EXPERIMENTAL INVESTIGATION OF THE PROCESS OF ARC PROPAGATION OVER AN ICE-COVERED INCLINED INSULATOR

The minimum flashover voltage, VMF, of a short insulator string of four units of IEEE standard insulators fully bridged with ice in two positions, at a 60° inclined angle and in vertical position, under dc+, dc- and ac test voltage were measured. A notable increase in insulation strength of the inclined position compared to the I-string vertical position under heavy icing conditions was observed. The increase in VMF under dc-voltage were 21% and 39% for applied water conductivities of 100 and 60 µS/cm, respectively. Such increase was also observed for dc+ and ac. Furthermore, this paper reports the processes observed by a high speed camera during arc propagation on the ice-covered inclined insulator.