PROJECT TITLE :

Comparison between AC and DC flashover performance and discharge process of ice-covered insulators under the conditions of low air pressure and pollution

ABSTRACT :

This study, primarily based on AC and DC flashover tests of porcelain, glass and composite insulators underneath the conditions of low air pressure and pollution, discusses the differences between AC and DC flashover performance and discharge method of icecovered insulators. Results of the study indicate that the influence of air pressure on ice-lined insulator string??s AC flashover voltage is bigger than that on DC flashover voltage, whereas the influence of pollution on both AC and DC flashover voltage is sort of the identical. Smart agreement is achieved between experimental results and the equivalent electrical circuit model proposed previously. Moreover, n (characteristic index of the influence of air pressure on ice-lined insulators?? flashover voltage) differs slightly when calculated with the icing-water-conductivity technique and solid-layer method, respectively, and also the period from the prevalence of native arc to flashover is longer below the condition of AC than DC. Though arc floats are a lot of seriously beneath the condition of DC.