The DC withstand voltage test voltage is high, which has a special effect on finding some local defects of insulation, and can be carried out simultaneously with the leakage current test. Compared with the AC withstand voltage test, the DC withstand voltage test has the advantages of light test equipment, low damage to insulation and easy to find local defects of the equipment.
Compared with the AC withstand voltage test, the main disadvantage of the DC withstand voltage test is that the DC voltage withstand test is not as close to reality as AC due to the different voltage distribution inside the insulation under AC and DC.
The AC withstand voltage test is an effective method to identify the insulation strength, especially for the local defects of the main insulation, such as the main insulation of the winding is damp, cracked or loosened during transportation, the lead distance is insufficient, and the insulation on the winding insulation Wait. The AC withstand voltage test is very strict on the insulation test, and can effectively find more dangerous concentrated defects. It is the most direct method to identify the insulation strength of electrical equipment. It is of decisive significance for judging whether electrical equipment can be put into operation. It is also an important means to ensure the insulation level of equipment and avoid insulation accidents. AC withstand voltage test may sometimes make some weak points in the insulation more developed. Therefore, the test must first test the insulation resistance, absorption ratio, leakage current and dielectric loss before the test. If the test result is qualified, it can conduct AC resistance. Pressure test. Otherwise, it should be dealt with in a timely manner. After the indicators are qualified, the AC withstand voltage test is carried out to avoid undue insulation damage. Although the AC withstand voltage test is effective for finding insulation defects, it is subject to test conditions. It is necessary to carry out transformer withstand voltage test of 66kV and above. Due to high voltage and high current, such high voltage test transformers and voltage regulators are not popular enough. The series reactor uses a method of generating a high voltage by resonance to perform a withstand voltage test on a high-voltage device. From the actual result, the effect is very good.
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