Repeated lightning flashovers on South Africas MV distribution networks can cause serious damage to conductors and pole-top hardware and in some cases lead to conductor burn-off or breakage. Eskom engineers, working with the University of the Witwatersrand, have developed and laboratory tested a device designed to prevent such failures by deliberately controlling where a flashover occurs.
The study, presented at the 12th CIGRE Southern Africa Regional Conference in October, describes the design and testing of an arc diverter that mounts on the phase conductor of an overhead line in conjunction with the tie that attaches the conductor to a post insulator.
According to co-author Andreas Beutel of Eskom, the device provides an intentional arc attachment point so that lightning-induced flashovers occur at a location engineered to withstand repeated short circuits protecting the conductor and the insulator hardware.