Abstract
We observed winter lightning on 500kV transmission lines from 1984 to 1993. The observation was lightning course by camera and lightning current at the lower part of transmission tower on 31 towers, in 12.7 kilo-meter transmission lines. And we also observed lightning on isolated tower in nuclear power station.
Through the ten-years lightning observations, we have confirmed lightning protection design on transmission line. The distribution of lightning incidence angle (θ) was m=2 (cosm θ) for the 3 dimensional case, and m=3.5 for the 2 dimensional. We had no case of shield missing on 500kV transmission lines. The ratio of lightning current at the top of isolated tower to the lower part was about 11 to 1. And the lightning current waveform at the top of isolated tower was similar to the one at the lower part.
