Practical design of counterpoise for transmission-line lightning protection

EXPERIENCE has shown that preventive lightning protection, involving the installation of overhead ground wires and the co-ordination of tower-ground resistances with insulation level, can be quite effective in preventing flashovers due to lightning. Studies presented in an earlier paper¹ indicated that the efficiency of preventive protection can be made practically 100 per cent for high-voltage lines having insulator flashover levels of 1,600 kv and above. If the flashover level is reduced, the efficiency of protection becomes less.