Applicability of Wenner’s Method for Measuring Resistivity and Permittivity of Deep Soil at High Frequency

摘要

Evaluating the frequency-dependent resistivity and permittivity of deep soil is necessary for accurately analyzing the transient performance of grounding device. In this paper the skin effect of soil and the effect of the current measurement lead of Wenner’s method on the current distribution in the soil at different frequency are investigated by numerical simulation, with which the applicability of Wenner’s method for measuring the frequency-dependent resistivity and permittivity of deep soil is analyzed. The results show that the Wenner’s method can definitely be used only at frequencies below 500 Hz for $100~{Omega }text{m}$ soil, because at higher frequency most of the current collects in the topsoil due to the skin effect and the induction of the current measurement lead on the current distribution in the soil. The higher the resistivity, or the shorter the distance between the current poles, the higher the applicable frequency.