直流开断中 MOV 均衡特性选配方法研究

Metal oxide varistor（MOV）is widely used in various DC circuit breakers for over⁃voltage suppression，system energy dissipation and set⁃ up of breaking voltage. However，the single MOV disc，due to the limitation of current processing technology，is limited in the current flow capacity. Therefore，the multi⁃column parallel structure is mostly used in circuit breakers. The uneven current distribution between columns will lead to overload and energy consumption of local MOV，resulting in failure of breaking and even equipment damage. In this paper，an electrical model of MOV under DC breaking condition is set up on the basis of experimental measurements. Based on this mod⁃ el，a method of MOV current sharing matching is proposed. It is verified by the experiment that the current sharing characteristics of the MOV，which is matched on the basis of traditional lightning impulse test method，can not fully meet the requirements in the DC fault interruption condition. The MOV which is matched on the basis of this paper can achieve good current sharing characteristics in the DC fault interruption condition.