Abstract
For the rationalization of lightning protection design of distribution lines, it is important to clarify the behavior of distribution line when direct or nearby lightning occurs. Because of the lower insulation level than is for transmission line, in study on lightning protection design of distribution line, not only direct lightning strokes but also induced voltages caused by nearby strokes must be taken into account. So it is necessary to grasp the frequency of occurrence on lightning phenomena around distribution lines. For this aim, lightning phenomena on TEPCO’s distribution lines in use had been continuously observed for 6 years (1996-2001). The observation was carried out in composite way, using still-cameras and sensors for acquisition of lightning surge waveform data. Through the observation, new interesting phenomena about lightning performance on distribution lines in fields became apparent. In some case, in spite of direct striking to the line, flashover did not occur. This fact means that distribution line has a certain level of lightning resistance. Moreover, it was confirmed that AC following current generated between both ends of insulator disappeared naturally. These results are the interesting discoveries that can be useful to estimate the fault ratio precisely.
