Abstract
Overhead transmission line outages have been mostly observed in areas where lightning is severe. It is necessary to evaluate lightning performance of any transmission line in a more detailed way for reducing the impact of lightning over-voltages. Therefore, in this study, the case of direct lightning to transmission line on double circuit - single ground wired lattice pylon in Turkey is analyzed. ATP-EMTP simulations are used to estimate the minimum(Ic) and maximum (IMSF) shielding failure lightning currents causing flashover of insulators on that towers. These minimum and maximum lightning currents are of great importance estimating the shielding failure flashover rates and transmission lines insulation coordination Works. Furthermore, estimating of that shielding failure rate is also worked for the case that surge arresters are not online because of the fact that they are in faulty position.