Flashover performance of EHV station post insulators covered with ice

The icing performance of standard-shed-design porcelain insulators, with a dry arcing distance of up to 4.17 m, corresponding to full-scale Hydro-Quebec 735 kV substation insulators, was investigated. Artificial ice was formed at -12°C in a climate room from supercooled water droplets produced by a set of pneumatic nozzles. The relationship between the maximum withstand voltage, V_WS, and insulator length was determined. With an applied water conductivity of 30 μS/cm and an ice thickness of 15 mm, measured on a rotating monitoring cylinder, flashover may occur at service voltage. Moreover, the V_WS of the ice-covered insulators tested increases non-linearly with an increase in insulator length. These results are of great importance for the design of EHV substation insulators used in cold climate regions.