Powell Electrical Systems, Inc.
Guide Specification
PowlVac 38AR® 38kV Arc Resistant 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 mentioned in this specification.
1.3Material used in the fabrication of the specified equipment shall be new, unused, and of the highest quality available.
2.0Scope
2.1Work Included
2.1.1Furnish metal-clad switchgear as detailed in Sections 3.0 through 12.0 of these specifications. Any drawings or data sheets attached to the inquiry shall be considered part of this specification. The equipment shall be complete and operable.
2.1.2Provide production tests and inspections as detailed in Section 13.0 of this specification.
2.1.3To reasonably prevent the possibility of shipping damage, the manufacturer shall prepare the equipment for transportation to the jobsiteand monitor the load out of this material.
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 to facilitate 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 warranty shall, 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. The latest 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 C37.20.2
3.1.2.2IEEE 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
3.1.4.4Canadian Standards Association
3.2It shall be the manufacturer's responsibility to be knowledgeable of these standards and codes.
4.0Service and Environmental Conditions
4.1.1The switchgear described in these specifications shall be indoor construction, with devices arranged as shown on contract drawings.
4.2Unless otherwise specified this equipment is intended for use in ambient temperatures that do not exceed a maximum of 40°C (104°F) or a minimum of -30°C (-22°F).
4.3This equipment is intended for use in an area where the elevation is less than 3300 feet above sea level. Above 3300 feet a de-rating factor as prescribed by ANSI standards will apply.
4.4The switchgear shall be installed in a clean environment that is relatively dust free.
4.5The switchgear and major components shall be tested and certified to meet all applicable seismic requirements of Uniform Building Code (UBC) at the installation site.
4.6The installing contractor shall follow mounting and installation guidelines as specified by the manufacturer.
4.7
5.0Basic Construction
5.1The equipment supplied shall be of metal-clad construction using weldedor bolted sheet steel. The construction shall be self-supporting and free standing. All metal work shall be free from burrs and sharp edges.
5.2The equipment shall be suitable for industrial or utility service and constructed with an enclosure as specified on the drawings or data sheets.
5.3The manufacturer shall provide minimum room dimensions and other guidelines related to the performance of the arc resistant switchgear.
5.4Each individual vertical section of the switchgear shall include integral and top mounted pressure release flaps to facilitate a controlled upward release of arc created overpressures, smoke, and gasses. Individual vertical sections shall be of a unitized design to allow removal of a damaged vertical section after a fault incident, without requiring the removal of the adjacent vertical sections.
5.5The rated enclosure internal arc-short circuit duration shall be 0.5 seconds.
5.6An enclosed arc-chamber with arc duct exit shall be furnished for installation above the switchgear. Arc-duct exit location shall be as shown on the drawing. Arc exhaust shall be vented from the arc-chamber to the exit location via arc-duct as shown on the drawings. Provide arc duct metal barriers as required to vent the arc exhaust from the arc-chamber to the exit location shall be provided. Field assembly of the arc-chamber and arc-duct shall be by installing contractor.
5.7Where applicable, the manufacturer shall provide a method of venting the arc fault byproducts out of the equipment room. Such venting shall be tested as part of the equipment in accordance with IEEE C37.20.7 and shall be held to the same performance level as the switchgear.
5.8Where the venting is intended to penetrate an external wall, the vent shall be covered such that it meets all specified environmental requirements (e.g., rain-tight, dust-tight, vermin-proof).
5.9The switchgear shall be capable of extension from either end at a future date without modification to existing structural members unless otherwise noted.
5.10Means 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.
5.11It shall be the manufacturer's responsibility to coordinate all necessary alignment and interconnection between component sections. The entire assembly must be electrically and mechanically assembled into one single line-up prior to final inspection and shipment.
5.12The equipment must be shipped complete, without missing components or "ship shorts". Purchaser may waive this requirement upon request prior to shipment.
5.13To 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.
5.14Power circuit breakers shall be shipped and packaged separately from the switchgear structure unless equipment is installed within a PCR.
5.15The depth of the finished equipment shall be sufficient to allow for entrance, bending, and termination of power cables. Individual units shall be provided for top or bottom entrance as specified. A minimum of 38 inches of clearance between terminal pads and the cable entrance shall be provided.
5.16Each switchgear cubicle shall have, at a minimum, 11 gauge sheet steel side panels. This provides two (2) steel sheets between adjacent sections so as to minimize the chance of fault propagation between sections.
5.17Main bus pass through insulators and main bus standoff insulators shall be molded cycloaliphatic epoxy or urethane.
5.18The main bus joints shall be insulated using vinyl joint cover boots with re-useable hardware.
5.19Main bus can be 1200A, 2000A or 3000A rating.
5.20The bus shall be braced to withstand fault currents equal to the close and latch rating of the breakers.
5.21All bus shall be covered with Epoxy insulation system that is flame retardant and track resistant.
