正极性电场中SF6气体对导电微粒带电特性的影响

Influence of SF6 on charging characteristics of conductive particle in positive electric field

针对气体绝缘金属封闭开关设备(Gas Insulated Suitchgear,GIS)中导电微粒运动容易引发电极间击穿和绝缘沿面闪络等问题,开展了正极性电场中SF6气体对导电微粒带电特性的影响研究.试验得到了空气、SF6环境导电微粒的运动轨迹,根据观测结果分析微粒的速度、受力提出微粒带电量估算方法并计算启举场强下空气、SF6气体环境微粒的带电量.结果表明,正极性条件下带电微粒启举场强明显高于真空及空气环境,且启举场强随SF6气体压力的升高而增大.电场强度相同时,SF6条件下微粒带电量小于空气环境,约为空气条件下的0.789倍.电极表面导电微粒附近电场集中及SF6电负特性是影响微粒初始带电量的原因.研究拟为GIS微粒抑制方法及针对微粒抑制的耐压试验方法的制定提供数据支持.

Conductive particles generated in Gas Insulated Suitchgear(GIS)may induce breakdown on the electrodes or flashover along the insulators. To solve this problem, the study of the influence of SF6 on the charging characteristics of conductive particles in positive electric field is carried out. The particle trajectories in air and SF6 are obtained by experiment, and according to the test results, the particle moving speed and forces on it, the charge evaluation method is proposed which can calculate the charged amount of air and SF6 gas particles under the lift-off voltage. The results show that the field strength of charged particles under positive field is significantly higher than that in vacuum and air, and the field strength increases with the increase of SF6 gas pressure. When the gas pressure is the same, the SF6 charged particle amount is less than that in the air, that is the charge on the particle in SF6 is about 0.789 of that in the air. The charge on the particle is influenced by the concentration of electric field near the particle and the electrical negative features of the SF6. This study aims to provide data support for particle restraint method of GIL and the withstand voltage testing method.