what is lightning impulse test of a transformer?

The lightning impulse test of a transformer is a high-voltage test designed to assess the insulation strength of the transformer against transient overvoltages, such as those caused by lightning strikes. During this test, a high-voltage impulse waveform, typically 1.2/50 microseconds, is applied to the transformer’s windings and insulation systems. This helps ensure that the transformer can withstand sudden voltage spikes without failure, thereby verifying its reliability and safety in real-world conditions.