Study on AC Discharge Process and Arc Development Performances of Icing Insulators

At Xuefeng mountain natural icing test base, this paper carried out icing flashover tests on composite post insulators with different pollution levels. According to the photos taken by high-speed camera, the AC discharge process of post insulators and the development law of arc speed and arc length are studied. The test results show that, 1) AC discharge process is clearly divided into unstable and stable development stages, the stable development stage is divided into slow development stage and critical flashover stage. 2) there are two phenomena: arc levitation and arc bridging. Arc levitation will lengthen the arc and arc bridging will shorten the arc length(L). Floating arc and short circuit are two ways of arc deformation. 3) There is a critical arc length(Lc) during the arc development, which is between 62.6%*H and 64.6%*H. 4) Significant differences exist in different discharge stages for arc velocity(Varc). When it is less than Lc, Varc is less than 4.8 m/s. When Lc is reached, Varc increases sharply, and Varc can reach 70.67 m/s or above. The research results could contribute to providing useful reference for the external insulation design and anti-icing flashover design of transmission lines with icing area.