Potential and electric-field distributions around an ice-covered post-type insulator

Abstract

To facilitate the study of phenomena preceding the flashover of an ice-covered station post insulator during a melting period, the potential and electric-field distributions along the insulator have been numerically calculated. Commercial software based on the boundary element method was used for this purpose, and a simplified three-dimensional model of the ice-covered insulator was developed and validated experimentally. Then, a station post insulator covered with wet-grown ice under a melting regime was numerically simulated on the basis of experimental results. The presence of a conducting water film at the ice surface, the shedding of ice deposits, and the presence of a partial electric arc along an air gap were taken into account in the simulations. The results obtained have made it possible to show that the water film, the number of intervals of air, and the presence of partial arcs have a considerable effect on the distribution of the potential and the electric field along the insulator. In the same way, the appearance of a partial arc as well as the occurrence of ice shedding lead to a redistribution of the potential along the ice deposit, either supporting or inhibiting the flashover process. The results obtained will help to improve insulator geometry for cold climate regions.