污秽不均匀度对XP-160绝缘子串交流闪络特性的影响

Effect of Non-uniform Pollution on the AC Flashover Performance of XP-160 Suspension Ceramic Insulator String

实际运行中的绝缘子上/下表面的污秽分布并不是均匀的,因此对不均匀污秽下绝缘子的污闪特性进行了研究。通过对7片XP-160标准瓷绝缘子串在污秽分布不均匀时的交流闪络特性进行试验,得到了不同盐密、不同污秽不均匀度(上、下表面盐密比,T/B)下的绝缘子串闪络特性。对不同污秽不均匀度下表面污层电导和泄漏电流与绝缘子串污闪电压的关系进行了分析,结果表明:盐密和污秽不均匀度对绝缘子串的污闪电压都有影响,且两者的影响互相独立;绝缘子串的污闪电压会随着T/B的减小而增大;7片XP-160绝缘子串的污闪电压(Uf)与附盐密度(ρSDD)、T/B分别满足幂函数和对数函数关系,通过数据拟合得到污秽影响特征指数b及不均匀污秽下修正系数C分别为0.365和0.501;不均匀污秽下,绝缘子表面污层电阻增大是导致XP-160绝缘子串交流污闪电压提高的主要原因。

During operation,the pollution distribution on the top and bottom surfaces of insulators is not uniform,thus we researched the effect of non-uniform pollution on the electrical performance of insulators.Through experiments of measuring AC flashover characteristics of an insulator string of 7 pieces of standard XP-160 ceramic insulators covered with non-uniform pollution,data of flashover voltage and critical leakage current under different non-uniform pollution（T/B） and salt deposit density（ρSDD） were obtained.Consequently,the relationship among the surface pollution conductance,the leakage current,and the flashover voltage can be obtained as follows：salt deposit density and T/B have their own effects on the flashover voltage of artificial polluted insulator string,and their effects are independent from each other;the flashover voltage of the insulator string increases with decreasing T/B;the flashover voltage of the sample insulator has a power function relation and a logarithmic function relation to SDD and T/B,respectively,and a pollution constant b of 0.365 and a non-uniform constant C of 0.501 which are gained through data regressing;the non-uniform pollution distribution along the insulator surface causes the decrease of the equivalent surface conductivity between the top and the bottom surfaces,which becomes the major cause of the increasing flashover voltage.