Research on the Influence of Different Proportions of Copper-Tungsten Material Electrodes on Ablation Characteristics

With the increasing voltage level of the power system, there are higher requirements for the interruption performance of high-voltage circuit breakers, the contact electrical endurance of the circuit breaker also needs to be improved accordingly. The copper-tungsten electrode is widely used as arc contact of high voltage gas circuit breakers due to its good ablation resistance. Its ablation resistance is directly related to the interruption performance of high voltage gas circuit breakers. However, the current study on the ablation characteristics of copper-tungsten electrodes in gas arc is still insufficient, and the study on the ablation behavior of copper-tungsten electrodes is often carried out only under a single experimental variable. Therefore, this article conducts experiments on the ablation of different ratios of copper-tungsten electrodes at different current levels respectively in SF6 and CF4 gases, obtained the trend of changes in contact erosion under different conditions, and analyzes the differences in the ablation performance of copper-tungsten electrodes in different gaseous media and their reasons. By comprehensively comparing the ablation characteristic curves of different ratios of copper-tungsten electrodes under the same experimental conditions, the optimal ratio of copper-tungsten electrodes for the comprehensive performance of electrode ablation resistance was obtained. This study helps to promote the optimal design of circuit breaker arc contacts, thus laying the foundation for realizing the improvement of the overall electrical endurance of gas circuit breakers.

I. Introduction

The circuit breaker is one of the critical safety and security equipment in the power system, which plays the roles of connecting or disconnecting AC and DC main circuits and rapidly cutting off the short-circuit current and is widely used in various electric power segments such as power generation, substation, power transmission, and power distribution [1]–[4]. The copper-tungsten electrode is often used in SF₆ gas circuit breakers as the arc contact part due to its good ablation resistance. It plays the core role of breaking short-circuit current. However, the copper-tungsten electrode is also the weakest part of the switchgear, which may lead to the failure of circuit breaker disconnection and then serious consequences such as fire and explosion. The direct cause of the failure of the copper-tungsten electrode system is the ablation behavior of the electrode by the arc during the breaking process. Throughout the arc burning process, the erosion of the gas arc will lead to the loss and transfer of the quality of the coppertungsten electrode material, changes in the composition and internal structure, and surface degradation, which will lead to the worse electrical performance of the copper-tungsten electrode and the reduction of the reliability of the switchgear, and ultimately make the service life of the high-voltage gas switchgear shrink [5,6].