The method of measuring AC withstand voltage with afrequency conversion series resonant withstand voltage deviceis to change the inductance and frequency in the test circuit, and the circuit is in a resonant state. This method can meet the testing requirements of high voltage and high current. When conducting AC withstand voltage tests on devices with series resonant frequency voltage, the following points should be noted:

1. Before the experiment, it is necessary to understand whether the non-destructive testing technology project management of the tested equipment is qualified. If there are any defects or abnormalities, testing should be conducted after they have been eliminated.  

2. At the site of the experiment, a fence should be set up, a warning enterprise sign should be hung, and a dedicated person should supervise.  

3. The insulation surface of the equipment to be tested should be cleaned before the test, and the test equipment, test object casing, and non test winding should be reliably grounded. For multi oil equipment, the test should be conducted after a certain period of static oil according to relevant regulations. For example, for large capacity transformers, the oil should be left to stand for 12-24 hours, and for 3-10kV transformers, the oil should be left to stand for 6-12 hours.

4. Adjust the gap between the protective balls to ensure that the discharge voltage is between 105% and 110% of the test voltage. Three consecutive tests with no significant difference were conducted to check the reliability of the overcurrent protection device.  

5. Connect the wires according to the test wiring diagram. Before preparing for pressurization, a dedicated person should check and confirm that there are no errors (including grounding distance, safety distance, etc.).  

6. Before applying pressure, check whether the regulator is in the zero position. Confirm that the pressure regulator can be pressurized after reaching zero position. Shout 'high family pressure' before proceeding with the operation.

7. The pressure increase rate can be slightly faster when the test voltage is less than 30%. Then the boost should be uniform, about 5% of the test voltage. Or 10-15 seconds when the rated test voltage rises.

8. During the boost design process, monitor changes in digital voltmeters and other enterprise instruments. When the rated voltage is 0.5 times, read the capacitance current of the tested equipment; When the voltage rises to the rated voltage, start calculating the time, then read the capacitor current, and slowly decrease the voltage to zero after time. Then disconnect the power supply.  

9. In the experiment, if it is found that the pointer of the voltmeter swings significantly, there is abnormal noise from the test sample, and the milliampere meter reading increases sharply. The test sample emits smoke, catches fire, and generates continuous spark discharge on the insulation surface. Immediate voltage reduction should be carried out, and the cause should be identified after hanging a grounding wire on the high-voltage side.  

10. If the tested equipment is not specified, the general voltage withstand time is 1 minute, and the withstand time of insulation rods and other electrical appliances is 5 minutes. After the test is completed, the grounding wire should be hung in a timely manner. Then contact the relevant components without heating.  

11. The insulation resistance and absorption rate of the tested equipment should be measured before and after conducting experimental research. The two measurement results are not significantly different.