De-magnetizing a Transformer

[dinocu]

What is the best and easiest way to de-magnetize the core of a 7.5MVA 34.5/25 kV transformer. Thanks

 

[mpparent]

I believe you can do it with a Doble test set, however, I'm not sure of the exact procedure, connections, etc.

Mike

 

[dinocu]

Yes, actually this is why I want to de-magnetize, I was doing the Doble tests on the transformer, and I didnt get the characteristic High-Low-High on my excitation test, so Doble recommended I de-magnetize the transformer and try again. Thanks

 

[Reactorman]

Although the method I'll describe may not be practical to do. It explains a proceedure to accomplish demagnetization.

"Energize the transformer no load, and then gradually reduce the voltage to zero. The core will be demagnetized."


Good Luck

 

[supraskate13]

I have never demagnitized a Power transformer but I have demagnitized CT's by doing just what Reactorman said. Ramp up voltage to the transformer and then ramp it back down to zero. When I do this with CT's I usually do it during the excitation test. I ramp up the voltage on the secondarys until the CT saturates and then I ramp the voltage back down to zero to demagnitize it.