HiPot Testing and Its Importance

HiPot Testing refers to a high potential or high voltage testing. A more technical term for this would be ‘Dielectric Withstand Test.’ The purpose of HiPot Testing is to determine proper insulation. In other words, the test is done to make sure that current doesn’t flow from one point to another, unlike a Continuity Test.

Continuity Tests are carried out to ensure that current flows easily from one point to another.

Why HiPot Testing is Necessary

The HiPot Test is a non-destructive test that aims to measure the level of electrical insulation. In other words, the test allows technicians to determine if the insulation can handle transient over-voltages.

Needless to say, it involves exposing the electrical insulation to high voltages. This is done for multiple devices over a specific amount of time. The objective is to make sure that the insulation is up to standards and not marginal or low.

HiPot Tests also help identify issues with the insulation. Insulation can often end up with cuts, braided shielding/stray wire strands, corrosive contaminants, tolerance errors, and terminal spacing issues, etc.

There are also manufacturing issues, such as improper clearance distances or creepage, which can be detected via HiPot Testing.

How is a HiPot Test Carried Out?

A typical HiPot test involves connecting one end of the supply to the ground or earth. The other side is then connected to the conductor that is supposed to undergo testing. Now, in a connection such as this, it is possible for a conductor to either be connected to a high voltage source or the ground.

So, when you have to test two contacts, you connect one to a high voltage source and the other to the ground. This way, your testing contact is isolated from all other contacts.

If the level of insulation between the two is high, you will observe a marginal flow of current after a large voltage is applied. This small amount of current should be low enough to prevent the breakdown of the insulation.

Standards

The duration of a HiPot Test must be in line with issued safety standards. In the US, the duration is typically one minute for products covered under IEC 60950. As for the current limit, it can be set by the user.

However, it is always a good idea to set an average by testing the trip level of multiple products. Then, the final leakage current trip level should be set a bit higher than the average figure.

Finally, the test voltage is set according to AC or DC. With AC, the insulation is stressed most at peak voltage; either at the negative or positive peak of the sine wave. With DC, the insulation is stressed most when a voltage is 1.414 times that of the AC test voltage. In other words, the DC voltage should be equal to the AC peak voltage.