What breakdown voltage value indicates acceptable transformer oil condition?

Acceptable BDV depends on the test method, the voltage class, and whether the oil is new, reclaimed, or in service. Utilities often set internal action limits and trending rules, but broadly, low BDV suggests moisture or contamination and triggers filtration, dehydration, or further investigation. Because BDV is highly method dependent, always state the method (IEC 60156, ASTM D1816, ASTM D877) and compare against your fleet limits and the oil supplier specification.