Study on the Electrical and Thermal Response of Circuit Breaker Carbon-Ceramic Closing Resistors Under Standard Impulse Voltage

As a critical component of circuit breakers, the closing resistor undertakes the protective role of suppressing overvoltages. Carbon-ceramic closing resistors have become the preferred choice for ultra-high voltage circuit breakers due to their excellent performance. Consequently, their reliability under typical impulse voltages requires comprehensive evaluation. This study applied standard lightning impulse (1.2/50 μs) and switching impulse (250/2500 μs) voltage sequences to multiple sets of carbon-ceramic resistor samples, systematically measuring the post-impulse resistance changes and the surface temperature rise after each impulse. The results demonstrated that under all test conditions, the resistance change rate after multiple impulses remained below 0.6%, confirming the integrity of the material’s macroscopic structure. The temperature rise was limited under lightning impulses, with the peak temperature constrained to below 55 °C. In contrast, the thermal effects were more severe under switching impulses, characterized by a significant temperature rise where peak temperatures reached 111 °C, accompanied by intermittent abnormal hot spots, indicating a potential risk of thermal runaway. Thus, while carbon-ceramic resistors possess excellent electrical endurance, their thermal stability under switching impulses warrants considerable attention. This research provides crucial experimental evidence for the engineering application of carbon-ceramic closing resistors.