulation co-ordination asper IEC 60071
[441.
The lines shall be fitted with vibrationdampers. At approximately 1krnintervals a sectionor
tension pole shall be installed.
All support structuresshall be earthed at the foot of the support andthe earth electrode should
have a maximumresistance of 10 ohm to the general mass ofthe earth.
Where stay wires are used, these shouldbe provided withinsulators.
9.24
Cathodic Protection System
Cathodic protection is an electrochemical technique for preventing corrosionof a buried or
immersed metalwork to an electrolytic media surrounding the metal. This can be achieved
either by sacrificial means or by applying dc current to the metal surface by external power
supply source.
The cathodic protection shall be provided for underground pipelines, tank internals, tank
bottoms, submergedpipelines, offshore steel structures etc.
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The cathodic protection system shall be designed and installed as per the guidelines of QP
Engineering Standard ES.2.14.0045[18].
Temporary cathodic protection shallbe provided, wherever required,to protect the corrosion
during constructionphase till the permanent cathodic protection systemis in place.
9.25
Annunciation Panel
Each sub-station and electricity generating stationshall be provided with a systemto monitor
and store the individual alarmand trip functions of the sub-station equipment.
Micro-processorbased systemsshall be specified.The system shall also provide common and
selected alarmsto the DCS for display in the central control room (CCR).
The annunciationpanel shall be provided withpower supply from AC UPS System.
This panel shall monitor at least the alarms andtrip functions of the following equipment:
Generator protection
HV switchgearincoming feeder and outgoing feeder protections
Transformer feeder protectionsand alarms
Trip circuit and closing circuit supply healthy status
AC UPS system fault
DC UPS system fault
EmergencyDG Set operating status
HVAC failure
The annunciationpanel shall be equippedwith reset and fault-acknowledgefacilities.
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10.0
InstallationDesign Philosophy
10.1
General
The electrical installation shallconformto good workingpractice of high quality and safety
and shall be in accordance with QP Engineering Standardfor Electrical Installation
RecommendedPracticesES.2.06.0001 [2].
The electricalequipmentshall be installed inaccordance withthe installation instructionsand
supportingdrawings providedby the manufacturer of therespective equipment. Forcorrect
civil design of the building housing theelectrical equipment andfoundations,all necessary
data and general arrangementmust be obtained fromthe respectiveequipment manufacturer at
an early stage of the procurementof the equipment.
The design of the electricalinstallationshall ensure that accessis provided forall operational
and maintenancepurposes.Proper careshall be taken to ensure safeand convenient operation
and maintenanceof the equipment.
Temporaryinstallationwork, required during erection of permanent
installations,should also
complywith the basic rules of designand engineering.
10.2
Cabling and Wiring System
10.2.1
General
The installationof cables and wiring is describedin detail in QP EngineeringStandard for
ElectricalInstallationRecommendedPracticesES.2.06.0001[2].
For on-shore installations, cables shall be laid, to the extent possible, underground. For
offshoreinstallations, cables shallbe laid using cabletrays and/ or cableracks.
At an early stage of the area plot plan development, reservation of
appropriateroutings and
adequate space for underground and above ground
cable installations shallbe made in cooperation with other engineering discipline concerned.
For underground cable installations,
a
dimensionalcable routingplan shall be made, indicating adjacentunderground servicesand
foundations.
When requisitionsfor cables are prepared,
the total theoreticallength requiredin accordance
with the layoutsand drawings, foreach type and size,shall be increasedby 5% of the total for
each type,to allow for slack, jointing, termination and waste.
It shall be ensured that duringtransport, storage and installation,cable ends ofall types of
cablesare suitablysealedto avoidingress of water.
For newplant construction, jointsin cabling shall be avoided.Tee-typecable joints shallnot
be used.
HV underground cablejoints shallbe recorded and their location marked accuratelyon the
'as-built' drawings.
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Changes of direction in cable trenches and on racks or trays shall cater for the following
minimum cable bending radii:
LV cables
10 times the cable OD
HV cables (multi-core)
:
15 times the cable OD
HV cable (single core)
:
20 times the cable OD
For all cases, manufacturer'srecommendations mustbe adhered.
At the end of hard-floored cable trenches, short ductsor pipes shall slope down into the
surroundingsoil, to avoid cable damage on the edges owingto settling of the soil.
Single-core cables pertaining to one 3-phase circuit shall be laid together, separated from
multi-core cables.They shall be laid in trefoil formation, rather than laid flat.
Instrument and telecommunication cables shall be laid in trenches or trays separated from
those used for HV and LV cables.
Open pipe trenches shallbe crossed by means of bridges or troughs over the pipe trench. The
troughs shall be constructed from reinforced concrete and backfilled with a 20:l sand and
cement mixture.
Where cable trenches cross roads, additionalminimum 3 nos. or 25% of the total pipes (ducts)
installed shall be provided to accommodatefuture cables.
Cables in the same trench or set of racks, or cables in adjacent trenchesor sets of racks, shall
be spaced to avoid the possibility of electromagnetic interference with instrumentation,
telecommunication, ESD, fire and gas, electronic system and similar cables. Theminimum
distances from instrumentation cables shallbe as follows.
Power,lightingand Control
Cables
Distancefrom ElectronicSystems
Cables inmilli-metres
The armouringof multi-core cablesshall be solidly earthed at both ends.
The armour and screen of single-core cables shall be earthed on one side. For longer cable
length due attention shall bepaid to open end voltages.The open end voltage shall not exceed
60 V under full load rated current conditionsand 430 V under maximumshort circuit current
conditions.
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10.2.2
UndergroundCabling
10.2.2.1
General
General distribution cables shall run alongside the roads,off plot of the plant area. Cables that
pass through a plant and which are not related to a particular plant ortank farm shall be routed
free from such installations.
Plant cables shall run in either of the two directions formed by the main axes of the plants,
avoiding as much as possible the main crossings with instrument cable trenches and pipelines,
and preferably away from heavy-load-bearingrestricted areas,e.g. transformer bays.
Furthermore, underground cable routes shall be designed to avoid close pipe crossings and
adjacent runs with undergroundpipelines. A minimum distance between cable and pipeline
shall be maintained, as indicated in QP Engineering Standard for Onshore Pipeline
Construction ES.5.14.0051 [32]. Cables shouldpreferably cross underneath buried pipelines.
If close crossings with underground pipelines canying hot liquids or gases, or which are
regularly steam-cleaned, cannotbe avoided, the pipeline shall be insulated in order to limit its
outside temperatureto a maximum of 60degrees C. In these cases cables may need to be run
above pipelines.
Single-core cables, when laid in trefoil formation, shall be braced by non-magnetic clamps
suitable for withstanding expectedshort circuit forces. Such formations shall be laid in their
own individual trench.
As a standard, power cables shall be laid in a single-layer formation.
Control cables shall be installed as an additional layer on top of the power cables or as an
adjacent block.
HV cables may be laid in the same trench with LV cables. HV distribution cables shallbe
separated from LV cabling, e.g. by means of a continuous row of cable tiles placed vertically
between the two cable types or by any other suitable barrier.
In plant areas the spacing between power cables shall be no less than 70 mrn edge-to-edge.
10.2.2.3
Cable Trenches
Cables shall be buried directly in theground, wherever possible.
The cables shall be laid on and covered by clean sand fill, duly compacted and protected by
protection tiles. The top finish over the protected tiles may be in accordance with the
surrounding area.
Cable trenches in concretepaved areas shall be in accordance with QP EngineeringStandard
for Electrical Installation Recommended Practices ES.2.06.0001 [2]. Cable trenches wider
than one metre shall be permanently coveredwith heavy or light duty paving compatiblewith
the surroundingpavement but coloured red. For cable trenches coveredby concrete, protection
tiles are not required.
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Except for short runs at termination pointsof the cables in the plant area, undergroundcable
ducts or pipesshall be avoided.
In order to facilitate cablelaying beforefinishing the concrete paving, the expansion seamsin
concrete floors should be located outside the cable trenches. The location of sleeves at
termination pointsof cables shall be indicated onthe civil drawings.
