Common use of Switchgear Clause in Contracts

Switchgear. This section covers the engineering, design, manufacture, installation and testing of 4160 volt and 480 volt switchgear as required for the project. The 4160 volt switchgear is to deliver power to the 4000 volt motor and 480 volt auxiliary power system. The 480 volt switchgear shall deliver power to large 460 volt motors and 480 volt motor control centers. All equipment furnished shall conform to applicable standards of IEEE, NEMA, ANSI and OSHA. The switchgear shall be UL-labeled. The switchgear shall be designed for use on 4160 volt or 480 volt, three phase, 60 hertz, three wire, resistance grounded systems. Grounding may be provided through a grounding transformer. Switchgear shall be housed in suitable enclosures for indoor service and of the metal-clad, drawout type. Switchgear may be located in weather tight, walk-through, outdoor enclosures. The arrangement of breakers and starters shall be determined by the Contractor. All switchgear shall have interrupting and bus bracing ratings that are adequate to withstand the worst case fault conditions. The spaces above switchgear and motor control centers shall be kept free of piping to avoid contaminants from entering the housings in the event of leaks. At least one equipped spare breaker of maximum rating shall be provided for each 4160V switchgear lineup, and at least one spare feeder breaker and one equipped spare shall be provided for each 480V SUS lineup. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 91 of 132 -------------------------------------------------------------------------------- Sufficient space shall be provided to allow easy withdrawal of breakers for operation or maintenance. Doors for equipment rooms shall be sized for the largest piece of equipment to pass through. All multiple breaker metal-clad switchgear assemblies shall consist of vertical sections mounted side-by-side and connected mechanically and electrically together. Each vertical section shall consist of separate compartments where all live parts are completely enclosed within grounded metal barriers. The switchgear assembly shall be suitable for bolting to the switchgear room floor. Each vertical section shall be of rigid self-supporting steel of welded construction. Access to high voltage equipment compartments shall be provided by bolted-on metal covers. Hinged panels shall enclose the front of the vertical section. Panels shall be used to mount relays and instruments and also serve to cover the circuit breaker compartment. When it is not possible to install all of the equipment in a breaker unit housing, an auxiliary unit shall be furnished. The auxiliary unit shall have no provision for accepting a circuit breaker and shall be used to house equipment such as potential transformers, lightning arresters, control power transformers, etc., as required. The circuit breaker compartment shall house a removable circuit breaker element and include primary and secondary disconnecting contacts. The stationary primary disconnecting contacts shall be electroplated copper and recessed within insulated supports. Automatic safety shutters shall cover the stationary primary disconnecting contacts when the breaker element is withdrawn from the connected position. The instrument compartment shall have a hinged panel for mounting instruments, control and protective devices. Terminal blocks, fuse blocks and some control devices shall be mounted inside the enclosure on the side sheets. The hinged panel shall have doorstops to hold the panel in the open position. Strong hinges of the disappearing or internal type shall be used in sufficient number per panel to ensure freedom from sagging, binding, or general distortion of door or hinged parts. Opening of adjacent hinged panels to any position shall not cause shorting or grounding of electric terminals or damage to panel-mounted equipment. The main buses shall be enclosed in a metal compartment with removable front and back covers to provide accessibility. The bus compartment shall be designed to permit future extension of the bus. The cable termination compartments shall have two side panels bolted to the rear of breaker compartment along with a roof cover and rear sheet. The rear sheet shall be bolted to the frame and be easily removed by removing the bolts. The compartment shall be suitable for line termination by nonsegregated phase bus or solderless-type cable connectors. Insulating clamps shall be furnished to separate the cables for solderless-type connectors. -------------------------------------------------------------------------------- EPC - Exhibit B -------------------- TENASKA GEORGIA GENERATION PROJECT Page 92 of 132 -------------------------------------------------------------------------------- The auxiliary compartment shall be used to mount current transformers, potential transformers with associated primary fuses, surge arresters, control power transformers, etc. Where rollout trays are provided to mount potential or control power transformers, the movable carriage shall be equipped with primary and secondary disconnecting devices, grounding and a safety barrier. Auxiliary compartments shall be furnished when all auxiliary equipment cannot be accommodated in the breaker unit. The circuit breakers shall be a removable air-magnetic or vacuum-type circuit breaker element. Breakers of the same rating shall be interchangeable and of standard drawout design. The breakers shall be operated by motor-charged, spring-type stored energy mechanism. The electric motor shall be rated at 125 V dc. The circuit breaker shall be furnished with mechanical indicators for: 1. Positive indication of the breaker open or closed position, and 2. Breaker closing spring, charged or discharged. The stored energy closing springs shall be suitable for manual as well as electrical charging, and a front-operated manual spring charging handle shall be furnished for emergency charging. Trip and close levers for manual operation shall be furnished on the circuit breaker element. All secondary contact surfaces and the main contact surfaces of all air magnetic-type circuit breakers shall be silver-plated and be designed and fabricated to be self-aligning and to resist burning and deterioration. No breakers shall be forced cooled.