The mechanism of salt migration phenomena in cooling water and its impact on ice flashover

Ice accumulation always happen to insulators in south China in early spring. In the year 2008, southern cities were suffered from serious icing disaster, leading to great economic loss, thus icing problems are paid more attentions. This paper is concerned with salt migration in ice layer, the relationship between pollution level and cooling time were presented, as well as interpretations on when the ice flashover is most likely to appear. Cooling water was freezing from the solid-liquid interface to the top of water film. Salt migration phenomenon appeared because of the decline of solubility under low temperature. Finally according to 110 kV full-size insulator test, melting water conductivity is nearly six times of the applied water conductivity and conclusions can be drawn that salt migration in ice layer was a critical reason to initiate ice flashover.