触头运动特性对直流接触器开断性能影响

Influence of contact motion characteristics on breaking performance of DC contactor

为研究触头运动特性对直流接触器开断性能的影响,建立直流空气接触器电磁操动机构与灭弧系统联合仿真模型,对接触器操动机构进行运动—结构—电磁耦合仿真,得到操动机构动作过程中触头位移—行程曲线,并与电弧磁流体模型相耦合,仿真得到了直流空气接触器从机构运动到触头打开电弧形成、弧根运动直至熄灭的全过程。讨论了接触器操动机构参数变化对开断性能的影响,并通过电弧现象背后的物理场变化分析了开断过程中重击穿现象产生的原因。结果表明:操动机构驱动动触头进而带动电弧完成了电弧拉伸、弧根转移以及被栅片切割等重要电弧演变过程;反力弹簧和触头弹簧预压力增大有利于提高触头的分断速度,加速电弧熄灭,但分断速度过高有可能导致电弧重击穿现象发生,其根本原因是栅片入口处产生的顺时针气流漩涡;通过控制触头的分断速度和灭弧室栅片区磁场分布,实现了对重击穿现象的抑制。

In order to study the influence of contact motion characteristics on the breaking performance of DC contactor,the combined simulation model of electromagnetic operating mechanism and the arc extin-guishing system of DC air contactor was established to simulate the movement,structure,and electromag-net of the contactor operating mechanism,so as to get contact displacement curves in the process of oper-ating mechanism motion,and couple with magnetohydrodynamics(MHD)model of the arc.The whole breaking process of the DC air contactor from mechanism movement to arc formation,arc root movement and arc extinction was obtained by simulation.The influence of the parameters of the contactor’s operat-ing mechanism on the breaking performance was discussed,and the reason of the restriking phenomena in the process of breaking was analyzed by the variations of the physical fields behind the arc phenomenon.The results show that the operating mechanism drives the moving contact and then drives the arc to com-plete the important arc evolution processes such as arc stretching,arc root transfer and splitter plates cut-ting.The increases of the pre-pressure of the counterforce spring and contact spring are beneficial to im-prove the breaking speed of the contact and accelerate the arc extinction,but too high breaking speed may lead to the restriking phenomena of the arc,the basic cause of which is the clockwise airflow vortex generated at the splitter plates entrance.By controlling the breaking speed of the contacts and magnetic field distribution in the splitter plates area of the arc extinguishing chamber,the restriking phenomena was suppressed.