Efficient computation of rodbed grounding resistance in a homogeneous earth by Galerkin's moment method

Abstract

This paper computes the grounding resistance of rodbeds in a homogeneous earth by a moment method with Galerkin's approach. The self and mutual resistances matrix result is quite small. It shows that an N rod assembly requires only an N*N matrix. The resistance of the rodbed grounding system calculated using this method has a percentage difference of less than 2% from the point matching moment method. Galerkin's moment method does not match the boundary potential at one point of a segment, but matches the boundary potential that is averaged over the whole segment. Such a simple change in the moment method makes the method variational and results in a very small error even with a substantial saving in computation effort. The effects of various system parameters on the rodbed parameters (such as rod sunken depth, rod length and radius, rod spacing, rodbed configuration, and number of the rods) are investigated and discussed in detail. The paper ends with a discussion on the accuracy of the surface ground potentials with the coarse segmentation of one segment per rod.