中文摘要：

绝缘子污秽闪络事故严重威胁电力系统的安全可靠运行，目前国内外对污闪机理的研究主要以平板模型为基础。以7片串XP-160绝缘子为例，开展染污绝缘子串直流污闪电路模型的研究。根据高速摄像机拍摄的结果得知，染污绝缘子串直流污闪放电过程中局部电弧存在飘弧现象，即局部电弧由沿面电弧和空气间隙电弧2部分组成；提出染污绝缘子串直流放电过程的电路模型由剩余污层电阻、沿面电弧和空气间隙电弧串联组成；根据模型推导得到染污绝缘子串直流污闪电压的污秽影响特征指数在0．22-0．34之间，并从理论上解释了不同型式绝缘子污秽影响特征指数存在差异的原因。

英文摘要：

Pollution flashover accident of insulators may threaten the operation safety of power system, whereas, the research on pollution flashover circuit model is based on the plate model by now. Taking seven units of XP-160 insulator string for example, the DC pollution flashover mechanism of polluted insulator string was researched. According to the insight from high-speed photography, it is shown that some of the partial arcs may deviate from the surface of polluted insulator string and form the air gap arc during the pollution flashover process, i.e. the partial arcs include two main parts： air gap arcs and surface arcs. The electrical circuit model explaining the DC flashover process of polluted insulator string is presented, which consisting of a surface arc, air gap arc and residual resistance of the pollution layer. The exponent describing the influence degree of pollution on flashover voltage for polluted insulator is in the range of 0.22-0.34 according to the deducing result from the model. At last, the reason that there is difference among exponents describing the influence degree of pollution on flashover voltage for different types of insulator is discussed in theory.