TECHNICAL SPECIFICATIONSFOR
ISOLATED PHASE BUS DUCT
AZZ Bus Systems
120 Aztec Drive
Richland, Mississippi 39218
Tel: +1.601.939.9191
Fax: +1.601.420.8334
Email:
Website:
1.0General:
1.1This specification provides for furnishing an Isolated Phase Bus system complete with accessories as per the Schedule of Equipment for connection between the generator and main step-up transformer. Taps shall be furnished from the main bus to:
1.1.1( ) Unit Station Service Transformer(s)
1.1.2( ) Potential Transformer Cubicles
1.1.3( ) Generator Excitation Cubicle
1.1.4( ) Other
1.2The manufacturer’s proposal shall contain complete descriptions of all equipment to be furnished, unit pricing of all equipment, commercial terms and conditions of sale, detailed data sheets listing the design criteria and to include calculated results of the predicted performance of the Isolated Phase Bus while operating under the specified environmental conditions. Technical notes explaining the data sheets shall be supplied. The commercial terms and conditions shall contain the bus manufacturer’s standard engineering, manufacturing and shipping schedule along with rates for field service engineers. The proposal shall identify any and all exceptions taken to the specifications with a clear explanation as to why the exception was taken.
2.0Standards and Codes:
2.1All Isolated Phase Bus and accessories shall be built to meet or exceed requirements as listed in the latest edition of ANSI C37.23 “Switchgear Assemblies including Metal Enclosed Bus”.
3.0Isolated Phase Bus Design Requirements:
3.1The Isolated Phase bus shall be of the Electrically Continuous, Self-Cooled design. Bus sections shall be constructed in sections as long as practical for installation to reduce installation time.
3.2The conductor shall be fabricated from high conductivity extruded aluminum tubes of a sufficient diameter and thickness to carry the specified continuous current without exceeding the allowable temperature rise as listed on the specification data sheet. At all field welded conductor splice joints, the conductor tube shall be factory prepared by beveling the ends of the tube and providing a backing ring to fit inside the tube to prevent any blow-through while welding. All conductor sections will be painted with flat black paint to aid in dissipation of heat.
3.3The enclosure shall be fabricated from high conductivity aluminum sheets and shall be of the necessary thickness to carry the enclosure currents without exceeding the allowable temperature rise as listed on the specification data sheet. All enclosure field splices shall provide sufficient space to allow proper welding of the conductor and shall have pre-rolled split weld-in-place covers. The enclosure interior shall be painted with a flat black paint to aid in the dissipation of heat. The enclosure exterior shall be painted with ANSI 61 enamel paint.
3.4The insulators shall be wet process porcelain designed for the voltage and BIL level as specified on the specification data sheet. The insulators shall be grouped in sets and spaced along the bus at intervals to supply ample bracing for the short circuit currents as listed on the specification data sheets. The bus shall be so designed where individual insulators may be removed for maintenance without disturbing the conductor or any other insulator.
3.5In the event that bolted covers must be used, bonding straps of sufficient size to carry the full enclosure currents shall be furnished.
3.6Expansion Joints shall be supplied where necessary to prevent undue stress on any components of the bus system due to expansion or contraction.
3.7Terminations of the bus enclosure to the equipment shall be accomplished with flexible insulating bellows to reduce vibration, stress, loading of equipment enclosures, and to reduce induced currents in the equipment. Termination of the bus conductors shall be accomplished with silver plated extra flexible connectors.
3.8Bonding bars or plates shall be supplied to bond between the enclosure phases at each equipment termination. The bonding bars shall be of sufficient cross sectional area to carry the enclosure current without exceeding the specified allowable enclosure temperature rise. The bus enclosure ends shall be insulated from the equipment flanges with insulating bellows to reduce induced currents in the equipment. Each enclosure bonding locations shall have provisions for attaching grounding.
3.9Connections of the isolated phase bus to all transformers shall be performed with flexible connectors of sufficient length to provide a minimum of 12” clearance between the bus spades and the transformer spades when the connectors are removed to facilitate testing of the transformers.
3.10The bus manufacturer shall coordinate the bus connections to the equipment connections from drawings to be supplied by the purchaser.
3.11Termination compartments constructed of aluminum and at locations as indicated on the drawings shall be furnished by the bus manufacturer. These compartments shall have removable bolted covers to provide ample access to the equipment terminations for installation and removable of the flexible connectors.
3.12Wall seal assemblies shall be provided where the bus penetrates an indoor to outdoor wall. The seal assemblies shall be fabricated from aluminum and must be complete to include seal-off bushings in the enclosure-conductor annulus. The seal assembly shall be designed to prevent the seal assembly from supporting of any of the bus weight. This seal assembly shall be insulated from the bus enclosure to prevent grounding at this point. Seal-off bushings shall be supplied in each phase at each equipment termination.
