We have 220V main lines where we currently live and we have a 3-Phase connection. We have an Air conditioning unit that requires 3 phase AC input with the correct phase sequence.
If the phase sequence is not right, it displays an error code for that. A while ago there was an electricity breakdown in our area and ever since that was resolved we are receiving that error. This happened a year ago as well but a quick phase load wire rotation by the electrician solved the problem.
This time, however, no matter what combination they try it does not seem to work. I have a sequence detector tool but that does not work now either.
The electricians from our maintenance company refuse to admit that the problem lies somewhere in the supply and claim that 380V - 396V are there the problem is with your unit. But if the unit had gone bad how come another device has also gone bad at the same time?
How can we verify their claim? The Air conditioning unit's electrician says that the main line is not supplying the 3 phases correctly and their electricians say that all our 390 volts are there between every 2 phases and the fault is indoors.
Please note: I do know that this is dangerous work, and I am not doing it myself. Only (so called) qualified electricians are working on this. I am just asking to learn so i can plead my case with their manager.