The effect of ground resistance on secondary arc current on an EHV transmission line

After a single-phase-to-ground fault occurs on an extremely-high-voltage transmission line, the duration of the secondary arc mainly depends on the magnitude of the secondary, which is determined by the ground resistance and the systemʹs equivalent impedance at the fault location. In this paper, analytical formulas for calculating the systemʹs equivalent impedance have been developed for three different arc-extinguishing techniques. These formulas show a satisfactory accuracy in comparison with electromagnetic transient program (EMTP) simulations. Then, the effect of the ground resistance on the secondary arc current has been evaluated by comparing it with the systemʹs equivalent impedance. The resistance hardly influences the secondary arc current when no arc-extinguishing facility is adopted or when four-reactor banks are employed; while the resistance significantly affects the current when high-speed grounding switches are used.