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10.5 Switching the UPS from Maintenance Bypass to Normal Operation
Follow the procedure below to transfer the load from the Maintenance Bypass system to the UPS
inverter output.
These conditions must be met for this operation to proceed:
• the UPS must be operating normally
• the BIB breaker must be closed
• the UPS system must be in the Maintenance Bypass mode of operation.
1. Verify that the Liebert
®
APM
™
is in Maintenance Bypass mode.
2. Open the Liebert BDC door to gain access to the bypass isolation breaker (BIB), maintenance
bypass breaker (MBB) and the maintenance isolation breaker (MIB).
3. When the Lamp indicator on the BDC is illuminated, press and hold the adjacent push button and
remove the key from the lock (K0).
4. Insert the key into the lock on the MIB, and turn the key.
5. Close the MIB.
6. Verify the MIB is closed. Failure to close the MIB will interrupt power to the load.
7. Open MBB.
8. Remove the key from the lock on the MBB.
9. Insert the key into the lock (K0) and turn the key.
The UPS system is now supplying power to the critical load.
10. Press the INVERTER ON button on the right side of the Operator Control Panel for longer than
2 seconds.
The Inverter indicator flashes while the inverter is starting.
After the inverter is ready, the UPS transfers from static bypass to inverter, the bypass indicator
turns Off and the inverter indicator turns On. The UPS is in Normal Mode. The indicator will
appear as shown in Table 32.
!
CAUTION
Risk of electrical shock and arc flash. Can cause property damage, injury and death.
This procedure must be performed by properly trained and qualified personnel who are
knowledgeable about the operation of this system. Failure to follow these instructions will
result in loss of power and possible damage to critical equipment.
Before performing this operation, read any messages on the LCD to be sure that bypass
supply is regular and the inverter is synchronous with it. If those conditions are not present,
there is a risk of a short interruption in powering the load.
NOTE
Pressing the Alarm Silence Switch cancels the audible alarm, but leaves the warning message
displayed until the appropriate condition is rectified.