局部放电对脉冲电容器的绝缘老化及其失效的影响分析

为了研究电容器的寿命与其工作可靠性的关系,笔者通过对脉冲电容器进行充放电老化试验,并对处于不同寿命阶段的电容器进行直流局部放电测试,得到最大放电量、平均放电量和平均放电重复率随寿命变化的曲线;借助电子显微镜观察处在不同老化寿命阶段电容器薄膜的表面微观形貌,分析充放电老化试验对其微观形貌的影响。最后结合电容器实际击穿情况,分析总结了导致脉冲电容器局部放电性能变化以及老化击穿的因素,指出电极边缘区域存在的局部绝缘缺陷是电容器失效的主要原因。

Influence of Partial Discharge on Insulation Aging and Failure of Pulse Capacitor

To investigate the relation of life-span and working reliability of a capacitor,repeatedly charge and discharge aging test was conducted on a pulse capacitor for measuring its local direct current partial discharge at different stages of life-span.Three curves of life-span versus maximal discharge magnitude,mean discharge magnitude,and mean discharge frequency were obtained.The morphologies of the capacitor film surfaces at different stages of life-span were observed by the scanning electron microscopy,and the influence of charge and discharge aging test on the surface topography was analyzed.Moreover,based on the analysis of the capacitor breakdown,the factors that result in the partial discharge performance variation and aging breakdown of a pulse capacitor were summarized,and the key reason for causing the capacitor breakdown was found that some insulation defects exist in the edge area of electrodes.