合成绝缘子直流污闪极性效应的研究

Polarity effect of DC contamination flashover of composite insulators

传统的瓷和玻璃绝缘子的副极性污闪电压低于正极性电压，该现象被称作极性效应。硅橡胶合成绝缘子正被日益广泛地用于电力系统外绝缘领域，但迄今为止，对合成绝缘子直流污闪是否存在极性效应这一问题未作详细研究。该文分析了瓷绝缘子的直流污闪极性效应，认为绝缘子串上的众多金具是造成极性效应的主要原因；而合成绝缘子只有上、下两个金具，但形成的电弧数量较多，因此形成的均为无金属电极的非极性电弧，从而使合成绝缘子的直流污闪不具有极性效应。

The negative contamination flashover voltages of porcelain insulators are lower than the positive ones, and this phenomenon is called polarity effect. Silicone rubber composite insulators have been extensively accepted in the region of external insulation, but up to now, it is not clear yet whether their DC contamination flashovers have polarity effect. In this paper, the polarity effect of DC contamination flashovers of the porcelain insulator is analyzed, and it is thought that those metal hardwares on the porcelain insulator string cause the polarity effect. Each composite insulator only has two hardwares and many short arcs can form in series on it before the flashover, so these arcs are non polarity ones and cause the non polarity effect of the composite insulator.