Lightning Strokes to Power Transmission Lines and the Shielding Effect of Ground Wires

A method for predicting the probability of lightning strokes to transmission lines and the shielding effect of ground wires is presented. This method, which is based on electromagnetic field concepts, also makes it possible to determine which parts of the system (ground wires, phase wires, etc.) are more attractive to various lightning strokes for a given geometrical configuration of the transmission line. The study presented showsthat the area " covered" by a transmission system, in which every lightning strikes the transmission line, and the shielding angle are not constant. They are a function of the down-going charges from the cloud and the configuration of the transmission line and cannot be expressed by simple geometrical methods.