2008 Volume 128 Issue 1 Pages 226-234
Lightning-related overvoltages on 6.6-kV overhead distribution lines can roughly be classified into the two types: overvoltages induced by a nearby lightning stroke and overvoltages due to a direct lightning stroke to the distribution line. Protection measures against the former, which is commonly called lightning-induced overvoltages, have been taken and can be considered as completed. Regarding the latter, recent experimental studies have revealed that protection against a direct lightning hit is possible by applying appropriate countermeasures. Studies of such countermeasures are now carried out by digital simulations using the EMTP (Electro-Magnetic Transients Program), and thus components of a distribution line must be modeled appropriately in the EMTP for accurate simulations.
This paper presents surge characteristics of a distribution line obtained by experiments using a reduced-scale distribution line model. The reduced-scale model includes a reinforced concrete pole, a ground wire, phase wires, a grounding lead conductor installed along the pole, and a lightning channel. Unlike preceding studies, the surge impedance of a reinforced concrete pole is measured considering the effects of a ground wire and phase wires. Voltages at various positions of the distribution line model have been measured with varying the wavefront time of the injected current simulating a lightning stroke and also varying the grounding resistance of the pole, and their effects are examined.
The transactions of the Institute of Electrical Engineers of Japan.B
The Journal of the Institute of Electrical Engineers of Japan