Electric field distribution on the outer surface of lower porcelain of an OIP transformer bushing-accumulation of metal-contained colloid

The Finite Element Method (FEM) is commonly used for electric field simulation. This paper presents, for the first time, the calculation of the electric field intensity on one phase of a 245-kV OIP condenser bushing by FEM considering the effect of metallic-contained colloids deposition on the outer surface of lower porcelain. The distribution of the electric field on the surface of the bushing is calculated and the location of maximum electric field intensity of the bushing is determined. The spots having the maximum electric field intensity are the vulnerable areas from which the partial discharge may initiate. The extension of stained area due to the trapping effect of electric field is been considered.