Hi guys please help
I got an earth fault problem, the main feeder (525V) which is equipt with 500mA E/sec with 630A main circuit breaker supplies the substation (with 2 x 120mm square cables). At the substation supplied, we have 250mA E/sec for load/equipment protection. There are plus minus 15 panels/loads on this main feeders at the SUB.supplied.
The problem is the 500mA E/sec (the main feeder) keep on tripping on earth fault. We tested all the cables, 250mA E/sec and they all tested positive we even change the 500mA E/sec both relay and the core balance (CT) at the main feeder but it still keep on tripping. we tested unbalance current on each load and we got something like 0.1A or 0.2A and on some panels we even got 0A, which is not enough to trip the 250mA E/sec. But on the main feeder cables unbalance current is around 0.8 to 0.9A which is enough to trip the 500mA E/sec.
Our final decision was to change the 500mA E/sec to 1000mA which will cater for 0.9A.
DO YOU GUYS THINK THIS WILL SOLVE OUR PROBLEM? BECAUSE ALL THIS YEARS THE 500mA WAS WORKING FIND.
Earth Fault Problem - Main Feeder Tripping on Earth Fault
Re: Earth fault
