The Impact of the Distribution of Lightning Strikes along the Span on Backflashover Rate of Transmission Lines

The impact of the distribution of lightning strikes along the span on the backflashover rate of transmission lines was investigated, by using advanced methodologies and a 138-kV line as reference. The results, obtained using an attractive radius given by Love's expression and distinct conditions of tower-footing grounding impedance and span lengths, indicated a larger span factor in relation to the traditional 0.6-factor. Factors about 0.81 for a 400-m span and 0.84 for a 600-m span length cases were found, suggesting that using the 0.6-factor would underestimate the backflashover rate.