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Friday, September 21, 2018

Uses 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.

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.

Faults in the design or disintegration of product insulation among many other reasons may be the cause of the excessive leakage. These flaws often cause excessive leaking of current and may give rise to electrical shock for any individual that comes into contact with the defective appliance. The essence of a hipot test is to ensure and verify that the product has enough insulation so that the user of the device may not be electrocuted.

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 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 aim of the test is to stress the insulation used in the product. However, besides stressing the insulation, the test is also used to detect defects in workmanship. The most important aspects of workmanship that are monitored are the small gap spacings that occur between current-carrying conductors and earth ground. Under normal operating environment, these small gaps can be closed by contaminants, shock, vibration, humidity, and dirt.

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.

Manufacturers use high potential testers to do the verification of electrical insulation. Often, this simple electric device comprises of a switching matrix, current meter, and a source for the high voltage. All the points located on the cable are connected to the high-voltage source and the current meter through the matrix. Including a display and a microcontroller helps to automate the testing process.




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