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The portion of faults cause by lightning tends to increase with often reaching beyond 30 %. However due to the recent progress of the lightning protection design of a medium-voltage line, the number of failure has decreased to 1/3 of that at 30 years ago. As for the low-voltage distribution line, the fault rate has been estimated primarily, although the details of the overvoltages have not been studied yet. For the further development of highly information-oriented society, improvement of reliability of electric power supply to a low-voltage customer will be socially expected in the near future. Therefore, it is important to establish effective lightning protection design for a low-voltage distribution system, comprising low-voltage distribution system and other components, which influence the lightning overvoltage waveforms on a low-voltage distribution line, namely a medium-voltage distribution line, customers' electric circuits and a telecommunication line
In this technical report, the following matters are covered: (1) the trend of the individual lightning protection design for a distribution line, customers' electric circuits and a telecommunication line, (2) lightning damage aspect of customers' facilities, (3) the standard related to lightning protection, (4) the lightning overvoltage analysis, and (5) the technical matter to be solved in the future. |
