Current-dependent grounding resistance model based on energy balance of soil ionization

Soil ionization occurs around a grounding electrode when current density in the soil exceeds a critical value and reduces grounding resistance. This paper proposes a current-dependent grounding resistance model considering the soil ionization. The proposed model is derived on the basis of energy balance of the soil ionization. The resistivity of the ionization zone depends on energy stored in the zone. Analytical expressions of the model are proposed to estimate the zone resistivity. The model is verified by comparing it with experimental results.