可溶盐成分对绝缘子表面污秽度评估的影响

Effect of Soluble Salt Composition on Contamination Degree of Insulator Surface

绝缘子表面污秽成分及其受潮情况与其污闪特性紧密相关,为此首先结合电导率测量,研究了自然污秽的可溶盐成分对于绝缘子表面污秽度的影响,并定量分析了CaSO4对等值盐密的贡献。然后以NaCl和CaSO4分别代表污秽中的易溶盐与难溶盐成分进行了人工污秽试验,通过改变污秽中可溶盐的成分与含量,研究了2类可溶盐对绝缘子泄漏电流及污闪电压的影响。结果表明:高湿度情况下的污秽表面电导率主要由盐的溶解度、含量和提供导电离子能力3者综合决定。污秽中可溶盐仅为CaSO4的绝缘子串,在低湿度条件泄漏电流都保持在极小范围,只有在完全饱和受潮条件下才具有良好导电性。NaCl和CaSO4混合盐人工污秽试验证明:绝缘子表面外绝缘性能主要由易溶盐(如NaCl)所贡献,微溶盐(如CaSO4)对泄漏电流、闪络电压的影响较小。

Contamination flashover seriously threatens the operation of power transmission lines, and the pollution flashover characteristics of insulators are closely related to the contamination＇ s composition and humid condition. Therefore, we firstly studied the effects of some common soluble salt components on the contamination degree of insulator surface through test surface conductivity, including a quantitative analysis of contribution of CaSO4 to equivalent salt deposit density（ESDD）. Then, we artificially tested contamination using NaCl and CaSO4 that represented soluble salt and slightly soluble salt, respectively. Finally, we obtained the effect of different salts on leakage current and flashover voltage by changing the composition and quantity of the two types of salt. It is shown that in environments of high humidity, the wetting degree of contamination is mainly affected by the hygroscopicity and solubility of salt, as well as the quantity of conductive ions provided by dissolved salt. As for insulators with CaSO4 as the only soluble salt in contamination, the leakage current is very small in low humidity. CaSO4 contamination would have good electrical conductivity only in fully saturated moisture conditions. In artificial contamination tests using mixed salt, leakage current and flashover voltage are mainly determined by NaCl, i.e. the soluble salt, while the contribution of CaSO4, the slightly soluble salt, is too small to be observed.