The test voltage for power frequency withstand voltage is much higher than the operating voltage of the equipment. Excessive test voltage can cause the insulation medium to heat up and discharge, accelerating the development of insulation defects. Therefore, it is a destructive test.
Before conducting the power frequency withstand voltage test, various non-destructive tests should be carried out on the tested equipment, such as measuring insulation resistance, absorption ratio, dielectric loss factor, and DC leakage current tests. After analyzing the results of all tests comprehensively, the power frequency withstand voltage test can be conducted. This is to prevent the expansion of defects during the withstand voltage test. Power frequency withstand voltage is an effective and direct method for evaluating the insulation quality of equipment and an important means to ensure the safe operation of equipment and power equipment.
1. During the power frequency withstand voltage test, there should be operators and inspectors in the control room; there should be a test leader and a supervisor in the test hall. The tested item should be under the unified command of the test leader throughout the entire test process. Anyone has the right to question unsafe factors to the leader and refuse to execute.
2. Before the test, check whether the test transformer and related supporting equipment are in good condition and the grounding system is correct. Close all the doors in the test hall and do not allow irrelevant personnel to enter.
3. Adjust the gap of the overvoltage protection device’s sphere to meet the requirements of the overvoltage protection of the tested item and verify its accuracy through no-load verification.
4. Place the tested item on the test stand, connect the ground wire and the high-voltage lead, and confirm that there are no errors. Then, the test personnel leave the site, the test leader and the supervisor leave the test area, and use an operation command or gesture to notify the operators that it is allowed to operate.
5. Operators should check that the control equipment switch is in the open position, the regulating device position is at zero, and after verification by the checking personnel, notify the personnel in the test hall “Start the test”. When the personnel in the test hall make a clear indication, the test can be carried out.
6. Operators and checking personnel must stand on the insulating platform pad. Close the power switch and the control switch, and the indicator lights on the control console should be on.
7. Press the high-voltage closing button. The indicator lights on the control console and the test hall should be on. Then press the voltage rise button and slowly increase the voltage. At this time, pay attention to whether the voltage meter indication is normal, and observe whether there are any abnormal phenomena in the test transformer and related equipment. All is normal before conducting the test.
8. According to the test data specified in the product regulations, conduct the power frequency withstand voltage test on the product. The test transformer should not exceed the voltage, and continuous operation should not exceed half an hour. 9. If there are any abnormal phenomena in the control room during the product test, the operators and checking personnel should stop the test according to the specific situation and notify the test leader. If there are any abnormal situations in the test hall, the test leader and the supervisor should notify the operators to stop the test.
10. After the product test is completed, turn off all switches, operators and checking personnel should leave the control room, confirm that there is no electricity, and ground the high-voltage part of the equipment before dismantling and installing the tested item.
11. During the entire power frequency withstand voltage process, it is strictly prohibited for any personnel to walk around or make loud noises in the hall.
12. After the work is completed, the power supply should be turned off, the equipment and the site should be cleaned, and the equipment operation status record form and test record form should be filled out.
Post time: Aug-27-2026