Review: Factors Affecting the Performance of Ground Electrodes under High Impulse Currents

Abstract

Most studies have observed that the impedance values of ground electrodes under high impulse conditions (Zimp) are lower than the resistance values under steady-state conditions (RDC). It has been suggested that this is due to the ionisation process in soil, where streamers will propagate away from the electrodes, causing an increase in the ionisation zone, thus reducing the Zimp values. The percentage difference between Zimp and RDC is found to be dependent on several factors. This paper aims to review and present the findings of previously published work on the percentage difference between Zimp and RDC in relation to various factors.