No. 1172
	Clarification of lightning damage mechanism on power�@distribution lines and upgrade of forecast technique of damage rate.
	Investigating R&D Committee on improvement of lightning damage mechanism on power distribution lines
	Keyword : Lightning, Power distribution lines, Lightning damage mechanism, Lightning protection design
	As the information-oriented and computerized society progresses, reducing power failures in electric power companies become important problems. On the other hand, reduction in costs is an important mission of the electric power company from the situation of the liberalization of the electric power. There is lightning in one of the big troubles related to the supply reliability of the electric power. It is necessary to examine the arrangement of lightning protection equipments that is appropriate for the region in detail to execute lightning protection design efficiently. It is necessary to calculate the lightning damage rate at the same time as understanding characteristics of the region of the lightning by observing and accumulating the equipment damage data for that by high accuracy. This technical report settled the result of the survey concerning these events. As the results, Influence of tree nearby distribution line, mechanism that becomes lightning accident from spark-over, breakdown aspect of lightning protection device were clarified, and the influence that these exerted on the presumption of the rate of accident of the distribution line was evaluated. In addition, difference of lightning protection design and Influence that various analytical models exert on rate of accident presumption technique were examined, and the directionality of the upgrade of the estimation approach was shown.
	©2007. The Institute of Electrical Engineers of Japan