Normally when a surge enters a structure, its remarkably close to combination Ring Wave surge (1.2/50µs or 8/20µs). However, by the time it travels over a length of mains cables and around the structure, the waveform dramatically changes – the current decreases and transforms into a decaying 100kHz wave show below.

This phenomenon also occurs when surge goes through the filter which causes the coils to ‘ring’ at the circuit’s resonant frequency or caused by switching of electrical networks, reactive loads, power-circuit failures, insulation breakdown or lightening in low-voltage cables.

IEC 61000-4-12 defines the test setup, test levels and procedure to perform the ring wave surge test.  Ring wave surge generator at INTL Inc. can perform testing as per IEC 61000-4-12 up to the test level of 6kV.