Heating Dissipation Study of a Pollution Layer on a Cap and Pin Insulator

Abstract

The flashover mechanism of outdoor insulators is stated in the literature, and follows several steps before occurring. Beginning by the wetting process; by rain or fog, of the pollution layer already deposited on the surface of the insulator, allowing leakage current to flow and causing heating dissipation in the pollution layer, leading to dry bands formation, and after, to the arcing of the latter due to the voltage concentration around them. Subsequently the flashover of the whole insulator occurs by the ionization of the arc path. In this paper, one of the flashover mechanisms is studied, namely the heat dissipation, due to the leakage current flow in a pollution layer deposited on a high voltage insulator surface. To achieve this work COMSOL-Multiphysics computes the temperature distribution on the pollution layer, having different values of the electrical conductivity. The obtained results show that the temperature is highest at the pin region where the electric field is most significant. Due to the non-regular shape of the cap and pin insulator there is peaks in the temperature repartition allowing dry band formation.