Earth Resistivity Measurements Using Cylindrical Electrodes at Short Spacings

Abstract

The accuracy of power system grounding analysis is critically dependent on the resistivity of the local soil surrounding the grounding system. This paper develops and discusses a new closed-form formula based on field theory relating soil resistivity to measured resistance which relaxes the requirement that rod electrodes have a large spacing compared to their buried length. The paper also demonstrates that the interpretation of practical resistivity measurements based on the new equation is significantly more accurate than the one based on the classical equation.

Theoretical Study on Geometries of Electrodes in Laboratory Electrical Resistivity Measurement

“…Large distances among electrodes in field tests force well-known theoretical equations (e.g., Wenner or Schlumberger method) to ignore the geometries of an electrode (radius and penetrated depth) and to only reflect electrode spacing [1,2]. With relatively short electrode spacing (e.g., laboratory tests), the penetrated depth of the electrodes has a significant effect on the electrical resistivity measurements [13,14]. In addition, the distortion of current flow occurs near the container and produces inaccurate electrical resistance [15].…”

Analysis of Current Density in Soil for Resistivity Measurements and Electrical Grounding Designs

“…This computation method is based on numerical techniques usually called 'Error Function Minimization' [14][15]. It determines the parameters of the presumed soil model that will minimize the sum of the squares of the difference between the measured and computed apparent resistivities (Least-Square minimization algorithm).…”

Analysis of a Simple Probe for <i>In-Situ</i> Resistivity Measurements

“…Measurements of a materials electrical resistivity can provide useful information for, indirectly determining soil moisture [1], assisting in the design of cathodic protection systems to prevent corrosion in buried metal structures [2], determining electrical substation grounding characteristics [3], measuring subsurface hydrological properties [4], and the extent of sub-seafloor sediment [5] [6] in oceanographic studies, to name but a few. Electrical Resistivity Tomography (ERT) also provides a useful geophysical tool in imaging resistivity variations in the subsurface [7].…”