DC performance of non-uniformly transversal polluted glass insulation under parallel electrical discharges’ effect

The aim of this paper is to quantify the evolution’s effect of parallel electrical discharges on the performance of a plane insulation placed simultaneously under conditions of a non-uniform transversal distribution of pollution and positive DC voltage. The results emanating from this experimental study revealed a maximum increase about 18% of flashover voltage of insulation’s non-uniform transversal distribution of the insulation compared to that obtained under uniform pollution distribution. The existence of a limit value of the electrical conductivities’ ratio of the lightly and the heavily contaminated bands, characterized by an early development of the electrical flashover arc of the insulation in the heavily polluted band, was demonstrated in this investigation. Also, a direct link has been established between the flashover frequency of the insulation’s highly contaminated band, under the effect of a non-uniform transversal distribution of pollution and its electrical resistance. Similarly, an approximation linking the insulation’s length to the effective width of an electrical arc in its last phase of development and consequently the number of electrical arcs that can develop in the two differently polluted bands just before the insulation’s flashover was done in this study.