Measurement of Soil-Ionization Characteristics of Groundingand its Analysis using Dynamic Grounding Model

It is well known that grounding resistance has a current-dependent characteristic, whose phenomena and models have been reported and proposed by many investigators as well as Liew and Darveniza. As far as lightning analysis, especially in Japan, the grounding resistance has been simulated as a simple constant lump resistance. The goal of the authors' investigation is to utilize those characteristics to lightning protection and make a certain methodology to save construction cost for UHV transmission tower on very high resistivity soil. We, therefore, focus on the characteristic of grounding resistance of tower footing for 500 kV transmission line. In this paper, we discuss measurement on high-current injected experiment using an actual tower footing base and its analysis, where we employ dynamic characteristic of the grounding resistance proposed by Liew and Darveniza. Comparison between the observed result and the calculated one is also discussed.