The dimensions forcable trenches shall be as follows:
Depth of trench
600 mm to 1000mm
Depth of powercable
500 mm to 900 mm
Depth of control cable
500 mm to 900 rnrn
Spacingof cables
70 mm
Depth oftiles
350 mm
Depth of earth wire, if used
375 mm to 425 mm
The depth dimensionsin rnilli-metresshall be measured from the finished level at the top of
the trench to the underneath surface of the tile or cable. The spacing dimensions in millimetres shall be measured fromthe side surface of one cable to the nearest side surface of an
adjacent cable, or to the side face of the trench, regardlessof the diameter of the cables. A set
of cross-sectional drawingsshall be prepared foreach new project based on the requirements
set out herein.
As regards to the width of cable trenches, there shallbe no restriction in the number of cables
that can occupya row within the direct-buried,back-filled trench. However, for pre-formed
concrete trenches with concrete lidsthe width of the trench shall be limited by the loadbearing strengthof the lid and walls when heavy weightssuch as road vehicles may pass over
the trench. The design and widthof these trenchesshall be submittedto QP for approval.
Cable trenches shall be constructed with25% spare capacityto accommodatecables in future.
Where cablesare directly buried in trenches but need to pass through a duct or bank of ducts,
e.g. road crossing, thenthe laying pattern in the trench shall be maintainedthrough the ducts.
Cable marking and numbering shall be in accordance withQP Engineering Standard for
Electrical Installation Recommended Practices ES.2.06.0001 [2]. If design calls for a
permanenttop finish of trenches, e.g. permanentconcrete paving inside plot limits,no marking
is required. Cablesshall be marked on termination points at bothends of the cable. For cable
marking purposes non-corrodingstrips should be used, each having ample length to be
wrapped twice aroundthe cable and in which the cable number has been imprinted by means
of letter or cipher punches. Spacing betweencable numbers along the route shall not exceed
10 m. Cables shall be numberedwhere they branch offfrom a main route and at both sides of a
road crossing.
In addition, route markers shall be provided atevery 30 metres and changeof drection in the
routing and at the points of crossing with roads or pipelines, except when cable routing is
already indicated by red-colouredconcrete pavement.
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10.2.3
AboveGroundCabling
Above groundcabling shallbe supportedby cable racks,trays or cableladders all the way up
to their terminations.Where necessary,e.g. particularlyon vertical runs,
the cables shallbe
fixed to the tray by straps. Individualcables,however,may be fixed directlyto the structures,
walls, ceilings orcolumnsby meansof properfixing and supportingmaterials.
All materials used shall be properly protected againstcorrosion, such as hotdip galvanised
CORTEN'A' grade steel, stainless steel,glass-reinforcedpolyester (GRP), andfire resistant
polyester, dependingon the severity of environmental conditions.
Stainless steel shall be of
grade 316. Galvanisingshall be carried outas per IS0 1461 [146]. Additional coatingmaybe
provided on galvanised
material for installationshavingseriouscorrosionproblem.
Normally for road crossings, the cablesshall pass through a duct or bank of ducts. In
installations,where overhead road crossings
are unavoidable,the cableracks shall be erected
with the followingminimumclear heights:
5.5 m for roads having vehiculartraffic
3.5 m for roads without vehicular
traffic
Overheadcable crossing passages
shall be boundwith yellow1black colouredmarking signs.
Bends and cornersin the cable racks, traysor laddersshall allowthe minimumcable bending
radii. Cable racks and traysshall be closed by removable top cover allowing adequate
ventilationin situationswhere:
Mechanicaldamageof the cablesis likelyto occurduringplant maintenanceactivities
Oil or chemicalspillageon the trays canbe expected
Sun shielding isrequired fordirect solarradiation
Cables on racks or trays may be bunched in maximum oftwo layers. HV cables shall be
segregated fromthe LV cables.25% extra spaceshall be left in each cable tray1rack for future
cables.
Single core cablesshall be laid in trefoilwith 150mm clear spacingbetweentrefoils.
Individual cables emerging from
floors or soil shallbe protected against mechanical
damage
by means of galvanisedsteel pipes or rigid PVC pipes to a minimumheight of300 rnmabove
the ground.
Proper sealing of openings around cables shall be done to prevent the leaking of oil or
chemicalsinto the cabletrench.
Cablesor cable supportsshall not be fvted directlyor indirectlyto plant equipmentor process
piping, whichmay requireremoval orreplacement.All cable trays shallbe installed insuch a
way that they are at least 150mm clear of piping.
Cables areto be laid on racks or trays strictly in accordance withthe laying patternsin the
layout drawings. Metal parts
of the cableracks andtrays shall be bonded andconnectedto the
commonearthinggrid.
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For cable marking1numbering,noncorroding marker strips shall be strapped aroundthe
cables. Spacingbetweencable numbersalong the route shouldnot exceed 25m. Cables shall
be numbered wherethey branchoff froma main route.
10.2.4
Wires in Conduit
outlets in closed
Conduit systemsmay be used for lighting,communication and convenience
buildingsin non-hazardousareas.
Conduit installations shallbe madewith rigidPVC conduit and non-metallic conduit
boxes.
Conduitbox coversshall remainaccessible.
10.3
LightingSystem
10.3.1
General
The installation of lightingsystems is described in detail in QP Engineering Standard for
Electrical InstallationRecommendedPracticesES2.06.0001[2].
The lighting system shall be designed to provide the averageillumination levels as given
below:
Location
Controlroom - General lighting
Rear of instrument panels
Illumination level
(Average)
500
250
Outside,near entrances
150
Indoor sub-station
200
Laboratoriesand offices
400
Drawing offices
500
Librariesand readingrooms
400
Offices
400
Cateringareas (food preparation& serving)
300
Recreation roomsand lounges
300
Print rooms
250
Pump areas, compressor houses, generator
room, 150
valves, manifolds,loadingareas etc
Process areas
50
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Tank farm
Plant rooms
Receptionrooms
Indoorstores and handling areas
Canteen(diningareas)
Lifts
Locker roomsand toilets
Outdoorstores and handling areas
Materialyards
Operational bulkstorage
Road tankerloadingareas
Car parks
Plant Roads - Main thoroughfaresand crossings
Secondary roadsand crossings
Workshops- Inside building
Outside lighting
A multiplying factor of0.8 (Maintenancefactor) shall be used in the calculations for the
illumination level.
10.3.2
Plant Lighting
Plant lighting shallbe fed from dedicatedlighting distributionboardsinstalled insub-stations.
Plant lightingdistributionboardsshall include 20% spare outgoing circuits. Tothe extent
possible,the lightingcircuits shallbe arrangedto give a balanced loadacross the three phases
at the distributionboard. Alllightingcircuits shallbe with double poleisolation facility.
Plant lighting circuits shallbe single-phase(phase andneutral) and protected withmaximum
16A fuses or MCBs. Lightingcircuits shallnot beloaded higher than12 A.
Adjacentlightingfrttingsshall not be supplied fromthe same circuit.
Lighting fittings shallbe mounted on the available structures and shall be so located that
maintenanceand lampchangingcan beeffected withoutthe use of ladders and scaffolding.In
tall buildings, suchas compressor andturbo-generator houses, maintenance and
lampchanging
shall be possible by using the overhead crane.When no structure is available to support
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lighting fittings, lightingpoles of adequate height shall be used to support the fluorescent
lighting fittings.
The plant lighting shall be designed in sucha way that in daytime, the lighting of furnaces,
boilers and the ground level can be switched onfrom the plant control centreby means of a
switch. Plant lighting circuits (excluding level gaugelighting) shall be designed for manual
control andautomatic switchingvia photoelectricrelays.
Internal lighting of non-process buildings and sub-station buildings
shall be switched from
inside the building.
The lighting installationin the control rooms shall be designed to enable groups of ceiling
lights to be switchedoff by the operator. The lighting fixturesshall be situated in such a way
that reflection on instrument windows and displays is avoided. Depending on type of
instruments installed,dimmersmay be required.
Lighting near navigational waters, e.g. jetties and loading platforms, shall not hinder
navigation and marinelife in any way.
10.3.3
Emergencyand Escape Lighting
Fixed emergency lighting shall be installed at strategic pointsin the installations, including
control rooms, switchrooms, fire-fightingstations, first-aid rooms, watchman's offices, the
main entrances and in all other buildings andareas where required for safety reasons.
