Figure 6.17 Transfer UPS to Normal Mode
6.3.4 Transfer from normal mode to maintenance mode
The following procedures will transfer the UPS from inverter output mode to the maintenance bypass mode.
CAUTION: Power supply interruption danger of the load: Before performing this operation, read the
information on the touchscreen to make sure that the bypass supply is normal and that the inverter is
synchronous with the bypass supply so as not to risk a short interruption in power to the load.
1. Shutdown the inverter according to Transfer from normal mode to bypass mode on page112.
NOTE: The alarm can be silenced but the alarm message displayed until the alarm condition is rectified.
2. Close the maintenance bypass switch Q3.
3. The maintenance bypass parallels with the UPS static bypass.
4. The Touchscreen displays Maint. Switch Closed.
CAUTION: When the UPS is in maintenance mode, the load is not protected against abnormal mains supply.
5. Pressing the EPO button stops the operation of rectifier, inverter, static switch and battery, but this action will not
affect the maintenance bypass power the load normally.
NOTE: Under maintenance mode, the load is directly fed by the mains power instead of the pure AC power from the
inverter.
6. Disconnect the rectifier input switch Q1, bypass input switch Q2, and output switch Q5.
114 Proprietary and Confidential ©2023 Vertiv Group Corp. 6 Single UPS Operation
Vertiv™ Liebert® APM2 30 to 120 kVA Modular UPS User Manual
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