Lightning performance of concentrated earth electrodes

The authors discuss the performance of concentrated earth electrodes for a tower of an overhead line struck by lightning. The study is based on an improved transmission line model for the current propagation in the lightning channel. The analysis assumes a vertical channel whose cross-section, is exponentially contracted upwards. The improved-even though approximate-use of the transmission line theory applied to the return-stroke propagation provides benefits in terms of accuracy in evaluating the surge earthing impedance, and the voltage across it