The Oil Breakdown Voltage Test is used to measure the dielectric strength of insulating oil, which indicates the oil’s ability to withstand electrical stress without failure. During the test, a gradually increasing voltage is applied between two electrodes immersed in the oil sample until electrical breakdown occurs. The voltage level at which the oil fails is recorded as the breakdown voltage. This test is essential for evaluating the quality and insulating performance of transformer oil, as lower breakdown voltage values may indicate the presence of moisture, contamination, or aging in the oil.