How is the breakdown voltage test of transformer oil conducted?

The breakdown voltage test of transformer oil is conducted using a device specifically designed for this purpose, such as the Globecore tester. The oil sample is placed in a test cell with two electrodes, typically made of stainless steel, with a specific gap distance. A controlled voltage is gradually applied across the electrodes while monitoring the voltage level. The dielectric strength of transformer oil is determined by the voltage at which a spark (or breakdown) occurs between the electrodes, indicating the oil’s ability to resist electrical breakdown. It’s important to ensure that the sample is free from contaminants and bubbles to obtain accurate results. The unit of dielectric strength of transformer oil is expressed in kilovolts per millimeter (kV/mm), providing a clear measure of the oil’s insulating properties.