Investigation of Field Distributions on a 24 kV AC Silicone Rubber Bushing Employing Nonlinear Field Grading Materials Under Various Wetting Conditions Using FEA

This paper investigates the efficiency of using nonlinear field-grading materials to reduce electric field intensity along the surface of a silicone rubber bushing. Three distinct configurations of zinc oxide microvaristors with nonlinear, field-dependent conductivity are analyzed to determine the most effective design for use as a field-grading material. Finite Element Analysis (FEA) simulations are performed on a 2-D silicone rubber bushing model with a 24 kV rating, both with and without the inclusion of zinc oxide microvaristors, while taking into account different environmental conditions. Tangential field distributions along the leakage path surface of the silicone rubber bushing are examined under varying surface conditions, such as clean surfaces, uniform pollution, non-uniform pollution, and the presence of water droplets. Comparative analyses demonstrate that stress in the crucial area close to the flange ground terminal can be reduced with zinc oxide microvaristor design.