Flash Test – Flash Testing Electrical Safety Equipment

A Flash Testing evaluates whether the electric insulation section of an electric equipment or parts have sufficient dielectric strength for the working voltage. It is also called dielectric withstand test or hipot test.

In Flash Testing, a voltage stress that is much higher than the voltage that is normally applied to the insulation section for a specific time to see whether a dielectric breakdown occurs. If a current flowing through the insulation section exceeds the limit during the test period, it is assumed that a dielectric breakdown occurred. If a dielectric breakdown does not occur, the insulator is assumed to have sufficient dielectric strength.

AC and DC Flash Testing

For the test between the primary circuit and an accessible section as shown in Fig. B-2, an AC voltage is normally applied. If a filter for eliminating the electromagnetic interference is present in the location corresponding to Z1 or Z2 and its capacitive component is large, the distinction between the current flowing through the filter and the current used to assume a dielectric breakdown will be difficult. In this case, it is recommended that the test be performed using a DC voltage equal to the peak value of the specific AC voltage.