Research On The Pollution Flashover Characteristics Of High Voltage Isolation Switch Insulators On CHR

The roof insulation system related to the secure and stable operation of the China High-speed Railway(CHR). In order to prevent the occurrence of pollution flashover accidents on the roof insulators of CHR under fog-haze days, this paper investigates the law of the pollution accumulation and the characteristic of the pollution flashover for high voltage isolation switch insulators of CHR. The distribution law of the pollution on the surface of insulators under high-velocity air flow is obtained by the natural pollution accumulation and the wind tunnel test. Besides, based on the characteristic of insulators' surface pollution accumulation, the pollution flashover discharge is investigated.Firstly, the pollution on the surface of insulators on the running CHR is collected and the relationship of the insulators' surface pollution and the air quality index(AQI) is analyzed by measuring each shed's surface NSDD and ESDD. Then, the pollution accumulation process of two different insulators under single-direction high-velocity air flow is simulated in the artificial wind tunnel system. The pollution deposited situation of each shed's windward, leeward, top surface and bottom surface under different function time for the two different insulators is measured separately and the law of insulators' surface pollution accumulation is analyzed. Finally, according to the acquired distribution law of the pollution accumulation, AC pollution flashover experiments of insulators' surface uniform pollution, top and bottom surface non-uniform pollution, windward and leeward surface non-uniform pollution are conducted. Moreover, factors related to the characteristic of pollution flashover are analyzed under different pollution distribution.Results of the study show that the pollution on the surface of insulators increases while AQI increases on fog-faze days and variation trends of the pollution on the insulators' top/bottom surface under different AQIs are basically the same. Compared with epoxy composite insulators, silicon rubber composite insulators reach saturation more easily under the wind tunnel experiment. Due to the single-direction high-velocity air flow, insulators' leeward is polluted more seriously than the windward and the leeward is between 20% to 30% of the total. Pollution accumulation results of both the nature and the wind tunnel show that the pollution on the top surface is more serious than that on the bottom surface of the two different insulators' sheds. Under the same conditions, the flashover voltage of non-uniform pollution top and bottom surfaces is higher than that of uniform pollution and the flashover voltage of non-uniform pollution windward/leeward surfaces is lower than that of uniform pollution. Moreover, the flashover discharge process is affected by the pollution distribution.