On discharge phenomena in a covered electrode system in air

The process of surface charge deposition in a dielectric covered electrode system in air has qualitatively been investigated for a sequence of lightning impulses of negative polarity using high speed photographing and current measurements. It was found that at moderate electric stress in the air gap, a limited and voltage dependent number of impulses deposited a sufficient amount of surface charge at the coatings to quench further discharge activity. At higher electric stress, the surface charging process was of a more complex nature. The charge deposition continued throughout the entire sequence, but parts of the previously deposited charge relaxed when the stress in the air-gap was lowered due to the decay of the applied lightning impulse.