直流接触器触头电弧侵蚀特性

Arc erosion characteristics of DC contactor contacts

触头开断过程中会产生电弧,从而导致触头表面被侵蚀,影响其电接触性能。由于直流供电系统不存在自然过零点,致使直流接触器触头受电弧侵蚀影响比交流接触器更加严重。为了研究电弧对触头的侵蚀作用,基于磁流体动力学理论,考虑电弧与触头之间的能量耦合,建立电弧-触头动态耦合模型,研究了电流等级和分断速度对触头电弧侵蚀特性的影响。仿真结果表明:近阳极区电弧温度高于近阴极区电弧温度;电流等级由20 A提高到30 A时,电弧温度和燃弧时间显著提高,燃弧能量增加75.93%,使得触头侵蚀更加严重;触头分断速度由0.1 m/s增加到0.2 m/s时,电压电流的变化率提高,燃弧时间和熔池体积减小,燃弧能量减少47.83%,电弧对触头的侵蚀作用降低。实验结果与仿真相吻合,验证了仿真模型的正确性。

The arc is generated upon contact breaking-off resulting in surface erosion in the terminals and affecting the performance of electrical contact.As there is no natural zero crossing point in the DC power supply system,the erosion caused by arcs is often more severe in DC contactors than that in AC contactors.The arc erosion effect on the contact terminals is analyzed in this paper.Based on the theory of magnetohydrodynamics,a dynamic coupling model of arc and contact terminals considering energy coupling is established.Then,the impacts of the electric current level and breaking speed on the arc erosion in contact terminals are studied by using the model.Simulation results show that the arc temperature near the anode is higher than that near the cathode.It can be noted that the arc temperature and arcing time rise significantly by increasing the current from 20 A to 30 A,which improves the arcing energy by 75.93%and thus worsening the contact erosion.Simulation results also indicate that increasing the breaking-off speed from 0.1 m/s to 0.2 m/s,results in an increase of voltage and current variation rates,an reduction of the arcing time and molten pool volume,a decrease of the arcing energy by 47.83%,and an reduction of the impact of arc erosion on the contact terminal.The experimental results are consistent with the simulations confirming the accuracy of the simulation model.