Sep 22, 2018

The Use Of A Hipot Tester

By Paul Olson


High potential is normally abbreviated as hipot. It is a term used in reference to a specific form of electrical safety testing apparatus, called a hipot tester. These apparatuses are used to verify electrical insulation of finished appliances, cables and other devices composed of wires. Transformers, printed circuit boards, and electric motors are among such devices.

Upon the manufacture or assembly of an appliance or product, it is usual for some degree of electrical leakage to occur. However, the leakage is usually very low and is brought about by internal capacitance and voltages inside the appliance. It is normal for such leakage to occur and it needs to be expected of every device. There exist a number of instances where the leakage, for some reason, may be excess.

Excess leakage may be caused by break down of insulation in the product, design flaws or many other causes. Such flaws usually lead to excessive current leaking and may cause electrical shock to anyone that comes in contact with the faulty product. The importance of a hipot test is to verify and ensure that the product is sufficiently insulated so as not to cause shock to the operator.

Another name used to refer to hipot test is Dielectric Withstanding Voltage (DWV). During this test, a high voltage is applied between the metallic shielding of the product and its current-carrying conductors. When this is done, there will be a resultant current that flows through the insulation. This current is known as leakage current and a high potential tester is used to monitor it.

This testing process makes one major assumption. The assumption is that if the insulation of the device is not broken by the deliberate application of excess voltage, then it should be safe for normal operation. The device should be able to withstand application of normal voltage, which is applied during normal use. The name Dielectric Withstanding Voltage comes from this assumption.

The test is aimed at stressing the insulator used in the appliance. Apart from stressing the insulator material, however, the test is additionally used to identify workmanship flaws in the product. The most critical monitored workmanship elements are minute spaces existing between the earth ground and current-carrying conductors. In ordinary environment of operation, shock, humidity, contaminants, shock, and dirt may fill these spaces.

When the gaps are closed, current is allowed to flow. Such conditions can be a major electrical hazard that must be corrected at the factory before the product is released into the market. Such defects cannot be detected by any other method besides DWV. Even though other methods may be used to attempt to resolve these problems, but they cannot be as effective as DWV.

A high potential tester is simply and electric device that manufacturers use to verify electrical insulation. It is comprised of a high-voltage source, current meter, and a switching matrix. The matrix is used to connect current meter and voltage source to all contact points in a cable. The testing process may be automated by the inclusion of a microcontroller and display.




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