Location and electrical arrangement shall be such that danger to personnel in the case of a
power failure is prevented, andescape routes are illuminated. Emergencylighting shall have
intensities as requiredfor purpose.
The emergency lighting system shall consistof a number of fittings of the normal lighting
installation. In remote areas, where only few fittings are required, and based on economic
considerations,self-powered emergencylighting fittingsmay be used.
In all other cases, a number of standardlighting fittings shallbe fed via circuitshaving a standby supply from an emergencydiesel generator.
In the case of emergency diesel generator supply,a number of lighting fittings in the control
room and the basement of the control room, as well as field auxiliary rooms, shall have
lighting fittings with self-contained batteriesto avoid completedarkness during start-up time
of the diesel generator. All battery backed lighting fixtures on offshore platforms shall be
suitable for Zone-1 hazardousarea.
The number of emergency lightingfittings to be installed as a percentage of the total number
of fittings shall be determinedas follows:
Utility area
Process area
Administrativearea
Control room
Switch houses, field auxiliaryrooms
20%
10%
5%
50%
30%
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Compressorand generator buildings 30%
For escape lighting, the lightingfixtures shallhave selfcontained batteries rated to maintain
the lighting for at least 60 minutes. Escape
lighting shall be provided in all buildings to
illuminatethe way for personnel leaving the building along defined escape routes
to defined
musterpoints.
10.3.4
Street,Fenceand Open AreaLighting
Generalstreet and roadwaylighting poles shouldbe of the hinged type that canbe raised and
lowered.
Fixed polesshall be providedwhere lampswill be changedwith the helpof a vehiclemounted
mobileplatform. The heightof the pole shall be up to 12 meters.
Street lighting, fencelighting and open area lighting shall be fed from dedicated lighting
distribution boards,installedin a safe area preferablyin sub-station.This lightingshall alsobe
photoelectric relay-controlled.
Generally, forstreet lighting a 3-phaseplus neutralLV supply shall be used. Each lighting
pole shall containa fuse boxas wellas terminatingbox for loopingthe feedercable. Tee-type
cable joints are not allowed. Adjacent lighting poles
shall not be supplied fromthe same
phase.
Fence lighting shallbe placed insuch a way that the fenceas well as the area outside thefence
is illuminated.
Normallyfence lighting intensity shallbe equivalent tothe street lighting intensity.If special
security fence lighting is required, floodlights with high-pressure dischargelamps shall be
used.
10.3.5
Special Lighting
Speciallighting,e.g. navigationaids, obstruction warninglights and aircraft navigationlights,
shall be installed in accordance with national and
internationalstandards. Longlife lamps at
reduced voltageshall be used. Theinstallationshall be backed up by an emergencysupply
system.
10.3.5.1 Aviation Warning Lighting
Aviation warning lightsshall be installedin accordance withthe requirementsof Chapter6 of
Annex 14 to the convention on International Civil Aviation Aerodromes,
ICAO[179].
The lamp fittings willconsist ofa double lamp unit with automatic switchoverto the stand-by
lamp uponfailure of the operatingone.
10.3S.2
Illumination ofAreasto be observedby TV Cameras
The lighting installationfor areas that require observation
by TV camerasshall be designedin
particular with regard
to uniformityof the level of illuminationas well as to the location ofthe
individuallamp fittings. The lux levelto be maintainedshall be compatible withthe camera
system utilised.
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Direct visibilityof light emittingbodies orreflectionsfrom covers ofthe lamp fittings shallbe
of the plant.
prevented.This shallbe checkedbefore commissioning
10.3.5.3
Helideck Lighting
Helidecklighting shallconformto the latesteditionof CAA CAP 437 [181].
10.4
EarthingandBondingSystem
The purpose of providing earthing
is to reduce and control voltagesto an acceptablelow level
for the following:
Electrical safety(to achieve safe touchand step voltages)
Lightningand static electricityprotection
10.4.1
Earthingof Equipment
For on-shore installations, earthingof electrical systems, equipmentand structures each
installation shallhave one mainearth grid connectedto at least two groups of earth electrodes.
The earth grid shall comprisecopper earthing cables withgreedyellow PVC sheathing.Each
equipmentto be earthedshall be connectedto main earth grid by two branchearth connectors.
The earth grid shall be installedthroughout the plantsite in the form of a main earth ring with
branch interconnections
to the equipment andstructuresto be earthed.
Each earthingelectrodeshall be sunk verticallyto a depth of2 metres belowthe summerwater
table. The earth resistanceof each electrodeshall be as low as is practicablebut shall in any
eventbe such that the electricalresistancebetweenthe main earth grid and the generalmass of
the earth shallnot exceed4 ohms when any onegroup of electrodes is disconnected.Earth
electrodes shall be galvanisedsteel pipe or other suitable material,which guaranteeslow
resistanceand longlife. Copper electrodesshall not be used in areas with impressed-current
cathodic protection.Aluminiumshall not beused for any part ofan earthingsystem.
Use of buried un-insulatedearthing cable,for achievingthe desired earth resistancevalues,
shall be subject toQP approval.
The connectionsbetween electrode headsand conductors shall be so executed that easy
inspectionand testingof the earth resistance of individual
electrodes is possible,
All bareparts of undergroundearthing conductorsshall be suitably protected against direct
contact withthe surface soil so as to prevent electrolyk corrosion of plantequipment. All
earthing terminationsshall be madewith compression-typecable lugs. Interconnectionsshall
be directlyclampedwith compression-type branch connectors
or 'cad-welded'.
The metallic enclosures ofelectricaland nonelectrical equipment,vessels, tanks, structures,
etc., shall be bondedand earthed by connectionto the commonearth grid orto be provided
with theirown duplicate electrodes.
Earthing of fencesshall be done as per the guidelinesgivenin IEEE80 [164].
Pipelinesshall not be used for earthing purposes.
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Main earthring conductorsshall have a cross-sectionalarea of 70 sq. mm.unless otherwise
higher sizes are required based on the earth fault current and its duration. Branch earth
conductorsshall have a cross-sectionarea as given below:
To metallicenclosuresof HV electricalequipment
: 70 sq. mm.
To metallic enclosuresof LV electrical equipmenthaving a supply : 70 sq. mm.
cable witha conductorof cross-sectionof 35sq. mm.or more
To metallic enclosures ofLV electrical equipment havinga supply : 25 sq. mm.
cable witha conductorof cross-section lessthan 35 sq. mm
To structures,tanks, processplant equipment and
other nonelectrical : 70 sq. mm.
equipment
To other nonelectrical equipment
: 25 sq. mm.
Branchearth conductors having cross-section
of 6 sq. mm.shall only be used in above ground
applications for small
electricalequipment like junctionbox, RCU etc.
For offshore installations,all electricalequipmentshall be earthedby means of bonding tothe
jacket steelwork usingcopper cables. Neutral of generators and transformers shall be
connectedto the sub-stationcopper bus-bar andthis copper bus-bar shall be bonded to the
jacket steelwork usingcoppercables.
The armourof cables shallnot be used as the solemeansof providingearth continuity.
10.4.2
Lightning andStatic Electricity
For protection against lightning
and the accumulation ofstatic charges, guidelinesgivenin BS
6651 [I611shall be used.
Earth electrodesshall be located near the base of elevatedstructures that require lightning
protection. Thisis to ensure a low impedance lightning dischargepath to earth. The
electrode(s)shall be connected tothe structureto be protected andto the main earth grid
conductors of70 sq. mm. cross-sectional area.
The combinedresistance to the generalmass of the earth of the electrodesproviding for
lightning protectionshall not exceed 10ohm whenisolated from the structureto be protected
and fromthe main earth grid.
Metal structures like tanks,vessels etc. do not require additional protectionbeyond the
earthingrequirementsprovidedall structuralelementsare bonded to form a single conductive
structure,which is to be connectedto the plantearth grid. Careshouldbe taken to ensure that
all structural elements forming part of lighting protection system are suitable both
mechanicallyand electrically.
For offshore platforms nospecialprecautionsneed to be taken for protection of personnel
and
equipmentfrom lightning.Onlythe bonding ofequipmentneeds to be done.
