硝酸盐污秽作用下绝缘子的交流闪络特性

AC Flashover Performance of Insulators Polluted by Nitrates

污秽成分会影响绝缘子的闪络特性,研究硝酸盐对绝缘子闪络特性的影响有长远的意义。为此,依次用氯化钠及几种常见的硝酸盐KNO_3、NH_4NO_3、NaNO_3、Ca(NO_3)_2、Mg(NO_3)_2来模拟可溶物,开展了不同污秽成分下耐污型绝缘子串XP4–160的交流污闪试验。试验过程中采用浸污法进行染污,并采用恒压升降法进行加压,得到了不同可溶物成分、不同等值盐密(ESDDρ)下绝缘子的交流闪络电压梯度(EL),然后结合试验结果和硝酸盐的理化性质分析了硝酸盐对绝缘子闪络特性的影响。研究结果表明:利用现有的闪络电压计算方法来预测硝酸盐下绝缘子的EL值,相对误差可达到24%;所采用的几种硝酸盐下绝缘子的EL值均大于氯化钠下的EL;硝酸钾对应较低的闪络电压梯度,硝酸钙对应较高的闪络电压梯度;硝酸盐下的绝缘子污秽影响特征指数b值在0.18~0.25之间;污秽成分为5种硝酸盐中的1种或几种时,绝缘子闪络电压梯度可用25.60.21ESDDρ-来表达。研究结果可为不同污秽成分下绝缘子闪络电压的计算提供参考。

Pollution materials affect the flashover performances of insulator, and it is of deep significance in researching the effects of nitrates on flashover performances of insulator. Consequently, adopting several common kinds of nitrates, such as KNO3, NH4NO3, NaNO3, Ca（NO3）2, and Mg（NO3）2 as the soluble pollutants, we experimentally studied the AC flashover on anti-pollution porcelain insulator XP4-160. During the tests, a digging method was applied, and the up-and-down method was used, after which the NC flashover voltage gradients of insulator under different pollutants and equivalent salt deposit densities PESDD values were obtained. Then based on the test results and combined with the physical and chemical characteristics, the effects of nitrates on insulator flashover performance were analyzed. The research results indicate that when the current method is used to calculate nitrates flashover voltage gradient of polluted insulators, the relative error will reach 24%; the flashover voltage gradient of insulators under nitrates are higher than that under NaCl; KNO3 corresponds to lower flashover voltage gradient while Ca（NO3）2 corresponds to higher; the pollution characteristic b under nitrates is within 0.18-0.25; the relationships between EL and ,OESDD of the insulators can be expressed by 25.6 ρESDD^0.21. Research results in this paper can provide references for the flashover voltage calculation of insulators under different pollutants.