Investigation of flashover phases in a lightning surge by new archorn and tower models

The paper has developed new archorn flashover and tower models. The models were applied to EMTP simulations of archorn flashover characteristics and a transient voltage at a UHV tower. Calculated results by the models agree satisfactorily with measured results. Finally, a field test result of multiphase flashovers on a 77 kV transmission line for summer lightning was simulated by using the proposed tower model and a conventional 4-story tower model widely used in Japan. The 4-story tower model shows a very low flashover probability on the lower phase and the flashovers being independent from an ac source voltage. On the contrary, the proposed model shows an equal flashover probability on each phase and the most flashovers during the AC voltage polarity being opposite to the lightning current polarity, which agree with the field test result.