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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.