Improving the lightning protection effect of multi-circuit tower by installing coupling ground wire

Abstract

Erecting coupling ground wire is a type of effective lightning protection measure to reduce trip-out rate of back flashovers. Nowadays coupling ground wires has been applied on some multi-circuits transmission lines in China. However, various setting positions of coupling ground wire have different impacts on the lightning protection effects, especially the multi-circuit lines. Taking the typical 500/220kV and 220kV quadruple circuit transmission lines for example, the paper presents and analyzes the effects of setting coupling ground wire on the center of cross-arm at different heights. The shunt coefficients of tower, ground wires and coupling ground wire, and the coupling coefficients are also compared and discussed in situations that the coupling ground wire is mounted in different positions.