The closing resistor for the AC filter circuit breaker is responsible for limiting the inrush current

and is prone to failure during operation. In order to analyze the intermittent defects of the closing resistor of circuit breaker for the 750 kV AC filter during switching period and assure the limit of the inrush current of the closing resistor during the closing period

in this paper

the record diagram

sound vibration signal and gas composition during switching of circuit breaker for the 750 kV AC filter are analyzed

the simulation and thermal capacity test of the closing current are performed based on PSCAD

the effective discrimination method on the intermediate discharge defect of the closing resistor and the improvement measures on the defects of the circuit breaker closing resistor are proposed. Both the effectiveness on defect discrimination method and feasibility of the proposed improvement measures for the circuit breaker closing resistor of AC filter verified through disassembly at the factory

and flashover due to defect of the closing resistor during the closing operation period is avoided.