Evaluation of grounding grid´s effective area

Grounding grid performance when subject to lightning current are different when compared to power frequency environment. Various computer models have been developed to understand transient grounding performance. The models led to the introduction of an “effective area” concept. It is an important concept as the parameter is used to optimize grounding-grid design. Several approaches and numerical equations are proposed by previous researchers to estimate the effective area. Each equation defines the grounding impedance at the injection point. In this paper, transient ground potential rise (TGPR) alongside the grounding grid is used to evaluate the empirical equations proposed by previous researchers. Simulations are based on the electromagnetic approach and the governing equations are solved using the Finite element method (FEM). Different soil resistivity and impulse front times were considered in the simulations.