We're trying to commission an MCC with about 20 motor starters and feeders, all with some form of earth leakage protection. Most of them were tested at the factory, and they worked fine. But now that the MCC is on site, the earth leakage protection doesn't work at all. When you press the "test" button on the relay, the breaker trips, but when you use an earth leakage tester, nothing happens.
We tested the test instrument, and it works.
There's no problem with the wiring. Like I said, in the factory it worked, and we even traced the wires again, just to make sure.
The only remaining possibility that we can think of is that the MCC isn't properly earthed. We will check that today.
Can anyone think of any other possible causes for this very frustrating pain in my behind?
Problem with Earth Leakage
Re: Problem with earth leakage
