Transmittal of generator prepurchase specifications, March 1998

NYC 9/11 Public Portal Document

PPS-Generators

Upon the master PLC failing or loss of the master DC power bus, the loa(^add/shed circuitry of the PLC becomes inoperative. Simultaneously, the Manual Override panel is enabled. The operator can manually add/shed loads through the activation toggle switches. These switches are individually wired in parallel with the PLC add/shed outputs. During this condition, the operator must observe the generator kW meters to ensure the generators are not overloaded. In the event that an overload condition does occur, all manually transferred ATS' will be shed from the bus. The operator would then deactivate the appropriate toggle switches to reduce the load. A manual reset button located on the override panel would have to be depressed to restore the manual override circuit.

An on-line UPS shall be provided as an alternate power source to back-up the system logic for the PLC. This UPS shall be constantly on-line when the engine generators are available. The on line UPS shall be sized to handle the PLC provided.

0. Master control cubicle shall be capable of mounting and wiring a remote I/O devices supplied by building management system. I/O device shall be capable of receiving an analog signal from the master PLC to represent total generator output KW available. Signal shall be 4-20mA and scale shall be shown on switchgear controls MFG interface dwg. Signal shall be used by BMS to evaluate if additional mechanical loads can be added to the generators. At least 5 digital signals shall be available for status indication to BMS for shedding or previously added loads due to generator failure or bus overload, or as a permissive to allow BMS load add.

I/O device should also be capable of receiving digital signals for all pre­ alarms and shutdowns for each generator as well as all status points in master control section. These points are defined in other parts of this spec section.

7, Each generator cubicle shall incorporate

a. Generator Circuit Breaker

A low voltage circuit breaker shall be furnished to provide overcurrent protection and paralleling functions. The breaker shall be as sized on drawings, 3 pole, electrically operated, drawout, with solid state trip elements. Trip elements shall include adjustable long delay, short delay, ground fault alarm only and instantaneous settings. Breakers shall have 5 cycle stored energy closing. Drawout feature shall provide for connected test and disconnected positions. In the connected position the main line

OEM PPS-36 Generators 7 WTC March 20, 1998

NYC-WTC_000166911