正负极性雷电冲击电压下4m棒-板空气间隙先导发展特性试验

Characteristics Experiment on Leader Propagation in a 4 m Rod-Plane Air Gap Under Positive and Negative Lightning Impulses

开展了正负极性雷电冲击电压下4m棒-板空气间隙放电试验,获得了正负极性先导发展过程的高速影像。基于高速图片,统计分析了正负极性先导的轴向速度与先导位置的关系,以及正负极性先导分支数量和先导分支角度的分布特性。试验结果表明,正极性先导轴向速度与电压幅值正相关,而负极性先导轴向速度与电压关系并不明显;正负极性先导轴向速度均随着与电极端部距离的增加而增大,而且正极性先导轴向速度在距离电极端部1.2 m内趋于稳定;2分支在先导分支中占91.8%,少数情况观测到3分支和4分支;正极性和负极性先导分支角度均近似服从对数正态分布,其平均值分别为44.9°和45.3°。

In this paper,experiments are carried out in a 4 m rod-plate air gap under positive and negative lightning impulses.High-speed images of leader development process are captured by using a high-speed camera.Based on the experiment results,the relationship between axial velocities of positive and negative leader and leader position are measured.Moreover,the distribution of the number of leader branches and the angle of leader branches are statistically analyzed.The experimental results show that the axial velocity of positive leaders is positively correlated with the voltage amplitude,while the negative-lead axial velocity is not significantly related to the voltage.In addition,the positive and negative axial velocities increase with the distance from the electrode tip.However,the axial velocity of positive leaders tends to be stable within 1.2 m from the end of the electrode.Moreover,two branches account for 91.8%in the leader branching phenomena,and three or four branches are observed in a few cases.Angles of positive branches and negative branches approximate respectively a lognormal distribution with average values of 44.9°and 45.3°.