Cables are critical components of a power facility. It carries the current to different parts of the power grid. However, there are times that the insulation fails because of weathering or stress. Cables should be tested for defects because it can affect the operation of the power facility if neglected.
Good insulators can withstand several Volts above its rating. When moisture or contaminants accumulate, the ability of the insulator to resist current is reduced. The lowered resistance causes current to flow which may lead to flash overs and eventually fail. The preferred method of diagnosing cables which have been in operation for a while is AC hipot testing. This test is safer than DC hipot because using AC current reduces the risk of insulation breakdowns. There are times when a cable fails the test even if it is in good condition because it uses a very high voltage that puts too much stress on the cable. DC high potential testing is usually done on new cable installations because of the absence of contaminants. Its purpose is to find cable factory defects before putting it into operation.
If you do not have the right equipment to test cables, you might want to consider renting fromProtec. We have equipment from major brands like Metrel test instruments, Siemens and more. Call us at 866-352-5550 if you have questions about our services.