An Estimator of the Resistance of Large Grounding Electrodes from Its Geometric Characterization

Abstract

An estimator of the grounding resistance of large extension electrodes from the total length and geometric properties of the electrode is proposed in this work. The approximation is valid for electrodes buried in a soil that can be assumed as homogeneous and it will be verified that the resistance estimation improves as electrode size increases. Both the burial depth and the radius of the conductors, within certain practical limits, have little effect on the value of the grounding resistance. The shape and size of the electrode are defined by a geometric index that measures the degree of compaction of the conductors that make it up, which has the greatest weight in the final value of the resistance. The expression obtained to quantify the estimate of the grounding resistance is tested in several numerical examples and in a currently operating grounding electrode, obtaining in all cases an estimated value of the resistance reasonably close to the true value.

Keywords

• grounding resistance estimator
• large grounding electrodes
• stretching index