Stress control on polymeric outdoor insulators

This paper investigates the effect of nonlinear grading material in controlling the electric field stress on outdoor polymeric insulator. Excessive electric stress combined with contaminations and moisture are responsible for the surface arcing, which may results in insulator flashover. The electric field and potential distributions along the leakage path on the surface of the insulator were computed using the Finite Element Method (FEM). The grading material was modeled by introducing a nonlinear field-conductivity relationship defined in the FEM package. Comparative studies of field and equipotential profiles for insulators with and without grading material under dry and uniformly contaminated surface conditions are presented.