Interview Question for QA/QC Electrical and Instrumentation Inspector
General Questions
Q
What is Q.C./Quality Control?
Ans
1)-Quality control is an inspection or testing of products to uncover defects and reporting to
management who make decision to allow or deny the product release.
2)-Quality control is an operational technique (inspection, testing, and examination) that are
used to fulfill the quality requirements.
Q
What is Q.A./Quality Assurance?
Ans
1)-Quality assurance attempts to improve and stabilize the production by avoiding or minimizing
the issues which led to defects.
2)-Quality assurance is the system of action and planning needed to provide a service or product
will satisfy the requirements of quality.
Q
What are the responsibilities of QA/QC inspector at site?
Ans
A QA/QC inspector is responsible for quality control and quality assurance of all the construction
works, and all the work at site should be according to standards, approved procedures and ITP’s.
When some construction activity starts, QC will do internal inspection and will do review of
documents before raising the RFI. If there is some violation or non-conformance in work then
QC shall raise NCR. When there is some issue/complication/irregularity regarding to
construction activity then QC will consult with his QC supervisor and construction representative
to resolve it.
Q
What is schedule Q? How many attachments it has?
Ans
Schedule Q is an Aramco document that describes the project quality requirements, inspection
schedules and procedures, documentation requirements, contractor and subcontractor quality
personnel qualification requirements and quality requirements for contractor supplied
materials.
It has 6 attachments:
(1) Attachment-I >> Contractor and Subcontractor Quality Personnel Qualification
Requirements
(2) Attachment-II >> Saudi Aramco Standards and Procedures Containing Quality Requirements
(3) Attachment-III >> Quality Requirements for Contractor Supplied Materials
(4) Attachment-IV >> Quality Requirements for the Construction Phase
(5) Attachment-V >> Summary of Quality System Deliverables
(6) Attachment-VI >> Project Specific Quality Requirements
Q
What is the quality plan?
Ans
1)-It includes procedures and documents, covering work activities and description of sequences
of work.
2)-Quality Plan include inspection, testing and proper documentation.
3)-Document specifying which procedures and associated resources will be applied by whom
and when to a specific project, product or process.
Q
What is SAES, SAEP, SAIP, SAMSS, SAER, GI, SATIP, ITP, SAIC, QMIS, RFI?
Ans
SAES: Saudi Aramco engineering Standards
SAEP: Saudi Aramco engineering procedures
SAIP: Saudi Aramco inspection procedure
SAMSS: Saudi Aramco materials systems specifications
SAER: Saudi Aramco engineering report
GI: Saudi Aramco general instructions
SATIP: Saudi Aramco typical inspection plan
SATIP is a document which provides us information related to activity, activity number, SAIC
number and responsibility of contractor and client QC personnel inspection level.
ITP: Inspection and test plan
SAIC: Saudi Aramco inspection checklist
QMIS: Quality management information system
RFI: Request for inspection
Q
Name some international standards which you follow for electrical and instrument work?
Ans
IEEE: Institute of electrical and electronic engineers
NEC: National electrical code
IEC: International electrotechnical commission
NEMA: National electrical manufacturers association
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NFPA: National fire protection association
NACE: National association of corrosion engineers
ANSI: American national standards institute
ASTM: American society for testing and materials
UL: Underwriters laboratories
AEIC: Association of Edison illuminating companies
ICEA: Insulated cables engineering association
IS: International standards
ISO: International standards organization
BS: British standards institution
Q
How will a QC inspector raise a RFI?
Ans
When some activity starts, QC will do internal inspection and will do review of documents and
then will raise the RFI.
Q
How much time before the inspection you will raise RFI?
Ans
24 hours before the inspection time.
Q
What is the inspection, documentation, document review, standards, hold point, witness point?
Ans
Inspection: An activity such as measuring, examining, testing one or more characteristics of a
product/equipment and comparing the results with specified requirements (standards and
procedures) in order to know whether conformity is achieved or not for each characteristic.
Documentation: Any record or pictorial information describing, defining the procedures or
results.
Document review: To collect all the documents related to an activity and to evaluate the
requirements for quality of that specific activity are fulfilled or not and to identify if there is any
problem or non-conformity exists.
Inspection assignment package: A set of documents that include details of purchased
material/equipment, needed to perform full inspection at the vendor/sub-vendor facility.
Standards: A document approved by a generally recognized body.
Specification: A detailed description of the design and materials used to make something.
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Quality management system: All activities that determine the quality policy, objectives and
responsibilities, and implement them by means such as quality planning, quality control, quality
assurance.
Quality System: Organizational structure, procedures, processes and resources needed to
implement the quality arrangements and requirements.
Quality audit: A systematic and independent examination to determine whether quality
activities and related results comply with the planned arrangements and whether these
arrangements are implemented effectively and are suitable to achieve objectives.
Hold point: Inspection or test stage beyond which work/activity should not proceed without the
QA/QC organization representative in attendance.
Witness point: A point that provides QA/QC representative with the opportunity to attend the
inspection/test at his option.
Surveillance: Generally visiting the site work without RFI.
Compliance: A judgment that the product or service meets the requirements of the relevant
specification or standard.
Non-conformity: Non-fulfillment of a specific requirement of the relevant specification or
standard.
Corrective action: Action taken
to eliminate the defect or existing non-conformity, or other undesirable situation.
Preventive action: Action taken to eliminate the causes of the existing non-conformity, defect
or other undesirable situation in order to prevent recurrence.
Procedure: A specified way to perform an activity.
Pre-commissioning: Testing of system components for continuity, operability.
Commissioning: Process by which an equipment, facility, or plant (which is completed or near
completion) is tested to verify if it functions according to its design objectives or specifications.
Q
What is NCR, Define and explain it with example?
Ans
None-conformance report, we raise NCR when there occur some non-conformity/violation at
the site during the construction work or when there is some non-conformity/violation occurred
during material receiving.
There are 4 parts of a NCR... (1) Violation occurred (2) Root cause analysis (3) Corrective action
to be taken (4) Preventive action (Recommendations to avoid re-occurrence of violation).
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Q
What will you do when you see some violation/non-compliance has occurred at site?
Ans
I will put internal NCR at once and then after that I will ask to construction team to take action
to rectify it.
Q
After how much time of occurrence of violation you will raise NCR?
Ans
Within 24 hours
Q
Within how much time the violation/non-conformity should be resolved?
Ans
As per ACD-(Agreed Completion Date).
Q
There are how many types of NCR?
Ans:
There are 2-types of NCR, and what is the difference between them?
1- Internal NCR
2- LBE Standard Violation/Client NCR
3- Company NCR
Internal NCR is a NCR which is raised by the Contractor QC-Inspector and LBE/Client NCR is a
NCR which is raised by PID (Client QC-Inspector)
Q
How many types of RFI are?
Ans
There are two type of RFI; (1) Internal RFI (2) QMIS RFI
Q
What is walk through?
Ans
Preparation of balanced work report (punch list items) upon completion of 80% of construction
work
Q
What is punch list items?
Ans
Any balanced work report during completion of work is called punch list items.
Q
What is two week look ahead schedule?
Ans
It is the schedule of work that have to do/complete in the next two weeks. The project planner/
project scheduler will prepare two week ahead schedule.
Q
What is the T.Q?
Ans
If there is some conflict/issue occurred to execute work as per approved IFC Drawing, T.Q is
raised according to site requirement and the designer/CSD/Client will approve it.
Q
What is red-mark/as-built drawing?
5
Ans
Changed drawing according to the site requirement, for example re-routing/re-location of
cable/conduit/equipment.
Q
To deviate from any standard and other Mandatory Saudi Aramco Engineering
Requirements (MSAERs), what is the procedure?
Ans
As per SAEP-302, if there any conflict between Mandatory Saudi Aramco Engineering
Requirements (MSAERs) or referenced industry standards shall request the Manager,
Consulting Services Department (CSD) of Saudi Aramco, Dhahran to resolve the conflict.
To deviate from any standard, requests shall be submitted electronically through the SAP
Waiver Process in accordance with SAEP-302.
Q
For obtaining a Waiver of a Mandatory Saudi Aramco Engineering Requirement which
standard we follow?
Ans
For obtaining a waiver of a Mandatory Saudi Aramco Engineering Requirement we follow
SAEP-302.
Q
What is a waiver?
Ans
To get favor to deviate from any Mandatory Saudi Aramco Engineering Requirements is
called waiver.
Q
What is FAT test?
Ans
The factory acceptance test procedure is a test that is performed to determine that an
equipment or product meets the requirements or specifications of a client before it shipped out
to its destination site.
The FAT is normally performed at the manufacturer’s workshop. The manufacturer checks that
the safety instrumented system works as intended according to the requirements stated in the
safety requirements specification (SRS).
Q
What are the test activities included in FAT?
Ans
During the FAT the manufacturer checks:
I)
II)
III)
IV)
V)
VI)
VII)
The equipment is according to the specification.
The equipment is installed according to the manufacturer’s specifications.
The inputs and outputs are connected according to the drawings.
The calibration of the equipment are correct.
The trip points operate according to the requirements in SRS.
The logic solver and associated software operate according to the requirements.
The outputs and their actions behave according to the SRS.
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VIII)
IX)
X)
XI)
XII)
XIII)
The reset function operate according to the SRS.
The alarms operate according to the SRS.
The operator functions operate according to the SRS.
The bypass function operate according to the SRS.
The manual shutdown function operate according to the SRS.
The diagnostic alarm functions according to the SRS.
Q
What is SAT test?
Ans
SAT is site acceptance test of an equipment to ensure that it is tested in accordance to client
approved test plan & specifications and to show the equipment is installed properly and
interfaces with other systems and peripherals in its working environment.
Q
How many test are done on circuit breaker? How we do pre-commissioning of circuit breaker?
Ans
The following test are performed on circuit breaker
1) Contact resistance test {this involves injecting a fixed current through the contacts and
measuring the voltage drop across it using Wheatstone bridge, kelvin bridge and ohm law.
This test is done with special contact resistance measuring instrument name microohmmeter (200A/600A) to check the contact condition/damage}
2) Current injector test/ Trip Test {primary current injection tests are normally conducted to
check the operation of circuit breaker and their protective relays and devices. The objective
of the test is to identify how the system operates under various levels of current load. By
injecting current into the system we can measure if the breaker will trip or fail. This test is
performed with Primary Injections Tester}.
3) IR test (megger test)
Q
How many test are performed on motor? How we do pre-commissioning of motor?
Ans
1) IR Test
2) Continuity Test
3) Low resistance test {low resistance ohmmeter – MOM milli-ohmmeter}
4) No load test / Solo run test (4 hours to check if voltage or current drop)
5) Temperature Test (With Temperature Gun, Assembly+ Bearing+ Shaft+ Non-Derive End)
6) Vibration Test (Vertically, Horizontally, Axially of Frame, Foot and Base with vibration tester)
7) Noise Test (DBA Meter-at derive end and non-derive end)
8) Full load test – Mechanical Run Test (it is performed by operation department to check the
capacity of motor for designed parameters of system for voltage or current)
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Q
How many test are performed on transformer? How we do pre-commissioning of transformer?
Ans
1) Low resistance test {low resistance ohmmeter – MOM (milli-ohmmeter)}
2) Winding Resistance Test (MOM-Micro ohmmeter) {the resistance can be measured by simple
voltmeter ammeter method, kelvin bridge meter or winding resistance measurement kit}
3) Turn ratio test (MOM)
4) IR Test
5) Continuity Test
6) Temperature Test
7) Breakdown test (oil di-electric strength test, for oil immersed transformer apply 50KV)
8) No load test
9) Gauge calibration (Level and Temperature)
Q
What is low resistance test?
Ans
Q
What is winding resistance test?
Ans
Q
What is temperature test of motor and transformer?
Ans
Q
What is the turn ratio test of transformer?
Ans
Q
How we do contact resistance of busbar and cable joints?
Ans
We do this test with ducter test.
Q
What is ducter test?
Ans
Contact resistance test (commonly known as the ducter test) measures the resistance of
electrical connections such as joints, terminations and connectors etc. This test measure the
resistance at the micro or milli ohm level and is used primarily to verify that electrical
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connections are made properly. This is particularly important for contacts that carry large
amount of current e.g. switchgear busbar.
------------------------------------------------------------------------------------------------------------------------------Material Receiving Questions
Q
How we do material receiving, describe the general procedure?
Ans
We collect all the documents related to the material to be inspected and after document review
we do the inspection and we check that the arrived material is according to the NMR, PO, MTO,
IRC and Delivery Note and verify that Aramco standards and specifications are complied, then
we raise the RFI for final inspection and acceptance.
Q
What documents are required for material receiving?
Ans
Material receiving RFI includes the following contents depending upon the type of material.
(1) MR/NMR---(Material Requisition> include the approved material’s details and specifications)
(NMR—If there is some conflict in MR then NMR >> non material requirement)
(2) IRC---(inspection release certificate/vender inspection certificate)
(3) MTC/MTR---(Material testing certificates/ material testing reports)
(4) PO--- (Pay order)
(5) Delivery note
(6) Aramco-manufacturer vender ID // Aramco-supplier vender ID
(7) MTO---(Material take off list/project complete items list)
(8) Calibration certificates/ ISS-Data sheets for instruments/ Technical Drawings for electrical
Equipment and instruments.
(9) If equipment/instruments are for hazardous area should have certificates of
flameproof/explosion proof (i.e. EEx D, IECEx).
(10) If Cable material then cable schedule/meggering & continuity certificate for cables
(11) Related Drawings
Q
What documents are required for material supplied by Aramco?
Ans
When material is supplied by Aramco, following document are required.
(1) Out Bond TO
(2) MTO
(3) Related Drawings
Q
What type of label or certification requirements are for equipment in classified (hazardous)
area?
Ans
IEC or EX labeled equipment meeting the requirement of IEC 60079.
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IECEx certification is needed and shall meet shall meet NEC requirements (Article 505).
Q
What type of label & certifications are required for enclosures in classified (hazardous area)?
Ans
Enclosures shall be flameproof (explosion proof), EEx D II certification, meeting the NEC
requirements (Article 505) & IP-54.
Q
What are the requirement for equipment used in severe corrosive environments (and offshore
locations)?
Ans
NEMA Type 4 X, IP-66
Q
Which document provide us information about the material inspection levels?
Ans
Inspection levels are mentioned in SAER-1972
(Saudi Aramco Materials Inspection and Testing, SA 175 Forms)
Q
What are the material inspection levels according to SAER-1972?
Ans
There are 5-levels
(1) Level-0 >> required documentation only, no vendor inspection required.
(2) Level-1 >> only final inspection is required prior to shipping
(3) Level-2 >> include pre-inspection meetings, one or more surveillance inspections, all witness
and hold points, final inspection and release for shipping
(4) Level-3 >> include pre-inspection meetings, surveillance inspections on regular basis (daily,
weekly or bi-weekly), all witness and hold points, final inspection and release for shipping.
(5) Level-4 >> resident inspector continuously monitoring the work
-----------------------------------------------------------------------------------------------------------------------------------------
Cathodic Protection
(SAES-X-400, SAES-X-600)
Q
What is CP and how we do it?
Ans
Cathodic protection (CP) is a technique used to control/prevent the corrosion of metal by
making it cathode of an electrochemical cell.
Q
Which standard we follow for the “cathodic protection of buried pipelines”?
Ans
SAES-X-400
Q
Where we use SAES-X-600?
Ans
SAES-X-600 is used for “cathodic protection of plant facilities”.
10
Q
How many types of CP are used?
Ans
There are two types of CP; 1) Galvanic Cathodic Protection 2) Impressed Current Cathodic
Protection
Q
What are the contents of permanent CP?
Ans
CP Transformer rectifier, DC Cable/ Separate negative leads, High silicon cast iron anode.
Q
What is galvanic/temporary cathodic protection, define it with diagram.
Ans
In galvanic cathodic protection, a galvanic anode, a piece of a more electrochemically active
metal, is attached to the required metal surface. The galvanic anode continues to corrode,
consuming the anode metal until it must be replaced.
Q
What is impressed current cathodic protection (ICCP), explain it with diagram.
Ans
Impressed current cathodic protection (ICCP) systems consist of anodes connected to a DC
power source, often a transformer-rectifier.
An ICCP system for pipeline consist of a DC power source, often an AC powered transformer
rectifier and an anode or array of anodes buried in the ground (the anode groundbed). The DC
power source would typically have a DC output of up to 50 amperes and 100 volts, but this
depends on several factors, such as the size of the pipeline and coating quality. The positive DC
output terminal would be connected via cables(25 mm2/ #4 AWG) to anode array, while another
cable would connected from the negative terminal of the rectifier to the pipeline, preferably
through junction boxes to allow measurements to be taken. Anodes can be installed in a
groundbed consisting of a vertical hole (50ft/15m minimum) and backfilled with conductive
coke (a material that improves the performance and life of the anodes) or laid in a prepared
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trench, surrounded by conductive coke and backfilled. The choice of groundbed type and size
depends on the application, location, and soil resistivity.
Q
What types of anodes are used in galvanic/temporary cathodic protection and impressed
current cathodic protection?
Ans
For galvanic cathodic protection mostly magnesium anodes are used (for dry, sandy, rocky areas
60lbs prepackaged Mg anode is used and for buried mechanical fittings 32 lbs prepackaged Mg
anode is used and for wet, subka areas 100 lbs bare-not prepackaged Mg anode is used) and
sometimes zinc anodes also used.
For impressed current cathodic protection mostly High Silicon Cast Iron (HSCI) anodes are used
and sometimes Mixed Metal Oxide (MMO) are also used (only for use in subka)
Q
What is the purpose of temporary cathodic protection?
Ans
The purpose of cathodic protection (CP) is to control the corrosion of new pipeline by making it
the cathode of an electrochemical cell.
Q
For how much length of pipelines the permanent CP is required?
Ans
Production pipelines that extend more than 25km
Q
Within how many days need to provide a temporary/permanent CP?
Ans
Within 30 days of burial.
Q
How to know that temporary CP is working is properly?
Ans
Potential survey data shall be submitted monthly to verify that temporary CP is providing proper
protection.
Q
For how long time the potential survey data should be submitted?
12
Ans
Pipe-to-soil potential survey data verifying that the temporary system is providing proper
protection shall be submitted to the CP proponent monthly for 6-months, and every 6-months
thereafter.
Q
What is bond cable?
Ans
A cable installed between two metallic structures to provide electrical continuity between the
structures for the purpose of cathodic protection.
Q
What is calcined petroleum coke breeze?
Ans
A carbonaceous backfill used as a conductive backfill media for impressed current anodes in soil.
Q
What does mean CP?
Ans
Cathodic Protection
Q
What is Cross Country Pipeline?
Ans
A pipeline between; two plant areas, another cross-country pipeline and a plant area, or
between two cross-country pipelines.
Q
What is CSD?
Ans
Consulting Services Department
Q
What is Deep Anode Bed?
Ans
Anode or anodes connected to a common CP power supply installed in a vertical hole, (typically
25 cm diameter) with a depth exceeding 15 m (50 ft.).
Q
What is Design Agency?
Ans
The organization or company contracted by client for the design of a system.
Q
What is Drain Point?
Ans
The location on the cathodically protected structure where the negative cable from the rectifier
or junction box is fastened.
Q
What are Galvanic Anodes/Sacrificial anodes?
Ans
Anodes fabricated from materials such as magnesium, zinc or aluminium that are connected
directly to the buried structure to provide cathodic protection. Galvanic anodes are also called
sacrificial anodes.
Q
What is Negative Cable?
Ans
A cable that is electrically connected (directly or indirectly) to the negative output terminal
of a cathodic protection.
Q
What is Positive Cable?
13
Ans
A cable that is electrically connected to the positive output terminal of an ICCP power
supply, including impressed current anode cables.
Q
What is Reference Electrode?
Ans
An electrode used as a common reference potential for cathodic protection measurements.
A copper/copper sulfate (Cu/CuSO4) reference electrode is typically used for soil
applications.
A silver/silver chloride (Ag/AgCl/0.6M Cl) reference electrode is typically used for aqueous
applications.
Q
What is GOSP and WIP?
Ans
Gas and Oil Separation Plant, Water injection plant
Q
What is thermite weld/ Cad Weld?
Ans
An exothermic process to make electrical connections between tow piece of metals.
Q
What is the content of the cad weld?
Ans
Mold, powder, steel plate, fire gun or lighter
Q
With one mold how many cad welds are allowed?
Ans
Fifty (50) CAD Welds are allowed.
Q
How we will verify that CAD Weld powder is okay to use?
Ans
It shall be of same number as mentioned on mold, and CAD weld powder & mold shall be from
same manufacturer and shall be UL listed.
Q
What are the dimensions for surface cleaning for CAD Welds?
Ans
Shall be cleaned 100 mm sq including 50 mm sq white cleaned and in case if two adjacent cad
welds or failure of cad welds the distance will be 75mm apart.
Q
What shall be the weight of the hammer to test cad weld?
Ans
It shall be one pound.
Q
How much value is for open circuit potential for galvanic anodes?
Ans
Magnesium anodes have an open circuit potential of -1.7 volts.
Q
What is project proposal package? And what shall it provide?