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11.0
Sub-station Design Philosophy
For land-basedlocations sub-stations
shall applyto switchroomsinside buildings,outdoor substations,switch-housesetc., where the main and auxiliaryHV and LV switchgear,generators,
grid intakes, transformersand the like arehoused.
For platform-based locations sub-stations
shall generally apply to switch-rooms
where the
mainHV and LV switchgearand transformersare housed.
11.1
General
The sub-stations shallbe locatedin non-hazardousareas and preferablynear the centreof load
they are requiredto supply.
In exceptionalcases, electricalsub-stationsmay be locatedin a hazardous area classifiedas
Zone-2subjectto approvalby QP. The following requirements
shall apply:
The interior of the sub-stationshall be pressurisedin accordancewith IEC 600791481.
An over-pressure of at least0.5 mbar shall be maintained usinga duplicatefan system
with a suitable dry-type dustfiltering system to ensurea supply of cleanair, each fan
system being capable of supplying the required pressure.
The air shallbe takenfiom nonhazardous area.
The fan systemsshall be suitable for a Zone-1 area and shall be supplied from two
differentand independent sources ofelectricity supply
Both fans shall be normallyin operationwith individual alarmsto indicate failurein a
mannedcontrol centre
In all cases,for reasons ofreliabilityand serviceability,the electricalswitchgear installations
including batteries shall be located indoorsin allocated buildings provided with HVAC
system.
HVAC systemshall be designed to extractthe heat dissipated fromthe equipment withinsuch
rooms. All the equipmentsin the room shall be assumedto be fully loaded andthe highest
design ambienttemperatureshall be used for such design purposes. The design contractor
shall calculate the necessary minimum numberof airchanges per hour thatare needed to
regulate the room temperatureand to removethe dissipatedheat. 100% redundancyshall be
providedfor the HVAC system
All rooms containing switchgearshall have two access doors to allow personneland the
largest equipmentto pass in to or out of the room. Safety and escaperoutes shallbe provided
all around switchgearwhere personnelmay need to operate or maintainthe equipment. Such
routes shall have two clearand unobstructed pathsto a door.
All doors shall be dust tightand weatherproof.
The locks used on access gatesor doorsof sub-stationsshall be of a special series,different
from locksused for nonelectrical buildings,premises oryards. Alsothe safety @ad) locks
used to lock off switchesor enclosures,chambersor cells containingexposedlive parts shall
be of a differentseries.
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33 kV switchgear shall be located in a separate room. Access to this room shall be through
lockabledoor.
The room containing gas-insulated switchgearshall be provided with gas detection and alarm
system. An exhaust systemshall be at floor level.
A separate battery room shall be provided for housing Ni-Cd batteries. The access to the
battery room shall be from the outside of the sub-station. The size of the room shall be
adequate to allow access to at least three sides of each batterybank for maintenance purposes.
A water tap, wash-basin, eye-washfacility, sink and drain shall be installed in the room. The
floor and walls (up to 2 m height) shall be provided with acid resistant tiles. Ventilation
system with 100% redundancy(positive exhaust type) shall be provided in the battery room
for diluting the concentrationof hydrogen present in the room by exhausting it to the outside
of the room. Necessary interlock to inhibit boost1 quick charging on failure of ventilation
system shall be provided. Air-conditioningducts shall be located near the floor. All electrical
equipment in the battery room e.g. lighting fixtures, exhaust fans, convenience outlets,fue &
gas detectors etc. shall be suitable for hazardous area classificationZone-1, Apparatus Group
IIC. Battery isolationdevice shall be mountedin the respectiveUPS cubicle.
Fire and smoke detection systemshall be provided throughout the sub-station building. A
weatherprooffire alarm pushbutton shall be located onthe external wall adjacentto the main
personnel access door and shall be connectedinto the fire alarm communicationsystem of the
plant, so that the signal can be alarmed inthe CCR or other nominated centre.
Portable fire extinguishers shall be provided inside the sub-station, in each separate room.
They shall have an extinguishing medium that is filly compatible with the electrical and
electronic equipment in the station. Instruction charts should be fitted on the wall adjacent to
each extinguisher.
Each sub-stationshall be provided withthe followingminimum items:
Fire extinguishers
Fire blankets
First aid kit andinstructionplate
Escape lights and emergencyexit signs
No smoking sign
Vertical drawingrack
White board
Framed single line diagrams
Telephone
Tools and spares cabinet
Key box
Rubber matting shall be provided in fiont of HV and LV switchboards.The matting shall be
1.2 metres wideand the thickness shall be 15 mm. The matting shall be minimum 650 V grade
tested to 15000V and shall be of black colour andwith non-slip finish.
The construction of sub-station building andthe material used shall be such that propagation
of fire through the building is minimal. The fire rating of the sub-station building shall be as
per QP philosophy forFire and Safety QP-PHL-S-001[34].
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Each sub-stationshall be numberedand warning platesshall be provided atthe outside ofthe
building.
For new land-basedsub-stations, their design
shall allow a future extension in their longest
dimensionby 25%.
11.2
IndoorSub-stations
The indoor sub-stationshall contain switchgear,UPS systems, batteries, annunciaterpanel,
transformers,fire detectionand fire fightingequipment,HVAC system, equipment forpower
management system, emergency
exit routesand handlamps.
The land-based sub-stationsshall normally be designed as elevated structures sittingon a
minimumnumber ofreinforced concrete legs.
The sub-stationsin townshiparea and plant substationshaving onlyLV switchgearneed notbe elevated. Typicalsub-stationlayout for raised
sub-stationsshall be as per QP Engineering Standard Drawing
ES.2.68.0001[31]. The substations shall have concrete floors, a concrete roof,and concrete-blockor brick-built walls.
Stairwaysand doors shall be provided for personnel access
and for the removal of the largest
itemsof internalequipment.Waterdrainagefacilities shallbe providedfor the roof.
The elevated sub-stationsshall have onefloor level.The clear height under the switchgear
floor shall not be less than2 metres andshall be used for cablingto the sub-stationequipment
from bottom.The height ofthe roof above the switchgearfloor shall be no less than 4.0
metres. For elevated sub-stations thepower cables shall enterfrom below the floor. In nonelevated type sub-stations,the cables between switchboards and roomsmay be run in
preformedconcretetrenches,coveredwith galvanisedsteel gratingor metal-chequered plate.
The land-based sub-stationsshall be provided with road access designed to enable heavy
vehiclesto deliver and removeheavy items of equipmentbelongingto the station,e.g. power
transformers, switchgear
etc. Theaccess road shall be laid up to at least the main equipment
doors and the transformerbays. The access doorways for equipment shall be designed to
enable temporary rollersto be used to manipulate equipment into the station. Concrete
pathwaysshall be provided betweenpersonnel access doors and
the road.
The liquid filled powertransformersshall be locatedin an adjacent fenced area intransformer
bays. Thetransformerbays for land-basedinstallations shallbe provided with concrete plinths
for transformers,oil catchment pitto contain major liquid spillage,oil collectionpit outside
the fence, pre-formedtrenches for cables, gravel,
access doors andgates with pad locks.Firewalls shall be provided for transformers ofrating 5 MVA and above. For offshore
installations,the transformer floorshall be watertight andshall be bunded to hold the total
volumeof the transformer oil. Drainfacility shall alsobe provided.
Dry-typetransformersshall be located inside the sub-station building.
There shall be space for at least two additional panels
for futureextensionat both endsof each
switchboard.
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The followingminimumclearancesaroundvariouselectricalequipmentshall be maintained:
Front clearance forHV switchboard
: 2.5 m
Front clearancefor LV switchboard
: 2.0 m
Rear clearancefor panels having maintenance access from
front only
: < 0.2 m
Rear clearance forHV switchboard requiring maintenance from rear : 1.5m
Rear clearance forLV switchboard requiring maintenance from rear : 1.0m
Side clearance between two switchboardsor from nearest wall/ : 1.5m
column
: 1.0m
Clearancebetweentransformerand nearestwall/ column
Clearance between two transformersnot having fire-wall between : 2.0 m
them
Front clearancefor wallmounted equipment
: 1.0m
Clearance between battery rackto rack and battery rack to wall : 1.0m
(doublerow, doubletier arrangement)
The roof shall be waterproofand provided with slopesand drain outletsto rapidly drainaway
storm rainwater. Drainpipes
shallbe providedfromthe roof to a ground level drainagesystem.
doors, which shall be separatedfrom each
There shall be no less than two personnel access
other by the greatestpracticaldistance.All doors shall be dust tight. Themain entrancedoor
shall be fitted with integrallockingfacilities.Emergencyexit doors shallbe fitted with crash
bars to enablethe doorsto open outwards from insidethe station.
