How is the dielectric strength test of transformer oil performed?

The dielectric strength test of transformer oil is performed using a standardized method, typically ASTM D877 or ASTM D1816. A sample of the oil is placed in a test cell with two electrodes, and an AC voltage is gradually applied. The voltage is increased until the oil breaks down, causing a spark between the electrodes. The dielectric strength is recorded as the voltage at which breakdown occurs, measured in kilovolts per millimeter (kV/mm). This test assesses the oil’s insulating properties.