Graphical Data for Ground Grid Analysis

The paper presents graphical data for the calculation of ground grid resistance, corner mesh potential and corner step potential for a restricted class of ground grids. The restricted class of ground grids are similar to those considered in the IEEE Guide for Safety In Substation Grounding, IEEE Standard 80-1976, where the primary restrictions are uniform soil, rectangular grid shape, and uniform conductor spacing. The data presented represents the computer analysis of over 2,385 ground grid configurations using the method of moments (also called a finite element analysis) computer algorithm GRID developed at Georgia Tech under EPRI sponsorship. This computer algorithm has been validated with several field measurement programs. The graphical data is for square grids with square meshes. Simple equations are presented to extend this data to rectangular grids with rectangular meshes.