Question

Dielectric strength of transformer oil per mm is expected to be

Answer 1

For mineral oil, a generally accepted minimum dielectric strength is 30 kV for transformers with a high-voltage rating of 230 kV and above and 27 kV for transformers with a high-voltage rating below 230 kV. New oil should have a minimum dielectric strength of 35 kV by ASTM methods of testing.