A large amount of snow accumulates on insulators which melts to humidify the filth layers

directly leading to the decline of the insulation capability. To study the insulation performance of post porcelain insulator covered with snow

we first established a model and simulated the electric field of snow-covered post insulators

then tested the flashover characteristics of different kinds of the insulators in condition of artificial snow-covering. The sample contains three post insulators of different shed geometry. It is shown that a heavily covered sample performs well in maintenance of the insulation capability. But when there comes the large-scale melting of the snow

the insulation performance turns severe because the melting snow forms the water film and some even drops from the edge. Such water film containing with soluble salts is of high conductivity and turns out to be the essential factor of the flashover voltage’s decrease. The snow flashover voltage and the snow melting time appears to be a U-shaped relationship

of which the trough point can be used to characterize the insulation capability of the post insulator on certain contamination level. Also

the shed geometry has an effect on the snow flashover characteristics of the post insulators.