Withstand voltage test

Withstand voltage test

Voltage withstand test is one of the main methods to test the overvoltage withstand capacity of electrical appliances, electrical equipment, electrical devices, electrical circuits and electrical safety appliances. It is divided into power frequency voltage withstand test and DC voltage withstand test. For power frequency withstand voltage test, the test voltage shall be more than one to several times of the rated voltage of the tested equipment, and shall not be less than 1000V. Pressurization time: 1 minute for equipment with porcelain and liquid as the main insulation, 5 minutes for equipment with organic solid as the main insulation, 3 minutes for voltage transformer and 10 minutes for oil immersed power cable. The DC withstand voltage test can draw the leakage current voltage characteristic curve through the leakage current value at different test voltages. Local defects, damp and aging of insulation can be found in electrical equipment through voltage withstand test.

Chinese Name: withstand voltage test foreign name: pulse test purpose: to test electrical appliances and electrical equipment

Comparison between DC and AC

Advantages and disadvantages of DC and AC voltage withstand test:

DC withstand voltage test: it can effectively find the overall defects such as damp and dirt of insulation, and find the local defects of insulation through the relationship curve between current and leakage current. Because the voltage is divided according to the insulation resistance under DC voltage, the end insulation defects can be found more effectively than AC voltage. At the same time, because the insulation basically does not produce dielectric loss under DC voltage, the DC withstand voltage has little damage to the insulation. In addition, because the DC withstand voltage only needs to supply a small leakage current, the required test equipment has small capacity and is easy to carry.

AC withstand voltage test: when the voltage of the tested equipment is 2.5 times or more, from the point of view of thermal breakdown of dielectric loss, local free defects and weakness of insulation aging can be effectively found. Since it is mainly divided by capacitance under alternating voltage, it can effectively expose equipment insulation defects. However, AC withstand voltage is more destructive to insulation than DC, and because the test current is capacitive current, large capacity test equipment is required.

To sum up, both DC voltage withstand test and power frequency AC voltage withstand test can effectively find insulation defects, but each has its own characteristics. Therefore, the two methods can not replace each other. If necessary, they should be carried out at the same time and complement each other.