Transmittal of generator prepurchase specifications, March 1998

NYC 9/11 Public Portal Document

PPS-Generators

3) Generator Frequency Proctective Relay (Device 81)

An underfrequency solid state relay utilizing full cycle zero crossing sensing shall be included to respond to the fundamental frequency of the system so as to ignore wave shape distortion resulting from solid state loads. The relay shall have an adjustable pick up range of 40 to 60 Hz and adjustable under frequency dropout range of 0.1 to 10 Hz below the pickup.

4) Frequency/Voltage Time Delay

An adjustable time on drop out of both Device 27 and 81 shall be provided to override loading transients. Range of adjustability shall be 0.1 to 6.0 seconds, factory set at 2.0 seconds, repetitive accuracy shall be within plus or minus 2 %.

5) Automatic Synchronizer (Device 25)

An automatic solid state active synchronizer shall be furnished to synchronize its respective incoming engine generator set with the paralleling bus. The synchronizer shall include a differential voltage detector, differential frequency detector, differential phase detector, raise/lower voltage output relays for generator voltage control, raise/lower frequency and phase angle control through a proportional DC output voltage, phase lock control and a circuit breaker closing signal. Synchronizers without phase lock control are unaccepuble. Synchronizer shall be ASCO or woodward SPM-A.

The differential voltage detector shall compare the voltage of the oncoming generator to the paralleling bus. If the voltage is not within the factory set difference of plus or minus 5 % (adjustable from 0 to plus or minus 10%), the voltage detector shall lockout the circuit breaker closing relay and simultaneously initiate adjustment of the voltage through the raise/lower voltage output relays. When the oncoming generator voltage is within the preset acceptable limit, the lockout shall be removed. Repetitive accuracy of the voltage detector shall be plus or minus 1.0 over the specified temperature range.

The differential frequency detector shall compare the frequency of the oncoming engine generator set to the paralleling bus. If the frequency is not within the preset acceptable difference of plus or minus 0.5 Hz (adjustable from 0 to plus or minus 0.5

OEM PPS-38 Generators 7 WTC March 20, 1998

NYC-WTC_000166913