Operation
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10.6 De-Energize Liebert APM with Maintenance Bypass Cabinet.
To de-energize the system:
1. On the UPS control panel, press and hold the INVERTER OFF button for 2 seconds.
2. Open all battery circuit breakers(s) including internal battery breaker (if applicable).
3. If the MBC is an Emerson cabinet, open the Maintenance Isolation Circuit Breaker (MIB). If the
MBC is a customer-issued switchgear or a non-Emerson cabinet, open the breaker(s) that supply
power to the critical bus.
4. Open the Rectifier Input Circuit Breaker and Bypass Input Breaker (if dual input). If the MBC is
a customer-issued switchgear or a non-Emerson cabinet, open the breaker(s) that supply power to
the UPS input and bypass input (if dual input).
5. Allow 5 minutes for all DC circuits and capacitors to fully discharge.
6. Open the external feeder breaker to the MBC or bypass switchgear.
7. Install a Lockout/Tagout on the external feeder breaker to the MBC or bypass switchgear.
8. Use a digital multimeter to verify there is no AC or DC voltage present at the UPS input, output
and bypass bus bars.
9. Use a digital multimeter to verify there is no AC or DC voltage present at the MBC BIB, MIB and
MBB breakers.
CAUTION
This procedure will remove power from the critical bus.
CAUTION
Performing the next step will shut down the critical load.
