Transformer Oil - Dielectric Tests

Dear Friend,

As far as my experience goes its the type of oil which determines the break down strength. The air gap,testing procedure,time are all the same for any voltage of application. The BDV value is independant of the service voltage where the insulating oil is supposed to be used.

Testing parameter and method of Transformer Oil is "NO DIFFERENCE" , even 400 KV or 4000 volts transformer voltage rating.

Dielectric breakdown voltage (KV) Minimum [0,040 inch gap thin ]

Hello karimalamiri!

I agree with Sabnavees answer, I want add that some vegetal origin oils dielectrics manufacturers had made a change about sample rest time indicated in ASTM D 1816, pass it from 5 to 15 minutes Due to their higher viscosity (see IEEE C 57.147- 2008), This modify the method in base of type of the oil.