Effect of insulator diameter on AC flashover voltage of an ice-covered insulator string

The effect of the diameter of an insulator covered with ice on its flashover voltage was investigated. The insulator diameter was simulated and varied by controlling the width of a layer of ice artificially accreted on a short string of 5 IEEE standard units. The 50% withstand voltage (V₅₀) was experimentally determined using the method described in IEC 60507. The results show that the V₅₀ decreases as the width of the ice layer increases. Moreover, a mathematical model for predicting the critical flashover voltage of ice-covered insulators is proposed, and is validated against the experimental results. The model is then applied to ice-covered industrial insulators with different diameters yielding good concordance between the results from the model and the experimental ones.