脉冲功率设备中绝缘材料的电老化特性影响它运行的可靠性、安全性及寿命。在最大幅值约34 kV、脉冲上升时间约40 ns、半高宽约70 ns的纳秒脉冲下, 进行了环氧树脂在不同脉冲重复频率下(1, 25, 50, 100, 300和500 Hz)的电树枝引发特性研究。实验得出环氧树脂电树枝老化的引发电压随频率变化的规律: 随着频率的升高, 环氧树脂材料老化产生电树枝的形态有所变化, 高频下丛林状电树枝明显增多；材料的引发电压基本随频率升高而降低, 正脉冲作用下E44环氧树脂的引发电压高于负脉冲作用下的；负脉冲下E44环氧树脂的引发电压高于有机玻璃材料的。讨论分析了各种因素随频率变化对环氧树脂材料电树枝引发特性的影响, 高频时空间电荷的作用明显增强。

Electrical aging of insulation materials affects the reliability and security of pulsed power equipments. Based on the present pulsed source, the electrical tree initiation characteristic of epoxy resin is studied under different frequencies (1, 25, 50, 100, 300 and 500 Hz). The parameters of the pulsed source are as follows: peak voltage about 34 kV, rise time about 40 ns and half pulse width about 70 ns. The relationship between epoxy resin aging and voltage frequency is studied. Experiments demonstrate that tree initiation voltage decreases as frequency increases. The initiation voltage under positive pulse is higher than that under negative pulse. Insulation characteristic of E44 is better than that of PMMA. Factors influencing electrical tree initiation characteristic of E44 are discussed, and it is found that the effect of space charge is obviously strengthened under high frequency.