Measurements and computations of the performance of grounding systems buried in multilayer soils

The resistances and earth potentials of two Florida Power Corporation electric substation grounding systems buried in soils with multiple horizontal layers were computed and measured at various phases of their installation, i.e., starting from a one mesh grid to the final design consisting of many regular meshes. Soil resistivity at each site was measured and interpreted to obtain equivalent two-layer and multilayer earth structures. It is shown that good agreement is obtained between the measured and computed values if multilayer earth structure models are used in the computations. Poor agreement results when uniform soil models are considered