Factors affecting the characteristics of earthing systems under transients by FEM

•Performance of earthing systems under transients are investigated using FEM.•Earth resistance was found to decrease with increasing currents under impulse conditions.•The reduction of earth resistance was found to be dependent on RDC, Ec and current magnitudes.

This paper investigates the effects of current magnitudes, steady-stage earth resistances, RDC, and threshold electric field, Ec on the characteristics of earthing systems under impulse conditions by using Finite Element Method (FEM). It has been reported in literature that there are three scenarios that can occur when the earthing systems are subjected under high impulse conditions as compared to its steady-state conditions, namely; (i) no difference in its resistance values between steady-state and impulse conditions, (ii) earth resistances under impulse were found to be lower than that at steady-state, and (iii) earth resistances were found to be higher under impulse than that at steady-state. It was found that the largest reduction in impulse resistance occurred for the earth resistance with the highest values for different factors; current magnitudes and Ec.