The effect of discontinuous non uniform pollution on the flashover of polluted insulators under Lightning impulse voltage

The goal of this paper is to investigate and model the effect of non uniform discontinuous pollution on flashover of laboratory plate insulator. The experimental results show that the discharges appear almost simultaneously at the point and the dry bands whatever the polarity of the applied voltage. The lengths of discharges as well as the critical flashover voltage depend on the configuration of pollution layer and the polarity of voltage. Thus the variation of the local equivalent impedance before each discharge determines the propagation conditions of discharges. The flashover voltages computed using the proposed model are found in a good agreement with the experimental ones. On the other hand, the deduced temperature of discharges depends on the configuration of pollution and the polarity of voltage.