Calculation of potential distributions along semiconducting glazed insulator for impulse voltages under icing conditions

The main objective of the present paper is to calculate the potential distributions along semi-conducting glazed insulator for impulse voltages under icing conditions to improve its electrical performance. Impulse voltages (switching impulse and lightning impulse) are approximated by its equivalent sinusoidal voltages. Thin semi-conducting glaze requires a very large number of elements for finite element analysis because of the open boundary around ice covered insulators. To reduce the number of elements and hence computation time, the region between the domain of interest and infinity is modeled simply by adding a circular boundary, a second mesh of the same size, and boundary constraints to force equivalent boundary potentials to be identical. Infinity lies at the center of the second mesh. In effect, second mesh represents the conformal transformation of all the space exterior to the first mesh into a circle. Conductivity of semi-conducting glaze is varied and its effects on the potential distributions along the insulator have been studied. Results are compared with a normal glazed standard porcelain post insulator under icing conditions. By the simulation results, it seems that switching impulse is the limiting factor for designing of semi-conducting glazed insulator under icing conditions.