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The Difference of AC hipot and Other Hipot Tests

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High potential testing or simply hipot is a method of testing insulators to see if it can withstand its rated current during operation. A test device either holds the test voltage or breaks down during the test.


A hipot test is done on electrical devices to ensure that the insulators will not breakdown during operation. There are several hipot tests which differ on the type of potential applied during the test. There’s the 
AC hipot test which uses 50 or 60 Hertz alternating current. The test voltage is determined by multiplying the voltage rating of the test sample by 2 then adding 1000 volts. The DC hipot uses direct current but is 1.414 times higher than AC hipot. This test is prone to flash overs and arcs. It is also believed that DC hipot degrades the insulation due to the very high potential used. VLF hipot or very low frequency hipot is almost the same with AC hipot. The difference is instead of 60 hertz AC, it uses 0.1 hertz or lower. This effectively reduces the needed current to conduct the test because at 0.1 hertz, the test sample has less reactance than using 60 hertz AC.

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