Influence of Inductive Coupling between Leads on Ground Impedance Measurements Using the Fall-of-Potential Method

Ground impedance measurements in various soil structures using the fall-of-potential method are modeled, taking into account the inductive coupling between current and potential leads. The variation of the inductive coupling with the separation distance between the current and potential leads, operating frequency, and grounding grid size is analyzed for uniform and multilayer soils. Numerical results are presented and compared. The analysis quantifies the inductive coupling between current and potential leads for typical separation distances between the leads. Coupling levels presented in this paper can be used as a reference to estimate possible errors in ground impedance measurements.