commissioning switchgear, low-voltage and circuit breakers

Note: The source of the technical material in this volume is the ProfessionalEngineering Development Program (PEDP) of Engineering Services.

Warning: The material contained in this document was developed for SaudiAramco and is intended for the exclusive use of Saudi Aramcos employees.Any material contained in this document which is not already in the publicdomain may not be copied, reproduced, sold, given, or disclosed to thirdparties, or otherwise used in whole, or in part, without the written permissionof the Vice President, Engineering Services, Saudi Aramco.

Chapter : Electrical For additional information on this subject, contactFile Reference: EEX30208 W.A. Roussel on 874-6160

Engineering EncyclopediaSaudi Aramco DeskTop Standards

Commissioning Low-Voltage

Switchgear And Circuit Breakers

Engineering Encyclopedia Electrical

Commissioning Low-VoltageSwitchgear and Circuit Breakers

Saudi Aramco DeskTop Standards

Content Page

INTRODUCTION................................................................................................................1

SAUDI ARAMCO COMMISSIONING REQUIREMENTS................................................2

Switchgear................................................................................................................2

Circuit Breakers........................................................................................................5

EVALUATING LOW-VOLTAGE SWITCHGEARAND CIRCUIT BREAKERS UPON RECEIPT...................................................................9

Visual Inspection.......................................................................................................9

Verification Against Specifications............................................................................9

Low-Voltage Switchgear Nameplate.............................................................10

Circuit Breaker Nameplate............................................................................11

EVALUATING LOW-VOLTAGE SWITCHGEAR AND CIRCUIT BREAKERINSTALLATION AND TESTING......................................................................................13

Visual Inspection......................................................................................................13

Suitability.....................................................................................................14

Physical Damage...........................................................................................15

Alignment.....................................................................................................15

Cleanliness....................................................................................................15

Arc Chute Assembly.....................................................................................17

Contacts.......................................................................................................17

Mechanism/Linkage......................................................................................18

Lubrication...................................................................................................18

Mechanical Inspection..............................................................................................18

Bolt Torque..................................................................................................19

Door Operation............................................................................................19

Rack In - Rack Out.......................................................................................19

Open/Close Operation...................................................................................20

Electrical Inspection.................................................................................................21

Insulation Resistance.....................................................................................22

Contact Resistance........................................................................................23




Functional Operation....................................................................................23

Auxiliary Equipment.....................................................................................24

SYSTEM PRE-OPERATIONAL CHECK-OUT PHASE REQUIREMENTS.....................25

Point-to-Point Wiring Check....................................................................................25

Subsystem Checkout................................................................................................25

Interlocks.................................................................................................................25

SYSTEM OPERATIONAL TESTING PHASE REQUIREMENTS....................................26

WORK AID 1: REFERENCES FOR EVALUATING LOW-VOLTAGESWITCHGEAR AND CIRCUIT BREAKERS UPON RECEIPT..............27

Low-Voltage Switchgear and Circuit Breaker Applications Checklist.......................34

WORK AID 2: REFERENCES FOR EVALUATING LOW-VOLTAGESWITCHGEAR AND CIRCUIT BREAKER INSTALLATIONAND TESTING.........................................................................................35

NETA Checklists......................................................................................................35

Information, Formulas, and Tables for Use in Evaluating the Results ofInsulation Resistance (Megger) Tests.......................................................................44

Saudi Aramco Pre-Commissioning Forms.................................................................45

GLOSSARY........................................................................................................................56

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Table of Figures Page

Figure 1: Westinghouse Type DS Low-Voltage Switchgear Section.........................3

Figure 2: GE AKR Manual Low-Voltage Circuit Breaker.........................................6

Figure 3: GE AKR Low-Voltage Circuit Breaker Contact Structure.........................7

Figure 7: Saudi Aramco Low-Voltage Power Switchgear Requirements(From 16-SAMSS-502)..........................................................................28

Figure 8: Low-Voltage Switchgear Buyer Data Sheet..............................................29

Figure 8: Low-Voltage Switchgear Buyer Data Sheet (Cont'd)................................30

Figure 9: Low-Voltage Switchgear Vendor Data Sheet...........................................31




Figure 10: Low-Voltage Power Circuit Breaker Rating, Design,Construction, and Auxiliary Device Installation Requirements.................32

Figure 10: Low-Voltage Power Circuit Breaker Rating, Design,Construction,and Auxiliary Device Installation Requirements (Cont'd).........................33

Figure 11: Low-Voltage Switchgear Construction General Requirements................39

Figure 12: Low-Voltage Switchgear Stationary Structure Requirements..................40

Figure 13: Low-Voltage Switchgear Bus Construction Requirements......................41

Figure 14: Low-Voltage Switchgear Bus Connection and Cable TerminationConstruction Requirements.....................................................................42

Figure 15: Low-Voltage Switchgear Nameplate Construction Requirements............43

Figure 16: Dielectric Absorption Ratio Chart...........................................................44

Figure 17: Saudi Aramco Pre-Commissioning Form, P-023, Switchgear-General.....46

Figure 17: Saudi Aramco Pre-Commissioning Form, P-023,Switchgear-General (Cont'd)...................................................................47



Figure 18: Saudi Aramco Pre-Commissioning Form, P-008,Low-Voltage Power Circuit Breakers......................................................50

Figure 18: Saudi Aramco Pre-Commissioning Form, P-008,Low-Voltage Power Circuit Breakers (Cont'd)........................................51



Figure 19: GI 2.l710 Excerpt...................................................................................54

Figure 19: GI 2.l710 Excerpt (Cont'd).....................................................................55



Saudi Aramco DeskTop Standards 1

INTRODUCTION

The selection of the type and size of switchgear and the associated power circuit breakers arebased on the technical, installation, and economic requirements of a facility. Facility switchgearand circuit breaker technical requirements include the system voltage level, fault current, and thenumber and type of loads. Once the type of switchgear and circuit breakers for a giveninstallation are chosen, the switchgear is assembled and the circuit breakers are installed. Thecommissioning process for low-voltage switchgear and circuit breakers in Saudi Aramco facilitiesensures that a safe and cost-effective system is installed and that this system will perform to thespecifications of the facility for the projected operating lifetime of the facility. Experience hasshown that the time and effort that is expended up front to ensure safety, quality control, andadherence to Saudi Aramco and industry standards minimizes subsequent equipment failure.

The commissioning process for low-voltage switchgear and circuit breakers involves evaluations,verifications, and checks that determine whether the proper switchgear and circuit breakerspecifications and installation requirements are met. Tests are also performed that determinewhether the electric power distribution system will operate properly and safely after installation.When the low-voltage switchgear and circuit breakers are inspected and tested satisfactorilyduring the commissioning process, the system should operate in accordance with manufacturer'sspecifications for its maximum useful life.

This Module provides information on the following topics and subtasks that are pertinent tocommissioning low-voltage switchgear and circuit breakers for Saudi Aramco installations:

Saudi Aramco Commissioning Requirements

Evaluating Low-Voltage Switchgear and Circuit Breakers Upon Receipt

Evaluating Low-Voltage Switchgear and Circuit Breaker Installation and Testing

System Pre-Operational Check Out Phase Requirements

System Operational Testing Phase Requirements




SAUDI ARAMCO COMMISSIONING REQUIREMENTS

Large process and process support equipment in industrial facilities requires electric power tofunction. Also, the operations, maintenance, and support personnel who work in an industrialfacility require electric power for lights, fans, computers, and other support equipment. Theelectric power that is required to run equipment is passed through a distribution system thatroutes the electric power to the correct equipment. The distribution system also provides electricpower control capabilities, as well as rapid fault isolation and protection.

Low-voltage switchgear and the circuit breakers that are contained in the switchgear are a smallbut important part of the distribution system. Low-voltage switchgear and circuit breakersgenerally supply power to support ancillary loads, such as a cooling fan. This section of theModule contains information on Saudi Aramco applications and requirements for low-voltageswitchgear and circuit breakers.

