2021-08-03 at 11:08 am
#1886
K B Santharam
Dear All, I know this is a riddle posted about a year back. Sorry , I came across this only now. All CT neutrals ( both main CT and auxiliary CTs shoulb earthed at only one point, preferably at the protection panel. Further there is no need to earth neutral of the operating winding of the differential relay in this case since zero sequence currents are filtered out from both sides of the differential relay. If the above precaution is not taken, during system earth faults, different CT neutral points would be at different potentials causing circulating currents in the CT secondaries and cause maloperation of the relay. Your comments please!