14
Ans
The Project Proposal package shall provide all general design considerations that can be
developed without requiring measurement of field data. The Project Proposal package
should include:
a) A scope of work including a specific statement that clearly identifies any additional
requirement to provide CP for any existing pipeline.
b) Proposed locations of new cathodic protection systems on an overall CP system layout
drawing, including proposed anode type(s) and estimated output ratings of the
proposed cathodic protection power source.
c) Information on spare cathodic protection capacity (from nearby or adjacent pipelines)
along the route of the proposed pipeline.
d) Information on all locations where the proposed pipeline will be mechanically
connected to other facilities (plants, pipelines etc.) with clear details on whether these
other facilities will be electrically isolated.
Q
At which locations the electrical isolation or supplemental cathodic protection is mandatory?
Ans
Electrical isolation or supplemental cathodic protection is mandatory at
(a)
(b)
(c)
(d)
(e)
Valve stations and scraper traps
Metallic supports
Pipelines between GOSPs, WIPs, or other production facilities
Product pipeline to bulk plant transitions
MOV
Q
What are the bonding requirements for buried pipelines?
Ans
Bonding shall be provided at the following locations
(a) At every 10 km intervals (at all negative drain points for ICCP power supplies) between the
parallel pipelines wherever pipelines are parallel within 50 meters
(b) At all buried pipeline crossings
(c) All the negative drain points for ICCP power supplies
(d) Within 500m start and end of parallel segment
*Bonding shall be completed according to Standard Drawing AA-036674.
*Bonding is only required between a crossing pipeline and the outer pipelines, provided
adjacent pipelines are not more than 50 meters apart.
Q
Which kind of anode shall install for temporary CP?
Ans
Install galvanic anode of Mg for temporary CP system using 3-pin test station.
Q
What is the size of cables used for CP bonding?
Ans
It is 10 mm sq. and 16 mm sq. (8-AWG & 6-AWG)
15
Q
What is the minimum size for the primary positive and negative DC cables from the rectifier?
Ans
The minimum size for the primary positive and negative DC cables from the rectifier shall be 25
mm2 (# 4 AWG)
Q
What is the size of bond conductor in Aramco standard?
Ans
The minimum bond conductor size shall be 6 AWG (16 mm2)
Q
How many anodes are installed at buried mechanical fitting?
Ans
One 32 lbs prepackaged anode in installed
Q
(1) How many anodes are installed at full thrust anchors?
(2) How many anodes are installed at trust bored road crossings?
Ans
Two 60 lbs prepackaged Mg anodes at each end, total of 4 anodes.
Q
At thrust anchor anode installation, how much distance is required from anodes to pipeline &
thrust anchor?
Ans
Four anodes are installed at thrust anchor two at each side, distance from pipe to anode shall be
1000mm/1m and 600mm apart from thrust anchor and 900mm deep.
Q
How many anodes are installed at camel crossings?
Ans
One 60 lbs prepackaged anode per pipe, plus one additional 60 lbs prepackaged anode, i.e. one
pipe requires 2 anodes and two pipes requires 3 anodes.
Q
How many anodes are installed for open road cut?
Ans
2 anodes, one at each side for the open cut road.
Q
How many anodes shall install at thrust anchor located inside the fence or plant area?
Ans
2 magnesium anode, one at each side.
Q
What is the mini length for the pipe line to be treated as cross country pipe line?
Ans
As per SAES-X-400, the minimum length for the cross country pipe line is 25-KM. if pipeline is
more than 25 km it shall be call or treated as cross country pipe line.
Q
What is the voltage value of CP cable holiday test?
Ans
18 KV - DC
Q
What the minimum life is of impressed current and galvanic anode system?
16
Ans
As per the SAES-X-600, the minimum design life of impressed current and galvanic anodes shall
be 20 years.
Q
What the minimum life is of temporary CP system?
Ans
The minimum design life of temporary CP system shall be 2 years.
Q
What is the capacity/rating of power source is required for ICCP?
Ans
50V & 100 Amps
Q
At what locations test station should be provided on pipelines?
Ans
Provide a test station for measuring pipe-to-soil potential at (a) at kilometer marker (1-pin) (b)
negative connection (3-pin) (c) thrust anchor (d) road crossings
Q
Within how many days of pipeline burial there should be installed 1-pin and 3-pin test stations?
Ans
Within 1-week of berming completed.
Q
What shall be the height of test station from grade level?
Ans
It shall be 1200mm/1.2m
Q
What is the purpose of test station?
Ans
The purpose of the test station is to take the pipe-to-soil potential measurements.
Q
What is the average current density of galvanic anodes for buried pipelines?
Ans
Average current density for bare pipelines is 20 mA/m2
Average current density for coated buried pipelines is 0.1 mA/m2 (design criteria) and 0.005
mA/m2 (temporary criteria)
Q
What is the maximum current density of impressed current anode?
Ans
For HSCI anode maximum current density is 0.7 mA/cm3
Q
What is the mini currents density value for bare buried steel?
Ans
Minimum current density for bare steel buried is 20 mA/m2
Q
What is the mini current density value for copper ground rod?
Ans
Minimum current density for copper ground rod is 50 mA/m2
Q
What is the minimum and maximum voltage for buried pipeline?
17
Ans
According to SAES-X-400 minimum voltage 1.V and maximum 3 V with the reference to a copper
/copper sulfate electrode.
Q
What types of reference electrodes are used for taking voltage potential value from pipe-tosoil?
Ans
Copper-copper sulfate (Cu-CuSO4) reference for soil, and silver-chloride electrode for aqueous
applications.
Q
How much depth require for installation of Anode for ICCP protection? and galvanic cathodic
protection?
Ans
For ICCP anode bed, minimum depth requirement is 15 meters (50 ft.)
Q
How much depth require for installation galvanic Anode?
Ans
For galvanic anode the required depth is 900 mm/ 90 cm from the ground level and in rocky
areas it should be 300 cm/ 30 cm, the clearance between pipe and anode should be 600 mm/ 60
cm.
*When parallel piping runs prohibit 600 mini clearance, anodes shall be buried a mini of 600
below pipe (except 300 min. in rocky areas).
Q
What should be the minimum distance between two anodes installed side by side?
Ans
There should be 1.5 m distance between two anodes.
Q
What should be the clearance/ distance between pipeline and anode in CP?
Ans
The clearance between pipe and anode should be 600 mm/ 60 cm
Q
What is the minimum HSCI anode bed distance from the buried pipe line or structure?
Ans
SAES-X-400 says minimum distance 35 meter and maximum 225 meter.
Q
What are the depth requirements for direct buried CP cable Trench?
Ans
For sand or subka area
Total 750mm is required including 150mm sand bedding and then after warning tap 450mm
sand cover.
For Rocky Area
Total 300mm is required including 75mm sand bedding and then 125mm cement backfill.
For Sand and Rock Area
18
Total 450mm is required including 75mm sand bedding and after warning tap 150mm crushed
marl backfill.
Over the pipeline crossing
Total 600mm required including 150mm sand bedding (distance between cable and pipe) and
450mm sand cover.
Q
What is the width of CP cable trench?
Ans
It is 200mm.
*Cathodic protection Junction Boxes and Bond Boxes shall be manufactured in accordance
with 17-SAMSS-008.
Q
What is the difference between the bonding box and junction box?
Ans
Bonding box is used in bonding two wires, while junction box in instrumentation for connection
of instrument wires.
Q
What is the difference between distribution board and junction box?
Ans
Junction box contains terminal blocks and is used for termination and joining of cables. While
distribution board contains breakers for distribution of electricity to one or more power circuits.
*Do not install the D.C power supply in hazards location
*Do not use DC power supplies with rated output voltage greater than 100 volts
*Do not install isolating devices in areas classified as hazardous locations.
*Do not install isolating devices in any buried or submerged portions of a pipeline.
*Install the rectifiers in non-hazardous areas where possible and use oil-immersed rectifier units
inside hydrocarbon plant areas.
*Conduct soil resistivity or soil conductivity measurements at 10-meter intervals over the full
length of the proposed remote surface anode bed location.
*The number and size requirements for the anodes shall be determined based on providing a
sufficient potential gradient over the entire length of the respective pipeline to achieve the
protection criteria.
*If impressed current anodes are placed within 50 meters of a thrust anchor, then two
additional impressed current anodes shall be installed within 15 meters of the anchor, and
placed on opposite sides of the anchor. If impressed current anodes are installed, galvanic
anodes are not required for the thrust anchor.
19
*Use 27.2 kgs (60 lbs) magnesium anodes for soil resistivities greater than 500 ohm-cm.
Grounding
(SAES-P-111)
Q
What is the difference between bonding, earthing and grounding?
Ans
Bonding: Bonding is simply a technique of joining two electrical conductors together to bring
them to the same electrical potential. Bonding has to be done by connecting of all the metal
parts (that are not supposed to be carrying current under normal conditions) to bring them to
the same electrical potential. Bonding ensure that these two things which are bonded will be at
the same electrical potential.
Earthing: Earthing means connecting the dead part (which does not carry current under normal
conditions) to the earth for example electrical equipment’s frames, enclosures, supports etc., to
minimize the risk of receiving an electric shock if touching metal parts when a fault occurs.
Grounding/Neutral: Grounding means connecting the live part to the earth, for example neutral
of the power transformer, for the protection of the power system equipment and to provide an
effective return path from the machine to the power source.
Q
What is the purpose of grounding?
Ans
The purposes of grounding are personal safety, equipment & distribution circuit protection,
electrostatic discharge, building safety protection etc.
Q
What are the names of international standards which are used for grounding and ground system
installation?
Ans
Grounding and ground system installation shall be designed in accordance with IEEE 142
and meet the requirements of NFPA 70 (NEC 250)
*Measurements of earth resistivity and ground impedance shall be made in accordance
with IEEE 81
Q
Describe the characteristics/properties of ground Conductors?
Ans
Ground conductors shall have the following characteristics:
(a) Should be of copper.
(b) If insulated should have green jacket or a green jacket with yellow stripes.
20
(c) If larger than 35 mm² (#2 AWG) be stranded.
Q
Describe the requirements/characteristics of ground rods?
Ans
Ground rods shall have the following characteristics:
(a) Shall be UL listed & meet the requirements of UL 467.
(b) i) copper or ii) copper jacketed-steel or iii) galvanized-steel
(c) Have a minimum length of 2.4 meters. (Jointed rods are permitted but each joint must be
2.4 meters long)
(d) Copper or copper jacketed steel rods be minimum of 16 mm in diameter,
Galvanized steel rods be minimum of 19 mm in diameter.
Q
What type of ground rod is used in areas of 70 ohm-meters resistivity areas or areas protected
by cathodic protection (low resistivity areas)?
Ans
In areas where cathodic protection is present (lower than 70 ohms-meters resistivity),
galvanized steel ground rods (minimum 19 mm dia) are used.
Q
What is the standard color for insulated grounding conductor?
Ans
The grounding conductor shall be green or green with yellow strip.
Q
What is the size of ground conductor is used for grid and equipment?
Ans
SAES-P-111 says that the cable size for grid interconnection and with ground rods shall be mini
70 mm2 and for the equipment grounding mini 25mm2 shall be used.
Q
What is the length of grounding rod?
Ans
SAES-P-111 says, ground rods have a minimum length of 2.4meter.
Q
What is the diameter of a copper and galvanized steel rod?
Ans
For copper or copper jacketed steel rod minimum diameter is 16mm.
And for galvanized steel rod diameter is minimum 19mm.
Q
How we do grounding at pipeline valve stations? What are the grounding requirements at valve
stations?
Ans
According to SAES-P-111, grounding at pipeline valve stations shall be done with zinc or
magnesium anodes interconnected by insulated copper cable. Each ground rod shall be replaced
by with a magnesium or zinc anode and a minimum of two anodes spaced a minimum of 2
meters apart.
Q
Which grounding rod is used when area is subject to cathodic protection?
21
Ans
According to SAES-P-111, the ground rods shall be galvanized steel if area is subjected to
cathodic protection.
Q
How much there will be distance between the ground rods installed in triangular shape for MIG
ground (master instrument ground)
Ans
There shall be a distance of 1.83m (6ft) between them.
Q
What is the goal of installing more than one ground rods?
Ans
To achieve resistance of 25 ohms
Q
What is the grounding electrode?
Ans
The electrode which is used for grounding purpose.
Q
What is the resistance for ground grid/ network of electrical system?
Ans
It shall be 5 ohms i.e., voltage drop 5V
Q
What is the resistance for ground grid/ network for instrument system?
Ans
It shall be 0 ohms i.e., voltage drop 0V
Q
How we do the below ground and above ground connections to grounding grid or ground rods
or between grounding conductors or ground rods?
Ans
(a) By thermite welding or brazing
(b) By irreversible compression type connectors
(c) To steel structure by compression type connectors bolted to bare steel.
(d) Approved mechanical connectors, where it is necessary to disconnect ground conductors
for test at ground test stations.
*Underground ground conductors shall be insulated when within 3 meters of a buried metal
pipeline or metal piping.
*Underground ground conductors electrically connected to buried metal pipelines, buried
metal vessels, or metal tanks sitting on grade shall be insulated.
*The goal of a grounding rod is to achieve a resistance of 25 ohms or less between the
rod/grounding conductor and the soil
*Master Instrument Ground grid is made by connecting the ground rods in ground in a triangle
shape each 1.83m apart.
22
Substation Grounding
Q
How we do the substation equipment grounding?
Ans
Substation equipment shall be grounded as follows:
(a) For substations having equipment operating at a nominal system voltage exceeding
1,000 Volts, a ground grid meeting the requirements of IEEE 80 for step and touch
potential shall be installed.
(b) All electrical equipment in the substation, substation yard, and within 5 meters of the
substation fence shall be connected to the grid or to a ground bus connected to the grid.
(c) Substation ground grids shall be constructed of minimum 70 mm² (2/0 AWG) stranded
bare copper cable.
Q
What is the size of substation ground grids cable?
Ans
Substation ground grids shall be constructed of minimum 70 mm² (2/0 AWG) stranded bare
copper cable.
Grounding Electrodes
Q
Can the reinforcing bar of building be used as a grounding electrode?
Ans
Reinforcing bar of buildings shall not be used as a grounding electrode.
Structural steel of a building may be used as a grounding electrode in accordance with the
NEC provided it is continuous and effectively grounded by connecting at least every other
structural steel column on the perimeter of the building to a concrete-encased electrode or
a ground ring installed per the NEC and this standard.
Q
If concrete-encased electrode is used, what type of conductor is should be?
Ans
If a concrete-encased electrode is used, the conductor must be bare copper.
Q
What type of ground rod is used for system grounding?
Ans
The ground electrode for system grounding shall consist of
(1) A rod or pipe electrode OR
(2) Combination of rod or pipe electrodes and a grid or loop of bare copper conductors
Q
How much the buried depth required for grounding conductor used to interconnect rod or pipe
electrode?
Ans
SAES-P-111 says, the conductor shall be buried a minimum depth of 460 mm.
Q
Where supplementary grounding electrode shall be provided?
23
Ans
Supplementary grounding electrodes (per NEC 250) shall be provided in outdoor industrial
areas, process plant areas, and in substations
Q
What is the minimum burial depth for ground conductor or loop?
Ans
The grids or loops shall be buried a minimum of 460 mm.
Q
Supplementary electrodes are made of what?
Ans
Supplementary electrodes shall consist of ground rods connected by bare or covered
conductors, bare ground conductors, or combinations.
Q
How many connections require for above ground supplementary electrode?
Ans
Two connection are required to supplementary electrode.
System Grounding
Q
What is system grounding?
Ans
System grounding is a technique used to protect a power system and to give the return path to
the current from load to the source.
Q
What is grounding system for three phase electrical system as per SAES-P-111?
Ans
As per SAES-P-111, three phase electrical system shall be grounded at neutral point of the wye
connection of the transformer or generator by connecting directly as possible to grounding grid
or grounding electrode.
Q
How we do grounding of dry type transformer?
Ans
Dry-type transformers in substations, in switchgear rooms, or in equipment rooms may be
connected to a ground bus that is directly connected to the grid or other grounding electrode.
Q
What is solidly neutral grounded system?
Ans
In solidly grounded system, the neutral point in connected to earth directly by ground electrode.
Solidly grounded systems are usually used in low voltage applications at 600 volts or less.
Solidly neutral grounding slightly reduce the problem of transient over voltages, found on the
undergrounded system and provide path for the ground fault current.
24
Q
What is the ground resistance in solidly grounded system?
Ans
According to SAES-P-111, for solidly grounded system, the resistance for above 600V is 1Ω, and
ground resistance for less than 600V is 5Ω.
Q
What is low resistance grounding?
25
Ans
A grounding in which a transformer or generator is grounded by connecting a resistor between
the system neutral and ground to provide the desired higher value of ground current. The
impedance is selected to limit line to ground fault current normally between 100A to 1000A
Q
What is high resistance grounding?
Ans
A grounding in which a transformer or generator is grounded by connecting a resistor between
the system neutral and ground to provide the desired lower value of ground current. The
impedance is selected to limit line to ground fault current normally less than 10A.
With an HRG system, service is maintained even during a ground fault condition. If a fault does
occur, alarm indications and lights help the user quickly locate and correct the problem or allow
for an orderly shutdown of the process.
Equipment Grounding
Q
What is the equipment grounding?
Ans
Equipment grounding is the grounding used for protection of our using equipment and for
protection of human life from electric shocks.
Q
How many grounding connection are provided from grounding bus to electrical panel board?
Ans
Ground busses (in switchgear, switchboards, and motor control centers) shall have two
connections to the local ground grid or the main ground electrode.
Q
How many grounding connections are provided from ground grid to ground bus?
Ans
Two connections
Q
How many grounding connection are provided from grounding bus to instrument panel board?
Ans
2 connections
Q
How many grounding connection are provided from grounding bus to instruments?
Ans
Two connections.
Q
How many grounding connection are provided from grounding bus to electrical equipments?
Ans
Under 1000 V panels shall be provided with one connection and above 1000V shall be provided
with two connections.
Frames of equipment (motors, generators and transformers and other equipments)
operating at 1000 V or greater shall have two connections to the grounding electrode.
Q
Which two grounding systems are required for instrumentation systems?
26
Ans
These two grounding systems are required for instrumentation systems:
a) Safety Ground for personnel safety.
b) Instrumentation DC & Shield Ground.
Q
What is the minimum size of equipment ground conductor?
Ans
The minimum size of equipment ground conductor is 25mm2/ 4 AWG.
Q
Metallic cable tray after how many meter need to be bond?
Ans
According to SAES-P-111, metallic cable trays shall be bonded at both end points a minimum of
25 meters.
*Aluminum cable trays containing only circuits operated at, or below, 50 V to ground may
be used as equipment grounding conductors
*A cable concentric neutral, if properly sized and not used as a current carrying grounded
circuit conductor (3 phase 3 wire system; no neutral loads are served), may be used as the
equipment grounding conductor.
*Electrical submersible pump motors in oil and water well service do not require a
dedicated equipment grounding conductor, provided the motor controller has ground fault
detection.
*The well head must be bonded by an approved means to the ground bus at the motor
controller or supply transformer.
*Armored submarine cables do not require equipment grounding conductors.
*Shields and armor of power cable shall be grounded at both ends. Continuity at splices
shall be maintained by bonding across the splice.
Q
How we do grounding of shields and armor of power cables?
Ans
Shields and armor of power cable shall be grounded at both ends. Continuity at splices shall
be maintained by bonding across the splice.
Q
How we do grounding of the metallic conduit?
Ans
Metallic conduit shall be grounded at both end points by bonding to a grounding conductor,
a grounded metal enclosure, or to a grounded metal cable tray. This may be accomplished:
a) With approved grounding clamps connected externally to the conduit or
b) Bonding to a grounded enclosure using threaded bushings or using a conduit hub which
is approved for grounding purposes or
c) Bonding to a grounding conductor using an approved grounding bushing.
27
*Grounding with locknuts is not acceptable.
*Isolated sections of rigid metal conduit that are buried at all points at least 0.5 meters
below grade are not required to be grounded.
*Conduit sleeves used to enclose power cables transitioning from above grade to below
grade are required to be grounded only at the above grade end.
Q
Why should we need to provide the temporary grounding?
Ans
The temporary grounding is for easy drain or easy way to fault current.
Q
How is the neutral conductor identify?
Ans
Neutral conductor is identified by colors white or grey.
Q
How is an insulated ground conductor identify?
Ans
An Insulated ground conductor is identified by colors green or green with yellow stripes.
Q
How we do grounding of metallic cable trays?
Ans
Metallic cable trays shall be bonded to the local ground grid or ground electrode at both
end points ensuring that bonding continuity is met throughout all the racks in the system.
Q
How many connections are required for ground bus to main ground electrode?
Ans
Ground busses (in switchgear, switchboards, and motor control centers) shall have two
connections to the main ground electrode.
Q
How electrical manholes should be grounded?
Ans
Electrical manholes shall be grounded using two ground rods located close to diagonally
opposite corners of the manhole. These rods shall be connected to each other, to a ground
loop or bus accessible from inside the manhole, and, where applicable, to a minimum 120
mm² (4/0 AWG) grounding conductor that is connected to the local (within 15 m) grounding
grid.
Q
How raised computer floors should be grounded?
Ans
Raised computer floors shall be grounded by bonding a minimum of two pedestals at
opposite corners to the nearest ground bus or grounding electrode.
Q
How Structural steel supports for process equipment and piping and structural steel
columns for buildings should be grounded?
28
Ans
Structural steel supports for process equipment and piping and structural steel columns for
buildings shall be grounded at least every 25 m (i.e., No part of the base of the structure
shall be more than 25 m from a grounded support or column.) with a minimum of two
connections at opposite corners of each structure or building.
