Conductivity effect on the flashover voltage of polluted polymeric insulator under AC voltage

Surface pollution of polymeric insulators constitutes one of the most important factors in the quality and the reliability of the energy transportation. Indeed by time of rain or fog, the polluting layer deposited on the insulating surfaces reduces considerably the resistivity and flashover can sometimes occur. In the present work, some tests have been curried out in the laboratory to determine, in one hand, the influence of discontinuity and the continuity of the pollution layer on the flashover voltage of the polymeric insulators and in the other part, to visualize the electric arc development on its surface. The results of this study show that the dielectric rigidity of the insulator is weaker for a uniform pollution distribution than that for the case of a non-uniform pollution. The flashover voltage decreases in a non-linear manner. For relatively high conductivities, the flashover voltage is affected slightly by the increase of the conductivity of the pollution layer.