5.22In order to minimize condensation, each cubicle designed for outdoor application shall have a space heater. Space heaters may be wired with other space heaters in parallel and shall be provided with a single adjustable thermostat to maintain cubicle temperature at desired levels.
6.0Arc Resistant Construction Types
6.1Type 1 gives the equipment arc resistant protection on the front only as defined by IEEE C37.20.7.
6.2Type 2 gives the equipment arc resistant protection on the front, rear and sides of the gear as defined by IEEE C37.20.7.
6.3Instrument compartment shall meet ANSI definition SuffixB; the arc resistant integrity shall be maintained with the instrument compartment door in the open position.
7.0Front Compartment Doors
7.1Each compartment housing a high voltage device shall be provided with steel hinged door.
7.2The door shall be provided with provisions for padlocking and a view window for observing circuit breaker position.
7.3The door shall be capable of withstanding the effects of an internal arcing fault as proven by successful testing per IEEE C37.20.7.
7.4No tie down bolts or other manual means shall be used to secure the door. A single handle must be provided to operate all required latching.
7.5No special tools shall be required to latch the front compartment door or engage the arc resistant function.
8.0Rear Compartment Doors
8.1Each rear compartment shall be provided with steel hinged door(s).
8.2Each rear compartment door shall be provided with provisions for padlocking.
8.3When Type 2 is specified, the rear door shall be capable of withstanding the effects of an internal arcing fault as proven by successful testing per IEEE C37.20.7.
8.4A single handle is required to operate all required latching.
9.0Instrument compartmentsshall have doors that have been tested per IEEE C37.20.7.
9.1Design must conform to the applicable IEEE standard construction and pass the requirements of IEEE C37.20.7 with respect to emission of ionized gas.
9.2When roof ventilation is required, provisions shall be included to prevent access by vermin.
10.0Power Circuit Breakers
10.1The power circuit breakers shall be electrically operated, three-pole, drawout type. The power circuit breakers shall use vacuum as an interrupting medium.
10.2Power circuit breakers shall be draw out construction to provide maximum operator safety.
10.3Safety interlocks and barriers as required by ANSI standards shall be provided to prevent personnel from inadvertent exposure to the bus while the switchgear is energized.
10.4A continuous silver-plated or tin-plated copper ground bus measuring ¼" x 2" shall be provided for the full length of the switchgear assembly. The ground bus shall be capable of carrying the rated short circuit current of the installed circuit breakers for a minimum of 2 seconds.
10.5The circuit breakers shall have an ANSI rating structure based on a K factor of 1.0 and interrupting rating of 40kA rms sym.
10.6The basic insulation level (BIL) of the power circuit breakers shall be not less than 150kV.
10.7The continuous current capacity of each power circuit breaker shall be 1200A,2000Aor 3000A as indicated on the drawings or data sheets. The 3000A rating shall be achieved without fan cooling
10.8The circuit breakers are available with 5-cycle standard interrupting time or 3-cycle as an option.
10.9Primary line and load connections shall be self aligning.
10.10The drawout mechanism shall be fully functional with the front cubicle door closed and shall hold the power circuit breaker rigidly in the fully connected position.
10.11The drawout mechanism shall require less than 25 turns to move the circuit breaker from the connected to the disconnected positions.
10.12Each circuit breaker will have four (4) wheels to allow for easy maintenance and movement.
10.13No lift truck, rails, ramps, channels, or transport device of any kind shall be required in order to move a circuit breaker from floor level to the fully connected position.
10.14Interlocks shall be provided to prevent the circuit breaker from disconnecting from the main bus stabs unless the circuit breaker is open.
10.15The power circuit breaker ground connection must be capable of carrying the short circuit rating of the circuit breaker for a minimum of 2 seconds and must also be capable of withstanding the peak current value (or 2.7 times the rated short circuit current) of the circuit breaker.
10.16A grounded metal shutter system shall automatically cover the line and load stab connections when the circuit breaker unit is moved to the disconnected position. The shutter shall be pad-lockable in the closed position.
10.17Auxiliary contacts to provide circuit breaker element position indication (Truck Operated Cell switch or TOC) and to provide circuit breaker contact position (Mechanism Operated Cell switch or MOC) shall be available when specified. Both switch operator and switch must be visible and accessible from the front of the low voltage compartment when the circuit breaker is in the fully connected position.
10.18Circuit 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.
10.19Control power and control circuit wiring shall be connected to the power circuit breaker by means of a 24 pin front connected umbilical cord and plug. This plug shall be mechanically interlocked. The plug shall not be removable while the circuit breaker is in the connected position. The circuit breaker cannot be inserted without the plug in place.
10.20For operator safety the circuit breaker shall have provision for padlocking it in the disconnected position.
10.21Each circuit breaker shall have a mechanical operations counter.
10.22Each circuit breaker shall have an easily accessible means for contact wear indication.
10.23A steel interference plate shall be mounted in the bottom of each circuit breaker cell assembly which only allows a higher rated circuit breaker (voltage, current, interrupting rating) to be inserted into a lower rated cell assembly.
