介绍了有机玻璃(PMMA)在纳秒脉冲作用下电树枝引发和生长的规律现象.采用压紧针电极与绝缘样品接触、多针并列式的方法制备实验试样,绝缘样品(有机玻璃)加工为120 mm×5 mm×25 mm的长方条.实验使用产生30 ns上升沿和70 ns脉冲宽度的负脉冲固态纳秒脉冲发生器MPC50 D作为激励源,在25℃的条件下,施加100 Hz的重复频率脉冲,设定初始电压,逐级升压,直至引发电树枝后停止升压,记录电树枝引发电压,观察电树枝生长特点及现象.实验发现PMMA中电树枝出现裂隙状破坏,经过分析讨论,认为是力作用导致的结果.实验中还观察到电树枝生长速度极快的现象,从电树枝引发到击穿只需几秒钟.通过研究证明绝缘油浸入导致了电树枝生长加速,深入讨论分析了绝缘油浸入促进电树枝快速发展的原因、机理及抑制方法.%A phenomenon that the insulation oil causes the acceleration of the electrical tree growth in Polymethyl-methacrylate ( PMMA ) under nanosecond pulses was introduced in this paper. A solid-state pulse generator MPC50D was used as source supply to output nanosecond pulses, the rise time of which is 30ns and the full width at half maximum of which is 70ns. The size of the sample was 120mm × 5mm × 25mm. Under 20℃ ~ 25℃, the repetition frequency was set to 100Hz, and the voltage is increased at 2kV every 2 minutes until the electrical tree was incepted. The sector structure of the electrical tree was observed. This phenomenon was regarded as the effects of forces. The experimental results showed that the growing speed of electrical tree was very fast. From the incep-tion of electrical tree to the breakdown, only several seconds was elapsed. Tree sealing methods were used to dem-onstrate that the reason of the acceleration phenomenon in electrical tree growth was insulation oil. The mechanism of this phenomenon was discussed and a method to prevent the growth of the electrical tree was proposed.
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