Transmittal of generator prepurchase specifications, March 1998

NYC 9/11 Public Portal Document

PPS-Generators

Section "A" 1.25 X "(Sum of Generator Trip^izes)" Circuit Breaker Trip Sizfes) x "(Sum of Feeder Breaker Frame Sizes Supplied by Section A)" divided by "(Sum of Feeder Breaker Sizes Supplied by Section A and B)"

b. It shall be braced to withstand the sttesses produced by the fully displaced peak of a symmetrical short circuit current equal to that produced by a bolted short circuit supplied by all generators, present and future, and a 50% motor load. In no case shall the bus be braced for less than 100,000 A/C.

3. It shall have a top pull box consisting of #10 gauge removable sheet metal plates mounted on an angle iron frame, a 1" polyester resin fiberglass bottom barrier and inside cable racks.

4. It shall incorporate isolation transformers, filtering equipment, current and voltage sensing devices which sense RMS values, frequency sensing devices which sense zero crossover and other appurtenances as required to compensate for the distortion produced by SCR power supplies as described hereinbefore.

5. It shall include one master cubicle and one cubicle for each of the generator sets.

6. The master cubicle shall incorporate

a. Priority Load Control

Output contacts shall be provided to control priority load blocks. The number of load blocks shall equal the number of engine generator sets plus future and shall be sizes such that the connectable load of each block is not greater than the kilowatt rating of the generator set connected. As the generators are randomly connected to the bus, the controls shall signal for the connection of the load blocks in an ascending sequential priority with the highest priority load requiring emergency power being connected first. Load shedding shall be done on a last-on, first-off basis.

A priority pass-along circuit shall initiate the connection of low priority loads to the first generator on-line if start signals have not been received from high priority transfer switches.

OEM PPS-30 Generators 7 WTC March 20, 1998

NYC-WTC_000166905