By hvhipot 
Series resonance experiment is an effective and direct method for identifying the insulation strength of power equipment. During the operation of power equipment, the insulation will gradually deteriorate over a long period of time under the action of electric field, temperature, and mechanical vibration, including overall deterioration and local deterioration, resulting in defects; For example, due to local electric field concentration or fragile local insulation, there may be local defects. Various preventive testing methods can be used to identify defects and react under insulation conditions, but the test voltage of other testing methods is often lower than the working voltage of power equipment, and the guarantee of safe operation is not strong enough. Although DC withstand voltage testing has a high test voltage, there are also some insulation defects; However, due to the fact that the insulation of power equipment is mainly composed of dielectric materials, under the action of DC voltage, its voltage is distributed according to resistance. Therefore, the weak link of AC power supply is that equipment under AC electric field does not necessarily need to be tested with DC electricity; The results indicate that slot defects in the generator are not easily detected under DC conditions. The AC withstand voltage test meets the electrical conditions of the operating electrical equipment. At the same time, the voltage for the AC withstand voltage test is generally higher than the operating voltage; Therefore, after the experiment is completed, the equipment has a large safety margin, making this test an important means to ensure safe operation.
However, due to the fact that the test voltage used in the series resonance test device is much higher than the test voltage used during operation, excessive voltage can increase dielectric loss, heat generation, and discharge, accelerating the development of insulation defects; Therefore, in a sense, the series resonance test is a destructive test.
Before the series resonance test, various non-destructive tests must be conducted in advance, such as insulation resistance, absorption ratio, dielectric loss factor, DC leakage current, etc; And conduct a comprehensive analysis of the test results to determine whether the equipment is wet or defective. If any problems are found, they need to be addressed in advance; During the testing process, in order to avoid insulation breakdown, expand insulation defects, extend maintenance time, and increase maintenance workload, it is necessary to eliminate defects before conducting series resonance tests.