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Liebert NXL UPS
2.6.4
Automatic Retransfers to UPS
The following critical bus conditions must be present to initiate an automatic retransfer of
the critical load from the bypass source to the UPS inverter:
1)
Critical load was initially transferred to the bypass source due to a system overload
only. A manual retransfer from bypass is required if the transfer to bypass was caused
by any condition other than output overload.
2)
Both output power and current have since dropped below 101% of the rated load.
3)
Both the Input isolator and the Battery (BCB) circuit breaker have remained closed
since the overload transfer.
4)
OK to Transfer signal received from the control logic.
5)
Cyclic-type overloads, which occur up to five (select range is 0 to 5) times in 60
minutes, are automatically returned to the inverter for each event including the Nth
overload.
NOTE
If you do not want the UPS system to initiate any automatic retransfers, this can be set
during the initial commissioning or by calling your local Liebert Services representative.
Page 48
Operation and Maintenance Manual
250-300-400-800kVA
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