Switchgear

Saudi Aramco uses compartmentalized, metal-enclosed, low-voltage switchgear assemblies inthree-phase electric power systems that have a maximum of 600 V ac (rms) at a nominalfrequency of 60 Hertz. When low-voltage power switchgear is received from the manufacturer, itis generally a finished product that is complete in all respects. A finished low-voltage switchgearthat is complete in all respects is factory assembled, wired, adjusted, and it includes power circuitbreakers, buses, instruments, switches, wiring, space heaters, terminations, painting, nameplates,and tests (as required) so that the low-voltage switchgear is ready for operation when it is set inplace. The low-voltage switchgear bus connections and cable terminations must be in accordancewith Saudi Aramco and industry requirements and standards. The minimum mandatoryrequirements for the design and construction of an indoor metal-enclosed low-voltage switchgearassembly are provided in Work Aid 1.

Figure 1 shows a Westinghouse-Type DS low-voltage switchgear section. The basic constructionof distribution switchgear is a stationary enclosure that contains buses, circuit breakers, andcontrol equipment. The stationary part of low-voltage switchgear must be a ventilated andverminproof NEMA Type 1 enclosure. To reduce future facility modification costs, the enclosuremust permit future extension at each end unless specified otherwise. For example, additionalswitchgear can be connected to the main buswork and the ground bus that are shown in Figure 1.The stationary structure will have the required number of compartments to house removable air orvacuum circuit breakers. Each circuit breaker must be provided with a breaker cover (safetybarrier) and latch that closes the compartment completely whether the breaker is racked in orremoved. Meters for system monitoring must also be provided along with the associatedindicating lights and selector switches. Each switchgear segment and circuit breaker compartmentmust have a nameplate that describes the associated electrical design parameters.




Figure 1: Westinghouse Type DS Low-Voltage Switchgear Section

Metal-enclosed low-voltage switchgear assemblies must be furnished from the manufacturer withthree-phase main and feeder buses, neutral bus (if specified), and ground bus. The incomingpower supply (with an associated isolation breaker) is connected to a three-phase main bus and aneutral bus (if specified). The incoming power supply is sometimes called the "incomer." Themain bus supplies power to a feeder bus (and associated feeder breakers) that feeds multiple low-voltage loads. Some switchgear may have multiple power supplies, in which case, the two powersupplies are joined by a "tie" bus (and an associated tie breaker) that can connect the two powersupplies. Each incoming or tie power circuit breaker must be located in a separate section of theswitchgear.




To facilitate future system expansion and to minimize expansion modification costs, spareswitchgear compartments must be provided. The following unused compartments should beprovided at the end of each metal-enclosed low-voltage switchgear assembly and as specified inthe Engineering Drawings:

SPARE A completely developed compartment (including a power circuit breaker,protective relays, control switches, and indicating lights) that is ready foroperation when the feeder and control cables are connected to a load.

SPACE A compartment that is developed similarly to the SPARE compartment butwithout an installed power circuit breaker.

FUTURE A compartment that is developed with stationary elements such as primarystuds, current transformers, safety shutters, sliding rail, rail guides, leveringmechanism, safety interlocks, secondary disconnects, and circuit breakercontrol devices and wiring.

For installation and maintenance, a circuit breaker lifting device and manual circuit breakerracking lever or ratchet handle must be provided with each switchgear assembly. Devicenameplates are also required for the identification of each breaker and auxiliary unit. Thesenameplates indicate the circuit number and the load that is served or the equipment that iscontained within the auxiliary cubicle (if present). To alert employees to the danger of electricshock during operations or maintenance, warning nameplates must be provided on eachcompartment door or auxiliary cubicle.

Data sheets are used to supply specific switchgear information to the manufacturer (when theswitchgear is ordered) and to Saudi Aramco (when the switchgear is delivered). The data sheetsshould contain information about the size, type, ratings, and control of the low-voltage switchgearand the circuit breakers that are to be installed in the switchgear. The data sheets are provided inWork Aid 1. Quality control, quality assurance, and test data should also be provided with theswitchgear by the manufacturer.




Circuit Breakers

Low-voltage power circuit breakers provide low-voltage system and load isolation during normaloperation and maintenance evolutions. Low-voltage power circuit breakers also provideautomatic system fault isolation to prevent damage to connected equipment during overload,abnormal, or fault conditions. Low-voltage power circuit breakers that are used in Saudi Aramcoinstallations are designed, rated, manufactured, and tested in accordance with the latest issue orrevision of the cognizant sections of ANSI/IEEE Standard C37. Each component of alow-voltage power circuit breaker must be fully capable of interrupting the available systemshort-circuit current that is indicated in the system engineering drawings. Each low-voltage circuitbreaker must have a three-phase short circuit current rating that is equal to, or larger than, therating of the switchgear assembly.

The low-voltage circuit breakers that are used in Saudi Aramco installations should be thedead-front, removable, drawout, air type. Insulated case or molded case circuit breakers must notbe used in the place of power circuit breakers in low-voltage switchgear installations. SaudiAramco uses the General Electric (GE) AK-type, the Westinghouse DS-type, and the ABB KD-type low-voltage circuit breakers in switchgear installations. The minimum mandatoryrequirements for the design and construction of a low-voltage circuit breaker are provided inWork Aid 1.

Generally, low-voltage power circuit breaker contacts are operated by a stored-energy mechanismin the form of springs; however, some low-voltage feeder breakers use manual operators.Electrical operation of a low-voltage circuit breaker is used when the breaker is controlledremotely, and manual operation is used when the breaker is controlled locally. Main breakers(e.g., incomer) are usually electrically-operated. Feeder breakers are manually operated. Inelectrically-operated breakers, the springs are electrically controlled through use of a chargingmotor that maintains the closing springs in a charged state. The closing springs must developsufficient energy to close and latch the circuit breaker.

Figure 2 shows an example GE AKR, manually-operated, low-voltage circuit breaker. Thebreaker is closed by first turning the manual operation handle up to four strokes to charge theclosing springs. Once the charging springs are charged, the breaker is closed by operation of theclose push-button. Some manually-operated low-voltage circuit breakers close on the final strokeof the manual operation handle, and they do not have a close push-button. Some electrically-operated low-voltage circuit breakers do not have a manual operation handle.




Figure 2 shows one set of breaker contacts with the arc chute assembly removed. When thebreaker closes, the moving contacts close against the stationary contacts. To trip the breaker, atrip push-button is operated. Low-voltage breakers use a shunt coil trip (or undervoltage release)device for remote trip operations. The low-voltage breaker also uses a solid-state, direct-acting,self-powered trip device. The trip device current trip levels are set at the breaker, and a portabletest instrument can be used to test each trip device setting. The nameplate contains low-voltagecircuit breaker manufacturer, type, and rating information.

Figure 2: GE AKR Manual Low-Voltage Circuit Breaker




Low-voltage circuit breakers that are electrically operated must be equipped with the following:

Motor-operated, stored-energy (e.g., springs) operating mechanism.

Shunt trip coil (or undervoltage release) tripping mechanism.

Trip push-button.

Close push-button.

Manual closing spring charge operation handle.

Control devices (as indicated on Engineering drawings).

Figure 3 shows a closeup view of the low-voltage breaker contact structure for one phase of thebreaker with the arc chute assembly removed. The movable contact arm opens and closes to makecontact between the movable contacts and the stationary contact. When the breaker is closed, themain contacts and the arcing contacts are held against the movable contact via pressure from thecontact springs on the contact pivot point. As the breaker opens, the main contacts open first,which is followed by the arcing contacts. Because the arc interrupting contacts open last, the arcthat is formed when the breaker opens is forced up the arc runner. The number of main andarcing contacts will vary based on the interrupting capability of the breaker. The arcing contactsare easily differentiated from the main contacts because the arcing contacts angle out slightlymore than the main contacts.

Figure 3: GE AKR Low-Voltage Circuit Breaker Contact Structure




The removable metal frame that surrounds the low-voltage circuit breaker consists of thenecessary circuit breaker bus disconnecting contacts, wheels, and interlocks for drawoutapplication. The removable metal circuit breaker frame allows the circuit breaker compartmentdoor to be closed with the circuit breaker in the following four operational positions: connected,test, disconnect, and fully withdrawn (e.g., removed). When a power circuit breaker ispadlocked, the breaker must not be able to be closed or moved to any other position.

