Powell Electrical Systems, Inc.
Guide Specification
PowlVac-AR® 5kV and 15kV Metal-Clad Switchgear
1.0General
1.1The intent of this specification is to have the manufacturer furnish the equipment and material specified herein complete and operable.
1.2All standard accessories to the equipment specified shall be supplied even if not specifically mentionedin this specification.
1.3Material used in the fabrication of the specified equipment shall be new, unused, and of the highestquality available.
2.0Scope
2.1Work Included
2.1.1Furnish metal-clad switchgear as detailed in Sections 3.0 through 12.0 of these specifications. Anydrawings or data sheets attached to the inquiry shall be considered part of this specification. Theequipment shall be complete and operable.
2.1.2Provide production tests and inspections as detailed in Section 13.0 of this specification.
2.1.3The manufacturer shall prepare the equipment for transportation to the jobsite, advise and monitorthe load out of this material so as to reasonably prevent the possibility of shipping damage.
2.1.4It shall be the responsibility of the manufacturer to furnish all material, connections, splices, links,special tools, and information required to completely reassemble the switchgear in the field or tofacilitate the installation of the switchgear when performed by an electrical contractor.
2.1.5Guarantee the performance of the switchgear during a reasonable warranty period. This warrantyshall, at a minimum, cover the equipment for eighteen (18) months from time of shipment or twelve(12) months from date of energization whichever occurs first.
2.1.6Supply all drawings, documentation, and information detailed in Section 14.0.
2.2Work Not Included
2.2.1Field installation of switchgear, unless otherwise specified.
2.2.2Connection of incoming cables or bus.
2.2.3Connection of outgoing branch feeder cables or bus.
2.2.4Connection of external control cables or wiring.
3.0Applicable Codes and Standards
3.1The applicable codes and standards listed below should be considered as part of this specification. Thelatest revision in effect at time of inquiry shall apply for all standards referenced.
3.1.1National Electrical Manufacturers Association (NEMA)
3.1.2Institute of Electrical and Electronic Engineers (IEEE)
3.1.2.1IEEE C37.20.7
3.1.3National Electric Code (NEC)
3.1.4American National Standards Institute, Inc. (ANSI)
3.1.4.1ANSI C37.04
3.1.4.2ANSI C37.06
3.1.4.3ANSI C37.09
3.1.4.4ANSI C37.20.2
3.1.5Underwriters Laboratories (UL)
3.2It shall be the manufacturer's responsibility to be knowledgeable of these standards and codes.
4.0Service and Environmental Conditions
4.1Unless otherwise specified this equipment is intended for use in ambient temperatures that do notexceed a maximum of 40°C (104°F) or a minimum of -30°C (-22°F).
4.2This equipment is intended for use in an area where the elevation is less than 3300 feet above sealevel. Above 3300 feet a de-rating factor as prescribed by ANSI standards will apply.
5.0Basic Construction
5.1The equipment supplied shall be of metal-clad construction using welded, industrial-riveted, or boltedsheet steel. The construction shall be self-supporting and free standing. All metal work shall be freefrom burrs and sharp edges.
5.2The equipment shall be suitable for industrial or utility service.
5.3The equipment shall be constructed for indoor installation and use.
5.4The Switchgear shall be:
Arc resistant ANSI Type 1, arc resistant from the front only
Arc resistant ANSI Type 2, arc resistant from the rear, sides, topand bottom
Arc resistant ANSI Type 2B, Arc resistant from rear, sides, top, bottom and between
adjacent cubicles
5.5The Switchgear instrument compartment shall meet ANSI Suffix B, arc resistant integrity shall be maintained with the instrument compartment door in the open position.
5.6The manufacturer shall provide minimum room dimensions and other guidelines related to theperformance of the arc resistant switchgear.
5.6.1Where applicable, the manufacturer shall provide a method of venting the arc fault byproducts outof the equipment room.
5.6.2Where the venting is intended to penetrate an external wall, the vent shall be covered such that itmeets all specified environmental requirements (e.g., rain-tight, dust-tight, vermin-proof).
5.6.3For double ended switchgear (Main-Tie-Main) application the vendor shall furnish two separate distinct and independent plenum systems.
5.7Front Compartment Doors
5.7.1Each compartment housing a high voltage device shall be provided with steel hinged door(s).
5.7.2The door(s) shall be provided with provisions for padlocking and a view window for observingcircuit breaker position.
5.7.3The door(s) shall be capable of withstanding the effects of an internal arcing fault as proven bysuccessful testing per IEEE C37.20.7.