Q
How many grounding connection require for equipment operating above 1000 V?
Ans
Equipment operating above 1000V (MCC, switchboard, switchgear) shall have two connection of
grounding electrode.
Q
How motors, generators and transformers operating at 480V should be grounded?
Ans
Motors, transformers, and generators operating at a nominal voltage of 480 V shall have a
minimum of one connection to a supplementary grounding electrode.
Offshore Platform Grounding
Q
What is the size of copper cable or copper bar for off-shore platform grounding?
Ans
A copper cable or copper bar minimum size 120 mm² (4/0 AWG)
Fence Grounding
Q
How we do the substation fence (not be PVC coated) grounding?
Ans
Electrical substation fences shall be grounded as following methods:
(1) Substation fences shall not be PVC coated and shall be grounded in a minimum of two
locations to the local ground grid or loop.
(2) The grounding conductor(s) shall be connected to the substation ground grid at a
minimum of four locations spaced equally around the loop.
(3) The fence shall be connected to the grounding conductor(s) at intervals not exceeding
15 m.
(4) Corner posts and gateposts shall be connected to the grounding conductor.
Q
How we do the non-substation fence grounding?
Ans
Non-substation fences shall be grounded as follows:
(a) Fences which are within 10 m of an enclosed ground grid or ground loop that is connected
to equipment operated at 1000 V or greater shall not be PVC coated and shall be grounded
at intervals not exceeding 15 m to the ground grid or loop.
(d) All fences within 3 meters of a ground grid or ground electrode shall be bonded at the
nearest fence post to the ground grid or ground electrode.
29
(e) Fences that pass under a transmission line operating at 69 kV and above shall not be PVC
coated and be grounded at intervals not exceeding 15 m on fence that is within 100 m of the
power line.
(f) Fences that pass under a transmission line operating at 34.5 kV and above shall not be
PVC coated and be grounded at intervals not exceeding 15 m, of the fence within 100 m
of the power line.
(g) Fences that cross over a ground grid, or conductors that connect two ground grids, shall
not be PVC coated and shall have a bond between the grid or conductors and the
nearest post. If the crossing area is extensive, the bond is required every 50 m.
(h) Fences constructed with concrete posts and PVC coated fencing material are not required to
be grounded.
Tank Grounding
Q
How we do grounding of shells of onshore storage tanks?
Ans
The shells of onshore storage tanks in hydrocarbon service shall be grounded at a minimum of
two points on diagonally opposite sides of the tank. Each point shall be bonded to the area
ground grid or to a minimum 16 mm x 2.4 m ground rod.
Lightening Protection
Q
Which standards are applied for design and installation of lightening protection system?
Ans
Lightning protection system design and installation shall be based on
NFPA 780 and UL 96A, IEEE 998
Or
IEC 61662, IEC 61024-1, and IEC 61024-1-1.
Q
Which Facilities shall be provided with a lightning protection system?
Ans
The following Facilities shall be provided with a lightning protection system:
a)
b)
c)
d)
e)
Buildings and occupied structures over 30 m in height
High Voltage outdoor substations and switchyards, if area is 3250 m² or greater.
If required by NFPA 780.
Schools
Hospitals
Q
For lightening protection system components which standard is used?
Ans
Lightning protection components shall be UL Listed or Labeled in accordance with UL 96 for
lightning protection service or have approved equivalent certification.
30
*Protection systems design for petroleum facilities shall comply with API RP 2003.
Q
Which standard is applied for static electricity grounding?
Ans
Tank trucks, tank cars, tanks, other large containers, associated filling apparatus, and other
equipment which during normal operation can cause accumulation of sufficient static
charge to cause an ignition of hydrocarbon vapors in the area shall be bonded and grounded
in accordance with API RP 2003.
Standard Drawings for Grounding
1) Library Drawing DD-950022 shows recommended details for making grounding connections.
2) Manually operated switches for overhead power lines shall have operating platforms
and be grounded as shown on Standard Drawing AA-036572.
3) Grounding Arrangement for Disconnect Switch Structure AA-036572.
General questions for electrical and instrumentation
SAEP-302 Instructions for Obtaining a Waiver of a Mandatory Saudi Aramco Engineering
Requirement
IEC 60529 Degrees of Protection Provided by Enclosures
NEMA ICS 6 Enclosures for Industrial Controls and Systems
NEMA 250 Enclosures for Electrical Equipment
NEMA VE 1 - 2002 (Design & specifications of Metal Cable Tray Systems)
NEMA VE 2 - 2006 (Cable Tray Installation Guidelines)
NFPA 70 - National Electrical Code (NEC)
NFPA 72 - National Fire Alarm Code
NEMA 250 Enclosures for Electrical Equipment (1000 Volts Maximum)
NEMA FG 1 Fiberglass Cable Tray Systems
NEMA ICS 6 Enclosures for Industrial Control and Systems
NEMA RN 1 Polyvinyl-Chloride (PVC) Externally Coated Galvanized Rigid Steel Conduit and
Intermediate Metal Conduit
NEMA TC 2 Electrical Polyvinyl Chloride (PVC) Conduit
NEMA TC 3 PVC Fittings for Use with Rigid PVC Conduit and Tubing
NEMA TC 6 & 8 PVC Plastic Utilities Duct for Underground Installations
NEMA TC 9 Fittings for PVC Plastic Utilities Duct for Underground Installation
31
SAES-B-068 Electrical Area Classification
SAES-O-113 Security Lighting System
ANSI C80.1 Rigid Steel Conduit - Zinc Coated
ANSI C80.3 Electrical Metallic Tubing - Zinc Coated
NEC 250
NEC 725
NEC 760
Q
What is hazardous and non-hazardous area?
Ans
Hazardous locations are areas where flammable liquids, gases, vapors or combustible dusts exist
in sufficient quantities to produce an explosion or fire, otherwise non-hazardous area.
Q
What is classified area?
Ans
Hazardous locations are called classified areas, where flammable liquids, gases, vapors or
combustible dusts exist in sufficient quantities to produce an explosion or fire.
Q
What is IP code? (Ingress protection rating or International protection rating)
Ans
Ingress protection classifies and rates the degree of protection provided against intrusion, dust,
accidental contact, and water by mechanical casing and electrical enclosures.
Q
How we classify the severe corrosive environment?
Ans
Severe corrosive environments include:
a) Offshore locations
b) Onshore locations within 1-Km from the shoreline of the Arabian Gulf; and within 3-Km from
the shoreline of the Red Sea.
Q
What is a substation?
Ans
A substation is a part of an electrical generation, transmission, and distribution system, which
transform voltage level from high to low, or the reverse. It contain transformers, and control
equipment, i.e. breakers, relays, contactors, disconnecting switches etc.
Q
What is electrical area classification?
Ans
Production facilities contain, or may contain, flammable gases and vapors, combustible dust or
fibers in normal operations. These can form an explosive environment that is ignitable by hot
surfaces, electrical arcs, and sparks. To prevent this from happening, facilities must be classified
properly, so that all electrical equipment and systems are properly selected and installed. (SAESB-068)
32
Classes:
There are three categories of hazardous materials that have been designated as Class I, Class II,
or Class III. The Classes define the type of explosive or ignitable substances which are present in
the atmosphere such as:
Class I locations are those in which flammable vapors and gases may be present.
Class II locations are those in which combustible dust may be found.
Class III locations are those which are hazardous because of the presence of easily ignitable
fibers or flying.
Each of the three Classes, discussed earlier, is further subdivided into two Divisions,
Division 1 or Division 2
Divisions:
The Division defines the likelihood of the hazardous material being present in a flammable
concentration.
Division 1: In which ignitable concentrations of hazards exists under normal operation
conditions and/or where hazard is caused by frequent maintenance or repair work or frequent
equipment failure.
Division 2: In which ignitable concentrations of hazards are handled, processed or used, but
which are normally in closed containers or closed systems from which they can only escape
through accidental rupture or breakdown of such containers or systems
Groups:
The explosive characteristics of the air mixtures of gases, vapors, or dusts vary with the specific
material involved. Materials have been placed in groups based on their ignition temperatures
and explosion pressures. Combustible and flammable gases and vapors are divided into four
Groups, A, B, C, D.
Zone Method of Area Classification
Class I, zone 0
Locations
(1) In which ignitable concentrations of flammable gases or vapors are present continuously for
long periods to time.
Class I, zone 1
Locations
(1) in which explosive or ignitable concentrations of flammable gases or vapors are likely to exist
under normal operating conditions.
(2) in which ignitable concentrations of flammable gases or vapors may exist frequently because
of repair or maintenance operations or because of leakages.
33
(3) in which equipment is operated or processes are carried on, of such a nature that equipment
breakdown or faulty operations could result in the release of ignitable concentrations of
flammable gases or vapors and cause simultaneous failure of electrical equipment in a mode to
cause the electrical equipment to become a source of ignition.
(4) that is adjacent to a Class I, Zone 0 location, from which ignitable concentrations of gases or
vapors could be communicated, unless such communication is prevented by adequate positivepressure ventilation from a source of clean air, and effective safeguards against ventilation
failure are provided.
Class I, zone 2
Locations
(1) In which ignitable concentrations of flammable gases or vapors are not likely to occur in
normal operation and if they do occur will exist only for a short period
(2) In which volatile, flammable liquids, flammable gases, or flammable vapors are handled,
processed, or used, but in which the liquids, gases, or vapors are confined within closed
containers or a closed system from which they can escape only in case of accidental rupture or
breakdown of such containers or system, or as a result of the abnormal operation of equipment
with which the liquids or gases are handled, processed, or used.
(3) In which ignitable concentrations of flammable gases or vapors normally are prevented by
positive mechanical ventilation, but which may become hazardous because of failure or
abnormal operation of the ventilation equipment.
(4) Which are adjacent to a Class I, Zone 1 location from which ignitable concentrations of
flammable gases or vapors could be communicated unless such communication is prevented by
adequate positive-pressure ventilation from a source of clean air, and effective safeguards
against ventilation failure are provided.
Unclassified
All areas in the facility that are not Zone 0, Zone 1, or Zone 2 are considered unclassified. Arcing
electrical equipment in unclassified areas need not be explosion-proof. General-purpose
enclosures are acceptable in these areas.
Q
What is cable?
Ans
A group of individually insulated conductors, twisted helically.
Q
What is cable gland?
Ans
A gland is a connector designed to attach, secure and seal the end of a power cable to
equipment.
Q
What are types of cable glands?
34
Ans
Types of glands
a) Metal glands (For Armored cables & Hazardous Area Applications)
b) PVC Glands ( For Non Armored and Flexible Cables)
Q
What is an electrical connector?
Ans
Electrical connectors join wires/cables to an electrical terminal.
Q
What are types of electrical connectors?
Ans
There are many types of electrical connectors
a)
b)
c)
d)
e)
f)
crimp-on connectors
twist-on (spring pressure type) connectors
plug and socket connectors
screw connectors
blade connectors
ring & spade terminals (fork or split ring terminals)
Q
What are terminal blocks?
Ans
A device that joins wires or cables to equipment, types are:
a) screw type terminal blocks
b) spring-clamp terminal blocks
c) panel mount terminal blocks
Q
What is conduit? Types of conduit?
Ans
An electrical conduit is a tubing system used for routing & protection of electrical wiring. Types
are:
a) Metal conduit (rigid metal conduit, galvanized rigid metal conduit, intermediate metal
conduit, electrical metallic conduit)
b) Non-metal conduit (PVC conduit)
c) Flexible conduit (flexible metallic conduit, liquid-tight flexible metal conduit, flexible metallic
tubing)
Q
What are cable raceways?
Ans
Cable raceways are enclosed channels of metallic or plastic materials designed to hold, hide and
protect cables.
Q
What is cable dressing?
Ans
Neat and clean arrangement of cables is called cable dressing.
35
Q
What is cable lacing?
Ans
Cable lacing is a method of arranging the cables and wires.
Q
What are cable ties?
Ans
A cable tie is a type of fastener, for holding together wires or cables.
Q
What are the types of cable ties?
Ans
hose-tie, zip-tie, tie-wrap, zap-trap.
Q
What is fastener?
Ans
A fastener is a hardware device that mechanically joins or affixes two or more objects.
Q
What is cable termination?
Ans
Cable termination is the process of connecting power or control cables up to the final
equipment or up-stream circuit breaker.
Q
What are the conduit fittings?
Ans
Conduit fitting are accessories used to connect, redirect, extend or terminate a pipe.
Q
Name some conduit fittings?
Ans
(a) bushing (b) hubs (c) locknuts (d) couplings (e) reducers (f) nipples (g) conduit union (h)
elbows (i) conduit bodied
Q
What are the conduit supports and their types?
Ans
A conduit or pipe support is a designed element that transfer the load from the pipe to the
supporting structures. There are many types of conduit supports.
(1) Clamps (2) Hangers (3) Clips (4) Brackets (5) Straps
Q
What are the cable tray fittings?
Ans
Cable tray fittings are.
1) Clamps 2) Hangers 3) splice plates 4) reducer plates 5) blind ends 6) tray cover
Q
What are the cable tray fasteners?
Ans
There are many types of cable tray fasteners.
1) Nuts 2) bolts 3) washers
Q
What is sealing compound?
36
Ans
It is a substance used to prevent the passage of gasses, vapors of flames from one portion of the
electrical installation to another through conduit.
Q
What is conduit sealing?
Ans
Conduit sealing is used at the conduit ends to effectively seal the conduit.
Q
What is cable tray? How many types?
Ans
A cable tray is a system used to support insulated cables used for power distribution, control
systems or communication.
Types are: 1) Ladder type cable tray 2) Perforated bottom & Solid bottom type cable tray
Q
What is duct bank?
Ans
A duct bank is a group of conduits, or ducts, which is encased in concrete.
Q
What is splicing? Splice?
Ans
The joining of wires in electrical wiring is called splicing.
Q
What is wire ferrule?
Ans
A plastic sleeve used on terminated ends of cables, which is imprinted with tag number.
Q
What is creepage distance?
Ans
The shortest distance between two conductors.
Q
What is electrical enclosure/terminal enclosure?
Ans An electrical enclosure/terminal enclosure is a cabinet for electrical or electronic equipment to
mount/install switches, knobs and displays and to prevent electrical shock to equipment users
and protect the contents from the environment.
Q
What is the junction box?
Ans
A box containing the connections and junctions and terminal blocks of wiring cables.
Q
What is distribution board?
Ans A distribution board (distribution panel or power panel) is an enclosure which distributes an
electrical power into subsidiary circuits, while providing protective fuse or circuit breaker for
each circuit.
Q
What is switch board?
37
Ans
An electric switchboard is an enclosure that controls electricity/electric power from one or more
sources of supply to several smaller devices of usage.
Q
What the difference is between switch board and switch rack?
Ans
Switch board is installed inside and switch rack is installed outside and electrical room, and it is a
package of transformer, busbar, and power control panels (DP’s).
Q
What is bonding box?
Ans
A box/electrical enclosure in which the bonding cables are terminated is called bonding box.
Q
What is megger and what is meggering?
Ans
A Megger meter (Insulation resistance tester) is designed to measure resistance. The
measurement of the insulation resistance of cables is called meggering/megger testing.
Meggering/Megger Testing is to check that electrical insulation of cables is intact and in good
condition.
Q
What are inspection points for a cable tray installation?
Ans
Checking of material as per approved spec, size and type, tray installation as per drawings,
clearance from top of the tray, proper distance from tray to tray i.e. power/control/signal/low
voltage and high voltage, supports are at proper distance, and splice plates are properly
installed. Cable tray is free of any debris.
Q
What are inspection points for field instruments with impulse tubing?
Ans
Checking of material as per approved material, type and size, installation as per IFC & hook up,
check the route to be free of any obstruction, check tube bending and check tube support,
fittings.
Q
What is inspection points for cable laying?
Ans
Material inspection as per approved material type and size, cable routing as per IFC drawing,
installation as per cable schedule (tray, conduit or trench etc.), meggering, dressing and cable
tags.
Q
What is the inspection points for junction box and marshalling cabinets (any
electrical/instrument enclosures)?
Ans
Checking of material is as per approved material, type and size, drain & breathers, installation
as per IFC & installation details drawing, hardware type, name plate, tag number and shall be
easily accessible for maintenance work.
Q
What are the inspection points for conduit installation?
Q
What are the inspection points for power penal/ distribution panel installation?
Q
What are the inspection points for duct bank installation?
Q
What are the inspection points for battery enclosure installation/ solar modules/ solar system
installation?
Q
What are the inspection points of lighting fixture/pole?
38
Ans
Material inspection as per approved material, type, installation as per IFC drawing and
installation details drawing, termination inside fixture, heat resistive sleeve over the cables
inside fixture, if armored cable then brass glands if non-armored then pvc glands, shrouds, tag
number on cables, color coding of cables, IR, continuity, termination inside fuse box/breaker
compartment, degree of lighting fixture.
Q
What is ITP?
Ans
Inspection & testing plan provide us details & sequence of inspections for material receiving,
installation & pre-commissioning.
Q
What is the maximum distance between supports for R G S conduit system?
Ans
Horizontal: 3 mtrs. (10 ft)
Vertical: 6 mtrs. (20 ft)>
Q
What are the material receiving inspection points for classified area/ hazardous area electrical
equipment/instruments?
Ans
Q
What is the standard work clearance around high voltage transformers?
Ans
Minimum ten feet (10') - 3mtrs. As per NEC table -110.31
Q
What is red line drawing? Brief its color coding.
Ans
In case of any change occur to the IFC drawing construction, installation or testing the relevant
drawing will be redlined. Following color coding shall be used for this purpose:
a) Red: If any addition required in the drawing.
b) Green: If any deletion is required from the drawing
(c) Blue: If any comment is added in the drawing.
Q
What are the difference between surveillance, witness and hold point?
Ans
Surveillance: Work can be executed without client's inspection and it can be inspect some part
of them if it required.
Witness: Work can be executed without client inspection and then it can be inspected upon the
completion of work.
Hold Point: Work can't be executed without client inspection.
Q
What is difference between Hazardous and Non Hazardous area?
Ans
Hazardous: A hazardous location is an area where a potential for fire or explosion exit due to the
presence of flammable gases, liquid or vapors, combustible dusts or fibbers' and flying in
sufficient quantities to produce an explosion or ignitable mixture .
39
Non-Hazardous: An area where no risk of presence of any kind of fire or explosion.
Q
What are different kinds of certification?
Ans
i) Weather Proof.
ii) Dustproof.
iii)Water Tight.
iv) Explosion Proof.
v) Flam Proof.
vi) Intrinsic Safety Proof
Instrumentation
(Electrical Systems for Instrumentation SAES-J-902)
Q
What is instrument termination?
Ans
Cable is run from the marshaling cabinet, or some control system to the instrument in the field.
The act of attaching the cables to the terminals of the instrument or input output terminal at
the transmitting or receiving end is called termination of the instrument.
Q
For what purpose SAES-J-902 is used?
Ans
SAES-J-902 is used for electrical systems for instrumentation
Q
What is the scope of SAES-J-902?
Ans
This Standard establishes the design criteria for the installation of power and wiring systems for
electrical instrumentation.
Q
Design and installation of power and wiring systems for instrumentation shall be in
accordance with which NEC/NFPA-70 Code?
Ans Design and installation of power and wiring systems for instrumentation shall be in
accordance with National Electrical Code (NEC) Article 725, Article 505.
Q
Fireproofing of cables in hazardous areas shall be in accordance with which standard?
Ans Fireproofing of cables in fire hazardous areas shall be in accordance with SAES-B-006. Q
Fire alarm systems shall be installed in accordance with which standard?
40
Ans
Fire Alarm systems shall be installed in accordance with NEC Article 760.
Q
What is Class-I Circuit, Class-II Circuit, and Class-III Circuit?
Ans
Class 1 Circuit: A circuit complying with National Electrical Code (NEC) Article 725, Part II.
Class 2 Circuit: A circuit that complies with National Electrical Code (NEC) Article 725, Part
III.
Class 3 Circuit: A circuit that complies with National Electrical Code (NEC) Article 725, Part
III.
Q
What is Data link?
Ans
An information channel used for connecting data processing equipment to any input,
output, display device, or other data processing equipment.
Q
What is drain wire?
Ans
In a cable, the non-insulated wire in intimate contact with a shield to provide for
termination of the shield to a ground point.
Q
What is home run cable?
Ans
A cable, typically multi-pair/triad, extending between the field junction boxes and marshaling
cabinets in control or PIB buildings.
Q
Electrical and electronic equipment in hazardous area shall be according to which standard?
Electrical and electronic equipment in hazardous area shall meet which requirements?
Ans
Electrical and electronic equipment in hazardous areas shall meet listing/certification
requirements specified in NEC i.e. IECEx & EEx d
Q
Where the intrinsically safe systems shall use?
Ans
Intrinsically safe systems shall only be used in Zone 0 hazardous areas? When the vendor's
standard product offering is supplied as intrinsically safe.
Q
What are the intrinsically safe systems?
Ans
Intrinsically safe systems are those equipments which are manufactured to be safe to use in
hazardous area.
Q
What kind of cable tie shall be used in field (outdoor) for instrumentation?
Ans
All cable ties shall be nylon coated 316 stainless steel.
Q
What kind of cable tie shall be used in indoor for instrumentation?
41
Ans
All cable ties shall be weather resistant nylon with a stainless steel barb.