3.13Custom tee-taps and elbows are available as required.
3.14All current carrying contact surfaces shall be silver-plated.
3.15All bus bolting hardware shall be zinc dichromate plated steel. All conductor bolted joints shall be silver-plated and incorporate spring washers.
3.16Design tests shall consist of Basic Impulse Level test, Temperature Rise test and Momentary Short Circuit test. Should the bus manufacturer have existing test reports on the bus of a design similar to the bus as covered by these specifications, and where interpolations may be used to justify the design submitted by the bus manufacturer, it shall be the purchaser’s option to waiver actual test on this specific design. Design test on the specific bus as covered by these specifications shall be quoted as an option.
3.17Production test shall consist of a factory Power Frequency Withstand test and shall be performed on each and every section of bus manufactured under these specifications.
3.18The bus manufacturer shall supply all bus supporting members, unless directed otherwise by purchaser. Indoor bus shall be supported from the ceiling beams with trapeze hangers. The trapeze shall be complete to include steel hanger beams and crossbeams, hanger brackets and bolting hardware. The trapeze shall be painted with enamel. Outdoor bus shall be supported with two or more steel column supports. The column type supports shall be fabricated from steel and hot dipped galvanized after fabrication. All bolting hardware to include anchor bolts and shall be furnished for the outdoor supports and shall be hot dipped galvanized.
3.19Potential Transformer and Surge Protection Cubicles shall be supplied by the bus manufacturer. The cubicles shall be constructed from 11-gauge steel or aluminum and shall be free standing, base mounted. Each phase cubicle shall contain a rear entry compartment, which will house the cubicle main bus surge arrestor and surge capacitor. This compartment shall have rear bolted covers for full access to the components. The cubicle main bus shall be copper and have a continuous current rating and short circuit current rating as shown on the specification data sheet. Each P.T. Compartment shall be equipped with disconnect/grounding switches, interlocked hinged doors, draw-out trays, primary and secondary fuses and current limiting resistors, if required. The cubicles shall be painted ANSI 61.
3.20A Neutral Grounding Cubicle shall be supplied by the bus manufacturer. The cubicle shall be constructed for ( ) Indoor or ( ) Outdoor use. The cubicle shall contain a dry type distribution transformer, resistor bank and other items as required by the specification data sheet. The cubicle shall be painted ANSI 61.
4.0Specification Data Sheet:
4.1BUS SYSTEM:
4.1.1Bus System Type Electrically Continuous
4.1.2Bus System Rated Voltage______kV
4.1.3Bus System Operating Voltage______kV
4.1.4Bus System Frequency______Hz
4.1.5Basic Impulse Level______kV
4.2AMPACITIES:
4.2.1Main Bus Ampacity______Amps
4.2.2Delta Bus Ampacity______Amps
4.2.3Auxiliary Transformer Bus Ampacity______Amps
4.2.4Potential XFMR/Surge Bus Ampacity______Amps
4.2.5Excitation Bus Ampacity______Amps
4.2.6Neutral Grounding Bus Ampacity______Amps
4.3SHORT CIRCUIT CURRENT:
4.3.1Main Bus (rmsAsymm)______kA
4.3.2Delta Bus (rmsAsymm)______kA
4.3.3Auxiliary Transformer (rmsAsymm)______kA
4.3.4Potential XFMR/Surge Bus (rmsAsymm)______kA
4.3.5Excitation Bus (rmsAsymm)______kA
4.3.6Neutral Grounding bus (rmsAsymm)______kA
4.4ENVIRONMENTAL PARAMETERS:
4.4.1Ambient Temperature______°C
4.4.2Max. Conductor Temp. Rise______°C
4.4.3Max. Enclosure Temp. Rise______°C
4.4.4Solar Radiation
4.4.4.1Already accounted for in Ambient, Rise or Ampacities listed above ( )
4.4.4.2Solar compensate per ANSI C37.24, for Site location ( )
4.4.5Site Elevation above Sea level______Ft
4.5P.T./SURGE PROTECION CUBICLES:
4.5.1Potential Transformers
4.5.1.1Primary Voltage______kV
4.5.1.2Secondary Voltage______Volts
4.5.1.3Frequency______Hz
4.5.1.4Basic Impulse Level______kV
4.5.1.5Power Rating______VA
4.5.1.6Accuracy ______
4.5.2Surge Capacitor
4.5.2.1Voltage Rating______kV
4.5.2.2Capacitance (microfarads)______
4.5.3Surge Arrestor______kV
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AZZ Inc. IPB2016-Rev 2