5.7.4No tie down bolts or other manual means shall be used to secure the door. A single handle mustbe provided to operate all required latching.
5.7.5No special tools shall be required to latch the front compartment door or engage the arc resistantfunction.
5.7.6Vendor can only furnish a single PT compartment above a breaker compartment.
5.7.7Multiple stacking of PT compartments above a breaker is not acceptable.
5.7.8The following interlocks shall be provided:
5.7.8.1Interlock to prevent racking a circuit breaker into a compartment with the door in the openposition. This interlock may be manually circumvented for maintenance purposes by adeliberate act on the part of the operator. This override shall require a minimum of twoseparate and distinct operations, neither of which is considered to be part of normaloperations.
5.7.8.2Interlock to prevent opening the compartment door unless the circuit breaker is in thedisconnected position and safety shutters are closed. This interlock shall also include anindication of shutter position on the front of the compartment door. This interlock may bemanually circumvented for maintenance purposes by a deliberate act on the part of theoperator. This override shall require a minimum of two separate and distinct operations,neither of which is considered to be part of normal operations. This interlock shall resetshould the compartment door be closed following maintenance after circumvention.
5.7.9Provisions for racking of the circuit breaker between the connected and disconnected positions shall be provided with the door in the closed position.
5.8Rear Compartment Doors
5.8.1Each rear compartment shall be provided with steel hinged door(s).
5.8.2Each rear compartment door shall be provided with provisions for padlocking.
5.8.3When specified, the rear door(s) shall be capable of withstanding the effects of an internal arcingfault as proven by successful testing per IEEE C37.20.7.
5.8.4A single handle is required to operate all required latching. Additional tie down bolts areacceptable. No special tools are required.
5.8.5The following optional interlock may be provided if specified on drawings or data sheets:
5.8.5.1Interlock to prevent opening the rear door(s) unless the removable element (circuit breaker)in the front compartment of the vertical section is in the disconnected position. This interlockmay be manually circumvented for maintenance purposes by a deliberate act on the part ofthe operator. This override shall require a minimum of two separate and distinct operations,neither of which is considered to be part of normal operations. This interlock shall resetshould the compartment door be closed following maintenance after circumvention.
5.9Instrument compartments shall have doors that have been tested per IEEE C37.20.7.
5.10Plenums
5.10.1Each arc resistant switchgear assembly shall include a plenum, to direct fault gases and associated pressure wave, installed on top of switchgear and extending over the entire length.
5.10.2For switchgear assemblies that are free-standing or not installed within a Powell PCR®, the plenum shall be self supporting and attach directly to the top of the switchgear.
5.10.3For switchgear assemblies that are installed within a Powell PCR, the plenum may optionally be constructed integral to the PCR and use portions of the wall or ceiling as barriers.
5.10.4In all cases, exhaust vents extending from the plenum to the outside shall be included with the switchgear assembly.
5.10.5The plenum may be shipped separately and installed in the field.
5.10.6The plenum shall be constructed of heavy gauge steel in such a manner to assure physical integrity in the event of an internal arc fault.
5.11Cooling vents may be provided in the switchgear for ventilation or cooling purposes.
5.11.1Design must conform to the applicable IEEE standard construction and pass the requirements of IEEEC37.20.7 with respect to emission of ionized gas.
5.11.2Design must be constructed so that accidental contact cannot compromise the ability of the design towithstand an arcing fault condition. Design must be constructed so that material cannot become trappedwithin the louver assembly and thereby prevent the arc resistant features from functioning.
5.12When roof ventilation is required, provisions shall be included to prevent access by vermin.
5.13The switchgear shall be capable of extension from either end at a future date without modification toexisting structural members unless otherwise noted. Means shall be provided to meet all requirements of the exposed ends of the switchgear assembly. The described means shall not prevent future additions to the switchgear assembly and shall be tested to IEEE C37.20.7.
5.14It shall be the manufacturer's responsibility to coordinate all necessary alignment and interconnectionbetween component sections. The entire assembly must be electrically and mechanically assembledinto one single line-up prior to final inspection and shipment.
5.15The equipment must be shipped complete, without missing components or "ship shorts". Purchaser maywaive this requirement upon request prior to shipment.
5.16To facilitate ease of handling, each shipping section will be no more than two (2) vertical structures. Each shipping section shall be provided with lifting lugs adequately sized for the equipment.
5.17Power circuit breakers shall be shipped and packaged separately from the switchgear structure.