Conduit and Cable Sealing
Q
Conduit and cable sealing shall be installed with which standard?
Ans
According to NEC article 505
Q
What type of cable glands shall be used on instruments and enclosures in hazardous and nonhazardous areas?
Ans
Certified flameproof (Type “d”) cable glands using a compound barrier seal shall be used on all
instruments and enclosures located in hazardous areas.
Certified Flameproof (Type “d”) cable glands shall be used on all instruments and enclosures
including those located in non-hazardous areas.
Enclosures
Q
Enclosure for instrumentation in outdoor & plant area shall be of which type?
Ans
For non-hazardous outdoor/plant area should be NEMA type 4, Type IP 65 (in accordance with
IEC 60529, NEMA ICS 6 and NEMA 250).
In severe corrosive areas shall be NEMA type 4X, Type IP 66 (in accordance with IEC 60529).
Q
What are the construction requirements for field junction box? What are the installation
requirements for field junction box?
Ans
The field junction box shall be a single door NEMA Type 4X, Type IP 66 (IEC 60529). The box
construction shall meet the following requirements:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
Type 316 stainless steel body, door and hardware.
Continuously welded seams, finished smooth.
Stainless steel hinge.
Stainless steel captive clamps.
Data pocket on inside of door.
Removable door.
Ground stud for terminating ground wire.
External mounting brackets.
Q
How junction box shall be installed?
Ans
All field junction boxes shall be mounted vertically, i.e., the door shall open from left-toright or from right-to-left.
42
Q
For what volume of instrument enclosures and junction boxes the breather and drain fittings
shall be provided and of what type?
Ans
Instrument enclosures and junction boxes having an internal volume exceeding 2,000 cm³ shall
be provided with Type 300 Series stainless steel breather and drain fittings.
Conduit, Conduit Fittings and Supports
Q
What is the distance between the field device and a conduit outlet box (GUAT)?
Ans
A conduit outlet box shall be installed within 18” of the field device.
Q
How we attach a conduit to the instrument?
Ans
A flexible conduit shall be used at the instrument end of the conduit to provide isolation from
vibration, protection against the thermal expansion and for ease of maintenance.
Q
For CLASS I ZONE 1 location which fitting shall be use?
Ans
For CLASS I ZONE 1, flexible fittings listed for the area shall be used.
Q
For CLASS I ZONE 2 which type of metal conduit shall be used at instrument end?
Ans
For CLASS I ZONE 2 locations and unclassified areas the flexible conduit shall be liquid tight
flexible metal conduit shall have a sunlight resistant cover which resist oil and chemical
breakdown and shall be rated for temperatures ≥ 90° C.
Cable Trays
Q
According to which standard, the cable trays shall be designed and manufactured?
Ans
Cable tray shall be designed, manufactured, and marked in accordance with NEMA VE 1 2002.
Q
Installation of instrumentation cable tray shall be as per which standard?
Ans
Cable tray installation shall be as per NEMA VE 2-2006
Q
What type of cable tray is used for homerun cables?
Ans
Ladder type cable tray.
Q
What type of cable tray is used for instrument cables from field instruments to junction boxes?
Ans
Channel cable tray
Q
What type of material is used for manufacturing of cable trays for instrument cables?
Ans
Cable tray material shall be copper-free aluminum.
43
Q
What is the distance between the consecutive rungs of ladder cable tray?
Ans
The distance between the consecutive rungs of ladder cable tray shall not exceed 9”.
Q
What are the components of the cable tray?
Ans
The cable tray system components are clamps, hangers, brackets, spice plates, reducer plates,
blind ends, connectors and grounding straps.
Q
In new grass project, how much spare space in cable trays is required for the future?
Ans
20% free space.
Q
What type of material/material grade is used for fasteners/hardware for cable trays in indoor,
outdoor and corrosive environments?
Ans
For indoor/outdoor areas, all fasteners/hardware shall be 304SS and for corrosive area it shall
be 316SS.
Q
What type of cable trays should use between field instruments and junction boxes?
Ans
Cable tray for armored cables between field instruments and junction boxes shall be ventilated
bottom, channel cable tray.
Q
Name the cable trays which are used in electrical system for instrumentation
Ans
1) Ladder Cable Tray, 2) Channel Cable Tray, 3) Perforated Cable Tray
Q
What is the width and depth of the channel tray?
Ans
The channel cable tray width shall be 3’’, 4”, or 6” and the minimum loading depth of 1 ¼”.
*The channel cable tray system shall be installed with flanged covers.
*Cable tray fill shall comply with NEC Article 392.
Connections at Field Instruments and Junction Boxes
Q
What kind of terminal blocks (T.B) shall use for field instruments?
Ans
Screw type terminal blocks.
*Wire nut and spring type terminal blocks shall not be used.
*The outer jacket of shielded twisted single pair/triad cables shall be left intact up to the
point of termination. Drain wires and mylar shields on shielded cables shall be cut and
insulated with heat shrink sleeve at the field instrument unless otherwise specified by the
44
instrument manufacturer. For armored cables, the "outer jacket" is the jacket covering the
pair or triad; not the jacket covering the armor.
*All instrument wiring shall be routed to field junction boxes. Conduit and cable entries to
field junction boxes shall be through the bottom. Top entry is allowable provided a drain
seal is installed on the conduit within 18" of the enclosure. Side entry (within six inches of
the bottom) shall be permitted only when space limitations dictate. The number of conduit
entries shall be kept to a minimum. All unused entry ports shall be fitted with approved
plugs.
*Conduit entries to junction boxes shall be through gasketed hubs, except in explosionproof installations where the connection shall be through threaded connections.
*In severe corrosive environments, cable glands shall be protected against corrosion, either
by a heat shrink sleeve, anti-corrosion tape or PVC shroud. Gasket materials shall be oil
resistant.
*Twisted, multi-pair/triad cables shall be cut to the appropriate length to minimize looping
and flexing of the cable within the junction box.
*For individually shielded twisted multi-pair/triad cables each pair/triad shall be heat shrink
sleeve insulated from the cable-jacket-end up to the point-of-termination to keep the foil
shielding intact and free from accidental grounds. The shield drain wire shall be insulated
from foil end to terminal. Approximately, two inches of heat shrink tubing shall be applied
over the jacket end.
*The terminals shall be mounted on vertical DIN rails (i.e., horizontal DIN rails are not
allowed).
*Twenty percent (20%) unused DIN rail length shall be provided in field junction boxes.
Power Supply
*Where instrument-circuit power distribution panels are used, each panel shall be
dedicated to a single voltage level. These panels shall not provide power to noninstrumentation circuits. Distribution panels shall be furnished with a minimum of 20%
spare circuit breakers.
*Redundant power supplies feeding process automation systems, emergency shutdown
systems, metering systems, auxiliary systems or field instrumentation shall be fed from
separate distribution panels.
*Power wiring for field instruments, two-wire analog transmission loops, field switch
contacts, etc., shall be individually fused and provided with a means of disconnecting the
45
power without disturbing terminated wiring. Visual indication of a blown fuse condition
shall be provided.
*Low level signals are defined as Millivolt, Microamp, Pulse and Frequency Signals under 1 Volt.
*Where multiple online DC power supplies are connected to a single power bus, diode
auctioneering shall be used to ensure bump less transfer in the event of a single power
supply failure.
*Where multiple DC power supplies are an integral part of a manufacturer's standard
product, the manufacturer's standard method of load sharing shall apply.
*UPS power and utility power shall not share the same cable or be routed in the same
conduit.
*UPS systems powering critical instrumentation shall consist of redundant UPS units.
*Critical instrument systems are defined as systems which, upon loss of their supply power,
would cause: 1) process failure in a non-failsafe mode, 2) area or plant shutdowns, 3) loss of
custody transfer metering or accounting systems, or 4) other adverse facility operating
scenarios.
*The time during which the battery bank shall supply power to the instrumentation system
shall depend on the application, but not be less than 30 minutes.
*Backup power supply shall be required for instrumentation systems containing volatile
memory. For all such systems, the manufacturers' recommendations shall be followed.
Q
What is the function of diode auctioneering? And where is it used?
Ans
Diode auctioneering shall be used to ensure bump less transfer in the event of a single power
supply failure.
Signal/Control Wiring
*Splices are not permitted in wiring. When wiring must be extended, connections shall be
made via terminal blocks in a junction box installed above ground.
*Twist-on wire nut connectors shall not be used for making any electrical instrumentation
terminations or wiring connections.
Q
What are the wire and cable minimum size requirements for field instrument to field junction
box in instrument circuits?
Ans
The minimum wire size for single pair cable from field instrument to field junction box shall be
16 AWG/300V, 600V.
46
Q
What are the wire and cable minimum size requirements for field junction box to marshalling
cabinet in instrument circuits?
Ans
The minimum size for multi-pair/triad cable from field junction box to marshalling cabinet shall
be 18 AWG/300V, 600V.
*The minimum size for multi-pair/triad cable should be 18 AWG. The minimum wire size for
single pair cable shall be 16 AWG.
*Type ITC cable shall not be installed on either non-power limited circuits or powered limited
circuits operating at more than 150 volts or more than 5 amperes.
*Differences in the manufacturer recommended cable and these requirements shall be resolved
with Instrumentation Unit/PID/P&CSD.
Q
How protection is provided against reverse EMF for inductive loads?
Ans
Protection against reverse EMF shall be provided for inductive loads such as relays, solenoids,
etc. This may be accomplished by installing a diode across the coil for DC loads or a metal oxide
varistor (MOV) across the coil for AC inductive loads.
*If a discrete loop length exceeds 1000 feet, 120 VAC signal shall not be used due to potential
capacitive or inductive coupling. In such cases, DC voltage shall be used.
*Cables used in Class 1, Class 2 and Class 3 circuits shall meet the requirements of Article 725 of
the National Electrical Code (NEC).
Q
What are the special cables?
Ans
1) Thermocouple Extension Cables
2) Data links
*All in plant process automation networks shall be redundant and shall be routed in
separate cables. The primary cable shall follow a different route from the backup cable.
Primary and backup data link cables shall preferentially enter cabinets or consoles from
opposite sides.
*Data link cables shall not be routed in the same conduit, duct, or tray with other
instrument cables.
*Fiber Optic data link Cables may be routed with other instrumentation cables – in existing trays
or ducts with prior approval of the Supervisor, Instrumentation Unit/PID/Proponent & CSD.
Q
How we do color coding for power and signal wiring?
Ans
Power and signal wiring shall be color coded as follows:
47
AC Supply
DC Supply
Signal Pair
Signal Triad
Phase
Neutral
Ground
Positive
Negative
Positive
Negative
Positive
Negative
Third Wire
Black
White
Green or green with yellow tracer
Red or red sleeve over any color except green
Black or black sleeve over any color except green
Black
White
Black
White
Red
Routing
Q
How the instrument cable is laid above ground from the field instrument to the field junction
box?
Ans
Single twisted pair/triad cables shall be installed in RGS or PVC Coated RGS conduits from the
field instruments to the field junction boxes and armored instrumentation cable shall be
routed on a cable tray.
Q
How an armored cable is laid above ground from the field junction box to marshaling cabinets?
Ans
Cables between field junction boxes and marshaling cabinets may be routed in conduits, on
trays, or direct buried.
Q
What is the marshaling cabinet?
Ans
A marshalling cabinet contains main terminal strips and wire terminations.
Q
How we use armored cables for instrumentation homerun application?
Ans
The use of armored cables for homerun application is not recommended. However, if they
are used, the cables shall be terminated using glands at both ends (Certified flameproof
(Type ‘d’) cable glands using a compound barrier seal shall be used in hazardous areas.
Certified Flameproof (Type “d”) cable glands shall use in non-hazardous areas). In addition,
the armor shall be grounded at both ends.
*Control room cabling/wiring must conform to NEC Articles 725.
*Wiring for millivolt, microamp, pulse, and frequency signals under one Volt such as
thermocouples, vibration elements, load cells, thermistor elements and transmitters with pulse
outputs may be directly connected to the I/O unless.
*Each cable or group of cables leaving a specific junction box and carrying similar signals
shall contain a minimum of 20% spare of the used pairs or triads.
48
*Emergency shutdown system (ESD) wiring shall have dedicated cabling, junction boxes and
marshaling cabinets.
*For offshore platforms only, ESD system wiring may be terminated in the same junction box as
general instrumentation wiring. Terminals shall be segregated and clearly labeled.
*Wiring for intrinsically safe (IS) systems shall be segregated and installed in dedicated conduit
or cable tray and terminated in dedicated junction boxes.
Q
How cables are laid above ground from the marshaling cabinets to Control Room for
Instrumentation and Control Systems?
Ans
Cables between marshaling cabinets to Control Room Instrumentation and Control Systems
may be routed in conduits, on trays, or direct buried.
Q
How cables are laid under ground beneath raised computer type floors in control rooms?
Ans
Instrumentation cables installed beneath raised computer-type floors in control rooms shall be
placed in ladder cable tray or trough or solid bottom cable tray.
Cable trays beneath raised floor shall be adequately identified using suitable permanent tag
plates. These tag plates shall be installed at each end, tee connection and at three-meter
intervals. The tag plates shall be located so that it is clearly visible. The tag plates shall
contain, as a minimum, the noise susceptibility level of the circuits enclosed source, and the
destination.
*Multi-pair/triad cable shall not be used to route more than one signal type. In addition,
junction boxes shall be segregated based on signal type (e.g., each signal type shall have its
dedicated junction box).
Signal Segregation, Separation and Noise Reduction
Q
How the signal wiring is categorized with NSLs?
Ans
Signal wiring (instrumentation cable) shall be categorized with noise susceptibility levels
(NSL) of ‘1’ or ‘2.’
Level 1 – High to Medium Susceptibility: Analog signals of less than 50 V and discrete
instrument signals of less than 30 V.
Level 2 – Low Susceptibility: Analog signals greater than 50 V and Switching signals greater
than 30 V, and 120-240 AC feeders less than 20 amps.
Level 3 – Power: AC and DC buses of 0-1000 V with currents of 20-800 amps.
49
* Multi-pair/triad cable shall not be used to route more than one signal type. In addition,
junction boxes shall be segregated based on signal type (e.g., each signal type shall have its
dedicated junction box).
* Cables with the same noise susceptibility level may be grouped in trays and conduit (e.g.,
all level-1 cables may be routed in one cable tray).
*When routing instrumentation and control signal cabling (level 1 or 2) near sources of
strong electromagnetic fields, such as large transformers, motors and generators, as greater
than 100 kVA, a minimum spacing of 2 meters shall be maintained between the cables and
the devices.
*When routing Instrumentation cables (level 1 & level 2) near power cables carrying higher
loads than the limits specified in level 3, the separation distances shall be 1.5 meters as a
minimum.
Q
What is the minimum separation between power and instrumentation cables?
Ans
Power cables and instrumentation cables have minimum separation between given blow:
1) Conduit to Conduit Spacing, millimeters (inches)
NSL *
Level 1
Level 2
Level 3
Level 1
0 (0)
75 (3)
300 (12)
Level 2
75 (3)
0 (0)
150 (6)
Level 3
300 (12)
150 (6)
0 (0)
2) Tray to Conduit Spacing, millimeters (inches)
NSL *
Level 1
Level 2
Level 3
Level 1
0 (0)
100 (4)
450 (18)
Level 2
100 (4)
0 (0)
150 (6)
Level 3
450 (18)
150 (6)
0 (0)
3) Tray to Tray Spacing, millimeters (inches)
NSL *
Level 1
Level 2
Level 3
Level 1
Level 2
Level 3
0 (0)
150 (6)
650 (26)
150 (6)
0 (0)
200 (8)
650 (26)
200 (8)
0 (0)
*Twisting and shielding of instrumentation wiring shall also be used as detailed below to
minimize the noise impact on instrumentation signals.
50
Q
Why we use shielded cables? What is the purpose?
Ans
Shielded cables shall be used to reduce electrostatic noise.
Q
How we do grounding in shielded cables?
Ans
The shield shall be grounded at one point only, typically at the marshaling cabinet in the
control room or process interface building.
*For individually shielded twisted multi-pair/triad cables each pair/triad shall be heat shrink
sleeve insulated from the cable-jacket-end up to the point-of-termination to keep the foil
shielding intact and free from accidental grounds. The shield drain wire shall be insulated
from foil end to terminal. Approximately, two inches of heat shrink tubing shall be applied
over the jacket end.
*Except for coaxial cables, instrument cable shields shall never be used or considered as signal
conductors.
Q
Why we do twisting of paired or triads of instrument cable?
What is the purpose of twisted paired/triads cables?
Ans
Twisted pairs/triads shall be used to reduce electromagnetic noise.
Termination
Q
What type of terminal blocks are used for termination of instrument cables?
Ans
Terminal blocks shall be screw type and channel (rail) mounted, strip type, with tubular box
clamp connector and compression bar or yoke for wire termination. As a minimum, the
thickness of the terminals shall be 5 mm or higher. Multi-deck and spring type terminal
blocks are not acceptable.
Q
What is instrument termination?
Ans
When installing instrumentation, cable is run from the marshaling cabinet, or some control
system to the instrument in the field. The act of attaching the cables to the actual electrical
terminals of the instrument or input output terminal at the Transmitting or receiving end is
called Terminating the instrument, i.e. instrument termination. Usually the instrument loop is
installed in stages, where the instrument is physically mounted in the field, cable is pulled and
run in cable trays or buried in trenches, and the ends of the cables are terminated.
Q
What type of terminal blocks are used for termination of instrumentation cables?
Ans
Screw-type terminals are provided on field instruments or other electrical devices, solder less
crimp/compression connectors shall be used for connecting stranded copper conductors.
51
*The thickness of the terminals shall be 5 mm or higher.
*Multi-deck and spring type terminal blocks are not acceptable.
Connections at Field Instruments:
(1) All connections at the field instrument shall be made on screw type terminal blocks. Wire
nuts and spring type terminals shall not be used. Instruments with integral terminal blocks shall
be connected directly to the field cable.
(2) If the instrument is fitted with factory sealed fly leads then they shall be connected to a
screw type terminal block installed in a GUA conduit fitting.
The outer jacket of shielded twisted single pair/triad cables shall be left intact up to the point of
termination. Drain wires and mylar shields on shielded cables shall be cut and insulated with
heat shrink sleeve at the field instrument unless otherwise specified by the instrument
manufacturer.
Connections at Field Junction Boxes
Conduit and cable entries to field junction boxes shall be through the bottom. Top entry is
allowable provided a drain seal is installed on the conduit within 18" of the enclosure. Side entry
(within six inches of the bottom) shall be permitted only when space limitations dictate. The
number of conduit entries shall be kept to a minimum. All unused entry ports shall be fitted with
approved plugs.
In severe corrosive environments, cable glands shall be protected against corrosion, either by a
heat shrink sleeve, anti-corrosion tape or PVC shroud with anti-corrosion compound. Gasket
materials shall be oil resistant.
Q
What are the terminals/terminal blocks accessories?
Ans
Terminals and terminal block accessories are end brackets, DIN rail mounting brackets for
electrical insulation, bus-bar support blocks, etc.
Q
What should be material specifications of terminal blocks accessories?
Ans
Shall be made of fire retardant, halogen free, high strength material such as polyamide or
equivalent in accordance with UL 94, V0. Brittle materials such as melamine shall not be used.
*Wires terminated on these terminal blocks shall not have the bare ends coated with or dipped
in solder (“tinned”). However, termination of wiring that has individual strands of the copper
conductor tinned during manufacture is acceptable.
*No more than two bare wire ends shall be connected to each side of a single terminal block.
Q
What type of wire ducts & gutters are used and what is the purpose?
52
Ans
Plastic wire ducts with removable covers shall be used in control panels and marshaling
cabinets.
The purpose is to provide a means of routing and organizing wiring between terminal blocks and
instrument racks or panels for cable termination.
Q
How much distance should be between the wire duct and the terminal strips?
Ans
A minimum of 50 mm (two inches) shall be maintained between the duct and terminal strips to
permit wire markers to be completely presented without being obscured by the duct.
Identification
Q
What is the wire tagging method? How we do wire tagging?
Ans
All wiring shall be tagged at each end. Each wire tag shall have two labels. The first label (closest
to the end of the wire) shall identify the terminal number to which the wire is physically
connected. The other label shall be the terminal number of the connection of the opposite end
of the wire.
Q
How we do wire tagging of instrument cables? What is the wire tagging method for instrument
cables?
Ans
Where wires terminate on instrument or device terminals, the instrument tag number and
terminal designation (+) or (-), shall be used in place of terminal strip identification.
*Wire tag information shall be permanently marked in block alpha numeric or typed on
tubular, heat-shrinkable, slip-on sleeves. Wrap-around, Snap-on or self-adhesive wire
markers shall not be used. Handwritten wire tags are not acceptable.
Q
What is cable tagging in instrumentation and how it shall be done?
Ans
All cables shall be tagged, at each end, with a cable-tag. Homerun cables shall be tagged
with the assigned “IC” cable number.
Cable-tags outside junction boxes and marshalling cabinets shall be 316 SS with
permanently marked alphanumeric characters. The cable-tag shall be securely attached to
the cable with stainless-steel cable ties. Where cable tags are required inside junction boxes
or marshalling cabinets shall be weather resistant, high quality plastic cable tags secured
using cable ties.
Q
How terminal blocks are identified by tagging?
Ans
Each row of terminals shall be uniquely identified alphanumerically, e.g., TS-101, TS-102,
etc.
53
The terminals in each row shall be sequentially numbered starting at number one (1).
Grounding
Q
Which two grounding systems are required for instrumentation systems?
Ans
Two grounding systems are required for instrumentation systems:
a) Safety Ground for personnel safety.
b) Instrumentation DC & Shield Ground.
*Both safety ground and instrumentation circuit ground must conform to NEC, Article 250.
Q
What size of cable is used for grounding systems for instrumentation?
Ans
Two copper conductors, 25 mm² minimum
Q
After how many time Instruments need to be calibrate?
Ans
After 6 month.
Q
What is loop check?
Ans
Loop check is a test of checking/testing the continuity of wires or cables.
Q
What are the contents of loop folder? What is the Loop Folder and what is the purpose of Loop
folder and which documents it contains?
Ans
Loop folder consists of:
(1) Punch list Form
(2) Loop Check Cover Sheet
(3) Instrument installation inspection report/form
(4) Calibration Certificates
(5) Data sheet (ISS)
(6) Instrument Block Diagram
(7) Instrument Interconnection Diagram
(8) Junction Box Connection Wiring Drawing
(9) ILD (instrument loop diagram)
(10) P&ID (piping and instrument diagram)
(11) Hook up drawing
(12) Instrument Points and Line (IPL)
(13) Instrument cable meggering report and continuity test report
(14) Instrument loop acceptance sheet
(15) Cable Conduit Schedule
Q
What is instrument termination? What is instrument commissioning?
54
Ans
The instrument terminated, calibrated and tested to be functioning at the control system, the
instrument is said to be commissioned, i.e. ready for service. That is called commissioning.
Q
(1) How we install an instrument like MOV, PIT, and flow meter? (2) What is the installation
procedure of an instrument? (3) Which things are required for the installation of an instrument?
(4) What will we do before installing an instrument?
Ans
(1) Data sheets and calibration sheets
(2) Hook up drawing, location drawing
(3) P&ID
Electrical
(Wiring Methods and Materials > SAES-P-104)
Q
SAES-P-104 is used for what purpose?
Ans
This Standard prescribes mandatory requirements for the design and installation of insulated
power and control wiring and cable systems.
Q
SAES-P-104 is used for what?
Ans
SAES-P-104 is used for “Wiring Methods and Materials”.
Q
Define control wiring and instrumentation wiring?
Ans
Control wiring:
Control wiring is wiring used to power up the electrical control devices, such as
pushbuttons, electromechanical relays, meters, transducers, etc.
Instrumentation/Signal wiring:
Wiring connected on one or both sides to instruments, distributed control systems, etc is
called instrumentation wiring.
*Signal cables carry signals of 24 VDC and 4-20mA.
Q
Which standard code is used for the design and installation of wiring and cable systems?
Ans
Design and installation of wiring and cable systems shall be in accordance with Saudi Building
Code, ANSI/NFPA 70, NEC 725.
Wire and Cable
55
Q
What type of conductor material is used for wires and cables?
Ans
Wires and cables shall have copper conductors. Aluminum conductors are permitted to be
used in community areas for sizes 25 mm² or larger.
Q
What are the low voltage Jacketed wire and cable specifications, according to SAES-P-104?
Which standards shall comply low voltage jacketed cables?
Ans
Low voltage jacketed cables shall comply with NEC or IEC 60502-1 and shall conform to UL
standards.
Q
What are the low voltage unjacketed wire and cable specifications, according to SAES-P-104?
Which standards shall comply low voltage unjacketed cables?
Ans
Low voltage unjacketed insulated wires shall comply with NEC, IEC 60227 or SASO 55 and shall
conform to UL standards.
*Low voltage unjacketed insulated wires shall not be used in cable trays, duct banks involving
manholes, or direct burial applications.
Q
What are the medium voltage power cables specifications, according to SAES-P-104?
Ans
Medium voltage power cables, rated 5 kV to 35 kV, shall comply with 15-SAMSS-502, and shall
be either IEC or ICEA & AEIC type cables.
Q
What are the high voltage power cables (rated 69 KV high voltage) specifications, according to
SAES-P-104? The power cables rated 69KV and above should comply with which standard?
Ans
According to SAES-P-104, Power cables rated 69 kV and above, with solid dielectric insulation,
shall comply with either AEIC CS6 (69 kV EPR insulated cable) or AEIC CS9 (69 kV and above XLPE
insulated cable).
Q
The submarine power cables rated 5KV through 115 KV should comply with which standard?
Ans
According to SAES-P-104, Submarine power cables, 5 kV to 115 kV, shall comply with 15-SAMSS503.
Q
What type of cables should use in areas Class I, Division 2 and Zone 2 (hazardous) locations?
Ans
Power cables meeting the requirements of NEC Article 501 are allowed.
*Power and control conductors shall be stranded
* Stranded power, control and grounding conductors shall have stranding in accordance
with ASTM B8 Class B or C, or ASTM B496, or IEC 60228 Class 2.
Q
How much thickness of the insulation required for power cables for high voltage?
56
Ans
According to SAES-P-104, insulation thickness should be 16 mm to 20 mm.
Q
What is the minimum size of control conductor?
Ans
The minimum size of control conductor for 600V and below shall be 2.5 mm2 (14 AWG)
Q
What is the minimum size of power conductor?
Ans
The minimum size of power conductor for 600V and below shall be 4 mm2 (12 AWG)
Q
What is the maximum size of power conductors rated 69KV and below
Ans
Maximum size of conductors rated below 69 kV shall be 500 mm² or 1,000 kcmils.
Q
According to which standards the armored cable shall be manufactured, as per SAES-P-104?
What are the standard requirements for armored cable?
Ans
Armored cable shall be manufactured to IEC 60502-1 or IEC 60502-2, and shall have galvanized
steel wire armor or galvanized steel tape armor under the jacket.
Q
What kind of cables used for security lighting (perimeter and area lighting)?
Ans
Cables used for security lighting (perimeter and area lighting) shall be armored or metal clad.
Q
What is the maximum number of field splices permitted in any one circuit for new installations
of cables rated above 1000 V?
Ans
Splicing of conductors shall be kept to a minimum. The maximum number that made
necessary by the use of the standard size reels with full length cables, but in case of accidental
damage of the cable during installation, one additional splice is permitted with the concurrence
of the cable proponent.
*For installation and application purposes, armored cable manufactured to IEC 60502-1 or IEC
60502-2 shall be considered equivalent to type MC (metal clad) cable.
*Type MC Cable and armored cable shall be permitted to be installed and exposed above
ground where it is not subject to damage by vehicular traffic or similar hazards.
Q
What type of cables are used for underground installations?
Ans
Type MC Cable and armored cable shall be used for underground installations.
*Un-armored type cables shall be used for cable tray and conduit systems installations.
*Fireproofing of cables shall be in accordance with SAES-B-006 (onshore facilities) or SAESB-009 (offshore facilities).
Q
What is the hazard location in area classification?
57
Ans
Hazardous locations are: CLASS I, ZONE 0 & CLASS I, ZONE 1
Connections and Terminations
*Compression (crimped) type connectors shall be used for splicing and terminating stranded
conductors.
*The use of solder lugs is prohibited.
*Compression terminal connectors for 4/0 and larger conductors shall be two hole NEMA
design.
*All compression connectors shall be tinned copper.
Q
What type of connectors are used for lighting and receptacle circuits?
Ans
Spring pressure type twist-on connectors, and pressure set screw connectors with insulating
caps are permitted for lighting and receptacle circuits in non-hazardous locations, and in nonindustrial applications.
Q
What type of connectors are used for control wiring?
Ans
Insulated ring tongue, locking fork tongue, flanged fork tongue and pin type compression
terminals shall be used for control wiring.
*All threaded cable fittings including terminators (glands) for metric size cables shall have
tapered (NPT) threads in accordance with ANSI/ASME B1.20.1.
Q
What is the cable identification method for electrical cables?
Ans
Identification of cables shall include the cable number and destination.
Individual control wires shall be identified by two labels at each end. The first label (closest
to the end of the wire) shall identify the number of the terminal to which the wire is
connected. The other label shall identify the terminal of the opposite end of the wire.
Q
What are marking methods for wires for terminations?
Ans
Wires at termination points shall be identified by the use of:
(a) Permanently imprinted or embossed wire markers of the heat-shrinkable or slip-on type.
Slip-on wire markers shall be sufficiently tight so that they will not slip unintentionally.
(b) Cables may be identified by special plastic or non-corrosive metal labels held with cable ties,
or similar methods.
(c) Colored insulating tapes may be used for phase identification of power circuit conductors.
58
* Wrap-around, rigid Snap-on, or adhesive type markers are not permitted for wire or cable
identification.
Q
How to identify the individual phases of power cable circuit?
Ans
SAES-P-104 describe that, individual phases of power circuit shall be identified by the
color-coding cable (Red, Yellow, Blue).
Q
What is creepage distance? How much creepage distance for 13.8 KV outdoor terminations?
Ans
The clearance between the terminated ends of phase to the ground is called creepage distance.
For 13.8 kV outdoor terminations, each phase shall have a creepage distance of 552 mm to
ground minimum.
Q
What is the creepage distance for medium and high voltage terminations installed outdoor?
Ans
Medium and high voltage terminations (operating at 2.4 kV and above) installed outdoors shall
have a minimum creepage distance to ground of 40 mm per kV line-to-line nominal system
voltage.
Q
What is the creepage distance for medium and high voltage terminations installed indoor?
Ans
Medium and high voltage terminations installed indoors shall have a minimum creepage
distance to ground of 25 mm per kV line-to-line nominal system voltage.
Q
What is the minimum creepage distance for MV/HV terminations?
Ans
For outdoors installed is 40 mm per KVL-L and indoors installed is 25 mm per KVL-L.
Q
According to SAES-P-104, Cable glands should be in accordance with?
Ans
Cable glands (for hazardous and non-hazardous locations) shall be in accordance with BS 6121
or BS 50262.
Enclosures
Q
According to SAES-P-104, which type of terminal/ equipment enclosure shall be used in outdoor
plant areas?
Ans
In outdoor plant areas, terminal/equipment enclosures shall be:
(a) NEMA Type 4
(b) NEMA Type 3
(c) IEC 60529, Type IP54 or better.
Q
According to SAES-P-104, which type of terminal/equipment enclosure shall be used in outdoor
plant areas in severe corrosive environment?
59
Ans
In outdoor plant and other industrial areas located in severe corrosive environments, equipment
and terminal enclosures shall be:
(a) NEMA Type 4X
(b) NEMA Type 4 or 3
(c) IEC 60529, Type IP 54 or better
Q
According to SAES-P-104, what type of enclosure material shall be?
Ans
Enclosure materials shall be
a)
b)
c)
d)
Aluminum (Copper Free -0.4%)
Plastic (Fiberglass)
Stainless steel (Type 304 or better)
Galvanized/Painted/Coated carbon steel in indoor air conditioned area.
Q
According to SAES-P-104, which equipment/terminal enclosure shall be used in outdoor nonindustrial area?
Ans
In outdoor non-industrial areas, equipment and terminal enclosures shall be:
(a) NEMA Type 3R, 3 or 4
(b) IEC 60529 Type IP34 or better
Q
According to SAES-P-104, which type of enclosure shall be used for dry-type transformers in
outdoor locations?
Ans
In outdoor locations, enclosures for small dry-type transformers shall be totally enclosed NEMA
Type 3R.
*In hazardous (classified) locations, enclosures that are required to be approved for Class I
locations by NEC Article 501 or 505.
Q
What type of breathers and drain fitting shall have in enclosures and junction boxes?
Ans
Enclosures and junction boxes having an internal volume exceeding 2,000 cm³ shall be provided
with Type 300 Series stainless steel breather and drain fittings.
Q
AS per SAES-P-104, what is the size of drain hole?
Ans
SAES-P-104, says thin wall enclosure and junction box may be drill by 5mm hole in the bottom.
Conduit, Conduit Fittings and Supports
Q
What are the specifications of direct buried PVC conduit, as per SAES-P104?
60
Ans
Direct buried conduit shall be PVC conduit Type DB-120 per NEMA TC 6 & 8 or Type EPC-40-PVC
per NEMA TC 2.
Q
What are the specifications of concrete encased underground conduit as per SAES-P104?
Ans
Concrete encased conduit shall be PVC conduit Type EB-35 or DB-120 per NEMA TC 6 & 8 or
Type EPC-40-PVC per NEMA TC 2.
Q
What are the specifications of direct buried conduit for corrosive area, as per SAES-P104?
Ans
Direct buried conduit in class I division I (Classified area) shall be PVC coated RGS conduit.
Q
What are the specifications of aboveground/exposed conduit, as per SAES-P104?
Ans
Conduit installed exposed, above ground in outdoor, industrial facilities shall be rigid steel per
ANSI C80.1, and in addition it shall be galvanized.
Q
What are the specifications of aboveground conduit in severe corrosive environments as per
SAES-P104?
Ans
Conduit above ground in severe corrosive environments shall be rigid steel per ANSI C80.1,
and it shall be galvanized, in addition, it shall be factory PVC coated (1 mm) per NEMA RN 1.
*Where flexibility is required, liquid-tight flexible metal conduit (non-hazardous and Class I,
Division 2 and Zone 2 locations) or explosion-proof neoprene coated or PVC coated flexible
couplings (in Class I, Division 1 and Zone 1 locations) shall be used.
*EMT (electrical metallic tubing) is acceptable only for indoor non-hazardous location. EMT
shall comply with the requirements of ANSI C80.3.
*Intermediate metal conduit (IMC) is prohibited.
Q
What is the minimum size of conduit shall be, as per SAES-P-104?
Ans
The minimum conduit size shall be ¾ inch or equivalent.
*In non-industrial areas and for instrumentation wiring the minimum size conduit shall be ½
inch.
*Conduit and threaded conduit fittings shall have tapered (NPT) threads in accordance with
ANSI/ASME B1.20.1.
*Field cut conduit threads shall be coated with a zinc rich protective coating.
Q
What type of conduit fittings are used for outdoor rigid steel conduit and liquid-tight flexible
metal conduit as per SAES-P-104?
61
Ans
Conduit fittings for outdoor rigid steel conduit and liquid-tight flexible metal conduit shall be of
steel, iron, either hot-dip galvanized, or zinc electroplated.
Q
What type of conduit fittings are used for aboveground rigid steel conduit and liquid-tight
flexible metal conduit, as per SAES-P-104?
Ans
Conduit fittings for rigid steel conduit and liquid-tight flexible metal conduit used above ground
in severe corrosive environments shall be steel, iron, either hot-dip galvanized, or zinc
electroplated and in addition, shall be factory-coating with PVC or field coating prior to
installation.
*Conduit fittings for direct buried PVC coated rigid steel conduit shall be factory PVC coated.
*Threads of plugs, junction boxes and other fittings shall be lightly lubricated with a rust
preventive grease before assembly.
*The use of conduit unions with underground conduit should be avoided. If this is not
possible, conduit unions must be protected with heat-shrinkable sleeves or wrap-arounds.
Q
As per SAES-P-104, pvc conduit fittings shall be in accordance with which standard?
Ans
Fittings for NEMA TC 6 & 8 Type PVC conduit shall be in accordance with NEMA TC 9.
Fittings for NEMA TC 2 Type PVC conduit shall be in accordance with NEMA TC 3.
Q
What type of supports are used to support conduits, cable trays, enclosures, lighting fixtures and
other electrical equipment?
Ans
Channel erector system components used to support conduits, cable trays, enclosures,
lighting fixtures and other electrical equipment shall be made of steel or iron, either hot-dip
galvanized (preferably), or zinc electroplated.
Q
What type of supports are used to support conduits, cable trays, enclosures, lighting fixtures and
other electrical equipment in severe corrosive environment?
Ans
Shall be made of
(A) Steel or iron, either hot-dip galvanized (preferably), or zinc electro plated and in addition,
shall be factory-coating with PVC or field coating prior to installation. (B) Stainless steel (C)
Fiberglass
Cable Trays
Q
What kind of material is used for the cable trays?
Ans
According to SAES-P-104, cable trays materials shall be
62
a) Aluminum (copper free 0.4%).
b) Fiber glass.
c) Stainless steel
d) Galvanize carbon steel in indoor air-conditioned area.
Q
According to SAES-P-104, Aluminum and galvanized carbon steel cable trays are designed,
manufactured, rated and tested in accordance with?
Ans
Aluminum and galvanized carbon steel cable tray shall be designed, manufactured, rated, and
tested in accordance with NEMA VE 1.
Q
According to SAES-P-104, Fiberglass cable trays are designed, manufactured, rated and tested in
accordance with?
Ans
Fiberglass cable tray shall be designed, manufactured, rated, and tested in accordance with
NEMA FG 1.
Q
What is purpose of providing the cover of cable tray?
Ans
Cover provide for protection from sun light and mechanical damage.
Q
How much spacing require on expansion joint for aluminum cable tray?
Ans
Spacing between expansions joint that allowed a 25 mm movement in 20 meters
Underground Cable Systems
Q
What are the minimum depth of burial requirements for underground installations?
Ans
Minimum depth of burial requirements for underground installations are as follows:
Millimeters from Grade Level to the Top Surface of Cable, Conduit or Duct
Bank
System Voltage
Direct Buried
Cables
Direct Buried
PVC
Duct Bank and Direct
Buried Rigid Steel
600 V and
below
610
460
460
Over 600 V to
35 kV
920
610
460
Over 35 kV
1070
760
460
63
Q
What is the underground conduit installation depth requirements in rocky areas, in areas where
cables being below the water table, or to avoid underground obstructions such as other cables,
conduits or piping?
Ans
In rocky areas where digging must be minimized, in areas where cables being below the water
table, or to avoid underground obstructions such as other cables, conduits or piping, cables may
be installed in one of the following configurations with total cover of 300mm or 150 mm:
(a) PVC coated rigid steel conduit with a total cover not less than 300 mm, which shall include a
50 mm thick (minimum) reinforced concrete slab over the conduit; or
(b) PVC coated rigid steel conduit with a total cover not less than 150 mm, which shall include a
100 mm thick (minimum) reinforced concrete slab over the conduit; or
(c) A reinforced concrete encased duct bank with 150 mm of total cover, measured from the
top of the upper conduit, which shall include a minimum of 100 mm of concrete over the
upper conduit.
*The top layer of the concrete slab or the duct bank shall be mixed with red dye. (Minimum
thickness of red concrete layer should be 5 mm).
Q
What is the mini thickness of red concrete tiles?
Ans
SAES-P-104, minimum thickness of red concrete tiles is 50mm/5cm and are placed 300mm
above direct buried cable or direct conduit, in addition, a yellow warning tape shall be installed
over the tiles. Tiles dimensions are 200x400 mm.
Q
What is the depth, width of trench? And what is the minimum sand bedding height? And what is
the minimum height of sweet sand before the yellow warning tape?
Ans
For direct buried cable trench the minimum depth is 610 mm from the top surface of the cable
and minimum sand bedding is 150 mm and minimum height of sweet sand over the cable is 300
mm and then put red tiles and yellow warning tape and then backfill it.
Q
What type of duct banks are used for underground cable systems?
Ans
Duct banks shall consist of PVC conduit, encased in concrete.
(1) The minimum burial depth from the grade level to the top surface of duct bank is 460 mm.
(2) There shall be a minimum of 75 mm of concrete from the outside surface of the duct
bank to any conduit or reinforcing steel.
(3) In duct banks with steel conduit, unreinforced non-structural concrete shall be used.
(4) In duct banks with PVC conduit, under areas with no traffic, or occasional traffic,
unreinforced non-structural concrete shall be used.
(5) In duct banks with PVC conduit, under areas with frequent traffic, such as roads and parking
lots inside plants or communities, reinforced concrete shall be used.
64
*There shall be a minimum of 75 mm of concrete from the outside surface of the duct bank to
any conduit or reinforcing steel.
*The top layer (5 mm minimum thickness) of the concrete shall be mixed with red dye.
Q
When is the duct banks used?
Ans
At cross under paved road, and railroads and when depth is restricted/minimized due to some
reasons.
Q
What is the minimum crossing or parallel clearance between direct buried cables or conduits
and underground piping?
Ans
The minimum crossing or parallel clearance between direct buried cables or conduits and
underground piping, shall be 300 mm.
Cable Testing after Installation
Q
Why we do hypo-test? For what purpose we do hypo-test?
Ans
To check the insulation condition (di-electric strength of insulation) of the cables.
Q
Why we do megger test/IR test? For what purpose we do megger test/IR test?
Ans
To check the insulation resistance of the cables.
Q
What is Hi-Pot Test?
Ans
The Hi-Pot leakage current technique is a diagnostic test which involves the measurement of
leakage current when a high potential (above nominal) is applied to the cable to determine the
condition of the cable, specifically the insulation.
Q
What is the procedure for DC Hi-Pot Testing of medium voltage cables?
Ans
STEP-BY-STEP PROCEDURE FOR DC FIELD TESTING
• Ground all conductors, except the one to be tested.
• Connect cable shield to ground; ground any adjacent equipment.
• Ensure adequate clearance of the conductor/terminals to be tested from ground to prevent
flash over.
• Carefully wipe terminals to remove any contamination (i.e. dust, moisture, etc.)
• Corona-proof conductor/terminal ends of cable by sufficiently taping them. If cable is
terminated, cover termination with a polyethylene bucket or bag.
65
• Fence test cable ends to ensure personnel safety.