Electrically- or manually-operated low-voltage circuit breakers use auxiliary devices. Auxiliarydevices are used for specific circuit breaker and electric power distribution system protection andcontrol. An example of a circuit breaker auxiliary device is a position indicator. The positionindicator is mechanically connected to the circuit breaker operating mechanism. An auxiliarycontact is also an auxiliary device. Auxiliary contacts consist of "a" (normally open) contacts and"b" (normally closed) contacts. Normally open "a" contacts follow the position of the circuitbreaker (i.e., when the circuit breaker contacts are closed, the "a" contacts are closed). Normallyclosed "b" contacts function the opposite to the position of the circuit breaker (i.e., when thecircuit breaker contacts are closed, the "b" contacts on the auxiliary switch are open). Auxiliarycontacts are used predominantly in electrical distribution protective relaying and breaker controlsystems. An example of an auxiliary contact use is a breaker "a" contact that is in series with thebreaker trip coil. The "a" contact is only closed when the breaker is closed. The breaker "a"contact prevents the trip coil from being energized unless the breaker is closed. Extra auxiliarycontacts must be provided by the manufacturer for Saudi Aramco use. The extra auxiliarycontacts are in addition to those contacts that are required for circuit breaker operation andindication. An alarm switch must also be provided for remote indication of an automatic trip by aprotective device.




EVALUATING LOW-VOLTAGE SWITCHGEAR AND CIRCUIT BREAKERS UPONRECEIPT

The installation of low-voltage switchgear and circuit breakers is a process that occurs over aperiod of time. The installation begins with an identified need for a new low-voltage powerdistribution installation (e.g., a new facility). Power is necessary for the new facility to function,so a switchgear and circuit breaker installation is designed. After the design is approved, theswitchgear and circuit breakers are ordered. Once the switchgear and circuit breakers arereceived from the manufacturer, they must be evaluated to ensure that they are proper for theinstallation. The purpose of the evaluation is to verify that correct low-voltage switchgear andcircuit breakers were received from the manufacturer and that the proper installationspecifications and parameters were met. This section will describe how low-voltage switchgearand circuit breakers are evaluated upon receipt.

Visual Inspection

When low-voltage switchgear and circuit breakers are received from the manufacturer, a visualinspection should be performed. The purpose of the visual inspection is to verify that theswitchgear and circuit breakers that were received from the manufacturer are in good physicalcondition and that all of the requested parts and accessories are present. Because of the damagethat can occur to the moving parts that are associated with low-voltage switchgear and circuitbreakers during installation, only a cursory inspection is performed at the receiving point. Duringthe cursory inspection, the inspection personnel look for obvious equipment damage anddetermine whether all necessary support equipment (e.g., racking lever, and technical manuals)are present. A detailed inspection of the low-voltage switchgear and circuit breakers is performedwhen they are completely installed at the site or facility.

Verification Against Specifications

When a new facility or facility modification is at the equipment installation stage, the design of theinstallation has already been completed. The type of low-voltage switchgear and circuit breakersthat are selected for a specific power system should be shown in the drawings, prints, orspecifications for the installation. The purpose of verifying low-voltage switchgear and circuitbreakers against the specifications is to ensure that the equipment that is being installed meetsSaudi Aramco and industry standards.




Generally, the verification against specifications consists of a determination of whether the typeand rating of the equipment that is to be installed matches the size and type of the equipment thatis required for the installation. In some cases, this determination is accomplished by reading anelectrical plan that identifies the low-voltage switchgear and circuit breaker sizes and types. TheEngineer inspects the manufacturer's nameplate data on each switchgear compartment and circuitbreaker, and he compares them to the requirements on the electrical plan to determine whetherthe correct equipment is being used. In other situations, the Electrical Engineer must rely on hisknowledge of the correct application of switchgear and circuit breakers sizes and types todetermine whether the correct equipment is being used. The data sheets that were used to orderthe switchgear from the manufacturer should also be consulted. Example switchgear data sheetsare provided in Work Aid 1. Any quality control, quality assurance, and test data that areprovided with the low-voltage switchgear and circuit breakers should also be reviewed. Aswitchgear and circuit breaker applications checklist is provided in Work Aid 1. The checklistitemizes what should be included in the verification of low-voltage switchgear and circuit breakersagainst specifications.

Low-Voltage Switchgear Nameplate

All low-voltage switchgear that is used in Saudi Aramco power systems should have a nameplatethat is clearly visible on the front of the switchgear. The nameplate should contain manufacturer-type information. The information that describes the type of switchgear should consist of themanufacturer's name, the type designation, and the serial number. Because switchgear maycontain different assemblies at various voltages, nameplates should be present at each switchgearsegment. In accordance with ANSI C37, the manufacturer and rating information that shouldappear on the low-voltage switchgear nameplate should contain the following ratings:

Rated frequency

Rated maximum voltage

Rated insulation level

Rated continuous current

Rated short-time current

Rated short-circuit current

Low-voltage switchgear and electric power distribution systems are designed to operate at aspecific frequency. Saudi Aramco electrical distribution systems are designed to operate at 60Hz.




Low-voltage switchgear is designed for and should be marked with the maximum voltage atwhich the switchgear can be applied. The rated maximum voltage levels of a low-voltageswitchgear is the highest rms voltage for which the switchgear is designed, and the ratedmacimum voltage is the upper limit for operation. The rated maximum voltage levels of low-voltage switchgear are 635 V, 508 V, or 254 V. The rated insulation level of low-voltageswitchgear at each maximum voltage rating is equal to the low-frequency one-minute withstandvoltage of 2.2 kV.

Low-voltage switchgear is designed for and should be marked with the continuous current thatthe switchgear is capable of carrying and the fault current values that the switchgear is capable ofinterrupting without damage to the switchgear. Specific current ratings for low-voltageswitchgear are as follows:

Rated Continuous Current at 60 Hz. The rated continuous current at 60 Hz isthe amount of current that can be continuously carried by the switchgear primarycircuit components (e.g., buses, bus connections) without exceeding switchgearequipment allowable temperature rise. Examples of switchgear equipment areprimary or secondary circuit components, insulation, and switchgear structuralcomponents.

The Rated Short-Time Current. The rated short-time current is the designatedlimit of available current at which the switchgear must interrupt the current withinthe required time at the rated maximum voltage. The required time is termed the"rated short-time duty" and corresponds to two periods of one-half second currentflow that are separated by a 15-second interval of zero current.

The Rated Short-Circuit Current. The rated short circuit current of low-voltageswitchgear is the designated limit of available current at the rated maximum voltagethat the switchgear must be required to withstand for a period of no less than fourcycles (on a 60 Hz basis).

Circuit Breaker Nameplate

All circuit breakers that are used in Saudi Aramco power systems should have a nameplate that isclearly visible on the front of the breaker. The nameplate should contain circuit breakermanufacturer-type information. The information that describes the type of circuit breaker shouldcontain the manufacturer name, the type designation, and the serial number.




In accordance with ANSI C37, the manufacturer and rating information that should appear on thecircuit breaker nameplate should contain the following rating information:

Rated frequency

Rated maximum voltage

Rated continuous current

Rated short-circuit current at the rated maximum voltage

Rated short-circuit current

Circuit breakers and electric power distribution systems are designed to operate at a specificfrequency. Saudi Aramco electrical distribution systems are designed to operate at 60 Hz.

Low-voltage circuit breakers are designed for and should be marked with the maximum voltage atwhich they can be applied. The rated maximum voltage of a low-voltage circuit breaker is thehighest rms voltage (three-phase or single-phase) at which the circuit breaker is designed toperform. A low-voltage circuit breaker is generally rated at 635 V (600 V for a fused circuitbreaker), 508 V, or 254 V.

Circuit breakers are designed for and should be marked with the continuous current that thebreaker is capable of carrying and the short-circuit fault current values that the breaker is capableof interrupting without damage to the breaker. Specific current ratings for low-voltage circuitbreakers are as follows:

Rated Continuous Current at 60 Hz. The rated continuous current at 60 Hz isthe amount of current that the low-voltage circuit breaker can continuously carrywithout exceeding the allowable temperature rise.

