铁路腕臂绝缘子污秽外绝缘状态评估方法研究

为了合理评估电气化铁路绝缘子的外绝缘状态,改进铁路绝缘子污闪预防措施,以电气化铁路腕臂绝缘子为研究对象,利用人工污秽试验方法,研究绝缘子在不同污秽度条件下的染污放电过程。通过监测染污腕臂绝缘子受潮期间的泄漏电流,提取出泄漏电流最大值I_h,依据I_h与污秽度和受潮程度的关联,建立I_h与试品闪络电压Uf的联系。在此基础上,综合考虑腕臂绝缘子的形状系数f和爬电距离L引入综合特征量I*,并提出形如U_f=a I~(*-b)的污闪预警模型。试验研究发现:对于不同结构参数的腕臂类绝缘子,由于放电特性接近,预警模型U_f=a I(*-b)具有一定的普适性,模型预测结果与实测结果吻合良好,且系数a、b可作常数处理;但是,当试验对象为输电线路用悬式绝缘子XWP2-160时,由于XWP2-160型绝缘子和腕臂绝缘子的结构有显著差异,导致两者的染污放电特征迥异,系数a、b要以变量对待。研究认为:对于外形结构接近的染污绝缘子,模型U_f=a I(*-b)能够有效预测该类绝缘子的闪络电压,并能以此评价绝缘子的外绝缘状态。本文相关结论适用于电气化铁路腕臂类绝缘子,对于绝缘子的日常维护工作有指导参考意义。

External Insulation Assessment Method for Railway Cantilever Insulators

In order to appropriately assess the external insulation of electrified railway insulatorand improve the efficiency of insulator pollution flashover prevention, this paper studies pollution discharge process of electrified railway cantilever insulators under different pollution conditions by means of artificial contamination test method. By monitoring the leakage current of insulator affected with dump,this paper extracts the maximum leakage current I_hand establishes Ufrelationship between I_hand flashover voltage of the tested sample on the basis of the correlation of I_hwith contamination degree and dump level. On this basis, comprehensive consideration of cantilever insulator shape factor f and creepage distance L is taken,general characteristic value I* is introduced and flashing warning model in the form of U_f= a (*-b)is proposed. Experimental study shows that for cantilever insulators with different structural parameters, warning model U_f= a (*-b)is generally applicable due to similar discharge characteristics. The model predicted results are in good agreement with the measurements,and the coefficients of a and b can be taken as constants; but when test object is the suspension insulator XWP2-160 for transmission line,coefficients of a and b shall be treated as variables because XWP2-160 type insulator and cantilever insulator differ much in structure,which results in significant difference in pollution discharge characteristics. Study suggests that model U_f= a (*-b)can effectively predict flashover voltage for insulators with similar shape and structure,and evaluate their external insulation conditions.Some findings in this paper are applicable to electrified railway cantilever insulators and may guide routine insulator maintenance.