Hipot Test (High-Potential Withstand Test)

A dielectric breakdown test in which a voltage significantly higher than the nominal operating voltage of a switchgear assembly, transformer, cable or other equipment is applied for a short, standardised time (typically 1 minute, sometimes 1 second for a routine test in production), to verify that the insulation can withstand a brief overvoltage without breakdown or flashover. Unlike an insulation resistance measurement with a megohmmeter, which applies a relatively low DC voltage and yields a resistance value in megohms, the hipot test is a pass/fail test at a much higher voltage level (for example 2× Un + 1000 V) that specifically looks for weak spots, air pockets or damaged insulation that would not yet fail at normal operating voltage. The test is applied both as a type/routine test in the factory (NEN-EN 61439-1/2 for low-voltage switchgear and controlgear assemblies) and during commissioning and periodic maintenance of cables and larger machines, using AC or DC voltage depending on the object under test.