Mechanism of insulator flashover under artificial rain

The paper gives a brief description of the variation of insulation-surface conductance under artificial rain from dry conditions until steady-state wetting is achieved. The effect of wetting on insulator voltage distribution is examined. Wet flashover tests with alternating voltage and switching impulses of both polarities on simple insulator models as well as long insulator chains and supporting columns are described with a view to clarifying the flashover mechanism. Comparison is made between conventional artificial rain and pulsating rain obtained from special wettest apparatus which permits longer spraying distances. An account is given of the variation of the dispersion of the flashover voltage under different test conditions.