Analysis and research on failure of B-phase lower bridge arm through wall casing in converter station

Abstract

Based on the actual failure of the bushing, this paper conducts analysis and research. Firstly, it analyzes the protection action, on-site harmonic components, bushing structure and disassembly step by step. Then it conducts the research on the discharge and breakdown characteristics of epoxy insulation. Finally, we results show that there are bubbles or impurities in the outer capacitor layer of the capacitor core inside the casing, and the harmonic content is higher under the operating conditions of the converter station. Meanwhile, we gives some relevant suggestions for the through-wall bushing in the design and manufacturing stage to consider relevant harmonic factors are of certain significance to extend the life of the bushing.