Evaluations of the apparent soil resistivity and the reflection factor effects on the grounding grid performance in three-layer soils

Abstract: In this study, the apparent soil resistivity evaluation is estimated for three-layer soils by four strategies and the
obtained values are compared with experimental measurements done by using the four-electrode method. Different methods
are suggested with the aid of IEEE 80 to estimate the apparent soil resistivity of three-layer soils, in which a grounding system consisting of a grid with rods is constructed. The effect of the reflection factor on the mesh and the step voltages, the grounding system resistance and the mesh voltage is investigated. It is concluded that the first three methods are close together, and also with the experimental findings done by the authors and others the fourth method gives some tolerance with the first three, but it is in agreement with the experimental measurements. It is concluded also that the reflection factors of non-uniform soil have
significant effects on the apparent soil resistivity, the step and the mesh voltages and the ground resistance. For the verification of the calculated results, experimental model is used. It is noted that the measured values are slightly high compared with the calculated values; the reason may be due to the boundary effects of the used model.

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