Impact of coupling ground wire on lightning protection effect of multi-circuit tower

Erecting coupling ground wire is a kind of effective lightning protection measure to reduce trip-out rate of back flashovers. Nowadays coupling ground wire has been applied on some transmission lines in China. However, various setting positions of coupling ground wire have different impact on the lightning protection effects, especially the multi-circuit lines. The paper presents and analyzes the effects of setting coupling ground wire on the center of different cross-arm. The shunt coefficients of tower, ground wires and coupling ground wire, and the coupling coefficient in the condition of various mounting positions are also compared and discussed.