Effect of Foils on Electric Field Distribution of a 245kV Condenser Bushing

Bushing is an important component that is fitted to electrical equipment like switchgear and transformer etc. High voltage insulated bushings are required to bring out the electrical energy through earthed barrier. Synthetic resin bonded paper condenser bushing (SRBP) and oil impregnated paper (OIP) bushing are commonly used bushings. In Indian scenario, it is observed that OIP bushing is used up to 765kV. These bushings have series of dielectric layers with conducting aluminum foils in between each layer to improve the distribution of electric field. The present paper discusses analysis of electric field distribution in a 245 kV OIP bushing with varying number of foils and their thickness using finite element method. Simulation results shows that 12 foils, 2mm thickness each and 6mm gap between the foils is optimum for better distribution of the field. The paper also discusses the experimental verification of the field estimated through the simulation.