Lightning protection modelling: Applications to revisited Electrogeometrical Model

The present paper aims to revisit the EGM and the rolling sphere method by introducing the upward leaders´ contribution. Using simple assumptions on the conditions for upward leader inception and downward-upward leader junction, the position of the downward and upward leader tips, just before the final jump, are firstly computed and a Modified Rolling Sphere (MRS) radius is deduced. Afterwards, the MRS is rolled on the extreme position of upward leaders tips. If the MRS is in contact at any point with the upward leader tip locus, we consider that this part of the structure must be additionally protected. The main application of this study is the improvement of the interception efficiency of the Lightning Protection System.