What is the acceptable breakdown voltage for transformer oil?

The acceptable breakdown voltage for transformer oil typically ranges from 30 kV to 50 kV for a 2.5 mm gap under standard test conditions. This value indicates the oil’s insulating strength and ability to prevent electrical breakdown. Regular testing is essential to ensure the oil maintains its dielectric properties, as lower breakdown voltages may indicate contamination or degradation, necessitating oil treatment or replacement to ensure transformer reliability and safety.