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Uses Of A Hipot Tester

By Paul Olson


The term hipot is usually used as an abbreviation for high potential. It is a term that is used to refer to a certain class of electrical safety testing instruments referred to as a hipot tester. These instruments are used in the verification of the electrical insulation in finished cables, appliances, and other wired assemblies. Such assemblies include electric motors, transformers, and printed circuit boards just to mention a few.

In many cases, after the assembling/manufacturing of an appliance/product some current leakage of some level occurs. The interior of the product contains internal capacitance and voltages that often cause this minimal current leakage. It is normal for all devices to experience this leakage. However, in some scenarios, the current leakage may too high that it should be due to certain reasons.

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.

Dielectric Withstanding Voltage, DWV, is another term used in reference to the hipot test. At the time of the test, a high voltage is applied between the conductors that carry current in the product and its metallic shielding. Upon completion, there will exist a resultant current that makes its way through the insulator material. The term used for this current is leakage current and is tested using a high potential tester.

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.

The flow of current is allowed when the small gaps between earth ground and current-carrying conductors in electrical devices. This may cause a major electrical risk that must be rectified during manufacture before the product is made available on the market. Only DWV can be used for defect detection. Other methods may not be efficient like the DWV even though they can attempt to identify these defects.

An electric device that manufacturers use in verification of electrical insulation is a high potential tester. It is made of a source of high voltage, a switching matrix and a current meter. Connection of the source of voltage and the current meter is done by the matrix switch. Including a display and a microcontroller automates the process of testing.




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