The Rated Short-Time Current. The rated short circuit current is the designedlimit of available (prospective) rms current at which the circuit breaker will berequired to perform its short-time duty cycle at the rated maximum voltage. Theshort-time duty cycle is defined by ANSI 37.13 as two periods of 1/2 secondcurrent flow, which is followed by a 15-second interval of zero current. Unfusedlow-voltage circuit breakers do not have a rated short-time current.

The Rated Short-Circuit Current at Each Rated Maximum Voltage(Interrupting Rating). The rated short circuit current of an unfused low-voltagecircuit breaker is the designated limit of available current at which the circuitbreaker must interrupt the current within the required time at the rated maximumvoltage.




EVALUATING LOW-VOLTAGE SWITCHGEAR AND CIRCUIT BREAKERINSTALLATION AND TESTING

The process of determining whether low-voltage switchgear and circuit breakers should becommissioned is to verify that all the electrical inspections and tests have been properly performedand to verify that the test results are within the specifications that are designated by the applicableSaudi Aramco and industry standards.

Installation inspections are performed to verify that proper switchgear and circuit breakerinstallation materials are used, that installation specifications and parameters are met, and thatproper installation procedures are followed. The installation inspection is conducted to ensurethat the switchgear and associated circuit breakers will properly function once they are installed.Electrical tests are performed to check the ability of switchgear and the associated circuit breakersto function under a variety of operating conditions and loads. Installation tests should detectshipping or installation damage, gross manufacturing defects, or errors in workmanship orinstallation. The Saudi Aramco Switchgear-General Pre-Commissioning Form (P-023) and theSaudi Aramco Low-Voltage Circuit Breaker Pre-Commissioning Form (P-008) contain guidanceon the items that should be inspected, checked, and tested during the commissioning ofswitchgear and low-voltage circuit breakers. The switchgear-general and low-voltage circuitbreaker pre-commissioning forms are provided in Work Aid 2.

The proper evaluation of inspection and testing data during the commissioning process canmaximize the operating time of equipment installations through a determination of trends towardfailure. Failure prediction can drastically reduce equipment down-time; if a failure is predicted,operational changes can be made, maintenance can be performed, or equipment that is failing canbe replaced in a controlled manner. If a problem is corrected before it causes damage, operatingcosts will be lower because a malfunction can cause associated (or nearby) equipment damage anddisruption of service, or the problem can activate emergency repair crews. A failure in any one ofthe many inspections, checks, or tests that are performed on a low-voltage switchgear and circuitbreakers during the installation and testing evaluation is sufficient to prevent the equipment frombeing commissioned.

Visual Inspection

Visual inspections are used to assess the physical condition of switchgear and the associatedcircuit breakers. A visual inspection is a pass/fail verification about a particular aspect of thephysical condition or the operation of equipment. Because the criteria that are established todetermine the acceptability of the visual inspections can be subjective, the visual inspectionsshould be performed by an experienced Electrical Engineer.




Because of the large number of inspection items that are associated with low-voltage switchgearand circuit breakers, there are several courses of action for visual inspection failure. The courseof action to be taken depends on the part of the equipment that failed the visual inspection. Afailure of alignment, mechanism/linkage, lubrication, or cleanliness inspection can usually becorrected through maintenance procedures. A physical damage or suitability inspection failurewill probably require the replacement of the damaged component.

The visual inspection of circuit breakers should be performed during the normal breakermaintenance cycle as determined by Saudi Aramco procedures or once every 2,000 circuit breakeroperations if the circuit breaker short-circuit interrupting rating does not exceed 29 kA inaccordance with ANSI C37.06. Technical data to evaluate the results of the visual inspection canbe found in the switchgear and circuit breaker manufacturer's technical manual. The followingvisual inspections are used to assess the condition of low-voltage switchgear and the associatedcircuit breakers in Saudi Aramco systems:

Suitability

Physical Damage

Alignment

Cleanliness

Arc Chute Assembly

Contacts

Mechanism/Linkage

Lubrication

Suitability

The purpose of the visual inspection for suitability is to determine whether the switchgear andassociated circuit breakers are appropriate for the application in which they are placed. Undernormal circumstances, the suitability of the equipment should be determined before it is placedinto the system; however, a visual inspection should be performed to ensure that changes that mayhave been made to the system have not exceeded the ratings of the switchgear or the associatedcircuit breakers.

To determine the suitability of switchgear and the associated circuit breakers, a visual inspectionof the nameplate data should be performed and compared to the electrical system single linediagram. For example, if the nameplate information on a circuit breaker does not match theratings of the electrical system, the circuit breaker should be replaced with a circuit breaker that iscorrectly rated.




Physical Damage

Physical damage to switchgear or to circuit breakers that are contained in switchgear can preventelectric power distribution or can lead to switchgear or circuit breaker failure during criticalsystem operations. The magnitude of the electric energy that passes through switchgear and thelarge forces that are required to open and close circuit breakers can propagate and amplify anyminor installation damage. Damage to switchgear and circuit breakers can lead to catastrophicequipment failure, fire, personal injury, or death. Any physical damage to switchgear or circuitbreakers that is noted requires the immediate replacement of the damaged component. The mostobvious and common forms of physical damage are cracks, dents, missing or broken pieces, bentdoors, and burned out indicator lights. The purpose of the physical damage inspection is toidentify whether corrective maintenance or component replacement is necessary. Switchgear andcircuit breakers that show any form of physical damage, no matter how small, should bedetermined to have failed the physical damage inspection.

Alignment

The purpose of the alignment inspection is to ensure that the switchgear and circuit breaker willproperly pass current when they are connected to the rest of the electrical system. Properalignment of a circuit breaker frame when it is installed in the switchgear will ensure that the lineand load buses are properly connected to the circuit breaker when the circuit breaker is racked in.Improper alignment can cause uneven circuit breaker heating and wear. Due to the constructionof circuit breaker frames, circuit breakers that are out of alignment are usually visually obvious.When the circuit breaker is properly aligned, the sides of the circuit breaker will be parallel to thecorresponding sides of the frame, and the proper clearance will be evident.

Cleanliness

The purpose of the cleanliness visual inspection is to ensure the proper operation of theswitchgear and the associated circuit breakers over the maximum operating life of the equipment.The accumulation of dirt over a period of time will impede the proper operation of the circuitbreaker and will reduce the dielectric strength of the switchgear and circuit breaker insulation.Dust and dirt can also reduce the speed and sensitivity of a circuit breaker under fault conditions.

The accumulation of large amounts of dust and dirt should be cleaned away from the switchgearand associated circuit breakers during maintenance cycles. Switchgear that is installed inextremely dirty, dusty, or humid areas may have to be cleaned more often than once during themaintenance cycle.




Arc Chute Assembly

The arc chute assembly on an circuit breaker is responsible for the suppression of the arc thatforms when the circuit breaker opens. The purpose of the visual inspection of the arc chuteassembly is to ensure that the arc chutes can safely suppress the arc that forms when the circuitbreaker opens under normal operating and fault conditions.

When a visual inspection of the arc chute assembly is performed, three conditions exist that willcause the arc chute assembly to fail inspection: burn marks, scale, and cracks. Burn marks changethe consistency of the surface of an arc chute. If burn marks are present on an arc chute, the arcchute should be replaced. Scale is the accumulation of foreign material in the arc chutes that canimpede the ability of the arc chutes to extinguish an arc. Because scale should not be removedfrom the surface of the arc chutes, the inspector must determine whether the scale will impede theability of the arc chute to extinguish an arc. If the inspector determines that the scale will impedethe ability of the arc chute to extinguish an arc, the arc chute is replaced. Cracks may form in thearc chutes during the normal operation of the circuit breaker. The inspector must determinewhether the cracks will interfere with the ability of the arc chute to extinguish an arc, and heshould replace the arc chute accordingly.

