Analysed Ranges and Auxiliary Curves for Analysis of ρ-a Curves Obtained with Wenner's Four Electrodes Arrangement
Takeshi Takashima, Handong Wang, Tadahiro Sakuta, Tosio Satoh · IEEJ Transactions on Power and Energy · 1995
For the design of a grounding electrode, the ground configuration at an intended site for the electrode needs to be clear. For this purpose, in many cases, a ρ-a curve from the measured results with Wenner's four electrodes arrangement is analysed by Sundberg's standard curves and Hummel's auxiliary curves. This paper is concerned with the analysis of the ρ-a curve for three-layer ground. First, for deduction of three parameters of ρ1, h1, and ρ2, the best analysed range of ρ-a curves is searched from many model data, and it is found that the best range is from the beginning point to 0.8 Li1, , where Li1 is the value of a at the first inflection point of the ρ-a curve. Next, for deduction of two parameters of h2 and ρ3, usual Hummel's and other four auxiliary curves are descussed from the view point of two layers displace-ment to one layer. For deduction of ρ3, usual Hummel's curves are good enough for all types of ρ-a curves. But, for deduction of h2, it is pointed out that, series-displacement curves are excellent for UD-type of ρ-a curves and Ono-displacement curves for DD-type, meanwhile usual Hummel's curves are good enough for DU-and UU-type. Then the best analysed range for deduction of h2 and ρ3 is also searched, and it is found that the best range is estimated from Li1 or Li2, where Li2 is the value of a at the second inflection point of the ρ-a curve.