In my Site, our Contractor is running a DG Set of 250KVA, 415V. to feed power to our site office
The entire distribution is through a 100A ELCB of 30mA. and it is unbalance load.

One morning, the ELCB has tripped but unfortunately "R" phase is continuously available from ELCB since there is internal problem in ELCB. The voltage on particular phase has gone high upto 270V and some of the tube light chokes got burnt and a personal computer power supply unit failed.
On investigation it was noticed that alternator neutral is not connected to the earth system.
I insisted the contractor to earth the alternator neutral. When they are trying to ground the alterantor terminal, the ELCB in the distribution board is tripping always.

Please suggest me, whether we can earth the alternator neutral solidly through some cu. flat.
I hope the any alternator netural should be earthed to avoid this kind of over voltage problem due to unbalance loads..

I understand, if we are earthing the neutral on the load side of ELCB, it may trip because there is difference in the return current through the neutral.
I am earthing the netural in the alternator terminal itself (-ie- Line side of ELCB) but why the ELCB should trip?

Pragathees..