Electric Stress Minimization in Outdoor Contaminated Polymeric Insulators Using an Appropriate Field Grading Material

This paper studies the silver-coated zinc oxide microvaristor’s capability as a stress grading material to reduce the electric field along the polymer insulator surface. Three different microvaristor configurations having non-linear field-dependent conductivity are analysed to find an optimum design that serves as an effective field grading material. Electroquasistatic simulations are carried out on an 11 kV, 2-D polymeric insulator model with and without microvaristor under various environmental effects using COMSOL Multiphysics. The tangential field distributions along the insulator have been evaluated under different surface conditions, like the clean, uniform, and non-uniform pollution and water droplets. Comparative studies show that an appropriate microvaristor design can reduce stress in the critical region.