ComAp IG-NT Reference Manual page 90

P
RINCIPIAL SCHEME OF A SITE IF
The COMMON option should be used if there is one common neutral contactor for
the whole site. The outputs
together and the combined signal is used to control the breaker. Three-pole GCB
must be used for this case.
N
OTE
If there are more logical groups the "common" option is related to the group. That
means one common neutral contactor is expected for each group.
P
RINCIPIAL SCHEME OF A SITE IF
Inteli NT MINT, SW Version 3.0, ©ComAp –May 2013
IGS-NT-MINT-3.0 Reference Guide.PDF
Neutral CB C/O
The output is always opened while the gen-set is not running.
The output is always opened while the MCB is closed.
While the gen-set is running the output closes when generator voltage in at
least one phase exceeds 85% of the nominal voltage. It opens when the
generator voltage in all phases drops below 50% of the nominal voltage.
That means if at least one gen-set in the site is running and having proper
voltage, the neutral breaker is closed.
:
N = EACH
EUTRAL CONT
from all controllers are combined
N = COMMON
EUTRAL CONT
90