磁场作用下直流电弧分断特性及触头侵蚀的研究

Study on DC arc breaking characteristics and contact erosion under magnetic field

直流电弧作用下,触头侵蚀现象会对电器接触系统性能产生影响,降低电器使用寿命。为探究触头分断时电弧特性以及对触头的侵蚀过程,本文基于磁流体动力学理论并结合动网格技术,以AgSnO_(2)为触头材料,建立了电弧-触头多物理场数值耦合仿真模型。分析了恒定磁场下电弧特性随时间的变化过程,并进一步探究了不同磁场强度电弧对触头侵蚀变化规律;考虑触头材料的相变并求解了触头内部温度分布和熔池的形成过程。仿真结果表明,电弧受洛伦兹力作用转移至触头边缘,触头材料温度上升发生相变形成熔池。在一定范围内,随外加磁场强度变大,电弧熄灭速度加快,触头表面熔池域变小。最后,采用粉末冶金法制备AgSnO_(2)触头材料并进行电弧分断实验,实验所得影响规律与仿真结果较为一致。

Arc erosion under the action of DC arc will affect the performance of the contact system of appliances and reduce the service life of electrical appliances.In order to investigate the arc characteristics and erosion process of contact during contact breaking,a numerical coupling simulation model of arc and contact with multiple physical fields is established based on magnetogas dynamics theory and moving grid technology,using AgSnO_(2)as contact material.The changing process of arc characteristics with time under constant magnetic field is analyzed,and the changing rule of arc erosion to contact with different magnetic field intensity is further explored.The phase transformation of the contact material is considered and the temperature distribution and the formation process of the molten pool are solved.The simulation results show that the arc is transferred to the edge of contact by Lorentz force.The temperature of contact material rises rapidly and the contact material changes phase to form molten pool.With the increase of applied transverse magnetic field,the quenching time shortens and the radius of molten pool decreases in certain range.Finally,the AgSnO_(2)contact material was prepared by powder metallurgy method and the arc breaking experiment was carried out.The experimental regularization is related to the simulation results.