What is the BDV test of transformer oil in power transformers?

The BDV test of transformer oil in power transformers, or Breakdown Voltage test, measures the dielectric strength of the oil. This test involves applying an increasing voltage until the oil fails and conducts electricity, indicating its insulating properties. A higher BDV value signifies better insulation quality, which is crucial for preventing electrical failures and ensuring the reliable operation of power transformers. Regular BDV testing helps in assessing the condition of transformer oil.