Electric field distribution characteristics of composite insulator with internal defect

In recent years, some events like insulator rupture failures were encountered in line operation. The inner defects, whose formation and development are heavily affected by electric field, would finally lead to the break of insulators. In order to study the electric field distortion of composite insulators with internal defects, the 3D electrical simulation models of 110kV AC composite insulator were built with the finite element software. According to the existence of some defects in statistics collected by the departments concerned, we have set several different microscopic internal defects of different lengths, different types (dry void, damp void or dielectric breakdown)and of different positions (high voltage side, low voltage side and middle part) between umbrella cover and rod. Besides, hole defects in umbrella cover were also set. Aimed at observing the characteristics of electric field distortion, the observation path was set through the defects in the model. After simulation, the simulation data such as electric filed distribution curves and electric field cloud charts were extracted and analyzed. The simulation results indicated that internal defects serve as the main reason of electric field distortion. Furthermore, the positions, lengths and dielectric constant of internal defects could play an important role on the extent of electric field distortion.