硅橡胶合成绝缘子染污放电机理的研究

Flashover mechanism of silicone rubber composite insulators

传统的瓷和玻璃绝缘子表面呈亲水性，耐污闪性能较差；硅橡胶合成绝缘子表面呈憎水性，且其憎水性能够迁移至绝缘子表面污层，因而具有优良的耐污闪性能，尽管目前对瓷和玻璃绝缘子的污闪机理已作了较深入的研究，但对合成绝缘子污闪机理的研究尚比较缺乏。该文详细分析了合成绝缘子的染污放电过程，提出了闪络通道由多条短电弧与狭窄水带串联而成的合成绝缘子直流污闪模型。模型表明，众多短电弧的阴阳极压降及水带的高阻值是其具有高污闪电压的原因，同时模型清楚地反映了合成绝缘子临闪电流低、临闪电压高的特点。

Conventional porcelain and glass insulators have hydrophilic surfaces, so they have poor contamination flashover resistance. Silicone rubber composite insulators have hydrophobic surfaces and their hydrophobicity can migrate into the surface contaminant layers, so their contamination flashover resistance is excellent. Up to now, the contamination flashover mechanism of conventional insulators has been studied in detail, but the study on composite ones is seldom. In this paper, the flashover mechanism of composite insulators was analyzed and their DC contamination flashover model with a flashover channel constituted by many series short arcs and narrow water ribbons was put forward. The model reveals that the cathode and anode drop of short arcs and the high resistance of water ribbons cause the high flashover voltage of composite insulators, and it also reflects the characteristic of this kind of insulator that the current is low and the voltage is high just before the flashover.