Arc Entry Test

The current waveform in the lightning strike is composed of several different components relevant to lightning verification testing, the first short stroke, the long stroke and the subsequent stroke.

The long stroke simulates the continuing current components, where a large charge is transferred to the grounded structure via a fairly low frequency (DC) current pulse. The impact of the charge transfer is erosion of all metallic surfaces at which arcing occur. This is typically the surfaces of air termination systems, spark gaps or brushes along the path of the down conductor.

In the arc entry test, oscillating current pulses of 20-50kA superimposed by a DC current are injected into the test sample. The impact simulates the long stroke component and the current pulse is injected into the air termination system via an open arc, giving rise to realistic arc root erosion on the surface of the attachment point. The air termination surface will be exposed to severe thermal heating and surface erosion, whereas the down conductor system is less affected.

The tests are performed according to Annex D of IEC 61400-24, with charge levels from 20-750Coulombs.

The arc entry test is documented with a test report containing pictures and test results.