Estimation of the expected annual number of flashovers in power distribution lines due to negative and positive lightning.

• The influence of positive strokes on the lightning performance is analyzed. • Time domain induced voltages by measured positive strokes are presented. • The correlation between peak amplitude and front time of positive currents is crucial. The paper deals with the estimation of the expected annual number of flashovers in overhead power distribution lines due to indirect lightning strokes and aims at extending a procedure previously proposed by the authors, limited to negative downward events, in order to include also positive events. The obtained results show that positive flashes need proper consideration for an improved selection of protection means and countermeasures against flashovers. [ABSTRACT FROM AUTHOR]