Why do you need to perform AC withstand voltage test on power equipment? The AC withstand voltage test is an effective and direct method to identify the dielectric strength of power equipment.

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During the operation of power equipment, the insulation will gradually deteriorate under the action of electric field, temperature and mechanical vibration for a long time. The standard oil cup is used for the withstand voltage test of insulating oil to hold oil. These include overall deterioration and partial deterioration, forming defects. For example, due to the local electric field is relatively concentrated or the local insulation is relatively weak, there are local defects. Various preventive test methods, each with its own strengths, can find some defects and reflect the insulation condition, but the test voltage of other test methods is often lower than the working voltage of power equipment, which is not strong enough as a guarantee for safe operation. .

Although the DC withstand voltage test is relatively high, some weak points of insulation can be found, but because most of the insulation of power equipment is a combination of dielectrics, under the action of DC voltage, the voltage is distributed according to resistance, so DC is used for the test. It is not always possible to find the weaknesses of AC power equipment under the AC electric field. For example, the slot defects of the generator are not easy to be found under DC.

The AC withstand voltage test conforms to the electrical conditions that the power equipment is subjected to during operation. At the same time, the AC withstand voltage test voltage is generally higher than the operating voltage. Therefore, after passing the test, the equipment has a large safety margin, so this test has become a guarantee for safety. an important means of operation. However, because the test voltage used in the AC withstand voltage test is much higher than the operating voltage, the excessive voltage will increase the loss of the insulating medium, generate heat, discharge, and accelerate the development of insulation defects. Therefore, in a sense, The AC withstand voltage test is a destructive test.

Before the AC withstand voltage test, various non-destructive tests must be carried out in advance, such as measuring insulation resistance, absorption ratio, dielectric loss factor tgδ, DC leakage current, etc. HV Hipot comprehensively analyzes the test results to determine Whether the device is wet or defective. If it is found that there is a problem, it needs to be dealt with in advance, and the AC withstand voltage test can be carried out after the defect is eliminated, so as to avoid insulation breakdown during the AC withstand voltage test, expand insulation defects, prolong maintenance time, and increase maintenance workload. .