Frequency conversion series resonance device covers voltage class of 100kV~800kV; it can perform high-voltage AC withstand voltage partial discharge test on various HV electrical equipment, components, insulating materials, etc. When conducting high-voltage AC withstand voltage tests in underground power stations or small spaces, only such products can be used. The resonant reactor has a high quality factor and can achieve large-capacity output with low power supply capacity. Suitable for power plants, substations, and other place where the power supply capacity is insufficient.