Contacts

The circuit breaker contacts provide a current path through the circuit breaker to interrupt thecurrent during normal operating and fault conditions. Damage can occur at the breaker contactsas a result of the mechanical stress from breaker closing operations and the electrical arc thatforms during breaker opening operations. The purpose of the visual inspection of circuit breakercontacts is to ensure that the circuit breaker contacts provide a low resistance current path andthat the circuit breaker contacts safely interrupt current during normal operating and faultconditions. During the contact inspection, the primary bushings, porcelains, and finger clustersshould be checked.

In general, the two types of current that are interrupted by a circuit breaker are low circuit currentand high circuit current. The arc that is associated with a low circuit current interruption will takelonger to extinguish than an arc that is associated with a high circuit current interruption. Lowcircuit current interruptions will leave small burn and pock marks on the surface of the contacts.These small burn and pock marks will not interfere with the operation of the contacts, but thecontacts will need to be replaced when they erode over time to some wear point that is defined bythe manufacturer.

Contacts that interrupt high circuit current will have burn marks and roughened edges that willaffect the amount of contact surface that actually touches when the circuit breaker's contacts areclosed. As was the case with the other type of contact wear, if the contacts become too thin, asdefined by the circuit breaker's manufacturer, then the contacts should be replaced.




Mechanism/Linkage

The mechanism/linkage assembly of a circuit breaker performs the actual movement of thecontacts when the breaker opens or closes. The purpose of the mechanism/linkage inspection isto ensure that the mechanism/linkage can move freely. Free movement of the mechanism/linkagewill ensure that the circuit breaker can properly and rapidly operate the circuit breaker contacts.The inspector should visually determine that no obstructions exist that will impede the movementof the mechanism/linkage. This inspection will also ensure that when the open/close operationtest is performed, no circuit breaker damage can occur.

Lubrication

The lubrication visual inspection should be performed in conjunction with the mechanism/linkagevisual inspection. The purpose of the lubrication visual inspection is to ensure that the circuitbreaker mechanisms, the moving parts, the bearing points, and the sliding mechanics are properlylubricated and free of rust.

Before the application of new lubrication can take place, hardened grease, dirt, and rust should beremoved from the surfaces that require lubrication. A cloth that is dampened with keroseneshould be used to remove the hardened grease and dirt. Care must be taken to ensure that thecloth does not deposit fibers on the moving parts of the circuit breaker. The deposit of cloth fiberson the moving parts of the circuit breaker can cause subsequent improper breaker mechanismoperation. After the proper preparation of the moving parts of the circuit breaker, a thin layer oflubrication should be applied. Excess lubrication should be wiped off with a clean cloth.

Mechanical Inspection

A mechanical inspection is used to assess the ability of switchgear and the enclosed circuitbreakers to physically perform the mechanical movements that are necessary for proper operation.Tests are also performed during the mechanical inspection to assess switchgear and circuit breakersafety functions. Because of the large number of mechanical inspection items that are associatedwith low-voltage switchgear and circuit breakers, there are several courses of action formechanical inspection failure. The course of action depends on the part of the equipment thatfailed the inspection. A failure of mechanism operation can usually be corrected throughmaintenance procedures. For example, a bolt torque test failure can be corrected throughadjustment of the bolts with a torque wrench.




The general mechanical inspections and tests that are performed on switchgear and circuitbreakers that are installed in Saudi Aramco systems are as follows:

Bolt Torque

Door Operation

Rack in - Rack Out

Open/close Operation

Bolt Torque

The purpose of a bolt torque inspection is to ensure that enough force is present to hold thebuswork and circuit breaker frames in place during circuit breaker operations and fault conditions.To determine the amount of force that exists between a bolt and a circuit breaker, a torquewrench is applied to the bolt in the direction that will tighten the bolt, and the amount of torque isread. Torque values for switchgear are listed in the switchgear technical manuals, and torquevalues for low-voltage circuit breakers are listed in the Saudi Aramco Low-Voltage CircuitBreaker Pre-Commissioning form that is provided in Work Aid 2. The manufacturer of the circuitbreaker will also provide a list of acceptable torques in the circuit breaker technical manual.

Door Operation

Each switchgear circuit breaker compartment must be provided with a door (safety barrier). Thedoor should also contain an interlock that prevents the closure of the door unless the circuitbreaker is racked in or completely removed. During the mechanical inspection, each switchgearcompartment door operating mechanism (e.g., handles and locking bars) should be mechanicallyoperated during the mechanical inspection, and the door interlocks should be tested.

Rack In - Rack Out

When a breaker is racked into the switchgear, the line and load sides of the breaker contacts areconnected to the electrical system. Additional control power connections are made to enable thecircuit breaker to be remotely controlled and automatically operated. The purpose of a rack in -rack out inspection is to ensure that the circuit breaker moves in and out of the switchgear freelyand that all connections and safety interlocks function correctly.




Circuit breakers generally have a test position to allow the operation of the breaker when it is atthe switchgear but is not connected to the electrical system. The circuit breaker test positionvaries from manufacturer to manufacturer. Generally, as a circuit breaker is pushed into itsswitchgear cell and the guides of the circuit breaker lock into place, the circuit breaker should bein the test position. In the test position, the circuit breaker protrudes from the switchgear so thatthe breaker operation can be observed. In the test position, the primary contacts of the circuitbreaker are not connected to the system, but the control circuitry of the circuit breaker can beenergized. In the test position, the circuit breaker can be cycled without affecting the rest of theelectrical distribution system. While the circuit breaker is in transit between the test and the fullyinserted position, the breaker should not have control power, and it should not operate.

Interlocks can be provided in low-voltage circuit breakers. Interlocks are designed to prevent theunsafe operation of the circuit breaker. A typical interlock that is provided on most circuitbreakers is the rack in - rack out interlock. To prevent racking in or racking out a closed breaker,circuit breakers are equipped with a rack-out interlock that trips a closed breaker when it ismoved from the fully inserted or test positions. A problem arises when a breaker has been closedin the test position and the breaker is subsequently racked all the way to the fully insertedposition. If the breaker is closed, the busbar connections will complete the electric circuit as soonas the busbar connections come in contact with the switchgear busbars. When a breaker is rackedinto switchgear in the closed position, dangerous arcing and uncontrolled equipment startupscould occur. Conversely, if a closed breaker that is in the fully inserted position is racked out, thecurrent interruption would take place at the busbar connections instead of the breaker maincontacts. Because there is no arc-suppression mechanism at the busbar connectors, dangerousarcing could occur. The rack-out interlock is designed to prevent dangerous arcing at theswitchgear busbar connections.

Generally, the mechanical inspections and tests that are performed on a circuit breaker follow alogical progression. To perform the mechanical inspections and tests, the breaker is first rackedto the test position. In the test position, the circuit breaker is cycled and the breaker operation isobserved. The breaker is left in the closed position, and the breaker is racked towards the fullyinserted position. When the breaker leaves the test position, the breaker should trip. After thebreaker trips (from the rack-out interlock), the breaker is returned to the test position and cycleda final time. During the racking operations, mechanical condition of all auxiliary devices,bumpers, position indicators, latching, tripping, and operating mechanisms are checked for properoperation.

Open/Close Operation

Some circuit breakers in Saudi Aramco electrical systems can go from maintenance cycle tomaintenance cycle without performing a single circuit interruption. A circuit breaker must alwaysbe in a condition to operate no matter how infrequently the circuit breaker has been used. Thepurpose of the open/close operation test is to ensure that the circuit breaker opens and closesproperly.




To perform the open/close operation test, the circuit breaker is racked to the test position. In thetest position, the circuit breaker is cycled, and the breaker operation is observed. The breakercontrol power is then disconnected (or bypassed), and the breaker is manually closed and tripped.During the opening and closing operations, the mechanical condition of all auxiliary devices,bumpers, position indicators, latching, tripping, and operating mechanisms are checked for properoperation. The moving contact travel for the circuit breaker is measured and recorded. Themanufacturer's technical manual should contain information on the minimum moving contacttravel distances.

Electrical Inspection

During the commissioning process, electrical inspections and tests are performed to check theability of the switchgear and circuit breakers to operate for a reasonable future period of timeunder a variety of operating conditions and loads. Acceptance or installation tests will usuallydetect shipping or installation damage and gross defects or errors in workmanship in equipmentconstruction. Once the installation and inspection data have been recorded and assembled, amethodical and consistent program of periodic data collection and evaluation should beestablished. As each new maintenance item, test, splice, system addition, or systemreconfiguration occurs, new inspections and data records will be required and should be added tothe existing data on file.