Diesel engine driven generator
sets shallpreferablybe locatedin a separate buildingotherthan
the sub-stationto reduce noise levelin the sub-station.However,in case the sameis locatedin
the sub-station building,the dieselgeneratorset foundationshall be structurallyseparatefrom
the foundation ofthe sub-station building.
Suitable ventilation system shall
be providedto avoidheat accumulationin the DG room.
OutdoorSubstations
HV outdoor switchgearinstallations shallbe designed andinstalled asper guidelinesgiven in
BS 7354 [I621and shall allow unrestricted walking access within
the installation.
The location of outdoor sub-station
shall be selected so as to provide adequate accessfor
maintenance, personneland vehicular accessand removalof the largest equipment.
The insulation class of all componentsshall be fully co-ordinatedin accordance withIEC
60071 [44].
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The insulation classand creepage distancesof insulators shallbe selectedin accordance with
IEC 60815 [107]. Unless otherwisespecified, a minimumcreepage distance of 40 mml kV
shall be applied forinsulators.
Bus-bars and the connectionsto the equipmentshall be madeof copper or aluminium. Bimetallicconnectorsshall be used at joints betweendissimilarmetal.
Equipmentsupportstructuresand line portalsshall be of hotdipped galvanisedsteel and shall
have integral climbingfacilitiesfor cleaningand repair purposes.
A 2.4 metres height fence with lockable access gates
shall be provided aroundthe outdoor substation.
Controlcables, and compressedair lines shallbe laid in hard-covered, pre-cast concrete cable
trenches,the top of whichshall be above the surroundinggroundlevel. The trenches shallbe
well drained.
The neutral systemearth(s)and all metal supportingstructuresand equipmentshall be earthed
to the commonearth grid.
The perimeter fence shall be earthed at regular intervals by means of earth rods directly
connectedto it.
Protection against direct lightning strikes
shall be providedby means of overheadearth wires
and1or lightningrods.
The sub-stationequipmentshall be protected againstlightningand switchingover voltagesby
surge arresters.
Control,protectionand auxiliarypower supply equipment associated
with outdoor switchgear
shall be installed in abuildingwhich shall complywith the relevantrequirementsfor indoor
sub-stations. Other switchgear
and controlgearcan also be accommodatedin this building.
11.4
PackageSubstations
Packagesub-stationmay be used for temporaryinstallations.Only in very special cases,these
shouldbe used forpermanentinstallations.
Packagesub-stationshall be suppliedas completefactory assembledand tested transportable
units.
and LV switchgear shall be located in separate
The HV switchgear, oil-filled transformer
compartmentseach accessiblefromthe outside by lockable doors.
Dry-typetransformer canbe
locatedin the same compartmenthavingthe LV switchgear.Sufficient space shallbe available
in the compartmentsfor termination ofcables and safe operation of the switchgear. The
IP55 as per
ingress protection ofthe compartmentshousing the switchgearshall be minimum
IEC 60529 [87]. The compartment having
the oil-filled transformershall be equipped with
leak-proofoil containmentarea.
Each compartmentshall be provided with lighting fixturesand convenienceoutlets of the
weatherproof andindustrialtype.
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HVAC system shall be provided for these package sub-stationsas necessaryto ensure that
operating temperature limits of
the equipment are not exceeded.
The enclosure of thepackage sub-stationshall be mounted on concrete plinthsfor on-shore
installationsand on steel structurefor offshoreinstallations withina fenced area with padlockable gates.
Care shall be taken for theremovalof the packagesub-stationused in temporaryinstallations
before commissioning
activitiescommencesfor plantsclassifiedas hazardous areas.
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12.0
Drawingsand Documents
All necessary drawings required for the design of electrical system, installation of equipment
and the interconnection of equipment, cables, and wires shall form part of the design. Such
information shall be updated when alterations to the design are made and shall include
additional information that is required during erection or may be required for future
maintenance,troubleshootingand operation. As-built drawings shall be prepared immediately
after completionof the project.
The drawings and documentsshall be prepared during various stagesof the project as perthe
details given in Appendix-C.
Project requirements may call for slight changes to the detailed list of drawings and
documents. However, these mustbe finalised in the early stage ofthe project.
13.0
Approvalto Deviate
Strict compliance withthe guidelines covered underthis document is required. Any deviation
must obtain priorwritten approval fromits custodian.
14.0
RevisionHistoryLog
A record or log shall be kept by the custodian for the revision history of each engineering
document.In this way, there shouldbe no need for a history logto be included in a document.
Only details of its latest approved revision needbe shown.
The followingis recommendedfor the contents of a document's revision historylog:
RevisionNumber
Prepared ByIDate
CheckedByIDate
ApprovedByfDate
Reason For Change
Releaselllate
A, B, C etc.
Name or reference indicator anddate (ddrnmyy)
Name or reference indicator and date(ddmtnyy)
Name or reference indicatorand date (ddmtnyy)
Short description,with "change request reference" if available
ReleaseItransmittalreference and date(ddmmyy)
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15.0
Bibliography
The following standardsand specifications shallbe referred:
Manual- Engineeringstandardsdraughting
Electrical installationrecommendedpractices
HV gas-turbine driven synchronous generators
Diesel engine driven generators
Navigationalaids
Electrical heat tracing
Electricalprocessheaters
HV switchgearand controlgearfor indoors
LV switchgearand controlgear
Bus-barducting
Liquidfilledtransformers
Dry-typepowertransformers(cast resinand resin
impregnatedtype)
HV inductionand synchronous motors
LV inductionmotors
Electricmotoroperated valveactuators
A.C. uninterruptiblepower supply systems
D.C. unintermptiblepower supply systems
Cathodicprotection system
Variable speed drive systems
Secondary selective system
Power managementsystem
Electricalpower,controlcables and cable glands
Overheadtransmission linesand accessories
Electrical bulk material
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HV capacitors
LV capacitors
Neutral earthingresistors
Power systemstudies
Electricalrequirementsfor packageequipment
Safetyinstructions electrical- General
-
Electricalsub-station (indoor) Typicallayout
Onshore pipeline construction
QP technical specification
for paintingand wrappingof metal
surfaces(new constructionand maintenance)
QP corporate philosophyfor fire and safety
QP specificationfor waste management
QP guideline- Wastemanagementfor offshoreoperations
and Halul island
IEC60034
Rotatingelectricalmachines
IEC60038
IECstandard voltages
IEC60044
Instrument transformers
IEC60050
International electro-technical vocabulary
IEC60051
Direct actingindicatinganalogueelectricalmeasuring
instrumentsand their accessories
IEC 60059
IECstandard current ratings
IEC60060
High voltagetest techniques
IEC60071
Insulation co-ordination
IEC 60072
Dimensionsand outputseries for rotating electricalmachines
IEC60073
Basic and safety principles forman-machineinterface,
markingand Indication- Codingprinciples forindicatorsand
actuators
[47] IEC60076
Powertransformers
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IEC 60079
gas atmospheres
Electrical apparatus for explosive
IEC 60085
Electrical insulationthermalclassification
IEC 60099
Surgearresters
IEC 60112
Methodof determinationof the proof and comparative
tracking indices ofsolid insulating materials
IEC 60120
