ns脉冲下有机玻璃电树枝的引发特性

Initial Characteristics of Electrical Tree in PMMA Under Nanosecond Pulses

脉冲功率装置中绝缘材料的老化问题影响装置的安全性、可靠性及效率，电树枝老化是最主要的老化方式之一。为此总结分析了目前高聚物绝缘材料中电树枝老化现象、电树枝引发影响因素的研究成果，进行了不同重复频率（75～300Hz）、不同电压等级ns脉冲（半高宽70ns）下有机玻璃电树枝老化特性的实验，重点研究了在不同条件下有机玻璃中电树枝引发阶段的特性，最后总结讨论了电树枝的引发条件和影响因素。实验表明不同频率ns脉冲下有机玻璃中电树枝引发的起始电压高于交流，低于直流．频率升高，电树枝起始电压有下降趋势；不同时刻有机玻璃的电树枝引发率，基本上随着电压等级的上升而下降；电子轰击、空间电荷分布和电机械应力对绝缘材料的电树枝引发具有关键作用，而在高频的脉冲强场下电机械应力起主要作用。

The aging of insulation material in pulse power devices affects the safety, reliability and efficiency of de vices. Electrical tree aging is one of main ways among aging mode in pulse power condition. We introduced the phenomenon, influencing factor and research status of electrical tree in polymer. The electrical tree aging in PMMA under repetitive（-300 Hz） nanosecond pulses（70ns） was tested. The initial rate of PMMA under different frequency pulses was given. Moreover, the influential factors and electrical tree introducing condition were discussed. It is found that the initial voltage of PMMA is higher than that of AC, and lower than that of DC; with the frequency increasing, the initial voltage of PMMA has a descending trend; with the voltage increasing, the initial rate of PMMA is decreased. The electrical field force plays a predominate role in high frequency and high electrical field.