1, insulation resistance test
Insulation resistance test is a widely used and convenient item in electrical equipment insulation test. Insulation resistance value can effectively reflect the overall humidity, pollution and serious overheating and aging of insulation. The commonly used instrument for testing insulation resistance is insulation resistance tester. The use of insulation resistance tester shall comply with the relevant provisions of DL/T596 Preventive Test Regulations for Power Equipment.
2. Leakage current test
The leakage current of electrical equipment can be measured by adding DC high voltage. Commonly used devices for measuring leakage current include high voltage test transformer and DC high voltage generator. When there are some defects in the equipment, the leakage current under high voltage is much larger than that under low voltage, that is, the insulation resistance under high voltage is much smaller than that under low voltage. Microammeter used for leakage current measurement is more accurate than insulation resistance tester.
3.DC withstand voltage test
The DC withstand voltage test has a high voltage, which plays a special role in finding local insulation defects and can be carried out simultaneously with the leakage current test.
Compared with AC withstand voltage test, DC withstand voltage test has the advantages of light test equipment, small insulation damage and easy to find local defects of equipment. Compared with AC withstand voltage test, the main disadvantage of DC withstand voltage test is that DC withstand voltage test is not as close to reality as AC withstand voltage because of the different internal voltage distribution of insulation under AC and DC dual use. Testing.
4. AC withstand voltage test
The AC withstand voltage test requires very strict insulation test, which can effectively find dangerous concentrated defects. It is a direct method to identify the insulation strength of electrical equipment, which is of decisive significance to judge whether electrical equipment can be put into operation, and it is also an important means to ensure the insulation level of equipment and avoid insulation accidents.
Ac withstand voltage test sometimes further develops some weaknesses in insulation. Therefore, insulation resistance, absorption ratio, leakage current and dielectric loss must be tested before testing. If the test results are qualified, AC withstand voltage test can be carried out. Otherwise, it should be handled in time, and AC withstand voltage test should be carried out after all indicators are qualified, so as to avoid unnecessary insulation damage.
5. Test of dielectric loss factor tgδ
Dielectric loss factor tgδ is one of the basic tests for insulation test of high voltage electrical equipment.
Dielectric loss factor tgδ is one of the basic indexes reflecting insulation performance. It can sensitively detect the overall damping, deterioration and deterioration of electrical equipment insulation, as well as the local defects of small-volume equipment penetration and non-penetration. Compared with measuring insulation resistance and leakage current, dielectric loss factor tgδ has obvious advantages. It has nothing to do with test voltage, sample size and other factors. It is more convenient to judge the insulation change of electrical equipment and effectively find insulation defects.