June 4, 2020

Hipot Test (Dielectric withstand test)

What is HIPOT test?

A Hipot test is a test for insulation. Its full name is high potential test, which actually means dielectric withstand test.

Why should we do the hipot test?

Hipot test is an important test, it helps users to identify the peek withstand value of insulation, and discrepancy of insulation material. In the electrical and electronic area, this test is required in many technical standard.

Hipot test in electrical lab

In many international or national standard like IEC, ANSI, ASTM, there are test method of hipot test. Operator shall take one piece or more sample of the material, for example, the polymer housing, or a silicon rubber shield of a wire or cable, put into this test. The hipot test will apply voltage of both end of the sample, and test equipment will show the high voltage and leakage current that the sample may withstand.

Sometimes, hipot test is not done separately. As in many standards, we have to test the insulation sample under severe circumstances. Like acid rain, or salty spray, which is to simulate the real environment of nature and see if these insulation materials can survive for a long run.

For example, for polymer insulators over 1000V, IEC standard requests that silicon rubber specimen shall pass the “Anti-leakage tracking erosion test”. For this test, we no long use small test equipment like a meter, instead, we use a more professional testing machine. (Because the polymer insulators for power distribution is at least on 11kV or 33kV, much higher than 1000V) This testing machine will apply high voltage on top end and bottom end of the rubber, and contaminated liquid will go through the surface of the rubber specimen with a certain speed of flow.

The anti-leakage tracking, erosion testing machine we have here:

Tracking & Erosion Tester of Composite Insulators

Hipot test  in the production line

Hipot test may also appear in the production line of manufacturers. In some places, it is one part of the factory acceptance test. It is to test in mass production when each batch of products is completed and ready to deliver. When every product go through a test, this test becomes a “routine test”. Routine test is an essential method of quality control, which shall not be neglected by any manufacturer of electrical components.

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