GE Industrial Solutions SG Series 225 & 300 Operating Manual - Manual (Page 15)

Modifications reserved Page 15/79
OPM_SGS_USM_M22_M30_2US_V010.doc User Manual SG Series 225 & 300 UL S2
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 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.
A Manual Bypass (operator initiated) will not be
considered as an alarm condition.
Fig. 4.2.5-1 Block diagram Automatic Bypass
In case of parallel operation
Each unit has its own internal Bypass.
These units are continuously exchanging information, enabling all of the internal Bypass circuits in a
parallel system to operate simultaneously.
If the Inverter of a unit fails, its Bypass circuit remains available to the Parallel System.
It is excluded only if the unit is separated from the common bus by opening its output switch Q1.
4.2.6 Manual Bypass (option)
The Manual Bypass circuit consists of Q1 and Q2
manual switches, which permits transfer of the
Load directly to the unconditioned AC power
without interruption, leaving the UPS available for
maintenance.
Fig. 4.2.6-1 Block diagram Manual Bypass