Potential Probe Position in Grounding Resistance Measurement of Combination Electrode in Multi-Layer Ground by the Fall-of-Potential Method

Abstract

A difficult problem is encountered when the grounding resistance of a large grounding system is measured by the fall-of-potential method. The problem is that a horizontal curve section does not exist with a fall-of-potential curve. In this case it is difficult to estimate the grounding resistance from the fall-of-potential curve.
In this paper, methods for determination of potential probe position to estimate the grounding resistance of a combination of horizontal and vertical electrode are proposed when horizontal curve section does not exist. First, for the electrode in two-layer ground, two methods are proposed. One is the method where the potential probe position is determined by application of the exact probe position for horizontal or vertical electrode. The other is the method where the potential probe is set at some point obtained here. This some point and error extents with the two methods are described. Next, for the electrode in three-layer ground, the potential probe is proposed to be set as some point obtained here. This some point and error extents in this case are also described.