Transmittal of generator prepurchase specifications, March 1998

NYC 9/11 Public Portal Document

PPS-Generators

2. Be such as to prevent transfer of the load onto the emergency source when the voltage on ay phases of the normal terminals is 70% or more (field adjustable) of the average value maintained under normal conditions. (Except under test con­ ditions.)

3. Be such as to retransfer the load to normal source when all phases of the normal source are restored to at least 90% of their normally maintained value. Retransfer controls shall incorporate a feature which provides for a 5 to 25 minute adjustable time delay between the sensing of the specified level of normal source and the initiation of retransfer. If generator voltage fails during the delay period, immediate retransfer shall occur.

4. Incorporate in both transfer and retransfer controls a feature which provides for an adjustable time period of 0 to 10 seconds during which the switch remains in its neutral position as described above.

5. Incorporate two pilot lights to indicate transfer switch position.

6. Incorporate a generator cranking feature including an open contact for use in an external circuit arranged to close whenever voltage on the normal supply drops below 70% of the average maintained value on any phase for an adjustable period from 0 to 30 seconds.

7. Incorporate a generator shut down feature including an open contact for use in an external circuit arranged to close after an adjustable time delay period of zero to twenty-five minutes following the return of the transfer switch to the normal power position.

8. Incorporate three auxiliary "open when normal, closed when emergency" contacts and three auxiliary "closed when normal, open when emergency" contacts which are not involved in the fimctioning of the switch and which are suitable for the present or future connection of independent external alarm or sensing circuits.

9. Incorporate a means for manually testing switch transfer and retransfer without necessitating the removal of voltage from the normal source terminals of the switch.

10. Each shall incorporate a control panel that shall direct the operation of the transfer switch. The panel's sensing and logic shall be controlled by a built-in microprocessor for maximum reliability, minimum maintenance, and inherent digital communications capability. The control panel shall be connected to the transfer switch by an interconnecting wiring harness. The harness shall include a keyed disconnect plug to enable the control panel to be disconnect from the transfer switch for routine maintenance.

OEM PPS-46 Generators 7 WTC March 20, 1998

NYC-WTC_000166921