Transfer a Parallel System from Maintenance Bypass Mode to Normal Mode

  1. Check that:
    • all UPS breakers (unit input breaker UIB, static switch input breaker SSIB, and unit output breaker UOB) and the external unit output breaker Ext. UOB are in the ON (closed) position

    • the battery breakers BB are in the OFF (open) position

  2. Reconnect the internal batteries of all UPSs and set all the battery breakers BB in the modular battery cabinets (if present) to the ON (closed) position.
  3. Turn the system isolation breaker SIB to ON (closed) position.
  4. Turn the bypass input breakers BIB of all UPSs to the ON (closed) position.

    Wait approximately 20 30 seconds until the bypass and the output LEDs turn green.

  5. Turn the external maintenance bypass breaker Ext. MBB to the OFF (open) position.
    NOTE: If the parallel system has dry contacts with Maint CB signal, select and then select Function > Clear alarm on all UPS displays.
  6. Turn the mains input breakers MIB of all UPSs to the ON (closed) position.

    The rectifier ramps up. After UPS self-test, the battery relay closes automatically.

  7. Close the external battery breaker if external batteries are part of the system.
  8. When the rectifier LED turns steady green, the inverter synchronizes with bypass.
  9. When the inverter LED turns steady green, the parallel system automatically transfers from static bypass to normal mode.
  10. Turn the battery breakers BB of all UPSs to the ON (closed) position.

    The LEDs on the user interfaces show as follows:

The parallel system is now in normal mode.
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