硅橡胶电树枝的引发与生长过程

Initiation and Propagation Processes of Electrical Tree in Silicone Rubber

交联聚乙烯电力电缆的应用日渐广泛,但电缆附件的电树枝击穿故障时有发生,电缆附件材料硅橡胶的电树枝引发和生长过程尚缺乏深入研究。为此,通过材料的测试分析与计算等手段,定量描述了硅橡胶材料微观结构,测试、分析了电树枝引发期的电树枝通道特征和局部放电特性。研究结果表明:硅橡胶中同时存在主链上的化学交联以及通过氢键吸附形成的物理交联;在交流场强下物理交联破坏使得材料中的微裂纹逐渐扩大,最终导致电树枝引发;硅橡胶电树枝通道呈现良好的绝缘特性,电树枝生长主要依靠局部放电下气体受热膨胀或电磁力产生的撕裂作用;增强机械性能尤其是撕裂特性可以提高材料的抗电树枝老化性能。研究硅橡胶材料的电树枝引发和生长过程为其在电缆附件中的合理使用提供了理论依据。

Cross-linked polyethylene power cables are more and more widely used, but they still have electrical tree break-down happened in cable accessories occasionally, while the mechanism of electrical treeing＇s initiation and propagation needs further research. Therefore, through material and calculative analyses, we described the microscopic structure of silicone rubber quantitatively, and obtained the channel characteristics and partial discharge characteristics during the initiation stage of electrical treeing. It is shown that the microscopic structure of silicone rubber includes a large number of physical crosslinking comprising the crosslinking in silicone rubber together with chemical crosslinking; The breakdown of physical crosslinking structure makes microscopic crack zones become larger, which further causes the electrical tree initiation. Meanwhile, channels of electrical trees have good insulation properties, and the trees＇ growth depends on the tearing effect of gas heat expansion or electromagnetic force under strong partial discharge mainly. Improving the mechanical properties, especially improving the tear characteristics, can enhance the silicone rubber＇s ability against electrical trees. The research on the initiation and propagation of electrical trees in silicon rubber provides theoretical basis for the proper application of silicone rubber in cable accessories.