Dielectric Breakdown Voltage

The dielectric strength of a transformer oil is defined as the maximum voltage that can be applied across the fluid without electrical breakdown.  Transformer oils are designed to provide electrical insulation under high electrical fields therefore any significant reduction in the dielectric strength may indicate that the oil is no longer able to function in this capacity.  The sample is carefully poured into a clean test vessel containing specific electrodes and placed in the test equipment.  A voltage is applied across the sample starting at zero and increasing until breakdown occurs.  The breakdown voltage is reported in kV.