Study On AC Flashover Performance And Valid Coefficient Of Creepage Distance For Different Types Of Artificially Polluted Insulators

The AC flashover voltage, voltage gradient along the leakage distance, valid coefficient of creepage distance and the arc advancing path of polluted insulators are related to its materials and configuration. Although the AC flashover performance of a polluted insulator has been studied well, there is few study on the valid coefficient of creepage distance of different types of insulators. Laboratory investigations on the AC flashover performances of five types of polluted typical porcelain and glass insulators were carried out in the climate chamber. Based on the test results, this paper studies systematically the AC flashover performance, voltage gradient, as well as the valid creepage distance of different types of artificially polluted insulators.This paper made the experimental and academic investigation as following:①The AC flashover performance of five types of polluted insulators.②The voltage gradient of five types of polluted insulators according to the leakage distance.③Analyzed the flashover process of five types of polluted insulator strings by high-speed camera.Based on the experimental and academic results, The conclusion of this paper can be put forward as following:①The polluted flashover voltages decrease with the increasing ofρESDD at the artificial pollution test. But the decrease trend are different for different of insulators, and that the flashover voltage are various at the same value ofρESDD for different types of insulators.②The valid coefficient of creepage distance is related to the material and configuration of insulators, that the valid coefficient of creepage distance of a glass insulator, which increases with the increasing ofρESDD, is higher than that of an porcelain insulator which decreases with the increasing ofρESDD. The reason is that the flashover voltage gradient of LXY4-160 and LXHY3-160 are higher as the under-rib of the insulators restrict the partial arc progressing, while the bridging of partial arc between adjacent sheds reduce the valid creepage distance greatly for XWP2-160 and XWP4-160.③According to the results of observation and photograph of the arc growing path in flashover process obtained by high-speed camera, the arc growing process are composed of the following phases: brush discharge, developing of the bright partial arc, developing of the master partial arc, elongating of the master partial arc , flashover. Moreover, the developing time and velocity of partial arc in the same phase are different for various types of insulators, as will as the same insulator in different phases. The velocity increases from several meters per second to...