Procedure
Step 1 Turn on the EPO switches connected to the dry contact cards on all UPSs one by
one or the general EPO switch.
----End
8.4 Isolating a Faulty UPS from a Parallel System
Context
CA UTION
● Only authorized technical engineers are allowed to isolate a faulty UPS from
the parallel system. Before the operation, consult professional maintenance
personnel.
● Before maintenance, use a multimeter to check faulty parts for dangerous
voltages.
● If the output switch does not have the neutral wire isolated, do not touch the
neutral wire.
● When the parallel system works properly, do not turn off the output switch of a
single UPS if the UPS does not stop supplying power. Otherwise, the parallel
system may become abnormal.
Procedure
Step 1 If the UPS needs to be disconnected, check whether the capacity of the remaining
UPSs in the parallel system meets the onsite load requirements.
Step 2 Turn the ready switch on the bypass control module to the not ready state. The
system reports alarm 0047-002 Not ready, which is normal. If the faulty UPS
works in bypass mode, there is no output. If the faulty UPS works in normal mode,
choose Common Functions > Inv. OFF on the LCD of the faulty UPS to shut down
the inverter. Then, the UPS has no output, and the other UPSs continue to work in
inverter mode.
Step 3 Turn off the output switch of the faulty UPS or the external output power
distribution switch.
Step 4 Turn off the battery switch of the faulty UPS. If there are multiple battery strings,
turn off the general switch between battery strings and the UPS and then the
switch for each battery string.
Step 5 Turn off the mains and bypass input switches on the input PDC or the upstream
power distribution switch of the faulty UPS.
Step 6 The faulty UPS is isolated from the parallel system. Perform maintenance on the
UPS.
----End
UPS5000-H-(400 kVA-800 kVA)
User Manual (100 kVA Power Module)
8 Parallel System Commissioning
Issue 02 (2021-04-22)
Copyright © Huawei Technologies Co., Ltd.
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