Study on Controlled Water Tree Degradation in Power Cable

水树化是电力电缆在交流电场和水存在下发生的主要降解机制之一。研究了聚乙烯（PE）的疏水性。我们测量了直流泄漏电流，观察了树木的形状，并分析了树木数量和长度分布的老化时间依赖性。在PE中，水树的再生似乎更不一样。本文认为悬垂硅烷起到了疏水性树的阻燃作用。PE分子间凝聚的硅醇基团可能对水的生成和生长起阻碍作用。从这些结果来看，聚乙烯中的硅烷醇基团有望抑制水树降解。随着HDPE添加量的增加，树形水柱长度减小，达到9.1%。高结晶度会抑制水树的生长，而水树被认为生长在无定形的富区里。HDPE簇界面处的水捕集也会影响到水树阻滞。

Water treeing is one of the major degradation mechanisms of power cable with polymeric insulation evolving in the presence of an ac field and of water. Water tree retardant characteristics of polyethylene (PE) were investigated. We were measuring dc leakage currents, observing tree shapes and analyzing aging time dependence of tree numbers and length distribution. It seems to be more different for water trees to redevelop in PE. Here, it is considered that pendent silane plays role of water tree retardant. The condensed silanol groups among PE molecules might act as obstruction to water initiation and growth. From these results, the silanol groups in PE are expected to suppress the water tree degradation. The lengths of water tree decreased with the increase in the amount of HDPE up to 9.1wt%. High crytallinity would suppress the water tree that is believed to grow through amorphous rich region. Water trapping at interface on HDPE cluster would also affect the water tree retardation.