• Preliminary step: ‘Megger’ cable to be tested. Any cable that exhibits low ‘Megger’ readings is
questionable and should be cleared before the high voltage DC test is performed.
• Connect output of test set to conductor/terminal to be tested and connect ground terminal of
test set to ground.
• Bring DC voltage up to prescribed test level in five equal steps. Raise the voltage at an even
rate, so as to reach the required level in not less than 10 seconds. Hold the voltage at each step
for 60 seconds. Read and record the leakage current at the end of each hold period.
• Hold the full test voltage for not less than 10 minutes or more than 15 minutes. Read and
record the leakage current at 15-second intervals for the first 2 minutes and then every minute
for the duration of the test.
• Bring the test voltage control quickly and smoothly to zero. Read and record the voltage
remaining on the cable after 30 and 60 seconds. Discharge the cable to ground using a properly
terminated resistor stick. When the test set voltmeter indicates zero voltage on the cable,
attach a solid ground to the cable and then disconnect the test set and resistor stick.
• Test each conductor/cable in the circuit in the same manner.
• Record all data concerning the circuit and test results.
Q
How can we check the condition of the cable insulation in field?
Ans
1. The insulation resistance test performed with a megger tester.
2. The DC high potential test or DC hi-pot test
3. The very low frequency high potential test (VLF hi-pot test)
4. The AC high potential test which is performed at power frequency (50 hertz or 60 hertz).
Q
For low voltage cable, how much megger voltage requires?
Ans
SAES-P-104, megger voltage shall be 1-KV (DC) for one minute.
Q
For medium voltage cables how much megger voltage requires?
Ans
SAES-P-104, for medium voltage cables (5KV to 35 KV), megger voltages shall be 5-KV (DC).
Q
What kind of cable testing shall be performed at medium voltage (5 kV to 35 kV) cables?
Ans
5 kV megger tested before and after backfilling and then DC- high- potential testing after
installation and prior to placing in service
66
Q
For how long time we applied the DC high potential test for 5kv and high rating direct buried
cables?
Ans
The DC high potential value shall be 4 kV/1 mm for one minute and not to exceed 10 kV.
Q
How we do megger testing of new cables spliced to existing cables?
Ans
New cables to be spliced to existing cables shall be 5 kV megger tested and DC high-potential
tested prior to splicing.
After splicing, the new and existing cable combination shall be 5 kV megger tested.
In addition, if the existing cable has been in service for less than five years, the new and existing
cable combination shall be high-potential tested.
Q
What kind of test may be applied to determine the condition of old cables?
Ans
Very low frequency (VLF) test.
Q
For what purpose we applied VLF test?
Ans
Very Low Frequency (VLF) test may be applied to determine the condition (dielectric
strength of insulation) of old cables.
Q
For high voltage cable (69 KV and above) how much voltage requires for Hi-Pot test?
Ans
SAES-P-104, Hi-Pot test voltages shall be 192-KV (AC)
Q
For what purpose we use high potential test and megger test?
Ans
To check to integrity of the cable jacket.
Q
How we check the integrity of overall jacket of direct buried cables rated 5KV and higher?
Ans
The integrity of the overall jacket of direct buried cables rated 5 kV and higher shall be tested by
conducting a 5 kV megger and DC high potential test between the cable insulation and ground.
Q
How we check the integrity of the overall jacket of direct buried low voltage armored or metal
clad cables?
Ans
The integrity of the overall jacket of direct buried low voltage armored or metal clad cables shall
be tested by conducting a 500 V megger test.
*IEC 60229 shall be used for HV cable jacket integrity testing.
Cable Separation
Q
What is the minimum separation b/w power and control cables?
67
Ans
At (1 kV to 34.5 kV), 300 mm separation is required
At (34.5 kV and above), 1 m separation is required
Q
What are the low voltage, medium voltage and high voltage values?
Ans
Less than 1000 V
→ Low voltage
1KV to 35 KV
→ Medium voltage
35KV to 69 KV
→ High Voltage
69KV and high voltages → Extra high Voltage
*Conduit sealing fittings shall not be used.
*Conduits that cross hazardous location boundaries shall terminate in the open air at both ends
of the conduit.
*The cables outside the building shall be direct buried for a distance of at least 2 meters
Conduit and Cable Sealing
Basic Power System Design Criteria
(SAES-P-100)
Q
SAES-P-100 is used for what?
Ans
SAES-P-100 is used for basic power system design criteria.
Q
What is the scope of SAES-P-100?
Ans
This SAES prescribes mandatory design basis and performance criteria of electrical power
systems.
Q
What is bus tie breaker?
Ans
A breaker used to connect the two busses of secondary-selective system.
68
Q
What is captive transformer?
Ans
A transformer whose output is dedicated to a single piece of utilization equipment.
Q
What are the critical loads?
Ans
Critical Loads are loads
a) Where a single possible failure could cause a loss of power which would create an
immediate hazard to human life.
b) Security systems.
c) Which cannot be shut-down for a minimum of 5 consecutive days annually for
scheduled maintenance on upstream power supply equipment.
Examples of critical loads are: major computer centers, major office buildings, process units
in gas plants and refineries.
Q
What is electrical load?
Ans
Electrical load is the averaged usage of electricity over a specified time period.
Q
What is distribution equipment?
Ans
The equipment used to distribute power to utilization equipment or other distribution
equipment. For example switchgear, Panel boards, Switch racks, switchboards, etc.
Q
What are the industrial facilities?
Ans
Industrial Facilities includes the following:
a) Facilities directly associated with production, processing, or bulk distribution of hydrocarbons.
This includes, but is not limited to, facilities such as the following:
I) GOSPs
II) Water injection plants
III) Refineries
IV) Bulk distribution plants
V) Pumping stations
VI) Gas plants
b) Hospitals.
c) Office buildings, exceeding three occupied floors.
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d) Control buildings.
Q
What are the non-industrial facilities?
Ans
Non-industrial Facilities includes commercial type building applications. This includes, but is not
limited to, the following:
a) Shops
b) Small office buildings
c) Schools
d) Community buildings
e) Warehouses
Q
What is the operated load?
Ans
Operating Load:
a) For new facilities: One-hour demand based on plant or facility design conditions.
b) For existing facilities: When data from metering equipment is available, maximum 60-minute
demand measured over a minimum of one year.
Q
What is secondary-selective switchgear?
Ans
A switchgear assembly consisting of two buses connected with a single bus tie breaker.
Each bus has one breaker to receive incoming power
Q
What is secondary-selective substation?
Ans
A substation fed by two independent power sources (different transmission or distribution
lines) which consists of one or more sets of two transformers and associated secondaryselective switchgear. Also referred to as a “double-ended” substation.
Q
What is utilization device/equipment?
Ans
The equipment whose primary function is to convert electrical energy to another form or
store electrical energy.
Examples of utilization equipment would be motors, heaters, lamps, batteries, etc.
Equipment directly feeding/controlling the utilization equipment is considered part of the
utilization equipment (e.g., AFDs, reduced voltage starters, battery chargers, etc.).
Q
what are the basic design codes for electrical power systems?
Ans
Electrical power systems shall be designed and constructed in accordance with the SBC,
NFPA 70 (National Electrical Code), NFPA 70 E (Standard for Electrical Safety in the
Workplace) and ANSI C2 (National Electrical Safety Code), as supplemented or modified by
the Saudi Aramco Engineering Standards.
*Only secondary-selective switchgear shall be used to feed critical loads.
70
Q
What types of loads are supplied by stand-by power or emergency power?
Ans
Loads to be supplied by standby power or emergency power include the following:
a)
b)
c)
d)
e)
Security system
Emergency control room or disaster response room.
HVAC and air handling control equipment for pressurized buildings
Emergency lighting, if DC power or UPS is not sufficient for the intended purpose.
Essential loads, that cannot be supplied from UPS or DC system
Q
What should be the sizing of the electrical system?
Ans
Sizing of the electrical system shall be based upon using 110% of the sum of the operating
load plus all known future loads.
*Electrical equipment for fire pump installations shall meet the requirements of NFPA 20
*The frequency of alternating current electrical power systems shall be 60 Hz.
*The primary distribution within industrial facilities shall be 13.8 kV, three-phase, threewire.
*The Secondary distribution shall be either 4.16 KV, three phase three wire and/or 480 V,
three phase three wire.
*Equipment suitable for Class 1, Zone 0 locations may be used in Class 1, Zone 1 locations.
Both areas are hazardous.
UPS and DC Systems
(SAES-P-103)
Mandatory Saudi Aramco Engineering Requirements (MSAERs) are Saudi Aramco Materials
System Specifications (SAMSSs), Engineering Standards (SAESs) and Standard Drawings (SASDs).
Q
What is the scope of SAES-P-103?
Ans
This standard prescribes mandatory requirements for installation and application of DC
power systems (stationary storage batteries and rectifiers/chargers), uninterruptible power
supply (UPS) systems, and solar photovoltaic systems.
Q
Describe DC Power System.
Ans
DC Power System shall consist of, but not limited to batteries, battery circuit breaker,
rectifier/charger, DC/DC stabilizer (if requested), output distribution panelboards (if
requested) and management system.
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Q
Describe Uninterruptible Power Supply System.
Ans
Uninterruptible Power Supply (UPS) System shall consist of, but not limited to batteries,
battery circuit breaker, rectifier/charger, inverter, static transfer switch, manual bypass line,
bypass shielded isolation transformer, output distribution panelboards and management
system.
Q
Describe Photovoltaic Power System.
Ans
Solar Photovoltaic (PV) Power System shall consist of, but not limited to batteries,
photovoltaic panels, charge regulator and output distribution panelboards. If AC output is
required, inverter (DC/AC converter) shall be included.
Battery Selection, Sizing and Load Determination
*Batteries shall comply with 17-SAMSS-511.
Q
What are the guidelines for the battery selection?
What is the criteria for battery selection?
Ans
Battery selection shall be made according to the following guidelines.
a) Lead-calcium or lead low antimony pasted flat plate batteries are generally the most
suitable for standby float service applications in an indoor temperature controlled
environment. Such applications include electrical substations and UPS systems where
shallow moderate cycling is expected. Lead-calcium batteries are not capable of many
charge/discharge cycles, i.e., up to 5 cycle operations per year. Nonetheless, lead
calcium battery features low current during float charging, and requires equalize
charging only as needed. In comparison, lead low antimony batteries are capable of
many charge/discharge cycles, but require equalize charging yearly.
b) Tubular plate lead-antimony batteries or lead selenium batteries are suitable for cyclic
loads (frequent charge/discharge cycles) and for high current short discharge
applications. Due to material retention properties of the tubular construction, such
batteries can also be successfully used in locations where frequent battery discharges
are anticipated. Lead selenium batteries feature low water loss.
c) Nickel-cadmium batteries are suitable for the applications described in this standard
including outdoor non-temperature controlled applications such as remote unattended
substations and photovoltaics systems. The batteries are fairly immune to corrosion, are
resistant to mechanical and electrical abuse, operate well over a wide temperature
range, and can tolerate frequent shallow or deep discharges.
72
Q
d) The use of valve regulated lead acid (VRLA) batteries shall be limited to applications
where flooded batteries cannot be used and when installed in temperature-controlled
(25°C) environment.
What are the factors to be considered for selection of batteries?
Ans
The following factors shall be considered in selecting a battery for a particular application:
a) The design life of the battery shall be at least 20 years for flooded lead acid/nickel
cadmium batteries, and at least 10 years for VRLA batteries.
b) The design life of the battery shall be based on 25°C.
Q
Describe the battery sizing criteria?
Ans
1- For applications involving a combination of continuous loads, non-continuous loads
and/or momentary loads (such as switchgears), lead acid batteries shall be sized in
accordance with the battery sizing worksheets of IEEE 485, and nickel cadmium batteries
shall be sized in accordance with the battery sizing worksheets of IEEE 1115, or the
equivalent IEC standards as applicable.
2- For photovoltaic (PV) applications involving a combination of continuous loads, noncontinuous loads and/or momentary loads, lead acid and nickel cadmium batteries shall be
sized in accordance with IEEE or IEC applicable standards.
3- For applications of constant current consumption loads, the battery ampere-hour
capacity shall be calculated as follows:
DC Loads:
Battery Ah Capacity @ CBT = L x BT x TC x AF x DF (1)
UPS Loads:
Where:
Battery Ah Capacity @ CBT = Ah capacity of battery at required backup time
Battery Ah Capacity = Ah capacity of battery at C8/C10 and C5, for lead acid battery and nickel
cadmium battery, respectively (consult battery manufacturer for the conversion factor to
convert Ah @ CBT to Ah @ C8/C10 and C5, for lead acid battery and nickel cadmium battery,
respectively)
L = Continuous load current (dc amperes)
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BT = Battery back-up time (hours)
AF = Aging factor (use 1.25 for all batteries)
DF = Design factor (use DF = 1.1 for all types of batteries)
kVA Load = Load designed apparent power (= Actual Load Power Consumption + Future Growth)
PF = Load power factor
No. of Cells = Number of series connected battery cells
Eff.Inverter = Efficiency of UPS inverter
VoltageEndCell = Battery cell voltage at end of discharge
TC = Temperature compensation factor (cell size correction factor)
4- If the calculated battery capacity exceeds a manufacturer's standard rating by more than
5%, then the next larger standard battery capacity shall be selected.
5- Paralleling up to 4 sets of battery banks of identical Ah capacity and potential shall be
allowed, to achieve the required Ampere Hour capacity.
6- The minimum battery backup time shall be in accordance with Table, and shall be based
on the actual load calculation. For applications where the battery backup time exceeds
Table 1 requirements, Electrical Equipment Unit, Consulting Services Department shall be
consulted.
7- Redundant DC system, which consists of 2 rectifiers/chargers connected in parallel, shall
have separate battery banks such that each battery bank shall be sized for 50% of the
required total battery backup time as specified in Table.
Table – Battery
Backup Times Load
Location
In-Plant or In-Office
In-Plant or In-Office
Type of Load
Primary Power
Source
Battery Backup
Time(1)
AC (UPS)
AC (UPS)
60 minutes
30 minutes
In-Plant or In-Office
In-Plant or In-Office
DC
DC
Remote
Attended
Substation(3)
Attended
Substation(3)
Unattended
Substation(3)
Unattended
Offshore Substation
AC & DC
DC
DC
Utility Only
Utility +
Generator(2)
Utility Only
Utility +
Generator(2)
Solar Photovoltaic
Utility +
Generator(2)
Utility
DC
Utility
8 hours
DC
Utility
12 hours
2 hours
30 minutes
5 days (120 hours)
2 hours
4 hours
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8- Battery backup time (battery duration) for emergency or life-critical loads shall be as
specified in NFPA 70 and NFPA 101
9- Battery backup time for all security emergency systems shall be per the requirements of
SAES-O Standards.
10- No-load losses of redundant systems shall be included in the battery sizing calculations.
11- Switchgear DC system shall be dedicated for loads that are critical and require
continuous operation during utility power loss.
12- In-plant DC loads shall not be connected to the battery bank which is dedicated to the
UPS system.
13- Substation battery systems shall be dedicated to connected DC loads and shall not be
part of a plant UPS or other DC system.
14- The minimum number of series-connected battery cells shall be in accordance with
Table or as determined by the calculations. Nonetheless, battery manufacturer's
recommended number of cells based on the specified battery backup time shall be
followed, if available. Nevertheless, for UPS applications, the number of series connected
cells (DC voltage value) shall be selected by the UPS manufacturer.
Required Number of Cells
Nominal
Battery
Voltage
(VDC)
12
24
48
120/125
240/250
360
408
480
Number of cells DC
Systems
Lead Acid
Nickel
Cadmium
Number of Cells
Photovoltaic Systems
Lead Acid
Nickel
Cadmium
6
12
24
60/62
120/125
180
204
240
6
12
24
60
120
NA
NA
NA
9
18
36
91
182
273
309
364
10
19
38
95
191
NA
NA
NA
15- The maximum number of series connected cells shall be calculated as follows to ensure
an optimal and safe DC system voltage and battery recharge voltage:
Max. Number of Cells = Max. Allowed DC System Voltage / Equalizing Volts per Cell
75
16- Based on the number of cells calculated, the end-of-discharge voltage for each cell shall
be calculated as follows to ensure that the system voltage does not fall below the minimum
acceptable level:
Voltage Discharge -of – End = Voltage System DC Allowed Min. / Cells of Number
Unless otherwise recommended by the manufacturer, the minimum allowed DC system
voltage shall be 87.5% of the nominal system voltage for DC and UPS systems, and 92.5% for
Photovoltaic systems.
17- The cell end-of-discharge voltages shall be per Table below:
Battery Cell End of Discharge Voltage
Battery Type
Lead-Acid
Nickel-Cadmium
General
Applications
1.65 VPC to 1.75
VPC
1.0 VPC to 1.14
VPC
PV Applications*
1.85 VDC
1.14 VPC to 1.2
VPC
VPC = Volt Per Cell
Battery Installations
Q
What are the international standard codes for installation of batteries?
Ans
All batteries shall be installed in battery rooms or battery enclosures in accordance with
NFPA 70 (NEC), IEEE 484 or IEC 50272-2.
*Batteries shall not be installed in enclosures inside a battery room.
*The minimum battery room ventilation shall be one complete air change every 3 hours, and
the temperature inside this battery room is maintained, but never exceed, 25°C.
*Batteries shall not be installed in Class I, Division 1 locations.
*Batteries installed in Class I, Division 2, locations shall be in a building or enclosure made
safe by pressurized air. Loss of pressurization shall be monitored in accordance with NFPA
496.
*Working space of at least 1 meter shall be provided in front of each battery rack or
enclosure.
*Batteries shall be supplied with covers for all inter-cell connecters and terminals or
insulated copper busbars to enhance safety.
Q
Battery room walls and floor shall be made of what type of material?
76
Ans
Battery room walls and floor shall be made of concrete construction and finishing.
*Battery room finishing shall not contain drywall (such as plasterboard, wallboard, gypsum
board, sheetrock, or gyprock).
*Manned workstations shall not be located in battery rooms.
*Battery rooms shall be provided with enclosed and gasketed (i.e., vapor tight) corrosion
resistant lighting fixtures
*Battery room lighting shall be installed to provide a minimum level of illumination of 30-ft
candles (300 lux).
*Emergency lighting with illumination level of 10-ft candles (100 lux) shall be installed to
operate in the event of loss of mains power supply.
Q
How shall be installed the battery room doors?
Ans
Battery room doors shall open outward, away from the room, to the outside of the building,
and be fitted with door closers and anti-panic (quick-release, quick-opening) hardware. No
hasp, padlock, or other device shall be installed which will hinder operation of the
emergency door opening devices.
*Doors between battery rooms and other rooms shall not be permitted.
*Potable water facilities shall be provided for rinsing spilled electrolyte in the battery room.
Raw water shall not be used (as it is rich of minerals and dissolved solids that may react with
the electrolyte). The amount of water supply shall be determined based on a risk
assessment of the extreme scenario where the largest battery or electrolyte container gets
spilled.
*Provisions for neutralizing the battery electrolyte (acid or alkali) and caustic spillage shall
be included in the battery room design.
*Floor drains shall comply with SAES-S-060.
*Sealed valve-regulated batteries do not require floor drains.
*Emergency eyewash facilities shall be provided as required by SAES-B-069.
*Sealed valve-regulated batteries do not require eyewash facilities.
Q
With what type of cover the battery room floor shall be covered?
Ans
Battery room floor shall be covered with an electrolyte (acid or alkali) resistant, durable,
antistatic and slip-resistant surface overall, to a height 100 mm on each wall.
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Where batteries are mounted against a wall, the wall behind and at each end of the battery
bank shall be coated to a distance of 500 mm around the battery with an electrolyte
resistant paint or tiles.
*A dry type chemical fire extinguisher shall be installed on the outside of the battery room.
*Cabinets or racks shall be provided in the battery room for storing maintenance tools and
safety equipment. These cabinets and racks shall be acid or alkaline resistant as applicable.
*Lead acid batteries shall not be mounted in the same room together with nickel cadmium
batteries, and vice versa.
*Battery rooms shall be vented to the outside air by forced ventilation to prevent
accumulation of hydrogen and to maintain design temperature. The ventilation system is
designed such that the hydrogen concentration shall not exceed 1% of the total air volume
of the battery room.
*The maximum hydrogen evolution rate for all kinds of flooded batteries is 0.000457 m³/hour
(0.016 ft³/hour), per charging ampere, per cell, at 25°C, at standard pressure. The worst
condition (the maximum hydrogen evolution) occurs when current is forced into a fully charged
battery (overcharge).
*An interlock between the air-handling unit and the high-rate charging switch shall be
provided, such that failure of the air-handling unit shall cause the high-rate charging of
batteries to stop.
*The ventilation system shall be 100% redundant. Only direct driven exhaust fans shall be
used. An interlock with the ventilation system shall be provided to stop the high-rate
battery charging if the exhaust fan stops.
*An alternative to interlocking with either air-handling unit or exhaust fans is to interlock
the high-rate battery charging system with either an air-flow or air-pressure measuring
device, such that ventilation insufficient to the 1% hydrogen limit will cause the high-rate
charge to stop.
*Audible and visual alarm shall be installed outside the battery room entrance to
annunciate a failure in ventilation for prompt repair.
*The minimum ventilation shall be one complete air change every 3 hours.
