Manual 37128A GCP-20 Series - Genset Control
Page 52/190 © Woodward
Return of the Mains for Interchange Switch Logic [GCP-22]
Return of the mains
After the return of the mains voltage the mains settling time is first finished. If no operating
request is present, reverse synchronization of the MCB is carried out following the expiry of
this time. Following the closure of the mains power circuit breaker, the generator power cir-
cuit breaker is opened following the reduction in power.
If the mains returns whilst the unit is starting, the mains power circuit breaker is not opened.
During the mains settling time, the unit operates without load, in order to enable the imme-
diate connection of the GCB in the event of further mains alarms.
Emergency Power for External Switch Logic
CAUTION
Emergency power in accordance with DIN VDE 0108 is not possible in this switch logic!
Emergency power op-
eration
Following the detection of a loss of mains, the emergency power delay time expires first be-
fore starting the genset. On reaching the voltage and frequency limit values, the MCB is
opened, the GCB is not activated. The GCB and the MCB are not otherwise operated. Not
even following the return of the mains.
Emergency Power with MCB Malfunction
MCB failure
In the "AUTOMATIC" operating mode without a starting request, the control system is set
to emergency power standby. If the mains power circuit breaker is tripped, the control sys-
tem attempts to reactivate this. If this is not possible (due to an MCB alarm), the unit is
started following the "MCB failure", emergency power subsequently supplies the busbar.
Only following the successful acknowledgment of the "MCB failure" alarm, is the MCB
synchronized and the unit shut off again on expiry of the mains settling time.
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