A DC hipot test or direct current high potential test is a diagnostic procedure done to cables or other high voltage equipment to check if the insulator can withstand the operating voltage without excessive leakage current flowing through the insulator. It is usually done on new cable installations because aged or damaged cables can fail during the test.
A DC hipot test is conducted by applying a high DC voltage on the test conductor and measuring the leakage current to determine the insulation resistance. The test voltage may reach as high as 20 kilovolts. Electrical precautions should be exercised during the test to avoid injuries and unnecessary damages on equipment. It is also important to perform proper termination and corona suppression to avoid accidents and to get an accurate reading. Improper termination can cause flash overs or generate a standing wave that can damage the cable or the test equipment. The ideal condition to conduct the test is during cool dry weather. The insulation resistance constant for insulators are given values at 60 degrees Fahrenheit. High temperature and humidity can impair the readings.
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