The evaluation of fifty percent breakdown voltage across Iranian 400 kV transmission line insulators

The Iranian isokeraunic map developed by the authors is presented. A statistical analysis of tower footing resistances of 400 kV lines in the Iranian national grid is also presented. An attempt has been made to evaluate lightning fifty-percent breakdown voltage (V/sub 50/) across 400 kV insulators in Iran, according to obtained keraunic levels and probabilistic results of tower footing resistances. A comparison between calculated V/sub 50/ and V/sub 50/ of presently installed insulators of 400 kV lines in the Iranian transmission system is also presented.<
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