Because an electrical inspection or test failure can be caused by a construction error, equipmentage, or operational misuse, some kind of troubleshooting or maintenance activity should beperformed on the faulty equipment. For example, a contact resistance test failure can be rectifiedby cleaning the contacts to remove carbon build-up or by replacing the contacts. Some electricalinspection or test failures are not repairable, and they will require the replacement of theequipment before low-voltage switchgear and circuit breakers can be commissioned. Forexample, an insulation resistance test failure usually indicates a gross imperfection in the circuitbreaker insulation.

The following electrical inspections, checks, and tests are performed on Saudi Aramco low-voltage switchgear and circuit breakers:

Insulation Resistance

Contact Resistance

Functional Operation

Auxiliary Equipment




Insulation Resistance

The purpose of the insulation resistance test is to directly measure the switchgear and circuitbreaker insulation resistance through use of a megger. In the insulation resistance test, themegger is used to set up an electromagnetic field, and the field that is created is used to produceleakage currents that will flow between the breaker phase and ground, or from phase to phase,through the insulation. The amount of leakage current flow that is detected through use of themegger results in a megger meter readout of insulation resistance (in megohms).

To conduct the insulation resistance test, the megger is connected between two conductors(phases) and the megger is operated. Insulation resistance tests should be conducted phase-to-phase and phase-to-ground on all buswork, bus insulation, and on the line side and the load sideof the each installed circuit breaker. Megohmmeter test voltages should be 1000 V dc. Themegger is then connected across the open contacts of one of the circuit breaker phases, and themegger is operated. Similar megger readings are taken across each remaining phase contact pairfor every circuit breaker that is installed in the switchgear. The insulation resistance values arerecorded on a test data sheet or in the appropriate Saudi Aramco pre-commissioning form.

The Electrical Engineer should evaluate the insulation resistance (megger) test values to ensurethat the insulation resistance values that were recorded are greater than the manufacturer'sminimum value. If the manufacturer's minimum value is not provided, the value of the insulationresistance should be greater than the rated voltage + 1 kV in megohms. For example, a 600 Vrated system should have a measured insulation resistance that is greater than 1.6 megohms. Anyvalue of insulation resistance that is less than the minimum specifications should be investigated bythe Electrical Engineer who performs the test data evaluation.

The ratio of two time-resistance readings (such as a 60-second reading that is divided by a 30-second reading) is called a dielectric absorption ratio. The dielectric absorption ratio is useful inrecording information about the insulation. If the ratio is a ten-minute reading that is divided by aone-minute reading, the value is called the polarization index.

Because constant cranking is required for hand-cranked megger instruments, it is easier to run thetest for only 60 seconds and take the first reading at 30 seconds. When a power-operated meggerinstrument is used, the results of running the test for a full ten minutes and taking readings at oneand ten minutes will give the polarization index. An explanation of the evaluation of the dielectricabsorption ratio is provided in Work Aid 2.

In accordance with the International Electrical Testing Association (NETA), all of the acceptableinsulation resistance values should be determined through consultation with the appropriateswitchgear or circuit breaker manufacturer technical manual. The insulation resistance test shouldonly be performed during the commissioning of the low-voltage switchgear and circuit breakersand during the first few maintenance cycles.




Contact Resistance

The purpose of the circuit breaker contact resistance test is to identify contacts that are defectiveor detrimental to the operation of the circuit breaker. The contact resistance test may alsoidentify loose connections in a circuit breaker. To conduct the contact resistance test, the circuitbreaker must be withdrawn from its compartment. With the circuit breaker in the closed position,the leads of a digital, low-resistance ohmmeter should be placed across the line and load sides ofthe circuit breaker, and measurements should be taken. A digital, low-resistance ohmmeter candeliver enough power to the circuit breaker to make accurate readings that have more validitythan readings that can be obtained through the use of an ordinary multimeter. The contactresistance is recorded on a test data sheet or in the Saudi Aramco Low-Voltage Circuit BreakerPre-Commissioning form, P-008.

Increased contact resistance may be caused by contacts that do not make proper contact or bypitting on the surface of the contacts. The contact resistance values that are recorded should beconsistent with manufacturer recommended values. Generally, values of contact resistance inexcess of 200 micro-ohms and deviations of more than +/- 20% should be investigated. Technicaldata to evaluate the results of the contact resistance test can be found in the circuit breakermanufacturer technical manual or in the Saudi Aramco Low-Voltage Circuit Breaker Pre-Commissioning form, P-008.

Functional Operation

The functional operation test of the low-voltage switchgear and circuit breaker is the test thatensures that all of the switchgear and circuit breaker parts are able to work in conjunction witheach other so that the circuit breaker can perform its protective responsibilities. Most of the teststhat have been performed so far have been tests that ensure the performance of the individualparts of the low-voltage switchgear or circuit breaker. The functional operation test will ensurethat the parts will work together so that the switchgear operates correctly when it is installed in anelectrical system. To perform the functional operation test, the circuit breaker must be rackedinto its switchgear compartment and put into the test position. In the test position, control poweris connected to the circuit breaker, but the main power connections remain unconnected.

Circuit breakers provide for normal circuit switching operations and provide a means fordisconnecting a faulty circuit or equipment from the electric system with minimum damage anddisturbance. Circuit breakers must be capable of closing, carrying, and interrupting the largestfault possible at their location.




To test the operation of a circuit breaker trip circuit, the circuit breaker test position is used. Withthe circuit breaker in the test position, trip signals can be sent to the breaker via test equipment,and the proper operational response of the circuit breaker can be monitored. With the breakercontacts closed, a signal is sent to the instrument transformers that is strong enough to activate acircuit breaker trip signal. The artificial trip signal should trip the circuit breaker and open thecircuit breaker contacts at the specified fault current level and within the specified amount of time.The trip test process is repeated for each of the phases of the circuit breaker to ensure that a tripsignal that is initiated in any of the phases will trip the breaker. The functional operational triptest information (e.g., current level and time) is recorded on a test data sheet or in the SaudiAramco correct pre-commissioning form. The functional operational trip test should be repeatedfor each device that is capable of tripping the circuit breaker (e.g., undervoltage relay, overcurrentrelay, and thermal relay). Circuit breaker trip test data are recorded in the Saudi Aramco Low-Voltage Circuit Breaker Pre-Commissioning Form, P-008.

Auxiliary Equipment

Auxiliary equipment that is used in low-voltage switchgear includes control, indicating, and testequipment. Examples of such equipment include instrument transformers, fuses and fuse holders,relays, annunciators, and meters. The low-voltage switchgear and circuit breaker auxiliaryequipment should be inspected, checked, and tested in accordance with the Saudi AramcoSwitchgear-General Pre-Commissioning Form, P-023.




SYSTEM PRE-OPERATIONAL CHECK-OUT PHASE REQUIREMENTS

The system pre-operational checkout phase of the commissioning cycle for low-voltageswitchgear and circuit breakers provides an opportunity for Saudi Aramco personnel to performwiring checks, subsystem component check outs, and circuit breaker interlock performance tests.Each low-voltage switchgear and circuit breaker component is checked to ensure that it worksindividually and as a complete system.

Point-to-Point Wiring Check

Point-to-point wiring checks are performed to verify low-voltage switchgear and circuit breakercompliance with wiring diagrams and manufacturer's specifications. Terminations and terminalblocks are also checked for routing and labeling. During the point-to-point wiring checks, controland metering transformers and fuses are checked for proper application and type. If necessary,adjustments are made to components such as relays, annunciators, alarms, and targets.

Subsystem Checkout

Subsystems are checked to ensure that electrical continuity exists for control and protectivedevices. The proper operation of all subsystems is tested through use of controlled operation andcheck out of the controls and protective devices. Each subsystem is performance tested throughthe application of full operational voltage to each subsystem through the proper protectivedevices. A complete operational test is performed on equipment controls, interlocks, protectivedevices, and components with each subcircuit connected to its main system. During theperformance test, the main systems are still isolated and independent from plant systems. Beforethe equipment is connected to the plant system, subsystem performance testing is critical to ensurethe proper and safe operation of the equipment protection and control subsystems.

