Abstract
In order to make clear the mechanism of double circuit accidents that occur on power transmission lines, an accurate multi-phase flashover analysis on transmission towers is necessary. This multi-phase flashover analysis is made for an 500kV transmission line when one of towers is struck by lightning. The nonlinear inductance model of the arcing horn gap is added to the authors' previously proposed tower model. The tower model can precisely calculate every arm voltage and the gap model can well simulate the flashover phenomenon from leader extension to breakdown. It is found that the probability that occurs flashover among more than 4 phases is considerably high for the case of lightning current with 200kA amplitude and 100kA/μs wave crest. On the contrary, flashover among more than 2 phases does not take place in either case where the lightning current amplitude is less than 100kA or the wave crest is less than 50kA/μs.
