IGS-NT-BC, SW Version 1.2.0, ©ComAp – January 2019
IGS-NT-BC-1.2.0 Reference Guide.PDF
Figure: Example of control groups
Once the BTB breaker is closed, the control group 2 and 3 become new group 2+3. The closed BTB and the
group link function influence the load reserve (i.e. increased by added gen-set of added gen-sets). Load
sharing applies for all gen-sets.
Load shedding
All LOAD SHED outputs are activated (closed) to trip the unessential load when gen-set goes to island:
a) When GCB is closed after mains fail and gen-set starts in SEM / AUT mode.
b) When MCB opens from parallel to mains operation in SEM / AUT mode.
c) Before MCB is opened in MAN mode by button.
The load shedding function is active in all controller modes except OFF.
Load shedding has three steps and each step is linked with its own Load shed x binary output. There is only
one load shed level and delay for all three steps as well as recon level and delay. Load shed can only move
from one step to the next, e.g. No LoadShed to LdShed S1 to LdShed S2 to LdShed S3 and vice versa.
If manual reconnection of the load is desired, the AutoLd recon setpoint needs to be disabled (AutoLd recon
= DISABLED) and the MAN load recon binary input needs to be configured.
Rising edge on this input resets the controller to a lower stage, but only if the load is under the Ld recon level
at that moment.
HINT
If no Load Shedding outputs are configured, there is no record to history and no scrren timer indication of the
activity of this function.
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