Strategies for bating enviromental influences on overhead lines to improve quality of supply

The environment possesses the most threat to the overall performance of overhead lines as they are continuously exposed to its harsh influences, e.g. birds, lightning, pollution and fires. These environmental influences contribute about 95% to the total transmission network faults. The quality of supply to Eskom's customers is then heavily affected, and hence strategies of combating these environmental influences had to be devised and implemented. The extent of these environmental influences can be reduced during the design phase of overhead lines. But in dealing with the already existing lines, there are strategies that can be implemented to combat these environmental influences, as they were not adequately considered in older designs. An analysis of various aspects that influence the performance of overhead lines was done for the period 1993 to 2004 (April). The study shows that failure rate of an overhead line varies in relation to line length, design parameters, geographic location and environmental influences. This paper presents background information on some environmental influences on overhead lines, and also presents strategies, with specific cases, that have been implemented to combat these environmental influences with reasonable success