Design of grading material for electric stress control in a polymeric disc insulator

摘要

In the present work, electric stress analysis is performed on a graded polymeric disc insulator. Excessive electric stresses near the high voltage and the ground end is observed for insulators without field grading which may lead to potential surface discharge or even flashover during pollution and wet conditions affecting the long term performance of the insulator. Considering the aforesaid fact, a non linear stress grading material using Zinc Oxide (ZnO) microvaristor is used in the present work to relief electrical stresses at the high voltage and the ground terminal of the polymeric disc insulator. The dimensions of stress grading material are varied to find an optimum design of stress grading layer. The electric field simulation is performed using Finite Element Method (FEM). Investigations reveal that there is a considerable reduction in electric stresses using the grading material compared to insulator without field grading. Moreover, a particular design of grading material is found to show better performance in electric field reduction compared to different designs of grading material.