Variable frequency series resonance is mainly composed of a variable frequency controller, an excitation transformer, a high-voltage reactor, a high-voltage voltage divider, etc. The variable frequency controller is divided into two types: 20kW and above are control consoles, and 20kW and below are portable box types; it consists of a controller and a filter. The main function of the variable frequency controller is to convert the fixed amplitude and fixed frequency power frequency sinusoidal AC of 380V or 200V into a sinusoidal wave with adjustable amplitude and frequency, providing power for the entire equipment. This product adopts the principle of series resonance, uses an excitation transformer to excite the series resonance circuit, adjusts the output frequency of the frequency converter controller, and the resonance voltage is the voltage applied to the test object. The variable frequency resonance test device is widely used in industries such as electric power, metallurgy, petroleum, and chemical engineering. It is suitable for transfer and preventive tests of large-capacity, high-voltage capacitive test objects. 1) The tuning curve is a curve) During the test, the primary voltage is relatively high, but the high voltage is relatively low, and even when the test voltage is not raised, the circuit automatically reduces voltage; 5) Generally, when the equipment outputs high voltage, high-voltage corona-resistant wires are used, or the ordinary high-voltage output wire is changed to a shorter connecting wire. 1) Check whether the grounding device of the variable frequency series resonance is reliable and whether the grounding connection wire is intact; 2) Check whether the signal wire of the voltage divider is well connected; 3) Check the on-off of each reactor;