Spacer cable lightning-induced overvoltages computed using measured groud resistances

Spacer cable provides compact distribution of 3-phase power. However, the close proximity of the phases to each other and the neutral carrier wire results in very high fields under lightning conditions. The concept of spacer cable is based on the assumption that the neutral carrier wire is grounded at each pole with an earth resistance no greater than 25 Omega. In many areas, this assumption is far from met. In the present study, we compute lightning induced overvoltages for long lengths of spacer cable including the effect of every lightning arrester, transformer, etc. on the line and using measured ground resistances, for a range of lightning currents and risetimes