Dimensionsof ball and socket couplings ofstring insulator
units
IEC 60137
Insulating bushings foralternatingvoltagesabove 1OOOV
IEC 60146
Semiconductor converters
IEC 60156
Insulatingliquids- Determinationof the breakdownvoltage
at powerfrequency
IEC 60183
Guideto the selectionof high voltagecables
IEC 60189
Low frequency cables and wires with
PVC insulationand
PVC sheath
IEC 60214
Tap-changers
IEC 60227
Polyvinyl chloride insulated
cables of rated voltagesup to
V
and including4501750
IEC 60228
Conductorsof insulated cables
IEC 60247
Insulating liquidsmeasurementof relativepermittivity,
dielectricdissipationfactor (tan)and d.c. resistivity
IEC 60255
Electrical relays
IEC 60265
Highvoltage switches
IEC 60269
Low voltage fuses
IEC 60270
Highvoltagetest techniques- Partial dischargemeasurements
IEC 60282
Highvoltage fuses
IEC 60287
Electric cables- Calculationof current rating
IEC 60309
Plugs, socket-outletsand couplers forindustrialpurposes
IEC 60326
Printedboards
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IEC60331
Tests forelectriccablesunder fire conditions
IEC60332
Tests on electriccablesunder fire conditions
IEC60354
Loadingguidefor oil immersed powertransformers
IEC 60364
Electricalinstallationsof buildings
IEC60376
Specificationand acceptance ofnew sulphur hexafluoride
IEC60383
Insulators for overhead
lines with a nominal voltageabove
1000
v
IEC60417
Graphicalsymbolsfor use on equipment
IEC60420
Highvoltagealternatingcurrentswitch-fusecombinations
IEC60433
Insulators for overhead
lines with a nominal voltageabove
1000v
IEC60439
Low voltage switchgearand controlgear assemblies
IEC60445
Basic and safety principlesfor man-rnachineinterface,
marking andidentification Identificationof equipment
terminalsand terminationof certain designated conductors
including general rules for
an alphanumeric system
IEC60446
Basic and safety principlesfor man-machineinterface,
marking andidentification- Identificationof conductorsby
coloursor numerals
IEC60466
A.C.insulation- Enclosed switchgear and
controlgearfor
rated voltagesabove 1 kV and upto and including38kV
IEC60470
High voltagealternatingcurrentcontactorsand contactor
based motorstarters
IEC60478
Stabilisedpower supplies, dc output
IEC 60502
Powercables with extrudedinsulationand their accessories
from rated voltage from1 kV up to 30 kV
IEC60507
Artificial pollutiontests on high voltage insulatorsto be used
on a.c. systems
IEC60529
Degrees of protectionprovidedby enclosures(IPCode)
IEC60542
Applicationguidefor on-loadtap-changers
IEC60549
High voltage fuses forthe external protectionof shuntpower
capacitors
-
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[90]
IEC 60584
Thermocouples
[91]
IEC 60605
Equipmentreliability testing
[92]
IEC60616
Terminal and tapping markings for power transformers
[93]
IEC 60617
Graphic symbolsfor diagrams
[94]
IEC 60623
Secondary cells and batteries containing alkaline or other
non-acid electrolyte - Vented nickel-cadmium prismatic
rechargeable singlecells
[95]
IEC 60644
Specifications forhigh voltage fuse linksfor motor circuit
applications
[96]
IEC 60662
High pressure sodium vapourlamps
[97]
IEC 60664
Insulation coordination for equipment withinlow voltage
systems
[98]
IEC 60686
Stabilisedpower supplies a.c. output
[99]
IEC 60688
Electrical measuring transducersfor converting a.c. electrical
quantities to analogue or digital signals
[loo]
IEC 60694
Commonspecificationsfor high voltage switchgearand
controlgear standards
[loll
IEC 60745
Hand held motoroperated electric tools
[I021 IEC 60747
Semiconductordevices - Discrete devices and integrated
circuits
[lo31 IEC 60751
Industrial platinum resistance thermometer sensors
[lo41 IEC 60754
Test on gases evolvedduring combustionof electric cables
[lo51 IEC 60781
Application guidefor calculationof short circuit currents in
low voltage radial systems
[lo61 IEC 60812
Analysis techniques for system reliability- Procedure for
failure mode and effects analysis(FMEA)
[I 071 IEC 60815
Guide for the selectionof insulators in respect of polluted
conditions
[I081 IEC 60826
Design criteria of overhead transmission lines
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[log] IEC 60831
Shuntpowercapacitorsof the self-healingtypefor a.c.
systemshavinga rated voltageup to and including1 kV
[llo]
IEC 60836
Specification forsilicone liquidsfor electricalpurposes
[Ill]
IEC60840
Powercables with extrudedinsulationand their accessories
for rated voltagesabove30 kV
[I121 IEC 60851
Winding wires- Test methods
[I 131 IEC 60865
Shortcircuitcurrents- Calculationof effects
[I141 IEC 60871
Shuntcapacitors fora.c. power systems havinga rated
voltageabove 1kV
[I 151 IEC 60885
Electrical testmethodsfor electric cables
[I161 IEC 60896
Stationary lead-acidbatteries
[I171 IEC 60898
Electricalaccessories- Circuit breakers forovercurrent
protection forhousehold andsimilar installations
[I181 IEC 60905
Loadingguidefor dry-typepowertransformers
[I191 IEC 60909
Shortcircuitcurrentcalculationin three-phasea.c. systems
[I203 IEC 60932
Additional requirements
for enclosed switchgearand
controlgear from1kV to 72.5 kV to be used in severe
climatic conditions
[I211 IEC 60944
Guidefor the maintenanceof siliconetransformer liquids
[I221 IEC 60947
Low voltage switchgearand controlgear
[I231 IEC 60993
Electrolyte for vented nickel
cadmiumcells
[124] IEC 61000
Electromagnetic compatibility
(EMC)
[I251 IEC 61008
Residual current operated
circuit breakerswithout integral
over current protection for household
and similaruses
(RCCBs)
Residual current operated
circuitbreakers withintegralover
current protection for household
and similar uses(RCBOs)
[I271 IEC 61010
Safety requirements ofelectricalequipment for measurement,
controland laboratory use
[I281 IEC 61029
Safety of transportable motor
operated electric tools
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[I291 IEC 61039
Generalclassificationof insulating liquids
[130] IEC 61056
General purpose lead-acid
batteries(valve regulated type)
[131] IEC 61084
Cabletrunkingand ductingsystemfor electrical installation
El321 IEC 61089
Round wireconcentriclay overheadelectricalstranded
conductors
[133] EC 61180
Highvoltagetest techniques forlow voltageequipment
[I341 IEC 61203
Synthetic organicesters for electricalpurposes- Guide for
maintenanceof transformeresters in equipment
[I351 IEC 61241
Electricapparatus for usein the presenceof combustible dust
[I361 IEC 61294
Insulating liquids- Determination ofthe partial discharge
inception voltage(PDIV) - Test procedure
[I371 IEC 61310
Safetyof machinery- Indication, marking and actuation
[I381 IEC 61434
Secondarycells and batteriescontainingalkalineor other
non-acidelectrolytes- Guideto the designationof currentin
alkaline secondarycell and batterystandards
[139] IEC61800
Adjustable speedelectricalpower drive systems
[I401 IEC 61850
Communicationnetworksand systemsin sub-stations
[I411 IEC 62040
Uninterruptedpower system(UPS)
[I421 IEC 62271
Highvoltage switchgearand controlgear
[I431 IP
IP modelcode forsafe practices
[144
Preferrednumbers- Seriesof prefened numbers
IS0 3
[I451 IS0 281
Rollingbearings- Dynamicload ratings andrating life
[I461 IS0 1461
Hot dip galvanised coatings
on fabricatediron and steel
articles
Acoustics- Test code forthe measurementof airborne noise
emittedby rotating electricalmachinery
Mechanicalvibration- Balancequalityrequirements of rigid
rotors
Eyebolts for generalliftingpurposes
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Graphicalsymbols- Safetycoloursand safety signs
Industrialvalves- Multi-turn valveactuatorsattachments
Industrialvalves- Part-turn valveactuatorsattachments
Reciprocatinginternalcombustion engine driven
alternating
current generatingsets
Qualitymanagementsystems- Fundamentalsand vocabulary
Qualitymanagementsystems- Requirements
Qualitymanagementsystems- Guidelinesfor performance
improvements
Rubbermats for electricalpurposes
General requirements for
rotating electricalmachines- Part
140: Voltage regulation
and paralleloperation ofa.c.
