绝缘子自然污秽下受潮及导电特性分析

Analysis on Wetting and Conductive Properties of Natural Polluted Insulators

自然污秽物成分、污层受潮程度是影响绝缘子外绝缘性能的重要因素。为此,以江苏某变电站实际获得的自然污秽为例,通过污秽物成分分析,初步掌握了污秽物中的成分及含量,并利用污秽受潮试验装置开展了受潮特性比较及导电性能分析试验。试验结果表明:相同盐密、灰密及受潮条件下,该组自然污秽绝缘子的受潮速度比人工污秽绝缘子快,但充分受潮后,自然污秽绝缘子的表面电导值要低于人工污秽绝缘子;自然污秽物中不溶物占绝大部分,对绝缘子表面电导率贡献较小,可溶物中微溶于水的Ca SO4比例最大;自然污秽物含有机物成分,对绝缘子污闪性能有一定影响。通过比较分析己内酰胺(CPL)特性发现:己内酰胺为吸水性物质,本身无导电性,在低湿度条件下易使绝缘子污层受潮,引起表面电阻降低;但污层饱和受潮后,己内酰胺对表面导电性贡献可忽略,对绝缘子污闪电压的影响不大。

The composition and wetting degree of natural pollution on insulators affect their flashover properties. Taking the pollution samples obtained from a substation in Jiangsu Province, China as the example, we obtained the composition data of natural pollution through component analysis. Then using a wetting test system, we conducted experiments to investigate the wetting properties and conductivity of natural pollution. The results indicate that, compared with the artificial pollution insulators of the same ESDD and NSDD, natural pollution has a higher wetting rate but lower conductivity after being fully wetted. For nature pollution, non-soluble substance is the main composition which contributes little to conductivity, while Ca SO4 is the main soluble substance. Organic content, mainly caprolactam（CPL）, is also observed in natural pollution, and affects the flashover properties of insulators. Further comparison and analysis of CPL indicates that, as an absorbent substance, CPL promotes the water absorption of pollution layer under low humidity conditions, which decreases the surface resistance of insulators. However, for pollution layer with saturated moisture, the influence of CPL on the flashover voltage of insulators is negligible.