Step voltages in a ground-grid arising from lightning current

Behavior of a grounding grid when subjected to power-frequency fault currents is well studied and probably well understood. However, the behavior of the ground-grid when subjected to transient or lightning currents is different when compared to power frequency currents. The objective of this paper is to provide a better understanding of the behavior of a ground-grid when excited by transient voltages and currents. The Finite Element Method (FEM) is used to solve Maxwell’s equations when modeling the grounding behavior under lightning current. In this study, step voltages above the ground are evaluated for different scenario. Effect of soil resistivity and grid size were analysed. Comparison with the safety limit, as proposed by previous researchers, is shown in the results