*A battery area that meets the above ventilation requirements and the high-rate charge
interlock shall be considered non-hazardous. Therefore special electrical equipment
enclosures to prevent fire or explosions shall not be required.
78
*Equipment with arcing contacts shall be located in such a manner as to avoid those areas
where hydrogen pockets could form. Electrical equipment shall not be located directly
above the batteries and, as a rule, shall have a minimum horizontal separation of 1.5 meters
from the nearest cell.
*Temperature in a room that contains batteries shall not exceed 25°C.
*If battery operating temperature increases by 10°C above the 25°C reference, battery design
life is reduced by: 50% for lead acid batteries, and 20% for nickel cadmium batteries.
*Return air-conditioning ducts from battery rooms shall be prohibited.
*Lighting fixtures shall be installed at least 300 mm below the finished ceiling.
*Inlets of air-conditioning shall be no higher than the top of the battery cell and the outlets
(exhaust) at the highest level in the room. Air inlets and outlets shall be located in such a
manner to provide effective cross ventilation over the batteries.
*Batteries installed in a sealed passively cooled shelter shall be located in a separate
compartment with a dedicated entrance. All battery cell vents shall be tubed so that
hydrogen gas is vented outside the battery compartment.
*Battery racks shall be constructed in accordance with 17-SAMSS-511.
*Battery racks installations shall meet NEC bonding and grounding requirements. Battery
racks shall be bonded at both end points to a local supplementary grounding electrode per
NEC 250 or EN 50178. Install lug and cable on the steel rack and tighten to ensure
ohmmeter reading between each component and a common point on rack frame indicated
continuity for proper grounding.
*Stationary batteries shall be installed on open battery racks within a battery room to
facilitate proper cooling, routine inspection, and maintenance.
*Either covers for all inter-cell connecters and battery terminals or insulated copper busbars
shall be supplied as part of the battery.
Q
How much clearance shall be for battery cell to the rack?
Ans
Clearance from the top of the battery cell highest point to the bottom of the rack above it
shall be 350 mm, and airspace between battery cells shall be approx. 10 mm.
Q
What are the requirements for battery enclosures?
Ans
Battery enclosures shall be in accordance with the following requirements:
79
a) The enclosure design shall include a removable lid, secured by quick- release latches,
type 316L stainless steel or equivalent. Hinged enclosures shall be designed to open at
least 120 degrees to facilitate proper maintenance access.
b) The enclosure base shall be provided with cell supports designed to raise the cells a
minimum of 5 cm above the enclosure floor.
c) For indoor use, the battery enclosures and cell supports shall be made of fiberglass
reinforced material or steel, with provisions for anchoring to the floor and grounding.
The ventilation requirements of paragraph 6.3 shall be complied with.
d) Valve regulated (sealed) lead acid (VRLA) batteries shall be mounted in ventilated
indoors enclosures unless installed inside a dedicated battery room, where battery racks
are sufficient. VRLA batteries shall not be used for outdoors applications.
e) Battery enclosures for outdoor use shall be made of fiberglass-reinforced material, and
shall be completely weatherproof, dust-tight, and rain-tight. The gasket shall be onepiece, heavy-duty black neoprene or Buna nitrile rubber, mechanically attached to the
enclosure lip and in continuous contact with the enclosure lid. Minimum protection
Class for outdoors mounting shall be NEMA 250 Type 4 (or IEC 60529 IP 65). For offshore
outdoors applications, corrosion resistance enclosure NEMA 250 Type 4X (or IEC 60529
IP 65 with corrosion protection) shall be required.
f) The fiberglass material shall meet the flammability rating of UL 94 type V-0.
g) Steel enclosures and grounding lugs shall be coated with an acid-resistant or alkaliresistant (as applicable), chip and scratch resistant, baked powder epoxy or propylene.
h) All hardware shall be 316L stainless steel or equivalent.
i) The enclosure shall have an adequate number of drain openings at the bottom and a
minimum of two ventilation openings at the top. The ventilation openings shall be fitted
with breather-type plugs to release hydrogen gas without allowing sand/dust to enter
the enclosure.
j) Clearance above each battery cell shall be 350 mm, to allow proper air circulation and to
permit filling, testing, and replacement of cells. Adequate clearance shall also be
maintained in between cells. Air space between battery cells, as well as between the
cells and external enclosure walls shall be approx. 10 mm.
k) Enclosures with front access only shall have no more than 2 rows of stepped cells.
Enclosures with access from the front and back sides may have a maximum of 4 rows of
stepped cells. In the stepped cell arrangement, for vented battery application, cells shall
be positioned in such a way that the electrolyte levels markings (both minimum and
maximum) can be easily seen.
Q
What are the cable requirements for battery cables?
Ans
Battery cables shall be sized for a total voltage drop of less than 3%. Positive and negative
battery cables shall be run in the same conduit to prevent inductive heating.
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*The positive and negative buses of batteries shall be isolated from earth ground.
*Each battery-based system shall be equipped with properly sized two-pole fused
disconnect switch or circuit breaker with an undervoltage release feature to prevent battery
discharge beyond the battery's end-of-discharge voltage. The undervoltage device shall
disconnect the battery from the load when the battery voltage drops to the end-ofdischarge voltage.
*An alarm to indicate the battery circuit breaker open condition (or fused disconnect switch
open or blown fuse condition) shall be provided on the charger cabinet or the UPS cabinet.
This alarm shall also be annunciated to the main control room DCS or to an area where
operators are present.
*The battery circuit breaker open condition (or fused disconnect switch open or blown fuse
condition) shall be routed via Standalone or the Supervisory Control and Data Acquisition
(SCADA) system or Network Management System (NMS), to the power control center.
*Another alarm to indicate the battery room high temperature shall be annunciated to
the main control room.
Q
What is wiring color coding for batteries wiring for grounded and ungrounded systems?
Ans
Ungrounded Systems for Industrial Facilities
Positive: Red
Negative: Black
Battery rack and other equipment grounding conductors: Green
Grounded Systems for Special Applications
a) Negative Grounded Systems
Positive: Red (ungrounded)
Negative: White (grounded)
b) Positive Grounded Systems
Positive: Black (grounded)
Negative: Red (ungrounded)
*Battery rack and other equipment grounding conductors: Green, or green with yellow
stripes
Q
What are the safety equipments shall be provided near stationary batteries?
Ans
The following safety equipment shall be provided near stationary batteries:
a. Safety face shields and goggles
b. Safety aprons
c. Acid resistant rubber gloves
81
d. Safety shoes
e. Eye washing facilities (refer to SAES-B-069)
f. Neutralizing agent:
- To neutralize lead acid battery:
Mix 0.1 kg bicarbonate of soda to one liter of water.
- To neutralize nickel cadmium battery spillage:
Mix 50 grams boric acid solution to one liter of water.
- Or use other suitable neutralizing agent recommended by the manufacturer for acid
electrolyte spillage or the manufacturer of alkaline electrolyte spillage, whichever
applicable.
Q
What are the safety signs shall be posted on battery room?
Ans
The following safety signs shall be permanently posted on battery room entrance at a visible
location in Arabic and English languages:
a. Sign: “DANGER CAUSTIC/ACID”
b. Sign: “DANGER CAUSTIC/ALKALINE”
c. Sign: “DANGER NO SMOKING”
d. Sign: “EYE PROTECTION REQUIRED IN THIS AREA”
Q
How the batteries shall be disposed?
Ans
All batteries are considered hazardous wastes and shall be disposed per Saudi Aramco
Supply Chain Management Manual CU 22.03 Processing and Handling of Hazardous
Material. This manual reference to: Saudi Aramco Form 112-H shall be used to dispose
(return to Reclamation) or to ship hazardous materials / chemicals.
Rectifiers/Chargers
*Rectifiers/chargers for utility type applications shall comply with 17-SAMSS-514.
*Parallel redundant rectifiers/chargers with dynamic load sharing capability shall be
provided for all double-ended substations.
*Each rectifier/charger shall be fed from a different source.
*A single rectifier/charger shall be provided for single-ended substations unless an
alternative power supply is available, in which case dual rectifiers/chargers shall be
required.
*For critical systems, two parallel battery chargers should be provided, so that maintenance can
be performed without loss of load supply.
*Critical DC load(s) that are sensitive to high DC supply voltage, that can reach up to +18%
of nominal, shall be supplied through DC/DC stabilizer. During loss of mains supply and fault
clearances, the DC/DC stabilizer shall be automatically isolated (bypassed) and load(s)
82
supply shall be directly from the batteries of the DC system. The DC/DC stabilizer shall
secure supply voltage to sensitive critical load(s) within ±1% of nominal under all operating
conditions. Voltage supply to sensitive load(s) through DC/DC stabilizer shall be performed
during normal operating conditions only.
Q
What type of enclosure is used for outdoors mounting rectifier/charger?
Ans
Rectifier/charger enclosure for outdoors mounting shall be completely weather-proof, dusttight and rain-tight. Enclosure minimum protection class shall be NEMA 250 Type 4 (or IEC
60529 IP 65).
Q
What type of enclosure of rectifier/charger is used for marine applications?
Ans
For marine applications, rectifier/charger enclosure shall have corrosion protection as
follows:
a) Outdoors Mounting: NEMA 250 Type 4X (or IEC 60529 IP 65 with corrosion protection).
b) Indoors Mounting: NEMA 250 Type 12 (or IEC 60529 IP 54) with corrosion protection.
*Rectifier/charger enclosure doors shall be hinged and designed to open at least 120
degrees to facilitate maintenance access.
*The Rectifier/Charger shall be monitored remotely and be equipped with, but not limited
to the following:
1) Rectifier/Charger management software and hardware.
2)
Web-based monitoring facility
a) Card for network connection
b) Software for network management
c) Web/SNMP manager
3) RS 232/RS 485 ports.
4) Battery management technology.
5) Environment sensor for SNMP/Web application (to monitor temperature and humidity).
Uninterruptible Power Supply (UPS) Systems
*UPS rating larger than 10kVA shall comply with 17-SAMSS-516.
*Industrial UPS rating less or equal to 10 kVA shall comply with UL 1778 or IEC 62040
UPS Specifications (Less or Equal to 10 kVA)
UPS Technology
Double Conversion True On-Line
83
Inverter Topology
AC Input
Input Voltage
Pulse Width Modulation
230 VAC 1-Phase, or 400 VAC
3-Phase, 50/60 Hz Or as per
project specified requirements
Voltage Tolerance
Frequency Tolerance
Inverter Output
±15%
± 5%
Output Voltage
Voltage Regulation
230 VAC 1-Phase, or 400 VAC
3-Phase, Or as per specified
requirements
50% unbalanced load
100% unbalanced load
Operating Frequency
Frequency Regulations
When Synchronizing
When Free Running
Maximum Total Harmonic Distortion at 100%
nonlinear loads
Steady State Condition: ±1%
±2% (for 3-Phase UPS only)
±5% (for 3-Phase UPS only)
50/60Hz
±1%
±0.1%
5% THDV
UPS Specifications (Less or Equal to 10 kVA)
Load Crest Factor
Load Power Factor
Overload Capacity (Inverter)
Equipped with
Built-in
Battery Backup
Time
Type
Recharge Time
Warranty
0.8 Lagging to 0.8 Leading
150% for 1 minute
125% for 10 minutes
Maximum Voltage Transient
5% for 0 to 100% step load with recovery
to ±2% of nominal within 1 mains cycle
a. Bypass static transfer switch – rated for continuous operation at full load
b. Manual transfer switch – for maintenance purpose
c. Battery circuit breaker that has low DC voltage disconnect
d. UPS management software
e. Battery management technology
f. Web-based monitoring facility
- Card for network connection
- Software for network management
- Web / SNMP manager
g. Environment sensor for SNMP / Web application
- Monitoring of temperature and humidity
h. RS232 port
i. 6 outlets, fused (UPS up to 6 kVA UPS only)
j. Input cable and plug
k. UPS control LCD display to
- Display UPS measurements and alarms
- Control UPS functionality
l. UPS manuals in English language (both hardcopy and softcopy)
- User Manual
- Maintenance, Troubleshooting and Repair Manual
- Complete circuit diagram(s)
Minimum 30 minutes at full load, or as per requirement/specifications.
Valve Regulated Lead Acid; Long lifetime type (design life >= 10 years)
Within 10 x battery backup time to 95%of battery Ah capacity
At least two (3) years from UPS successful commissioning
84
*UPS enclosure doors shall be hinged and designed to open at least 120 degrees to facilitate
maintenance access.
Q
What are the input requirements for UPS?
Ans
1) UPS rating larger than 50 kVA: Normal and alternate source voltages shall be 3 phase, 3
wire + ground.
2) The normal input to the UPS rectifiers/chargers and the feed to the bypass shielded
isolation transformer (alternate source) shall be from different sources. The separate
sources could be separate buses of a double-ended system. If separate sources are not
available, then the UPS shall be supplied from separate breakers of the same source.
3) UPS rectifier/charger shall contain a programmable walk-in ramp circuit, for which input
current shall gradually increase from 0 to UPS rated power in approx. 10 seconds after the
rectifier/charger input circuit breaker is closed.
Q
What are the output requirements for USP?
Ans
1) UPS Systems Rating <= 50 kVA: 1 phase, 2 wire; or 3 phase, 4 wire, plus ground.
2) UPS Systems Rating > 50 kVA: 3 phase, 4 wire, plus ground.
*The power (kVA) rating of the UPS system shall be equal to or greater than the steadystate kVA of all the downstream loads plus a future load growth factor.
*The load power factor (PF) of 0.9 lagging shall be considered in sizing the batteries for the
UPS system. The UPS inverter shall be sized to deliver full rated power at PF = 0.8 and PF =
0.9 lagging without derating, for Plant UPS and IT UPS, respectively.
*Every UPS system shall have the following fully rated and designed for continuous
operation: static bypass switch and maintenance (manual) bypass switch.
*Steady-State Load Conditions: Determine the average power requirement of all
downstream loads based on their operating duty cycle.
*Transient Conditions: Determine the transient current peaks (inrush currents) and the time
duration of such peaks which may occur during the start-up of all load devices. Analyze the
UPS to determine if it can withstand the inrush current requirements of the loads based on
the following overload capabilities 150% for 1 minute.
*A workspace of 1 m shall be provided in front of the UPS cabinets. If rear access or side
access is required for UPS maintenance, a clearance of 1 m shall be allowed.
85
*UPS system shall be located in a temperature-controlled room in which the temperature is
maintained at 25°C. Redundant AC systems are preferred for continuous and reliable
operation.
*Cables for the primary AC input, output, and the alternate AC source shall be run in
separate raceways.
Q
Ans
AC input power to industrial UPS systems shall comply with the following:
a) The initial magnetization current shall be limited to 600% of the rectifier/charger
rated input current for a duration of one main cycle.
b) The circuit breakers for both the primary and alternate AC sources shall be equipped
with overcurrent protection, sized and coordinated with upstream and downstream
protections
c) When a generator and automatic transfer switch arrangement is used to extend the
protection time of a UPS system, it shall be connected to deliver power to the UPS
rectifier, but not directly to the critical load.
d) The UPS static switch shall be arranged to transfer the entire UPS load to the
alternate AC source (bypass line) in the event of a malfunction of the inverter or to
clear a load fault. After fault clearance, the load shall be transferred automatically
from the mains supply to the UPS output supply.
e) The kVA rating of a backup generator used for supplying emergency backup power
to the UPS system shall be at least 2.25 times the rated kVA of the UPS.
f) The UPS system shall automatically block (inhibit) battery charging during supply of
power through the emergency generator.
*UPS loads shall be distributed through panelboards. Protection for the outgoing circuits
shall be accomplished through circuit breakers rated for continuous operation with
capability to quickly open and clear short-circuit and/or overload conditions.
*Ratings of distribution panel's main feeder and branch circuits shall be coordinated
with UPS and bypass ratings. The maximum current rating of the largest branch circuit
breaker in the distribution panel shall be no greater than one-half the rated current
output of the inverter. In the case of fuses, the largest load-side fuse shall be no greater
than one-fourth the rated current output of the inverter. This is to ensure proper
selectivity between the tripping of the load circuit protective devices and the inverter's
internal protective devices. These requirements shall not apply when the UPS is
equipped with a static bypass switch for transferring to the bypass (alternate) line. In
that case, the protective devices for the outgoing loads shall be selected to achieve
selective coordination with the primary breaker on the line side of the bypass
transformer.
86
*Branch circuit breakers shall be coordinated with the load crest factor (in-rush current)
as applicable.
*A bolted fault test (three phases connected to ground) shall be conducted on the UPS
distribution system to establish that proper fuse coordination has been achieved.
Conduct the test by placing a bolted fault, by means of a contactor, on a typical branch
circuit of the UPS distribution system. The branch circuit fuse shall clear the fault
without affecting any upstream fuses and circuit breakers.
Photovoltaic (Solar) Systems
*Solar photovoltaic systems shall be installed in accordance with NFPA 70/NEC, Article 690
*Enclosures housing electronic equipment and batteries shall be shaded from direct
sunlight regardless of the sun inclination angle.
Q
What type of enclosure is used for housing electronic equipment and batteries for solar
system?
Ans
Minimum enclosure protection class for all outdoors mounting applications shall be NEMA
250 Type 4X (or IEC 60529 IP 65 with corrosion protection).
*Each solar photovoltaic module shall be equipped with a Shottky blocking diode to prevent
reverse flow of power into the photovoltaic module.
Q
How much should be the tilt/inclination angle of the solar photovoltaic array?
Ans
Solar photovoltaic array shall be installed at a tilt (inclination) angle equal to the latitude of
the location plus 10-15 degrees.
*Solar photovoltaic array shall be directed toward the geographical south (±5 degrees).
*Battery shall be selected for minimum topping-up interval of 1 year, at 25°C operating
temperature and float charging.
Q
Battery selected for photovoltaic application should be of how many cycles?
Ans
Battery shall be selected for photovoltaic application with a cycling life of at least 8000
cycles to a shallow cycle of 20% depth of discharge (DOD), and 1000 cycles to 80% DOD.
*The charge regulator shall be designed to provide two-step (stage) charging for the
batteries (float charging and equalize charging) and to provide the power requirements of
the load when the photovoltaic solar array is producing power.
87
*On-off type regulators, which simply disconnect the solar array from the entire system
when the battery reaches a certain terminal voltage, are not acceptable.
*The charge regulators shall be of the solid-state design.
*The charge regulator shall be designed to operate continuously at full rate in ambient
temperatures between 0 and 55°C.
*The charge regulator shall be equipped with a Shottky blocking diode to prevent reverse
flow of power into a faulty regulator.
*The charge regulator shall be equipped with temperature compensation feature to adjust
the charging voltage with temperature.
*The charge regulator shall be equipped with a low-voltage battery disconnect which shall
act to disconnect the load from the battery when the battery reaches the end-of-discharge
voltage (1.85 Volts per cell for lead-acid batteries and1.14 Volts per cell for nickel-cadmium
batteries) to prevent severe battery discharge. Battery manufacturer's recommended cell
end of discharge voltage shall be followed.
*The charge regulator shall include the following instrumentation and alarms:
a.
b.
c.
d.
e.
f.
Battery voltage
Battery current (charging or discharging)
Solar array current (for each array)
Load current;
Local indication of high and low battery voltage plus normally open and normally closed
voltage free contacts for activating remote alarms
All alarms shall be indicated on the charge regulator cabinet and a set of normally open
and normally closed voltage free contacts shall be provided for annunciating the alarms
to a central control room via Remote Terminal Units (RTUs) or similar facilities, where
such facilities are available.
* Surge protection shall be provided for the DC load bus.
*All controls and instrumentation shall be housed in a NEMA 250 Type 4X (or IEC 60529 IP
65 with corrosion protection) enclosure.
Q
What are the sizing parameters for solar photovoltaic power system?
Ans
Solar photovoltaic power system shall be sized as follows:
1) Maximum autonomy (backup) time shall be 5 days or as per application requirement.
2) Charge regulator shall be rated for the maximum array current plus 10% design margin.
88
Solar photovoltaic array shall be sized with the following factors:
1) The solar array shall be sized to fully recharge the battery to 95% state of charge in 30
days.
2) The array shall be sized based on 5 effective sun hours for all installations in Saudi
Arabia.
3) The array size shall be derated 10% for dust accumulation.
4) The array size shall be derated 10% for aging over the array expected useful life.
5) The array sizing shall include additional 10% capacity for future growth.
Battery Tests and Records
The initial battery capacity test and commissioning records are pertinent to the
maintenance and optimum operational life of the battery. All commissioning data shall be
dated, recorded, and maintained in a permanent file to facilitate required future
maintenance and interpretation of the operating data.
* The following data shall be maintained in a permanent record file:
a) Initial battery capacity test performed in accordance with IEEE 450 (for lead acid), IEEE
1106 (for nickel cadmium), or IEEE 1188 (for VRLA) or the IEC equivalent standard, as
applicable.
b) The initial resistance values of the intercell connections.
c) The initial individual cell voltages and specific gravity measurements.
* Routine battery maintenance and testing shall be in accordance to SAEP-350.
Overhead Distribution Systems
(SAES-P-107)
Q
What are the environmental conditions on which overhead line design is based?
Ans
Overhead line design shall be based on the following environmental conditions:
a) Minimum temperature: 0°C
b) Maximum temperature: 50°C
c) Wind speed (50 yr.): 160 km/h
Q
What is the length of distribution line span?
