By hvhipot 
The correct operation method of series resonance (also known as AC withstand voltage test equipment) is introduced as follows:
1. Cable testing operation:
Notes:
(1) The 10kV cable withstand voltage device adopts series resonance;
(2) A voltage withstand test device for 10kV and 35kV cables, with 10kV cables connected to the low end of a voltage withstand excitation transformer and 35kV cables connected to a voltage withstand excitation transformer;
(3) For 10kV, 35kV, and 110kV cables: 10kV, connected to the excitation transformer, the low end 35kV voltage cable of the excitation transformer 110kV cable contact pressure;
2. Operation of motor withstand voltage test:
Notes:
(1) Series resonance technology is used to control the voltage withstand device of motors, and the excitation transformer is generally connected to the low end;
(2) A voltage withstand test device used to control motors and cables. The cables are connected to the low end of the voltage withstand excitation transformer, and the motor is equipped with a voltage withstand excitation transformer connection;
(3) Typically, resonant devices used for motor voltage resistance are compatible with low-voltage cables.
3. GIS、 Test method operation for switches and transformers:
Notes:
(1) Series resonance technology is used to control switches GIS、 The voltage withstand device of the transformer and the output working voltage of the excitation transformer generally have a high voltage;
(2) Voltage withstand test device for controlling switches and GIS, with excitation transformer connected and transformer subjected to voltage withstand. Excitation transformer connected to the low end;
(3) Usually, the model is compatible with cables that are larger than the resonant device connected to the lower end, and the excitation transformer has a shorter length;
(4) When conducting AC withstand voltage tests on test samples used for controlling switches and low capacitance, it is necessary to connect all reactors of the enterprise in series in the high-voltage system circuit to effectively ensure resonance;
(5) Used for controlling switches GIS、 When the transformer is subjected to voltage, it is necessary to connect the reactors in series system, and the number of reactors in series should be determined according to the actual test working voltage of the enterprise.