Electric Fields Distribution of EHV AC Transmission Line Composite Insulators with Internal Conductive Defects

The internal conductive defects occur when the core rod of the composite insulator is damaged due to moisture. The accurate detection of the defective composite insulator is vital to the safety of the live working on transmission lines. Based on the finite element method, the 3D models 500 kV EHV transmission line composite insulators with the internal conductive defects were built in this paper. The electric field distributions of the different defective composite insulators were calculated, and the influences of the conductive defect length and position on the electric field distribution were also given. The calculation results show that the electric field distribution of the composite insulators with the internal conductive defects will appear obvious distortion. The electric field values at the high voltage end of the insulator and the both ends of the defect will also be increased significantly. These features can be directly applied to the defective composite insulators detection.