Ground resistance of concrete foundations in substation yards

The reinforced concrete foundations in a substation yard have extensive reinforcing steel in metallic connection with the ground conductor. The foundations may contribute significantly to the dissipation of the fault and leakage currents. Simple-to-use equations and graphs are presented to determine the ground resistance of various types of foundation encountered in substation yards. The validity of the analytical approach has been verified with scale model tests. The ground resistance of the foundations, estimated as suggested in the paper, can be used to evaluate the role of the foundations as a grounding element