1991 Volume 111 Issue 1 Pages 17-23
Mono- or multi-pole towers are sometimes adopted instead of traditional lattice towers, in order to minimize the environmental impact of power transmission lines. The pole-type tower is expected to have the larger surge impedance than a lattice tower because the former has a smaller average diameter than the latter. This paper investigates experimentally the lightning surge performances of the pole-type tower models of various geometry. Then the empirical formulas of surge impedance are derived for the mono- and multi-pole towers as a function of their geometries: the height and the radius of the pole and the distance between two neighboring poles. The equivalent pole radius is derived and given by the function of the radius at the top and the bottom of the pole. The equivalent pole distance is also derived and given by the function of the distance between two neighboring poles at the tower top and the tower base.