Induced Electromagnetic Fields on Underground Cable Due to Lightning-Struck Wind Tower

In regions having high activity of lightning flashes, it is important to investigate the lightning-induced electromagnetic (EM) transients affecting buried cables, particularly if such buried conductors are extending close to grounded towers, such as wind towers. In this article, the impact of the grounded wind tower, ground conductivity and permittivity, depth of the cable, and its position from the return stroke on the lightning-induced EM fields on the cable sheath are investigated. In addition, the lightning-induced EM fields on the cable sheath are also calculated with the presence of bare-underground wire above the cable as a protection against lightning strikes. The 3-D finite difference time domain method with nonuniform grid technique is implemented for this study. From the results, it is shown that the presence of wind tower increases the magnitude of lightning-induced EM fields on the cable sheath, particularly for close distances between cable and tower. Moreover, the impact of soil permittivity on lightning-induced EM surges becomes significant for low soil conductivity. Also, the impact of cable depth becomes more significant for higher soil conductivity. Furthermore, the bare-underground wire reduces the magnitude of lightning-induced electric field.