For Synchronisation of DG Sets Sometimes we people use NIC
(Neutral Isolation Contactor) Instead of 4-pole ACB or any
switchgerar..Please guide me why is it so????

Answer Posted / vinod

when a DG set is started and as dg voltage is building up it is necessary to connect the lowest potential point of generator first with the system which it is to be feed, that is the neutral as first. then the breaker can be closed if the set is required to be parallel first. the reason is the system which the DG is intended to supply may have a neutral potential which can be at a different potential other than the DG. so in order to establish a common neutral NIC is used. if NIC is not there and DG neutral is always solidly connected to the BUS then grounding impedance of the whole system is reduced and in turn fault in system can lead to a higher fault current.

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