5.18The depth of the finished equipment shall be sufficient to allow for entrance, bending, and termination ofpower cables. Individual units shall be provided for top or bottom entrance as specified. A minimum of26 inches of clearance between terminal pads and the cable entrance shall be provided.
5.19Power circuit breakers and voltage transformer assemblies shall be drawout construction to providemaximum operator safety.
5.20Safety interlocks and barriers as required by ANSI standards shall be provided to prevent personnelfrom inadvertent exposure to the bus while the switchgear is energized.
5.21A continuous silver-plated or tin-plated copper ground bus measuring ¼" x 2" min shall be provided for the full length ofthe switchgear assembly. The ground bus shall be capable of carrying the rated short circuit current ofthe installed circuit breakers for a minimum of 2 seconds.
5.22In order to minimize condensation, each cubicle designed for outdoor application shall have a spaceheater.
5.22.1Space heaters may be wired with other space heaters in parallel and shall be provided with asingle adjustable thermostat to maintain cubicle temperature at desired levels.
6.0Power Circuit Breakers
6.1The power circuit breakers shall be electrically operated, three-pole, drawout type. The interruptingmedium shall be vacuum.
6.2The circuit breakers shall have an ANSI rating structure based on a K factor of 1.0 and interruptingrating of ______[36kA at 5kV, 50kA at 5kV, 63kA at 5kV, 25k at 15kV, 36kA at 15kV,50kA at 15kV, 63kA at 15kV] (user to specify applicable rating).
6.3The basic insulation level (BIL) of the power circuit breakers shall be not less than 60kV for 5kVapplications and not less than 95kV for 15kV applications.
6.4The continuous current capacity of each power circuit breaker shall be 1200A, 2000A, or 3000A asindicated on the drawings or data sheets. An increased continuous current rating of 4000A may beachieved by fan forced air cooling.
Capacitor feeder circuit breakers shall be definite purpose type rated and tested for capacitor switching duty. Vendor shall provide a copy of certified test reports with the proposal.
Generator feeder circuit breakers (10-100MVA) application shall be specifically rated for the rigorous service duty requirements of a generator circuit application in accordance with standard C37.013-1997. Vendor shall provide a copy of certified test report with the proposal.
6.5Primary line and load connections shall be self aligning.
6.6The drawout mechanism shall be configured to operate with the compartment door closed.
6.7The drawout mechanism shall hold the power circuit breaker rigidly in the fully connected positions.
6.8The drawout mechanism shall require less than 25 turns to move the circuit breaker from the connectedto the disconnected positions.
6.9Each circuit breaker will have four (4) wheels to allow for easy maintenance and movement.
6.10No lift truck, rails, ramps, channels, or transport device of any kind shall be required in order to move acircuit breaker from floor level to the fully connected position.
6.11Interlocks shall be provided to prevent the circuit breaker from disconnecting from the main bus stabsunless the circuit breaker is open.
6.12The power circuit breaker ground connection must be capable of carrying the short circuit rating of thecircuit breaker for a minimum of 2 seconds and must also be capable of withstanding the peak currentvalue (or 2.7 times the rated short circuit current) of the circuit breaker.
6.13A grounded metal shutter system shall automatically cover the line and load stab connections when thecircuit breaker unit is moved to the disconnected position. The shutter shall be pad-lockable in theclosed position.
6.14Auxiliary contacts to provide circuit breaker element position indication (Truck Operated Cell switch orTOC) and to provide circuit breaker contact position (Mechanism Operated Cell switch or MOC) shall beavailable when specified. Both switch operator and switch must be visible and accessible from thefrontof the low voltage compartment when the circuit breaker is in the fully connected position.
6.15Circuit breaker operating mechanism shall be completely trip free both mechanically and electrically. Mechanical tripping of a closed circuit breaker shall be possible with the front cubicle door closed.
6.16Control power and control circuit breaker is in the connected position. The circuit breaker cannot be inserted without the plug in place.
6.17For operator safety the circuit breaker shall have provision for padlocking it in the disconnected position.
6.18Each circuit breaker shall have a mechanical operations counter.
6.19Each circuit breaker shall have an easily accessible means for contact wear indication.
6.20Each circuit breaker shall have a mechanical emergency push-to-trip switch to be utilized in case of loss of control power.
6.21A steel interference plate shall be mounted in the bottom of each circuit breaker cell assembly whichonly allows a higher rated circuit breaker (voltage, current, interrupting rating) to be inserted into a lowerrated cell assembly.