Interlocks

Operation tests are performed to ensure that the various switchgear and circuit breakeroperational interlocks function properly. For example, if the circuit breaker has a lockout relay,the lockout relay should be tested. Lockout relays are used in circuit breaker control circuitry toprevent a circuit breaker that has tripped due to fault conditions from closing until the lockoutrelay is manually reset. With the circuit breaker contacts open after a trip test, appropriate signalsshould be sent to the circuit breaker to close the circuit breaker. If the circuit breaker is equippedwith a lockout relay, the circuit breaker should not close even though the input signal indicatesthat the circuit breaker can reclose. All other operational interlock devices on the circuit breakerthat prevent the closure of the circuit breaker should be tested in a similar manner.




SYSTEM OPERATIONAL TESTING PHASE REQUIREMENTS

The operational testing phase of the commissioning cycle for low-voltage switchgear and circuitbreakers provides an opportunity for Saudi Aramco personnel to perform the following:

Switchgear source feed compatibility checks

Complete switchgear functional test

Switchgear source feed compatibility checks are performed on low-voltage switchgear and circuitbreakers through application of the full system voltage onto the switchgear with the circuitbreakers installed and racked in. With the voltage applied, voltage phasing, synchronizing, devicerotation, and other source feed compatibility checks are performed. Parallel or alternate powersource feed operations are also performed to ensure the total operation of the major componentsof the low-voltage switchgear system.

A complete system functional test is performed on low-voltage switchgear and circuit breakers toensure that the entire low-voltage electric power distribution system functions in accordance withthe system design. During the complete system functional test of low-voltage switchgear andcircuit breakers, the switchgear is allowed to assume a fully loaded condition for a period of timethat is adequate to obtain the maximum system temperature. After the loaded time period, theswitchgear temperatures are monitored. The low-voltage cable and busbar temperatures can bemonitored locally through use of temperature monitoring equipment or through use ofthermographic surveys. Temperature monitoring equipment can be temporarily installed at theswitchgear vents or in the switchgear. Particular attention should be paid to wiring and terminalconnections during the complete system functional test.




WORK AID 1: REFERENCES FOR EVALUATING LOW-VOLTAGE SWITCHGEARAND CIRCUIT BREAKERS UPON RECEIPT

Figure 7 shows a table of Saudi Aramco low-voltage power switchgear general requirements. Therequirements are excerpted from documented Saudi Aramco standards and specifications (e.g.,16-SAMSS-502).

GeneralRequire-

Compartmentalized, metal-enclosed switchgear must be used. Station-type cubicleswitchgear is not permitted for Saudi Aramco installations.

ments Design and installation of all switchgear must be in accordance withANSI/NFPA 70 (NEC).Short-circuit ratings of buses and current interrupting devices must not be less than105 percent of the calculated fault current at the point of application for presentand future planned conditions.The system design must use only fully-rated interrupting devices. Series-connected,series-rated or cascade breaker interrupting ratings are not allowed for SaudiAramco installations.Switchgear and motor control centers, except for switchracks, must be of theindoor type, installed in an air-conditioned environment.Power circuit breaker switchgear must be used in industrial facilities and hospitalsin place of switchboards.Switches, circuit breakers, motor controllers, and fuses must not be located inDivision I classified areas.Transformer line and load circuit breakers must have a continuous rating that is notless than the forced-cooled rating of the transformer.The current carrying capacity of the main switchgear bus must not be less than thecontinuous rating of the main incoming circuit breaker.When switchgear bus-tie circuit breakers are used, they must be fullyinterchangeable with the switchgear main circuit breakers.Bus-tie breakers must be kept normally-open. Controls must be provided to allowthe bus-tie breaker to be closed for a short period of time with both main breakersclosed to provide planned load transfers without a power outage.Short circuit ratings for switchgear with normally open bus-tie breakers must becalculated with the bus-tie breaker in the open position.Low-voltage switchgear must comply with 16-SAMSS-502.Low-voltage power circuit breakers must be of the manually operated type, exceptfor remote tripping, motor controller and specific auto/manual transfer applications.Each breaker line-side (and each bus section in bus-tie applications) must bemonitored by an unswitched voltmeter. Each switchgear main isolation breakerline-side must be monitored by an unswitched ammeter.

Figure 7: Saudi Aramco Low-Voltage PowerSwitchgear Requirements (From 16-SAMSS-502)




Figure 8 shows the data sheet that is used by Saudi Aramco to supply low-voltage switchgearinformation to the manufacturer (Vendor)

Figure 8: Low-Voltage Switchgear Buyer Data Sheet




WORK AID 1 (Cont'd)

Figure 8: Low-Voltage Switchgear Buyer Data Sheet (Cont'd)




Figure 9 shows the data sheet that is used by the manufacturer (Vendor) to supply low-voltageswitchgear information to Saudi Aramco

Figure 9: Low-Voltage Switchgear Vendor Data Sheet




Figure 10 shows a table of rating, design, construction, and auxiliary device information for low-voltage power circuit breaker installations.

Rating Low-voltage power circuit breakers must be designed, rated, manufactured,and tested in accordance with the latest issue or revision of the following:

ANSI/IEEE Standard C37.13 ANSI/IEEE Standard C37.16 ANSI/IEEE Standard C37.17 ANSI/IEEE Standard C37.50

Each unit of the low-voltage power circuit breaker must be able to interruptthe available short-circuit current that is indicated in Engineering Drawings.

Design Low-voltage circuit breakers must be the air circuit breaker type. Oil circuitbreakers and oil-immersed contactors are not permitted for Saudi Aramcoinstallations.Stationary mounted type power circuit breakers, fused circuit breakers,series-connected, series-rated or cascade rated circuit breakers must not beused.Low-voltage circuit breakers should be the dead-front, removable, drawouttype.Insulated case or molded case circuit breakers must not be used in the placeof power circuit breakers.

ConstructionLow-voltage power circuit breaker contacts must be operated by astored-energy mechanism in the form of springs. The springs must beelectrically controlled and must develop sufficient energy to close and latchthe circuit breaker.Low-voltage circuit breakers that are electrically operated must beequipped with the following:

Motor-operated, stored-energy operating mechanism. Shunt trip coil tripping mechanism. Trip push-button. Close push-button. Manual closing spring charging handle. Control devices (per the Engineering drawings).

The removable element in the metal frame configuration must consist of apower circuit breaker equipped with the necessary disconnecting contacts,wheels, and interlocks for drawout application.

Figure 10: Low-Voltage Power Circuit Breaker Rating, Design,Construction, and Auxiliary Device Installation Requirements




Construction(Contd)

The removable element must permit closing the compartment door with thecircuit breaker in the following four operational positions:

connected test disconnect fully withdrawn (or removed)

Each circuit breaker enclosure door must have a provision for padlocking(with up to three locks) in all three open (off) positions. When padlocked,the circuit breaker must not be able to be closed or moved to any otherposition.

AuxiliaryDevices

Each circuit breaker must be equipped with a position indicator that ismechanically connected to the operating mechanism.Unless specified otherwise, each circuit breaker must have a minimum offour convertible auxiliary contacts, in addition to those contacts that arerequired for circuit breaker operation and indication, that are available forSaudi Aramco use.An alarm switch must be provided for remote indication of an automatictrip by an overcurrent or other protective device. The alarm switch mustnot be operated by other trips.A minimum of one "a" (normally open) contact and one "b" (normallyclosed) contact must be provided.

Figure 10: Low-Voltage Power Circuit Breaker Rating, Design, Construction,and Auxiliary Device Installation Requirements (Cont'd)




Low-Voltage Switchgear and Circuit Breaker Applications Checklist

Low-voltage switchgear and circuit breaker rating information can be found on the equipmentnameplate or in the manufacturer technical manual. The following is a checklist that is used toverify that the type, rating, and operational characteristics of low-voltage switchgear and circuitbreakers are correct for the application based on Saudi Aramco and industry standards:

Verify that the low-voltage switchgear meets the Saudi Aramco requirements that areshown in Figure 10.

