Electric field analysis and calculation on the lightning performance of transmission towers

Transmission towers are usually represented as inductances or as vertical transmission lines when struck by lightning. However, it is believed that the best approach to an understanding of the phenomenon occurring in a transmission system is through field theory. The lightning stroke pluses a positive wave of charge and current that moves vertically upward above the tower. The waves of charge and current produce electric fields along the tower, the ground wire and the conductor. On the basis of the electric field analysis, general principles concerning the performance of tower, ground wire, and conductor combinations when struck by lightning are established and some equations used for calculation are proposed. The effect of the point to which the potentials are referred and current division are analyzed in this paper. The method, called an improved field-cancellation method, provides an improvement for computing the lightning performance of transmission towers.