铜蒸气对密封直流接触器氢-氮混合气体电弧特性的影响

Effect of Copper Vapour on the Arc Characteristics of Hydrogen-nitrogen Gas Mixtures in Sealed DC Contactors

密封直流接触器开断过程电弧烧蚀触头产生的铜蒸气对氢-氮混合气体电弧特性及开断性能具有重要作用。依据平衡态等离子体理论计算出铜蒸气不同占比的氢-氮混合气体的各项物性参数,引入铜蒸气影响,建立了基于磁流体动力学理论的氢-氮混合气体电弧模型,系统研究了铜蒸气在混合气体中占比及分布规律对燃弧特性、电弧发展演变特性等的影响规律。基于可拆卸腔体开展了实验验证,750 V/250 A密封直流接触器实验中电弧重击穿概率、熄弧时间变化等规律与理论分析结果基本相符,验证了铜蒸气对燃弧特性的影响。研究表明:随着铜蒸气在混合气体中占比提高,燃弧过程电弧温度缓慢降低,熄弧时间逐步提高,重击穿概率增大,且铜蒸气不均匀分布比均匀分布熄弧时间有所降低。研究结果为混合气体直流燃弧特性和高可靠性密封直流接触器优化设计提供理论参考。

The copper vapor generated by the arc ablation contact during the opening process of sealed DC contactors plays an important role in the arc characteristics and opening performance of the hydrogen-nitrogen gas mixture.In this paper,the physical parameters of the hydrogen-nitrogen gas mixture with different percentages of copper vapor are calculated based on the equilibrium plasma theory,and the influence of copper vapor is introduced to establish an arc model of hydrogen-nitrogen gas mixture based on the magnetohydrodynamic theory,and the influence laws of the copper vapor percentage and distribution law in the gas mixture on the arc ignition characteristics and arc development and evolution characteristics are systematically studied.Based on the disassembled cavity,simulated experiments were carried out to verify the arc re-strike probability and arc extinguishing time in the 750 V/250 A sealed DC contactor experiments,which are basically consistent with the theoretical analysis results.The study shows that,as the proportion of copper vapor in the gas mixture increases,the arc temperature decreases slowly,the arc extinguishing time increases gradually,and the probability of heavy breakdown increases;meanwhile,the uneven distribution of copper vapor decreases compared with the uniform distribution of arc extinguishing time.The results of the study provide theoretical reference for the optimization design of DC arc burning characteristics of mixed gas and highly reliable sealed DC contactors.