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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.

After a product/appliance has been manufactured or assembled, it is usually normal that there will be some level of current leakage. The amount of current leakage experienced is usually minimal and is caused by voltages and internal capacitance within the product. This leakage is normal and should be expected in every device. However, there are certain cases where excessive leakage current flow can occur due to various reasons.

Several causes lead to the excessive current leakage, including flaws in design and break down of internal insulation. Anyone that gets exposed to such faulty devices may be electrocuted from the excessive current leakage. To protect the operator from shock, it is important to conduct a hipot test for verification purposes to ensure that the product has sufficient insulation.

Dielectric Withstanding Voltage (DWV) is another term used in place of the term hipot test. This process involves application of a high voltage between the earth ground shielding and the conductor in the product that carry current. Exposure to excessive voltage causes resultant current flow through the product. A high potential tester is the gadget used in monitoring of this resultant current, which is also called leakage current.

This process of testing has its basis on a major assumption. The assumption is that if the device works safely without its insulation breaking after being exposed to high voltage, then it can work fine under normal working conditions. During normal operation, the device should be able to withstand standard voltage application. This assumption is the source of the term Dielectric Withstanding Voltage.

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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