There are several hipot tests done to check the effectiveness of insulators on electrical devices. Let’s discuss the differences between DC and AC hipot.
measures the insulation resistance of cables by applying a high voltage on the test device. The leakage current is measured and computed to get the insulation resistance. The drawback of this test is that it can damage old cables during the test. This procedure is only advisable to be conducted on new cables. The voltage applied on the test cable is several times higher than AC hipot. This is why DC hipot test is more prone to flash overs and corona discharges.
AC hipot test is done by applying a high AC voltage on the test conductor and measuring the leakage current. This test gives a higher leakage current reading because a cable can act as a capacitor. AC current flows easily on a capacitor than DC. The test voltage applied on the test conductor is lower compared to DC but more power is required because at 60 hertz, the capacitive reactance is low.
There are special instances to use a AC or a DC hipot test. Protec has a vast line of high voltage equipment for rent or for purchase.
Related electrical test equipment available for rent from Protec: