The ultra-low frequency insulation withstand voltage test is actually an alternative method of the power frequency withstand voltage test. We know that when power frequency withstand voltage tests are performed on large generators, cables and other test products, due to their insulation layer presents a large capacitance, we need a large-capacity test transformer or resonant transformer to complete the testing. Such huge equipment is not only cumbersome and expensive, but also very inconvenient to use. In order to solve this contradiction, the electric power department adopted to reduce the test frequency, thereby reducing the capacity of the test power supply.
Through many years of theory and practice at home and abroad, it has been proved that using 0.1Hz ultra-low frequency withstand voltage test instead of power frequency withstand voltage test can not only have the same equivalence, but also greatly reduce the volume and weight of the equipment, and the theoretical capacity is about one-fifth of the power frequency. The test procedure is greatly reduced, and it has more advantages compared with the power frequency test.