Ans
Distribution line spans should normally not exceed 90 m in length
Q
What type of lugs are used for overhead line connections
89
Ans
Compression type lugs shall be used for overhead line connections to equipment furnished with
pad type terminals.
Compression lugs or splices used for connections of insulated or covered cables to overhead
lines shall have a closed barrel or solid center stop to prevent ingress of water into the insulated
cable.
Non-current carrying metallic enclosures, brackets, and braces shall be bonded together via
grounding lugs and shall be connected to a grounding electrode conductor. Pole ground
conductors shall be minimum 4 AWG, stranded, soft drawn, bare copper.
Q
What should be the vertical clearance above grade for desert installation of conductors?
Ans
Vertical clearances above grade for desert installations of conductors, including service drops,
messengers, and guys shall be minimum 8.5 m at final unloaded sag, no wind, and 50°C ambient
temperature.
Q
What type of Arial-to-ground transitions should be?
Ans
Aerial-to-underground transitions shall be in rigid galvanized steel conduit or PVC coated
galvanized rigid steel conduit
Q
What type of material supporting structures for overhead lines shall be?
Ans
Supporting structures for overhead lines shall hot dipped galvanized steel or seamless aluminum
alloy poles in plants and other industrial facilities and fiberglass poles or wood poles.
Q
What type of wood poles for supporting structures shall be?
Ans
Wood poles used for supporting structures shall be Class 4 or better as defined in ANSI O5.1.
Q
Where wood poles shall be used?
Ans Wood poles shall be permitted for use in stand-alone Water Injection Plants, Water Treatment
Plants, and for supply lines located outside of industrial and plant areas (for example, Cathodic
Protection supply lines in desert areas).
Q
On which bases the locations of supporting structures, guy, messenger and anchor shall be
selected?
Ans
Supporting structure, guy, messenger, and anchor locations shall be selected based on
accessibility, limited use of guys, minimal obstructions to pedestrian and vehicular traffic, and
shall be as inconspicuous as possible.
Q
Supporting structures located less than 9m from a roadway shall be protected by what?
90
Ans
Where required supporting structures located less than 9 m from a roadway shall be protected
by barriers meeting the requirements of the Highway Design Manual, Volume 2, and Part 1.
Q
What is the clearance between supporting structures and curbs?
Ans
Supporting structure clearance from curbs shall be maintained at a minimum of 0.6 m from face
of curb.
Q
What is the height of dating nail above grade for wood supporting structures?
Ans
Wood supporting structures shall have a dating nail indicating the year of installation located at
approximately 2 m above grade.
Q
Where we use armless type construction?
Ans
Armless type construction shall be used for the conductor support system.
Q
What is the value limit for horizontal loading for line post insulators?
Ans
Horizontal loading for line post insulators shall not exceed 2.2 KN for initial sag at the minimum
temperature, and wind loading of 430 pa.
*Line conductors up to 336.4 kcmil ACSR shall be dead-ended for line angles larger than 30°.
*Line conductors 336.4 kcmil and larger shall be dead-ended for line angles larger than 5°.
*Lines more than 2 km long shall be double dead-ended a minimum of every 1.5 km.
Q
What should be the angle between the down=guy and the supporting structure?
Ans
The angle between a down-guy and the supporting structure shall not exceed 60°.
Q
What is the load limit of supporting structure for sidewalk guys?
Ans
The use of sidewalk guys shall be limited to supporting structure loads of less than 6.6 kN.
Q
What type of structure for sidewalk guy horizontal member shall consist of?
Ans
Sidewalk guy horizontal member shall consist of a 2 in galvanized pipe at a minimum height of
2.4 m above grade.
Q
What type of sidewalk guys shall be?
Ans
Sidewalk guys shall have reflective finished guy guards with the open side of the guard facing
away from the sidewalk.
Guys from supporting structures having ungrounded or resistance grounded circuits shall be
insulated with strain insulators.
Q
What is the height of insulators from above grade shall be?
91
Ans
Insulators shall be located a minimum of 2.4 m above grade and below the lowest power
conductor.
Q
What type of guy insulators shall be used?
Ans Guy insulators shall not be used with guy strands having ultimate strengths greater than 80 kN. Guy
insulators shall have a rated ultimate strength greater than the rated breaking strength of the
guy.
Q
What type of messengers shall be used?
Ans
Messengers shall be of the stranded steel type. Messengers shall be sized for the ultimate
number of cables to be installed.
Q
What is the minimum insulator creepage shall be?
Ans Minimum insulator creepage for components shall be 40 mm per kV line-to-line nominal system
voltage.
Q
What types of insulators shall be used?
Ans
Post and suspension type insulators shall be used.
*Pin type insulators shall not be used. Insulator brackets shall be metallic. Semiconducting or
resistive glaze insulators shall not be used.
Q
What requirements shall meet the insulators used on overhead distribution systems?
Ans
Insulators used on overhead distribution systems shall meet the requirements of the ANSI C29
series of standards.
(1)
(2)
(3)
(4)
(5)
(6)
Insulators shall be tested in accordance with C29.1
Suspension type insulators shall be in accordance with ANSI C29.2
Strain type insulators shall be in accordance with ANSI C29.4
Line-post type insulators shall be in accordance with ANSI/NEMA C29.7
Station-post type insulators shall be in accordance with ANSI C29.9
Preferred insulator color is chocolate brown.
Q
What is the load limit for insulators for overhead distribution systems?
Ans
Insulators shall not be loaded in excess of 40% of their rated ultimate strength.
Q
Where we use the Fog type porcelain suspension insulators?
Ans
Fog type porcelain suspension insulators shall be used to terminate overhead circuits at a
substation bay or supporting strain bus. For these applications, an insulating string shall consist
of a minimum of 2 units at 13.8 kV and 4 units at 34.5 kV.
92
Q
What type of conductors shall be used for overhead distribution systems?
Ans
Conductors shall be ACSR/AW (aluminum clad steel reinforced)/AW per ASTM B549
*Phase rotation shall be x y z (a b c) counterclockwise.
Q
What are the normal service conditions?
Ans
Normal service conditions are defined as follows:
80°C conductor temperature
50°C ambient temperature
0.6 m/sec wind velocity
Q
What are the emergency service conditions?
Ans
Emergency service conditions are defined as follows:
120°C conductor temperature
50°C ambient temperature
0.6 m/sec wind velocity
Q
What should be the conductor tension?
Ans
Conductor tension shall not exceed 10% of the conductor ultimate strength.
Q
Sag and tension calculations shall be based on what?
Ans
Sag and tension calculations shall be based on maximum and minimum ambient temperatures.
Q
How transformer primary connections shall be made?
Ans
Transformer primary connections shall be made with hot line clamps connected to a bail
(stirrup) compressed on the line conductor.
Q
What is the minimum height between any parts of a pole mounted transformer or its mounting
bracket or plate form and grade?
Ans
Minimum height between any part of a pole mounted transformer or its mounting bracket or
platform and grade shall be 4.9 m.
Q
What should be the minimum stress safety factor shall have supporting structures for
accessories?
Ans
Supporting structures for accessories shall have a minimum stress safety factor of 4.0
93
Q
What should be the minimum separation between underground conductors?
Ans
Minimum separation between ungrounded conductors shall be
System
Voltage (kV)
4.16
13.8
34.5
Clearance mm
230
410
710
Q
What the of load break switches should be?
Ans
Load break switches shall be provided at sectionalizing points.
Q
where the surge arresters shall be installed?
Ans
Surge arresters shall be installed at distribution transformer installations, capacitor bank
installations, recloser installations, metering installations, and aerial-to-underground cable
termination points
Q
what type of surge arresters shall be and what are the ratings of hem?
Ans
Surge arresters shall be of the distribution class, metal-oxide, gapless type and shall have the
ratings as follows:
System Voltage (kV)
4.16
13.8
34.5
Arrester Rating (kV)
6.0
12
27
Q
What type of grounding electrode for surge arrester used and of what dimensions?
Ans
The grounding electrode for surge arresters shall be minimum 16 mm (5/8 in) diameter by 3 m
(10 ft) local copper or copper clad ground rod(s) driven along the center line of the circuit.
The ground rod(s) shall also be bonded to the plant or substation ground grid if located within 15
m of the rod.
Q
what should be the ground resistance of surge arrester?
Ans
The resistance to ground of the surge arrester ground shall not exceed 25 ohms.
Q
what is the minimum arrester-to-arrester clearance shall be?
Ans
Minimum arrester-to-arrester clearance shall be
94
System Voltage (kV)
4.16
13.8
34.5
Clearance mm
230
410
710
Q
from where fused cutouts shall be fed?
Ans
Fused cutouts shall be provided for transformers fed directly from overhead distribution lines.
*Load break switches and fused cutouts shall be provided for capacitor installations on
overhead distribution lines.
Motors and Generators
(SEAS-P-113)
Power System and Equipment Protection
(SAES-P-114)
Q
SAES-P-114 is used for what?
Ans
SAES-P-114 is used for power system and equipment protection
Q
which standard is used for power system and equipment protection?
Ans
SAES-P-114
Q
What is the scope of SAES-P-114?
Ans
This Standard prescribes minimum mandatory requirements for the design and installation
of protective relaying for power systems and equipment.
Switchgear and control equipment
(SAES-P-116)
General Questions
95
Q
Define switchgear/control gear/control panel?
Ans
In an electrical system, a switchgear/control gear/control panel is the combination of electrical
disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical
equipment
Q
What is a control system?
Ans
A control system is a device or set of devices, that manages, commands, directs or regulates the
behavior/working of other device(s) or system(s).
Q
what is a transfer switch?
Ans
A transfer switch is an electrical switch that switches a load between two sources.
Q
What is bus bar?
Ans
In electrical power distribution, a busbar is a strip or bar of copper, brass or aluminium that
conducts electricity within a switchboard, distribution board, substation, battery bank, or other
electrical apparatus.
Q
What is an automatic transfer switch (ATS)?
Ans
An automatic transfer switch is used to switch a load automatically between two sources.
Q
What is the difference between the ATS (Automatic Transfer Switch) and AMF (Auto Man
Failure Panel)?
Ans
ATS (automatic transfer system panel) will transfer load from main power to emergency load
when the power source drop below 80% or normal voltage while AMF (automatic main failure
panel) this will substitute as main electricity source and reserve the generator if the main supply
fail or down.
Q
What is PFI panel?
Ans
Power factor improvement panel. It controls power factor.
Q
What is MCC (Motor Control Center) panel?
Ans
MCC (Motor control center) panel is used for distributing power to electric motors. MCC is
consists of an enclosure which contains the combination control units, wire ways, internal wiring
and bus bars.
Q
What is electrical enclosure/junction box/terminal enclosure?
Ans
An electrical enclosure/junction box/terminal enclosure is a cabinet for electrical or electronic
equipment to mount/install switches, terminal blocks, knobs and displays and to prevent
electrical shock to equipment users and protect the contents from the environment.
96
Q
What is the junction box?
Ans
A box containing the connections and junctions and terminal blocks of wiring cables.
Q
what is PCC panel?
Ans
There is no difference between PCC (power control center) and PDB (power distribution board).
They have same functions i.e. controlling power feeders.
Q
What is distribution board?
Ans
A distribution board (panelboard or breaker panel) is a component of an electricity supply
system which divides an electrical power feed into subsidiary circuits, while providing protective
fuse or circuit breaker for each circuit, in a common enclosure.
Q
What is switch board?
Ans
An electric switchboard is a device that directs electricity/electric power from one or more
sources of supply to several smaller devices of usage.
Q
Define DOL circuit?
Ans
DOL (direct on line starter) is a circuit used for the starting of the induction motors because the
induction motors draw more starting current during starting. DOL consists a circuit breaker,
contactor, and an overload relay for protection.
Q
Define working load?
Ans
The maximum load that a machine or other device is designed to bear.
Q
What is the testing and commissioning of control panel?
Ans
we do the:
a)
b)
c)
d)
e)
f)
g)
all wire connections are cleaned and checked for tightness
megger test and continuity test (phase to phase and phase to ground) of control wiring
proper clearance between the connections
check insulation, insulating tapes and insulated epoxy for damage
check the safety and electrical interlocks for correct operation
inspect grounding
to check if all the components/circuit elements are working by energizing the circuit
Q
How we do circuit breaker test? Pre-commissioning?
Ans
The tests/pre-commissioning includes:
a) trip test/current injection test
b) Contact resistance test
97
c) megger test/ continuity test (from phase to phase and phase to ground)
Q
How we do contactor test? Pre-commissioning?
Ans
Turn the control switch to ON status to energize the coil in the contractor.
Get the volt ohmmeter and turn it on and make sure that the ohm is positioned in front of the
selector switch. Proceed to testing the L-side with its corresponding T-side as L-1 to T-1, reading
must be 0 ohm.
Q
How we do relay testing? Pre-commissioning?
Ans
we do following tests
a) megger test, insulation resistance test
b) test of tripping circuit
Q
What is low voltage switchgear?
Ans
Low voltage switchgear is that operate within low voltage range.
Q
What is disconnecting switch? Define it? How many types are?
Ans
In electrical engineering, a disconnector, disconnect switch or isolator switch is used to ensure
that an electrical circuit is completely de-energized for service or maintenance.
a) Center-break disconnector
b) Double-side break disconnector
c) Knee type disconnector
Q
What is a switching device?
Ans
Device used to make or break the current in one or more electrical circuits.
Q
What is the current rating of switchracks?
Ans
Maximum switchrack rating is 600A. The current rating of a switchrack shall be a maximum of
600A and a minimum of 125% of the switchrack maximum operating load.
Q
What is the current rating of switchboards?
Ans
Switchboards shall have a maximum rating of 2000 A.
*Switchracks shall only be used in low voltage applications.
Q
What is the current rating of Panelboards?
Ans
Panelboards in industrial facilities shall be rated 400A or less. Panelboards in non-industrial
facilities shall be rated 1000A or less.
98
Transformers and reactors
(SAES-P-121)
Q
How many types of transformer testing/pre-commissioning?
Ans
there are many types:
a)
b)
c)
d)
e)
Q
Oil level checking
Gauge checking
Verify operation of temperature alarm
Perform winding insulation test
Turns ratio test
how many type of transformer are used in field?
Ans Power Transformer, Dry-Type Power Transformer, Overhead-Type Distribution Transformer,
Pad-Mounted Distribution Transformer, Instrument Transformer, Current Transformer (CT),
Voltage Transformer (VT), Control Transformer, Current-Limiting Reactor
Tests of Transformer
Type tests of transformer includes
1. Transformer winding resistance measurement
2. Transformer ratio test.
3. Measurement of insulation resistance.
4. Temperature rise test of transformer.
5. Tests on on-load tap-changer.
Lighting
(SAES-P-123)
*IESNA >> Illuminating Engineering Society of North America
Ambient Temperature: Average temperature of air or another medium in the vicinity of the
luminaire. Ambient temperature is expressed in degrees Celsius.
99
Operating Temperature Range: Ambient temperature range within which the luminaire
with regard to the specification can be operated. The operating temperature range is
expressed in degrees Celsius.
Luminaire: Apparatus which distributes, filters or transforms the light emitted from one or
more lamps and which includes all the parts necessary for fixing and protecting the lamps
and, where necessary, circuit auxiliaries together with the means for connecting them to
the electric supply. The words “luminaire” and “lamp system” are often assumed to be
synonymous. For the purposes of this standard, the word “luminaire” is restricted to
apparatus used for distributing light in general lighting, while “lamp system” implies use of
lamps in other than general lighting applications.
Luminaire Lifetime: Length of time during which 70% of the measured initial luminous flux
value are provided, as a function of maximum operating temperature range. The luminaire
lifetime of the module is expressed in hours.
Lumen Maintenance: Value of the luminous flux at a given time in the life of a luminaire
divided by the initial value of the luminous flux of the luminaire and expressed as a
percentage x of the initial luminous flux value. The lumen maintenance of a luminaire is the
effect of decrease of lumen output which is sometimes referred to as depreciation or lumen
loss factor.
Luminaire Efficacy: Quotient of the luminous flux emitted by the power consumed by the
luminaire. The efficacy is expressed in lm/W.
Lighting Requirements
Q
Lighting design should be according to which standard?
Ans
Lighting design shall be in accordance with IESNA RP-7
Q
Lighting standard for parking facilities shall be in accordance with which standard?
Ans
Lighting design for parking facilities shall be in accordance with IESNA RP-20.
Q
For photometric measurements of sports which standard we follow?
Ans
Photometric measurements of sports lighting, when required shall be performed as per the
IESNA LM-5
Q
For photometric measurements of parking areas which standard we follow?
Ans
Photometric measurements of parking areas, when required shall be performed as per the
IESNA LM-64.
Q
what is ambient temperature for continuous operation of photocell switches?
100
Ans
Photocell switches shall be suitable for continuous operation in an ambient temperature above
40°C.
*Where floodlights are installed on steel towers, the towers shall be equipped with steel service
platforms located 1.5 m below the fixtures.
Q
What are the requirements for poles in lighting areas and street lighting?
Ans
Poles for area lighting and street lighting shall meet the following requirements:
(1) Poles used in process areas shall be hot-dipped galvanized steel.
(2) Poles outside process areas shall be hot dipped galvanized steel or seamless aluminum alloy.
(3) Aluminum, steel, and fiberglass poles shall be provided with a suitable wiring compartment
located at a height of not less than 150 mm nor more than 900 mm from the base.
*Lighting poles installed within 5 meters from roads having a speed limit in excess of 50 km/h
Q
What type of lamps are used in lighting fixtures for offices, control buildings, and in industrial
areas?
Ans
Energy-efficient fluorescent lamps type T5 or T8 and compatible energy efficient electronic
ballasts having less than 10% THD (total harmonic distortion) shall be used in lighting fixtures for
offices, control buildings, and in industrial areas where fluorescent lighting is required.
Q
What type of fixtures are used for outdoor area illumination?
Ans
High-pressure sodium fixtures shall be used for outdoor area illumination.
Q
What type of fixtures are used for high-bay or low-bay indoor industrial applications?
Ans
High-pressure sodium or Metal Halide fixtures shall be used for high-bay or low-bay indoorindustrial applications.
Q
What type of fixtures are used in workshops, repair shops and maintenance shops?
Ans
Metal halide fixtures shall also be permitted in workshops, repair shops and maintenance shops
where a high Color Rendering Index (CRI) is essential.
*The use of energy-efficient fixtures like High Pressure Sodium, Metal Halide shall be maximized.
Mercury vapor fixtures shall not be used.
*Battery rooms shall be provided with enclosed and gasketed (i.e., vapor-tight) corrosionresistant lighting fixtures.
Q
For street lighting design which standard is used? Street lighting design shall be in accordance
with which standard?
101
Ans
Street lighting design shall be in accordance with IESNA RP-8
Q
What is the height of light fixtures positioned over stairways, platforms, elevated walkways and
landing?
Ans
Light fixtures positioned over stairways, platforms, elevated walkways and landings shall be
positioned at a height of 2.03 m.
Q
What is the mini time duration of normal power failure for emergency lighting?
Ans
Minimum duration of emergency lighting in the event of normal power failure, shall be one-andone-half hours.
Q
What is the minimum emergency illumination level in manned switchgear rooms and control
room?
Ans
In manned switchgear rooms and control rooms where essential activities continue during
failure of the normal lighting, a minimum emergency illumination level of 100 lux (10 fc) shall be
provided at 760 mm above the floor.
Q
Where the normal and emergency task lighting should be provided?
Ans
Normal and emergency task lighting of at least 200 lux (20 fc) shall be provided for the
following:
A. In plant areas to illuminate equipment required for use in emergencies, such as: emergency
telephones, shutdown and emergency isolation stations, fire water pump areas, central
foam concentrate mixing areas, fire control panels and stand-by generators.
B. B. In evacuation assembly areas and in off-shore platform escape capsule areas and boat
landings
Q
illuminated exit sign shall be manufactured and installed in accordance with which standard?
Ans
Illuminated exit signs shall be manufactured and installed in accordance with NFPA 101
requirements.
Q
where the emergency egress lighting shall be provided?
Ans
Emergency egress lighting shall be provided for the following.
1)
2)
3)
4)
5)
Q
Control Rooms
Process Areas
Switchgear Rooms
In-Plant Buildings
Offshore Platforms
What is the emergency lighting illumination minimum and maximum lux value?
102
Ans
Emergency lighting facilities shall provide initial illumination that is no less than a maintained
maximum of 10 lux (1 fc) and a minimum at any point of 1 lux (0.1 fc) measured along the path
of egress at floor level.
*A maximum to minimum illuminance uniformity ratio of 40:1 shall not be exceeded.
*Fluorescent and incandescent fixtures installed in the control room shall provide shadow less
illumination.
Q
What is the efficiency and color rendering index of fluorescent lamps?
Ans
The fluorescent lamps shall have 82.5 lumens per-watt efficacy and a color rendering index (CRI)
of 82 at a correlated color temperature of 3,500 K or higher
*General illumination for offices, computer rooms, interface rooms and general service areas
shall be provided by fluorescent fixtures. Office lighting shall be done as per IESNA RP-1.
*Offices containing computer visual display terminal (VDT) shall be done as per IESNA RP-24.
*Fixtures for suspended ceilings shall be recessed mounted and shall be self-supporting in
accordance to NFPA 70.
*Incandescent spot fixtures with dimmers to provide variable illumination of up to 1,000 lux shall
be used for supplementary task lighting in work areas within the control room as required.
Power System Automation
(SEAS-P-126)
103