Laboratory study of flashover performance of polluted and ice-covered insulators exposed to impulse overvoltage

Line insulators are subjected to environmental, electrical and mechanical stresses. The presence of an ice layer of pollution or ice on an insulator can significantly reduce its flashover performance. The probability of insulation breakdown rapidly increases when the insulator is exposed to a combination of pollution, ice and transient overvoltage. The understanding of arc initiation and propagation under such conditions is very important for insulator design and insulation coordination. The flashover performance of an insulator covered with a polluted ice layer was investigated by generating three impulse voltages of different shapes: lightning impulse with front time of 1.2 µs and half time 50 µs, switching impulse with front time 100 µs and half time 2500 µs and switching impulse with…