Verify that the low-voltage switchgear matches the information sheet that is providedin the data sheet (Figure 9).

Verify that the following low voltage switchgear nameplate ratings are correct for theapplication:

Rated Frequency

Rated Maximum Voltage

Rated Insulation Level

Rated Continuous Current

Rated Short-Time Current

Rated Short-Circuit Current

Verify that the circuit breakers do not use oil as the current interrupting medium.

Verify that the following low-voltage circuit breaker ratings are correct for theapplication:

Rated Frequency

Rated Maximum Voltage

Rated Continuous Current

Rated Short-Time Current

Rated Short-Circuit Current at the Rated Maximum Voltage (Interrupting Rating)

Verify that the circuit breaker's frame is sufficiently rated for the amount ofasymmetrical short-circuit current that the circuit can produce.

Verify that the circuit breaker's operational characteristics will provide adequateprotection for the electrical equipment that is in the circuit with the circuit breaker(e.g., long-time-delay protection; short-time-delay protection; and instantaneousprotection).




WORK AID 2: REFERENCES FOR EVALUATING LOW-VOLTAGE SWITCHGEARAND CIRCUIT BREAKER INSTALLATION AND TESTING

NETA Checklists

The following checklist is excerpted from the International Electrical Testing Association (NETA)checklist for the inspection of switchgear - general:

1. Inspect the physical, electrical, and mechanical condition.

2. Compare the equipment nameplate information with the latest single line diagramand report any discrepancies.

3. Inspect for proper alignment, anchorage, and grounding.

4. Inspect all bus connections for high resistance with a resistance ohmmeter. Checkthe tightness of the bolted bus joints through use of a calibrated torque wrench.Refer to the manufacturer's instructions for the proper foot-pound levels.

5. Key interlock systems should be physically tested to ensure that they operateproperly as follows:

Attempt to close a locked open device.

Attempt to open a locked closed device.

Attempt to exchange keys with devices that are not in their normal operatingpositions.

6. All switchgear doors, panels, and sections must be inspected for paint, dents,scratches, and proper fit.

7. Inspect the switchgear for cleanliness and proper lubrication.

8. Exercise all active components.

9. Inspect all indicating devices for proper operation.




The following circuit breaker test information is excerpted from the International ElectricalTesting Association (NETA) checklist for the inspection of low-voltage circuit breakers:

Circuit Breakers - Low Voltage (Air)

Visual and Mechanical Inspection

1. Inspect for physical damage, cleanliness, and nameplate compliance with the singleline diagram.

2. Mechanical operational tests must be made in accordance with the manufacturer'sinstruction manual.

3. The circuit breaker cell fit and element alignment must be checked.

4. Check the tightness of connections.

5. Dashpots must be removed, inspected, cleaned, and refilled with proper oil.

6. Make a very close inspection of the operation of main and arcing contact of thecircuit breaker to ensure that the springs that are responsible for maintainingprimary contact pressure are in good condition.

Electrical Tests

1. A contact resistance test must be performed.

2. An insulation resistance test must be performed at 1,000 volts dc for one minutefrom pole to pole, from each pole to ground, and across the open contacts of eachphase.

3. (Optional) The minimum pickup current of trip devices must be determined byprimary current injection.

4. The long time delay must be determined by primary injection at 300% of thepickup current.

5. Short time pickup and time delay must be determined by primary injection ofcurrent.

6. The instantaneous pickup current must be determined by primary injection.




7. Trip unit reset characteristics must be verified.

8. Adjustment must be made for final settings in accordance with the engineer'sprescribed settings.

9. Auxiliary protective devices, such as ground fault or under voltage relays, must beactivated to ensure operation of shunt trip devices.

10. If the circuit breaker has a charging motor, the springs and other devices that areassociated with this charging motor must be closely inspected. The circuit breakermust be electrically operated to verify the performance of the limit switchesresponsible for stopping and starting the charging motor.

11. Circuit breakers with solid state trips must be tested in accordance withmanufacturer's instructions.

a. Primary injection is recommended to evaluate complete trip circuitoperations.

b. Secondary injection can be used for evaluating the electronic portion of thetrip unit.

Test Values

1. Contact resistance must be determined in micro-ohms or millivolts. Values thatdeviate from adjacent poles or similar breakers by more than 50% should beinvestigated.

2. Insulation resistance must not be less the 50 megohms.

a. Do not megger solid state devices.

3. Minimum pickup current, trip times, and instantaneous pickup values must beadjusted to engineer settings. Test values should fall within manufacturer'spublished time-current characteristic tolerance band.




NETA Values for Overcurrent Trip Test(at 300% of Rated Continuous Current of Breaker)

Voltage,Volts

Range ofRated

ContinuousCurrent,Amperes

Tripping Time, Seconds

Minimum MaximumTrippingTimes for

CableProtection*

ThermalBreakers

MagneticBreakers

Maximum

(1) (2) (3) (4) (5) (6)240 15-45 3 -- 50 100240 50-100 5 -- 70 200600 15-45 5 5 80 100600 50-100 5 5 150 200240 110-225 10 5 200 300600 110-225 10 -- 200 300600 250-450 25 -- 250 300600 500-600 25 10 250 350600 700-1200 25 10 450 600600 1400-2500 25 10 600 750

* These values are based on heat test conducted by circuit breaker manufacturers onconductors in conduit.




Figure 11 shows a table of low-voltage switchgear construction general requirements.

General The metal-enclosed low-voltage switchgear must be completely factoryassembled, wired, adjusted, and tested.Switchgear design must have a ventilated and vermin proof enclosure, NEMAType 1, and must permit future extension at each end, unless specifiedotherwise.It must consist of a stationary structure assembly and one or more removableair or vacuum circuit breaker units.All circuit breakers installed in the switchgear assembly (except for spaceheater circuit breakers) must have the three-phase short circuit current ratingequal to or larger than the rating of the switchgear assembly.The overall height of the switchgear lineup must be maximum 2300 mm (90in.).

Figure 11: Low-Voltage Switchgear Construction General Requirements




Figure 12 shows a table of low-voltage switchgear stationary structure construction requirements.

StationarySwitchgearStructure

The stationary steel structure assembly must be a self-contained multiple unithousing having a required number of vertical sections.

Each incoming or tie power circuit breaker must be in a separate verticalsection.Each incoming line, tie, or 3200 A and above feeder power circuit breakermust be located in the lower portion of its vertical section.A compartment that is identified as "SPARE" must be available (including apower circuit breaker, protective relays, control switches, indicating lights,etc.).The continuous current rating of the "SPARE" circuit breakers must be asspecified in Engineering Drawings (Data Sheet No.1).A compartment that is designated as "SPACE" must be developed similarly tothe "SPARE ," but without the installed circuit breaker.A compartment that is designated as "FUTURE" must be developed withstationary elements (e.g., primary studs, CTs, sliding rail, rail guides, leveringmechanism, safety interlocks, secondary disconnects, circuit breaker controldevices, and wiring).An additional compartment, within the switchgear assembly and readilyavailable, must be provided to store engineering and installation drawings,instruction books, parts list, special tools, and spare fuses.When specified, the "SPARE", "SPACE", and "FUTURE" compartmentsmust be located at the end of each metal-enclosed switchgear assembly and asspecified in the Engineering Drawings.The rear sections of all vertical sections must be developed as separate spacesfor main and incoming buses or cables and for outgoing power cables andpower cable terminations.All switchgear compartments must be separated by grounded steelpanels-barriers with a nominal thickness that is not less than 3 mm (MSGNo.11 or 0.1196 in.).Other barriers, blank steel panels, and formed steel doors must be made ofsheet metal with minimum thickness of 1.9 mm (MSG No.14 or 0.0747 in.).

Figure 12: Low-Voltage Switchgear Stationary Structure Requirements




Figure 13 shows a table of low-voltage switchgear bus construction requirements.

Buses(General)

Metal-enclosed low-voltage switchgear assemblies must be furnished completewith three-phase main and feeder buses, neutral bus (if spe

commissioning switchgear, low-voltage and circuit breakers

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