直流接触器分断过程中弧根演变及对重燃的影响分析

Arc Root Development and Its Influence on Arc Reigniting During the Breaking Process of the DC Contactor

直流接触器灭弧室中弧根的演变对其开断性能有重要的影响。该文搭建实验平台,采用高速相机拍摄了磁场作用下金属栅片式直流接触器开断过程中的弧根转移过程,并基于磁流体动力学理论,建立空气电弧数学模型,对电弧等离子体鞘层进行假设,并且在计算中耦合分断回路方程。通过对温度场、电流密度、电导率和气压分布的仿真分析,得到分断过程中弧根转移产生的根本原因,在现有的仿真条件下研究分断速度、差异外施横向磁场对弧根演变规律的影响。结果表明:在一定范围内,灭弧室入口区磁场大于栅片区时,弧根转移加速,熄弧时间缩短;由于灭弧室入口两侧气流漩涡的存在,当分断速度较小时,阳极弧根运动至引弧片时会出现停滞现象,该停滞现象随着分断速度的增大而消失,并且燃弧时间缩短,仿真与实验观测结果较为一致。本文的研究对提高直流接触器分断能力,优化灭弧室结构具有一定的意义。

The evolution of the arc root in arc extinguishing chamber has a very important influence on the breaking performance of the DC contactor. In this paper, an experimental platform was built, and a high-speed camera was used to capture the arc root transfer process of a DC contactor with metal plate at the function of a magnetic field. Based on magnetohydrodynamic theory(MHD), a mathematical model of air arc is built. The assumption of the arc plasma sheath is made, and the loop equation is coupled in the calculation.Based on the simulation analysis of temperature field, current density, electrical conductivity and air pressure distribution, the fundamental cause of arc root transfer is obtained, and the influences of breaking speed and different transverse magnetic field distribution on arc root evolution are studied under the existing simulation conditions. The results show that the arc root transfer accelerates and the extinguishing time decreases when the magnetic field in the entrance area of the arc chamber is larger than the area of metal plate in certain range. Due to the existence of airflow votex on both sides of the arc chamber,when the breaking speed is relatively small, the stagnation phenomenon appears when the anode arc root moves to the arc inducing plate, and the stagnation phenomenon vanishes with the increase of breaking speed, and the arcing time is shortened. The results of simulation and experimental observation are in great agreement. The study of this paper has a certain guiding significance for improving the breaking capacity of the DC contactor and optimizing the structure of the arc extinguishing chamber.