synchronous generators
PVC insulatedcablesfor switchgearand controlgear wiring
Electric cablesPVC insulated,armouredcables for voltages
of 600/1000V and 1900/3300V
[I611 BS 6651
Code ofpractice forprotectionof structuresagainst lightning
[I621 BS 7354
Designof high voltage open terminalstations
[I631 IEEE 32
Standardrequirements, terminology and
test procedures for
neutral grounding devices
[I641 IEEE80
Guide forsafety in a.c. substationgrounding
[I651 IEEE 81
Guidefor measuringearth resistivity,ground impedance,and
earth surface potentials of
a groundsystem
[I661 IEEE C37.2
Standardelectricalpower system devicefunctionnumbers
and contact designations
[167] IEEE399
Recommendedpractice forindustrial andcommercialpower
systemsanalysis
[I681 IEEE485
Recommendedpractice forsizinglead acid batteriesfor
stationary applications
[I691 IEEE493
Recommendedpracticefor design ofreliable industrialand
commercialpower system
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Recommendedpractices and requirementsfor harmonic
control in electrical power systems
[I711 IEEE 979
Guide for sub-stationfire protection
[172] IEEE 980
Guide for containmentand control of oil spills in sub-stations
[I731 IEEE 1100
Recommendedpractice for powering and grounding
electronic equipment
Recommendedpractice for sizing nickel-cadmium batteries
for stationary applications
[I751 IEEE 1188
Recommendedpractice for maintenance,testing and
replacement of valveregulated lead acid (VRLA) batteries
for stationary applications
[I761 IEEE 1189
Guide for selectionof valve regulatedlead acid (VRLA)
batteries for stationary applications
Recommendationsfor the notation of luminous intensityand
range of lights
[I781 APIRP 14F
Recommendedpractice for design and installation of
electrical systems for fixed and floating offshore platform
facilities for unclassified and class-1 Division-1and
Division-2 locations
11791 ICAO
International civil aviation organisation
[I801 CAACAP 168
Civil aviation authority- Licensing of aerodromes
[I811 CAACAP437
Civil aviation authority- Offshore helicopter landing areas
All the above references are subjectto change from time to time. The user is required to first
check with the custodianof this document to find out the latest status with respectto above
bibliographiclist.
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APPENDIX- A
SELECTIONOF ELECTRICALEOUIPMENTFOR HAZARDOUSAREAS
For electricalequipmentin hazardousarea, theminimumprotectionshall be as below:
Equipment
HV motors(11kV)
HV motors(4lkV)
LV motors
DC Motor
RCU
Listing fixtures(normal)
Highpressure dischargelamps
Weldingsocket
Conveniencesockets
Cable glands
Local control panels
Electric heaters
Telephones
Plant communicationequipment
Warninglights
Junctionboxes
Marshallingboxes
Local control panels
Distributionboard- Electrical
heat tracin~
I
Apparatus
Apparatus
GroupIIAmB GroupIIC
Apparatus
Apparatus
GroupMAB GroupIIC
Exd / Ex-p
Exd / Ex-p
Exde / Exe
Ex4
Exde
Exe
Exd
Exd
Exe
Exd
Exd 1 Ex-p
Exd
Exe
Exe
Exe
Exe
Exe
Exd / Ex-p
Exd
Exd / Ex-p
Ex-n
Ex-n
Exd
Exde
Exe
Exd
Exd
Exe
Exd
Exd / Ex-p
Exd
Exe
Exe
Exe
Ex-n
Ex-n
Exd / Ex-p
Exd
I
Exd / Ex-p
Exd / Ex-p
Exde / Exe
Exd
Exde
Exe
Exd
Exd
Exe
Exd
Exd 1Ex-p
Exd
Exe
Exe
Exe
Exe
Exe
Exd / Ex-p
Exd
1
Exd / Ex-p
Ex-n
Ex-n
Exd
Exde
Exe
Exd
Exd
Exe
Exd
Exd / Ex-p
Exd
Exe
Exe
Exe
Ex-n
Ex-n
Exd / Ex-p
Exd
I
Notes:
Motors fed by Variable Speed Drivesshall be tested and certified alongwith the VSD by
recognisedtesting1certifymgagencies
Any electrical equipment installed in Zone-1 or Zone-2 andis required to operate under
emergencyconditionsshall be Exd as a minimum
Equipment with protectionType 'p', on failure of pressurisation, shall be provided with
followingadditional features:
AreaClassification
I
Eauinmentnot canableof
producingspark
Zone-1
Alarm
Zone-2
No action required
I
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Eaui~mentcanableof
producians~ark
Alarm andpower supply
switched off
Alarm
I
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bmarine Cables (sending end)-Si
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DESCRIPTIONSOF IEEE DEVICENUMBERS AND NOTES
DeviceNumber
DescriptionRelatingto Amlication for OP Documents
23
Thermalcontrolof transformerforced air-cooling fans
25
Synchrocheckrelay
26
Winding temperaturelow or high device
27
Under-voltagerelay
32
Reversepowerrelay
40
Field failure relayenergisedby stator current and voltage signals
46
Negative phasesequence (NPS) relay energised by stator current
signals
Thermalimagerelay
Instantaneousover currentrelay energised by phasecurrentsignals
Instantaneous earth fault
relay energisedby the out-of-balance current
of a window orcore-balance current transformer
Time dependent over-current
relay energised by phase current signals.
The time dependencymay be a fixed time delay or an inverse
characteristicor a combinationof both e.g. IDMT, inverse definite
minimum
time delay.
51
Voltage restrained form of
Similarto 51 but the earthfault current is detected by summationof
the phase currents
Similar to 51 but the earth fault currentis detected by a dedicated
current transformerin the star point or earth conductor
A relay usually forming part
of the AVR (90) which detectsthe failure
of diodes and thyristorin the rotor excitationsystem of generatorsor
synchronousmotors
Over-voltagerelay
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Restricted earth fault relay, usually voltage
operated, sensitiveand fast
acting
Under-frequency relay often combined with an over-frequency
function. Usually time delayed
and often used with load shedding
schemes.
Lockout relay used to prevent reclosure after it has tripped a circuit
breakerof contactor. Itis reset manually byan operator.
High-speedsensitive differential protection
relay
Notes:
(1)
The generator switchgearshall have two separatelockout relays. One
will receiveall the electricalprotectionrelay trip signals and denoted
as 86-1. Theother will receive a master trip signal (or severaltrip
signals)fromthe turbineunit control paneland denotedas 86-2.
Devicerequired forstartingand stopping forced air cooling fans.
Unrestricted earth faultrelay connected in the star-point to earth
circuit of the equipment being protected. The
characteristic is time
dependentso that time coordinationis achievedwith the 50N devices
downstream.
Restricted earth fault relay
used with generators and transformers to
detect internal faults.The relay will usuallybe of the voltage operated
instantaneous type.
Undervoltagerelay usually provided with time delay
settings. Usedto
trip the consumersfed fromthe particular bus-section.
Modern relays combine the 46, 49, 50, 51N and 86 requirements;
together with other functions such
as, motor stalling,numberof starts,
highthermal state at the time of starting, undercurrent, overloading,
set current limit.
Static load andvariable speed drive manufacturers
may requirespecial
protection devices for their equipment.
Some protection devicesmay be providedby the variable speed drive
manufacturerin his unit control panel, which
may be inter-tripped with
the main circuit breaker.
The 87 relay may be required dueto a recommendation of the variable
speed drive manufacturer. It
may be part of the UCP as describedin
1.5.MW.
Note 8. It shouldnot benecessary for motors below
Where distance protectionis employed, it shall be provided in
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conjunction withover currentand earth fault protection.In such cases,
the over current and earth fault protectionshall serve as back-up
protections.The relays shouldbe fitted into themain switchboard,not
at intermediate locations
along the overheadline route.
The use of a 50N relay shall alsobe consideredin relation to the
maximumearth-loopimpedanceallowed for the particularconsumer.
This will be a function ofthe motor rated power,the route lengthand
the typeof armouringused for themotor powercable.
The use of the 49 and 50 relay(s) may be replaced by thermal and
magnetic elements within thecircuit breaker or starter unit for the
particular motor. This should normally onlybe the case for small
motors.
