Monday, 10 September 2018

Uses Of A Hipot Tester

By Paul Olson


The abbreviation used in place of the word high potential is hipot. This term is used in reference to a given group of instruments used for testing electrical safety in electric products. Hipot tester is used to verify the electrical insulation in various wired assemblies including appliances and finished cables. Some of these wired assemblies are printed circuit boards, transformers, and electric motors.

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.

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.

One major assumption is made in hipot testing. The assumption is that by applying excessive voltage, the insulation of the product should break, and if it does not, then the device should work fine under normal conditions. The appliance is supposed to be resilient against normal voltage, which is often applied in ordinary everyday use of most devices. It is this assumption that gives rise to the name Dielectric Withstanding Voltage.

The objective during testing is to stress the insulation in the product. However, apart from inducing stress on insulation, the test detects any workmanship defects that may be present. The workmanship monitoring focuses on the tiny gap spaces occurring between the earth ground and conductors that carry current in the device. In normal working environment, these small gaps can be closed by dirt, humidity, vibration, shock, or contaminants.

When these small gaps close, the flow of current is enabled. This flow of current can be a major electrical hazard. Prior to product release into the market, it must be tested verify that such hazards cannot occur. The only applicable method that can be used in the detection of this type of defects is DWV. This is true in spite of there being other viable methods.

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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