10.24Each breaker shall be operated by a motor-charged stored energy spring mechanism, charged normally by a universal electric motor and in an emergency by a manual handle.
10.25The Breaker front cover shall be removable when the breaker is withdrawn for ease of inspection and maintenance
10.26The breakers shall be electrically operated by the following control voltages; 120 or 240 volt AC close and AC capacitor trip.
10.27AC control voltage shall be supplied by customer or derived from a control power transformer mounted in the switchgear and backed by a capacitor trip device.
10.28DC control voltage shall be supplied by purchaser.
10.29Each breaker shall be complete with control switch and red and green indicating lights to indicate breaker contact position.
11.0Power Bus
11.1Main power bus shall be tubular or rectangular bar type copper with silver-plated or tin-plated joints.
11.2Main power bus shall be silver-plated or tin-plated along the entire length to a thickness between 0.0001 inches and 0.0005 inches.
11.3The entire bus shall be completely isolated with metal barriers and insulated as required by ANSI Metal-Clad construction standards. Epoxy based bus insulation system is preferred.
11.4The main power bus shall be supported on molded cycloaliphatic epoxy insulators and mechanically braced to withstand stresses resulting from current values equivalent to the close and latch rating of the largest circuit breaker in the assembly.
11.5Molded cycloaliphatic epoxy inserts are required whenever bus passes through a barrier of any type.
11.6Bus joints shall be made with sufficient bolts and torqued to preserve initial contact pressure over the service life of the equipment. Bolts that are torqued to appropriate levels at the factory shall be identified with paint markings. Bolts shall be rated Grade 5 and plated for corrosion resistance.
11.7Power 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.
11.8Main bus can be 1200A, 2000A or 3000A rating. The temperature rise of the bus and connections shall be in accordance with ANSI standards and documented by design tests.
11.9All bus shall be covered with Epoxy insulation system that is flame retardant and track resistant.
11.10A bare copper ground bus shall extend the entire length of the switchgear and be rated to withstand for 2 seconds the short circuit current rating of the lineup.
12.0Instrument Transformers
12.1Current Transformers (CT)
12.1.1Current transformers shall be installed so that they can be easily maintained or replaced from the front of the switchgear without entering the power bus or cable termination compartments. Unless specified otherwise, the polarity marking shall be toward the circuit breaker.
12.1.2Each current transformer shall be rated to withstand the thermal and mechanical stresses imposed by the short circuit rating of the applied circuit breaker.
12.1.3The secondary termination of current transformers shall be on a shorting terminal block.
12.1.4Current transformers shall have a rated 5 ampere secondary current unless otherwise specified.
12.1.5Metering and relaying accuracy classification shall be as specified in the data sheets and shall be suitable for the connected burden.
12.1.6Current transformers, when installed, shall be fully rated for the appropriate voltage class. Current transformers with 600 volt insulation levels may be used if installed with fully rated insulation barriers such as around primary disconnect bushing assemblies.
12.2Voltage Transformers (VT)
12.2.1Voltage transformers and associated fuse assemblies shall be installed in drawout assemblies so that they may be readily disengaged from the power bus.
12.2.2Where physical size restrictions do not allow the voltage transformer to be mounted in a drawout assembly, the voltage transformer may be stationary mounted with the fuses only mounted in the drawout unit. The appropriate interlocks shall be provided to insure maximum operator safety.
12.2.3When 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. The ground may not be a momentary or sweeping action, but must be maintained as long as the drawout assembly is not in the connected position. The ground must be maintained even in the event of blown fuses.
12.2.4The voltage transformer primary connections shall utilize Epoxy Hipoxy-2000® insulated bus bar.
12.2.5An insulating shutter system shall automatically cover the line and load stab connections when the voltage transformer unit is moved to the disconnected position.
12.2.6Voltage transformers shall have 120 volt secondaries unless otherwise specified.
12.2.7Voltage transformers shall have an accuracy rating comparable to the metering equipment and a burden capacity equal to twice the initial load.
12.2.8Current limiting fuse protection shall be provided on the primary side of each voltage transformer.
12.2.9Voltage transformers shall be designed to withstand the basic impulse level of the switchgear.
12.3Control Power Transformers (CPT)
12.3.1Control power transformers shall be fixed mounted with the primary current limiting fuses mounted in a drawout unit.
12.3.2When moved to the withdrawn position, the fuse drawout unit shall automatically ground the fuses. A visible indication of positive ground is required. The ground may not be a momentary or sweeping action, but must be maintained while the drawout assembly is not in the connected position.
12.3.3Each control power transformer shall have a secondary molded case circuit breaker interlocked with the drawout assembly so that the load is disconnected prior to drawout.
12.3.4All control power transformers shall be provided with one (1) 5% tap above and below rated voltage.
12.3.5Secondary winding shall be 120/240Vac, single phase, 60Hz, 3 wire unless otherwise specified.
12.3.6Control Power Transformer larger than 50KVA shall be mounted external and remote from the switchgear