7.0Power Bus
7.1Main power bus shall be copper bar.
7.2Main power bus shall be silver-plated or tin-plated along the entire length to a thickness between 0.0001 inches and0.0005 inches.
7.3The entire bus, except for terminations, shall be completely isolated with metal barriers and insulated asrequired by ANSI Metal-Clad construction standards.
7.4The main power bus shall be supported on molded cycloaliphatic epoxy insulators (glastic for 5kVapplications) and mechanically braced to withstand stresses resulting from current values equivalent tothe close and latch rating of the largest circuit breaker in the assembly.
7.5Molded cycloaliphatic epoxy inserts are required whenever bus passes through a barrier of any type on15kV applications.
7.6Bus joints shall be made with sufficient bolts and torqued to preserve initial contact pressure over theservice life of the equipment. Bolts that are torqued to appropriate levels at the factory shall be identifiedwith paint markings. Bolts shall be rated Grade 5 and plated for corrosion resistance.
7.7Power bus orientation shall be A-B-C top to bottom, front to back, and left to right when viewed from the front of the switchgear.
8.0InstrumentTransformers
8.1CurrentTransformers (CT)
8.1.1Current transformers shall be installed so that they can be easily maintained or replaced from thefront of the switchgear without entering the power bus or cable termination compartments. Unlessspecified otherwise, the polarity marking shall be toward the circuit breaker.
8.1.2Each current transformer shall be rated to withstand the thermal and mechanical stresses imposedby the short circuit rating of the applied circuit breaker.
8.1.3The secondary termination of current transformers shall be on a shorting terminal block.
8.1.4Current transformers shall have a rated 5 ampere secondary current unless otherwise specified.
8.1.5Metering and relaying accuracy classification shall be as specified in the data sheets and shall besuitable for the connected burden.
8.1.6Current transformers, when installed, shall be fully rated for the appropriate voltage class. Currenttransformers with 600 volt insulation levels may be used if installed with fully rated insulationbarriers such as around primary disconnect bushing assemblies.
8.2Voltage Transformers (VT)
8.2.1Voltage transformers and associated fuse assemblies shall be installed in drawout assemblies sothat they may be readily disengaged from the power bus.
8.2.2Where physical size restrictions do not allow the voltage transformer to be mounted in a drawoutassembly, the voltage transformer may be stationary mounted with the fuses only mounted in thedrawout unit. The appropriate interlocks shall be provided to insure maximum operator safety.
8.2.3When moved to the withdrawn position, the transformer drawout unit shall automatically ground the transformer primary windings and the fuses. A visible indication of positive ground is required. Theground may be a momentary or sweeping action that occurs as the unit moved out of theconnected position.
8.2.4Voltage transformers shall have 120 volt secondaries unless otherwise specified.
8.2.5Voltage transformers shall have an accuracy rating comparable to the metering equipment and aburden capacity equal to twice the initial load.
8.2.6Current limiting fuse protection shall be provided on the primary side of each voltage transformer.
8.2.7Voltage transformers shall be designed to withstand the basic impulse level of the switchgear.
8.2.8Primary connection to voltage transformers can be hard copper bus upon request.
8.3Control Power Transformers (CPT)
8.3.1Control power transformers shall be mounted for sizes above 15kVA with the primary current limiting fuses mounted in a drawout unit.
8.3.2When moved to the withdrawn position, the fuse drawout unit shall automatically ground the fuses.
8.3.3Each control power transformer shall have a secondary molded case circuit breaker interlockedwith the drawout assembly so that the load is disconnected prior to drawout.
8.3.4All control power transformers shall be provided with either one (1) 7-1/2% tap or
(2) 2-1/2% tapsabove and below rated voltage (user to specify).
8.3.5Secondary winding shall be 120/240VAC, single phase, 60Hz, 3 wire unless otherwise specified.
8.3.6Primary connection to control power transformers can be hard copper bus upon request.
8.3.7Control power transformer larger than 50KVA need to placed remote from the switchgear,
9.0Control and Secondary Wiring
9.1Control wiring shall be SIS type #14 AWG, 41 strand extra flexible, stranded copper or larger.
9.2Current transformer secondary wiring shall be SIS type #12 AWG, 65 strand, extra flexible, strandedcopper or larger.
9.3Current transformer secondary wiring shall terminate on shorting type terminal blocks.
9.4All control wiring shall be UL listed and have a VW-1 flame retardant rating.