短间隙放电中的电晕型先导特性

Characteristics of Corona-type Leader in the Short Gap Discharge

该文针对短间隙(15mm)气体预击穿过程中电晕型先导存在的可能性进行了进一步的研究。采用放电电流脉冲分析、电磁波检测、PRPD谱图和高速相机拍摄的方法对短间隙两种棒–板放电结构(尖–板和球–板)进行了实验。研究表明:在尖–板结构预击穿阶段,电流脉冲上升沿和电磁波脉冲发展初期存在分段现象,球板结构没有,计算表明这两段的速度是和先导速度以及先导头部的流注速度对应。曝光时间为200ns和200us的照片证实了尖–板电极放电中的"茎"结构。上述结果说明,在短间隙尖–板放电预击穿阶段中长刷状电晕转化为电晕型先导。电晕型先导和普通电晕放电的电磁波在PRPD谱图中存在明显不同,上升延时间对电流幅值和电流变化率的影响解释了电磁波幅值差异。这种放电阶段的划分以及PRPD谱图对先导的表征有助于对电晕局放严重程度的判断。

In this paper, further concerns have been focused on the possibility of the existence of corona-type leader in the short gap （15mm） pre-breakdown stage. Methods of analyzation of the current pulse of discharge, detection of electromagnetic wave, the pictures of ultra high frequency （UHF） phase resolved partial discharge （PRPD） and high speed camera were applied into the experiment of two kinds of short gap （15mm） rod-plate （point head electrode-plate and ball head electrode-plate） apparatuses. The research indicates that at the stage of pre-breakdown, two sections can be found in the rising edge of the current pulse and initial development of electromagnetic wave, but this phenomenon cannot be observed in ball head electrode-plate short gap. It is found that the time of two sections in the current rising edge corresponds to the velocities of leader and streamer prior to leader. The pictures with the 200ns and 200us exposure time prove the existence of “stem” in point head electrode-plate short gap. The results mentioned above show that the long brush-like corona in the structure of short gap point electrode-plate apparatus converts to corona-type leader discharge. The difference between corona-type leader and corona discharge in electromagnetic wave is observed in the pictures of PRPD. The difference in the amplitude of electromagnetic wave is illustrated by the effect of the time of current rising edge on the rate of change and magnitude of the current of radiation source. The partition of the stage and representation of the picture of PRPD to leader discharge contribute to the judgment on corona partial discharge severity.