Energy Tolerance and Failure Characteristics of Carbon-ceramic Closing Resistor for Circuit Breaker
The thermoelectric endurance and performance stability of the closing resistor under high energy injection are critical factors for the safe and stable operation of EHVAC/UHVAC circuit breakers.In this study,the energy injection experiment of closing resistor was carried out,and the thermoelectric coupling simulation model of carbon-ceramic com-posites microstructure was established.The material temperature-rise characteristic,dynamic conductivity,performance deterioration and structural destruction behavior of carbon-ceramic resistor under different intensity energy injection were studied,aiming to analyze the energy tolerance and failure mechanism of carbon-ceramic closing resistor.Results show that the carbon-ceramic resistor exhibits dynamic conductivity varying with temperature,and both the conducting re-sistance and recovery resistance decrease with the increase of energy injection intensity.Under high energy injection,the deterioration and damage modes of carbon-ceramic resistor include the decrease of recovery resistance,lateral insulation breakdown,and resistor fragmentation.According to the simulation results of multi-physical field distribution inside the resistor under high energy injection,combined with the microstructure of carbon-ceramic composites,and the electrical contact conduction mechanism,the performance deterioration and structural destruction electrothermal positive feedback physical mechanism derived from the uneven distribution of current density,temperature and thermal stress inside the carbon-ceramic resistor are revealed.
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