Study on the Dynamic Resistance Characteristic of Circuit Breaker Closing Resistor Under Impulse Current

To investigate the variation characteristic of circuit breaker closing resistors under transient impulse currents in actual operation, this paper focuses on the closing resistor in an LW13-800 SF<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> dead-tank circuit breaker. An impulse current test platform was established to simulate high-current impact scenarios during switching operations. By applying microsecond-level impulse currents to resistor discs, the time-domain evolution of closing resistance was calculated and analyzed. Experimental results indicate that under impulse current, the closing resistor exhibits a significant oscillatory downward trend in resistance, with resistance further decreasing as injected energy increases. When the resistor disc suffers mechanical damage or insufficient clamping force, its dynamic response characteristics are significantly degraded. When a damaged resistor string exists within a shunt-type pre-insertion resistor structure, its energy absorption capacity is significantly reduced. This study provides experimental and theoretical support for structural optimization, operational condition monitoring, and lifespan evaluation of closing resistors.