Defect Analysis of the Basin-type Insulator in a 500kV SF6 Current Transformer

Abstract

Abstract A rigorous examination and analysis were conducted on a fault incident involving an SF6-insulated current transformer. The investigation revealed an intrinsic defect in the basin-type insulator within the current transformer, leading to a discharge pathway formation from the shell base flange to the secondary lead shielding tube. To further analyze the insulation characteristics of basin-type insulator, a three-dimensional simulation model of current transformers was established using simulation software to study the electric field distribution law of basin-type insulators with pores, metal impurity pollution, and microcracks. Simulation tests indicated that micro-cracks can result in severe electric field distortion in the basin-type insulator, followed by metal particle pollution, and bubbles cause the least degree of electric field distortion. The findings of this article can serve as a reference for the production of basin-type insulators and the operation, maintenance, and fault analysis of SF6-insulated current transformers.