Analysis of insulation breakdown fault in 500kV SF6 current transformer

This article introduces an accident case of a 500kV SF₆ current transformer insulation breakdown leading to fault tripping. The on-site testing and disassembly of the faulty current transformer were described in detail, and the discharge path at the time of the fault was analyzed. Using simulation software to calculate the operating overvoltage value of the fault point during the switching of the filter bank, the cause of the current transformer fault is determined based on the disassembly and simulation results, and operation and maintenance suggestions are provided for SF₆ current transformers operating under the same working conditions.