We recently performed IR test on our oil filled transformer on the primary winding with 5000V tester. At first moment I was surprised to see the value, almost around 200MOhm as The rated voltage of primary is 34.5kV. When I checked the original test values during commissioning, it was 250MOhms. This transformer is in service now. But I still think that all the thumb rules and formulas meant to know the IR value are not at all useful. Sometimes it may create a big confusion if the original values are not known.

Comments????

 

Panthripu... I strongly disagree with your conclusion. Quite a few threads can be found in the Control.Com archives.

I suggest you start with the latest:

http://www.control.com/thread/1310129369

Regards, Phil Corso