Analysis and Research on Fault Characteristics of 110kV Cable Termination Based on FEM

Cross-linked polyethylene cables (XLPE) are widely used in high-voltage transmission systems due to their excellent performance. However, in accidents occurring during the operation of high-voltage power cables, those caused by insulation defects in terminals and intermediate joints account for the majority. Therefore, it is necessary to conduct in-depth research on relevant insulation defects to provide a basis for the operation, maintenance, and condition monitoring of power cables. This article dissects a fault in a 110kV cable termination and preliminarily analyzes that improper chamfering of the outer semiconductor layer during terminal installation and excessive polishing of the main insulation surface resulted in the presence of air gaps. Utilizing finite element method, the fault characteristics were studied in depth. Electric field simulation analysis was conducted on air gaps at the fracture of the semiconductor layer and on the main insulation surface under normal conditions. Combined with the partial discharge signals measured at the terminal before the fault occurred, it was verified that the electric field intensity at the air gap was much greater than the breakdown field strength of air under operating voltage. Prolonged operation led to localized partial discharge, ultimately resulting in insulation breakdown.