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Efficiency evaluation of lightning fault inspection in 66‐kV transmission line

A transmission line must be immediately inspected when it is struck by lightning, and damaged parts must be found and changed promptly if the damage is serious. However, such cases are now uncommon owing to the effective design of the lightning protection system now in use. Therefore, it is important to compare data on past lightning events and on transmission lines and to formulate criteria for deciding more precisely in which cases an actual inspection should be carried out. The criteria identified are as follows: (1) the insulator voltage exceeds the critical voltage; (2) the arc current and arc duration exceed the characteristic of insulator breakdown; (3) the number of accident phases is more than 3 ground faults per circuit; (4) the tower foot resistance is 10 ohms or more; (5) the lightning current has a positive characteristic. By using these criteria, the number of lightning fault inspections was reduced by 34%. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(2): 15–22, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20724