Flashover discharges dynamic with continuous and discontinuous pollution layer under lightning impulse stress

The paper is aimed at the study of the dynamic of discharges propagating at the surface of flat PVC insulator (i) with uniform continuous pollution layer and (ii) with uniform discontinuous pollution layer of different conductivities, under lightning impulse voltage for both polarities. It is shown that the morphology of discharges, the current and the voltage as well as the discharge velocity depend on the polarity of voltage, the configuration and the conductivity of the pollution layer; and the behavior of discharges is similar to that of discharges in long air gaps.