Principle of ultra-low frequency insulation withstand voltage test

The ultra-low frequency insulation withstand voltage test is actually an alternative method to the power frequency withstand voltage test. We know that when conducting power frequency withstand voltage tests on large generators, cables, and other test samples, large capacity test transformers or resonant transformers are required due to the large capacitance of their insulation layers. These huge devices are not only bulky and expensive, but also very inconvenient to use. In order to solve this contradiction, the power department has adopted reducing the testing frequency, thereby reducing the capacity of the testing power supply. Through years of theoretical and practical experience both domestically and internationally, it has been proven that0.1HReplacing the power frequency withstand voltage test with the ultra-low frequency withstand voltage test not only provides the same equivalence, but also greatly reduces the size and weight of the equipment In theory, the capacity is about one fifth of the power frequency. The experimental procedure is greatly simplified and has more flexibility compared to power frequency testing. That's why developed countries generally adopt this method. The Ministry of Electric Power of our country commissioned Wuhan High Voltage Research Institute to draft《35kVCross linked polyethylene insulated power cables with ultra-low frequency and below（0.1Hz) Industry standard for voltage withstand test method. This method is being promoted in our country, and this instrument has been developed according to the needs of our country. It can be widely used in AC withstand voltage tests for cables, large high-voltage rotating motors, and power capacitors.