Abstract
It is not clear how widely available the tower models which have been derived from the lightning surge response measurements of transmission towers, because those measurements have not been done for so many towers and for so many cases. It could be very useful if the surge response characteristics can be obtained from the tower geometry. In order to do this, the surge response of each tower constructing elements (four main poles, tower arms and lattices) has to be made clear and then the total tower surge response should be derived by combining those responses.
In this paper, firstly the lightning surge responses of vertical cylinders of various radii and heights are measured by the direct method. Then the empirical formula of surge impedance is obtained for the vertical cylinders as a function of time, its radius and height which produces the surge response wave shapes close to the actual measurements. Next, the empirical formula of surge impedance for the multiple vertical cylinder is also obtained from the lightning surge response measurements. Then, the equivalent single cylinder radius for multiple vertical cylinder is derived and is proved to be expressed as a function of the conductor radius, the mutual distance of the conductors and the number of conductors. The above results especially for four vertical cylinder systems would be very useful for the estimation of the total tower surge response characteristics.