The use of a 51N should be considered when time coordinationis
required withdistributionboard consumerse.g. lighting,small power
socket outlets, and welding socketoutlets. Static loadswhich do not
feed downstream consumers
should be fitted with a 50N relay e.g.
process heaters.
The 86 relay may be replacedby the handreset featureof a moulded
case or miniature circuit breaker. However, it is the general
requirement ofQP to use Wes. For low powercircuits an auto-reset
device (29) may be acceptable, providedthat it does not reclose the
circuitbreakeror contactor.
In the situation where a generator hasa unit transformerit shall be
provided two forms for differential protection. One will be for the
generatorby itself, and denoted 87G. The second will be an overall
schemefor the generatorand the unittransformer,and denoted87T.
Bus-zoneprotectionshall be of the high speed balanced voltagetype.
Each section of busbars shall be protectedas one zone. The various
zones shall be overlapped at bus-sectionand buscoupler circuit
breakers.The bus-zoneprotection schemeshall be provided witha test
facilitythat canbe used while the switchboardis in normal energised
operatione.g. a fault is simulated andthe trip signals are seen to be
sent to the circuitbreakersin the faultedzone.
The need for Trip Circuit Supervision depends
to a large extent on the
importance ofthe circuit connectedby the power circuit breaker,e.g.
main generator,HV feeders,HV motors,KAHRAMAAincomers,LV
incomersto process switchboards.One of the IEEEcode numbersin
the range 95 to 99 canbe used to identify theTrip Circuit Supervision
relay.
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APPENDIX-C
DRAWINGSAND DOCUMENTS
The list of drawings1documentsto be preparedduring various stagesof the project shall be as follows:
Tvae of Proiect
FEED
-
EPIC
Power system description
X
X
Power system operatingphilosophy
X
X
Control, monitoring andprotection
philosophy
X
X
Descri~tion
Power managementsystem
requirements andconf~guration
Electrical equipmentlist
Electrical load schedule
Single line diagram
Protection diagrams
Area classificationdrawings
Electrical sub-stations(quantityand
location)
Electrical sub-station layout
Cable routing layout
SAFOPstudy and reports
Load flow calculationsand report
Fault levelcalculationsand report
Motor start-up studies
Transient stability studiesand loadsheddingphilosophy
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Harmonicpenetration studiesand
report
Power factor correction calculations
and report
Relay studies/ protection studies
Earthing system studiesand report
Electrical equipmentsizing
calculations
Cable sizing calculations
Lighting selectionand report
Block diagramsfor control,
interlocking,synchronising,alarms,
annunciations,indications, metering
Interfacing detailswith other
disciplines
Electrical equipmentspecifications
Electrical equipmentdata sheets
filled up with purchaser data
Single line diagrams
(by switchboard)
Single line diagrams
(UPS systems)
Illumination levelcalculations
Lighting layout
Earthing layout
Lightning protectionlayout
Protectiverelaying settingschedule
Protectiondiscriminationgraphs
Cable schedules
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Cable drumschedules
Interconnection diagrams
Cable trenching,racking and routing
plans and elevations
Switchboard schematicdiagrams for
feeders, starters, interconnectors etc.
Switchboardwiring diagrams
Control panelwiring diagrams
Equipmentwiring and terminal block
diagrams (e.g. generators,skids,
compressors)
VSDS schematic and wiring
diagrams
Marshallingbox wiring and terminal
block diagrams
Junction box wiring andterminal
block diagrams
Equipment fixing and installation
drawings
Earthing equipment fixing and
installation drawings
Cabling MTOs
Lighting MTOs
Earthing MTOs
Spare parts list
Equipmenttest record forms
Manufacturer's drawings
Installation and commissioning
manuals for electrical equipment
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Operation and maintenance manuals
for electricalequipment
Commissioning and test equipment
brochures anddetails
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APPENDIX - D
DEFINITIONS
Definitionof Non-Technical Terms
Commissioning
This shall be taken to mean energisation and the finaltests and checks at QP's site subsequent
to the energisation necessaryto ensure that each circuitsatisfactorilyperforms its function.
Contractor
Is the party which carries out all aspects or part of the design, engineering, procurement,
construction and commissioningof the plant.
Inspection
This shall be taken to mean a visual inspection of the equipment/ installation.
Manufacturer
Is the party that manufacturesequipmentand servicesto perform the duties specified.
Must
The word 'must' is to be understood as mandatory.
Is the party that initiates the projectand ultimately pays for its design and construction. QP
will specify the technical requirements.QP may also include an agent or consultantto act for
QP
Shall
The word 'shall' is to be understood as mandatory.
Should
The word 'should' is to be understood as being strongly recommended.
Supplier
Is the party that suppliesequipment andservices to perform the duties specified.
Testing
This shall be taken to mean the performance, routine and special tests normally carried out at
the factory of the manufacturer.
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D.2
Definition of TechnicalTerms
The technical definition of the electrical terms1 words shall be as per IEC 60050 1401.
However, following are the additional definitions and some definitions those are different
from those in IEC 60050 [40]:
Autonomy time (of a battery)
The duration for which the battery can supplyits rated loadwithin its specified voltage limits,
following a prolonged periodof battery float charge operation.
Certificate
Document issuedby a recognised authoritycertifying that it has examined a certain type of
apparatus and, if necessary,has tested it and concludedthat the apparatus complies withthe
relevant standards for such apparatus.
Certificate of conformity
Document issued by a testing station and approved by a national or other appropriate
authority, stating that a prototype or test sample and its specification have a levelof safety
equivalent to that of an electrical apparatus for potentially explosive atmospheres which
complies withthe requirements of one or moretypes of protection as laid down in a national
or international standard.
Certified electricalapparatus
Electrical apparatus for whicha certificateof conformity ora certificate of inspection hasbeen
issued.
Declaration of conformity
Document issued by the manufacturer stating that the electrical apparatuscomplies withthe
requirementsof one or moretypes of protection for usesolely in locations where the danger is
limited andthe electrical apparatus complies withthe requirements of nationalor international
standard.
Distribution sub-station
A sub-station mainlyused for distributingpower to several plant sub-stations.
Electrical installation
Civil engneering works, buildings, machines,apparatus, lines and associated equipmentused
for the generation, conversion,transformation, transmission, distribution and utilisation of
electricity.
Electrical powersystem
All installationsand plant provided forthe purpose of generation, transmittingand distributing
electricity.
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Emergencylighting
Lighting provided for use when the supplyto the normal lighting fails.
Escapelighting
That part of emergency lighting which is provided to ensure that the escape route is
illuminated at all time.
Firm capacity
The installed capacity less the standby capacity.
High voltage(HV)
Voltage exceeding 1000V ac.
Intakesub-station
A sub-station at which the supplyprovided by KAHRAMAAis inter-connected with theplant
electrical distribution system.
Low Voltage(LV)
Voltage up to 1000V ac.
Marking
Data put on the apparatus by the manufacturergwing information for safe use of the apparatus.
Power managementsystem
A computerised system that is dedicated to monitoring and controlling defined aspects of an
electrical system.
Remotecontrolunit (RCU)
A control device in the vicinityof a motor1consumer for operation of the remotely installed
controlgear of the consumer.
Spare capacity
The differencebetween firm
capacity and the maximumcalculated (peak) load.
Standbycapacity
The capacity provided for the purpose of replacing that which might be withdrawnfrom
service under plannedor unplanned circumstances.
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Switchgear (switchboard)
A general term covering switching devices
and their combinationswith associated control,
measuring, protectiveand regulating equipment, also assemblies
of such devices and
equipmentwith associated interconnections,
accessories, enclosuresand supporting structures,
intended for usein connection with generation,
distributionand conversion ofelectricpower.
A room in a sub-stationor building intended exclusively
for the installationof one or more
switchboards,distributionboards etc.
Test report
Document prepared by the manufacturerindicating in detail the tests and verificationsto
whichthe electricalapparatus hasbeen subjectedand their results.
Variable speed drive system
(VSDS)
A line-fed acto ac conversion systemconsistingof all facilitiesrequiredto operateits electric
motorat variable speeds.
"...end of document...'
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