Lightning performance of grounding electrode is one of the most important lightning-protection features of power distribution lines. It is well known that ground resistance has current-dependent characteristic due to soil ionization. Moreover, it also has time-dependent characteristic. But especially transient behavior has not been represented by EMTP models well because its mechanism is not cleared.
In order to clarify the transient behaviors of the grounding electrode, experiments were conducted with full-scale grounding systems. In this study, the paper describes a grounding electrode model that can be easily used in the EMTP analysis. The proposed model considers both current-dependent and time-dependent characteristics. It is verified by comparing calculated results with the experimental results.