Automatic Bypass - ABB MegaFlex UL S1 Series User Manual

16/86 MegaFlex 1000 to 1600 UPS User Manual / REV-A

4.2.5 Automatic Bypass

In normal operation, the Load is supplied by
the Inverter.
When the control system detects a fault in the
Inverter, an overload condition or a short-
circuit condition, the Automatic Bypass will
transfer the critical Load to the Utility without
interruption.
When the Inverter recovers, or the overload or
short-circuit condition is corrected, the Load
Fig. 4.2.5-1 Block diagram Automatic Bypass
will be automatically transferred back to the
Inverter.
If the UPS is unable to return to normal mode following an automatic transfer to Bypass mode, an alarm
condition will be initiated.
In case of RPA Parallel System
Each unit has its own internal Static Bypass.
These units are continuously exchanging information, enabling all of the internal Bypass circuits in an RPA Parallel
System to operate simultaneously.
If the Inverter of a unit fails, its Bypass circuit remains available to the RPA Parallel System.
It is excluded only if the unit is separated from the common bus by opening its "Q1 – External UPS Output Circuit
Breaker".