Impulse voltage performance of ice-covered post insulators

In this paper are presented the results of laboratory investigations on the influence of atmospheric icing on the flashover performance of post type insulators under lightning and switching impulse voltages. Using the "up and down" method, the critical flashover voltages (V/sub 50/) of an ice-covered post insulator under both positive and negative lightning and switching impulse voltages were experimentally determined in a climate chamber at the CIGELE laboratories. The difference between the properties of an ice-covered insulator under lightning and switching impulse voltages was analyzed. The possible mechanism underlying this difference was explored. The results may be useful for a more adequate design and selection of insulators for cold regions.