Methodologies Regarding the Application of Optimum Criteria to the Vertical Earth Grounding Design, with Rectangular Outline

Abstract

The earth grounding (EGR) computation model contained in normative acts has multiple nonlinearities and functions with implicit definitions. In addition, through the values indicated for the utilization coefficients, the designers are oriented towards relatively large distances between electrodes and no optimal criteria are defined. In earlier works, the authors have realized nomograms in order to calculate the earth resistances for both simple and multiple EGR with more electrodes and have proposed a number of five overall characteristic sizes for the EGR that may constitute optimal criteria. Continuing the development of the dimensioning methods with the application of optimal criteria, the algorithms for the application of two of the optimal criteria, namely the EGR footprint area and the EGR total volume, are formulated and exemplified in the paper. The minimum of the ground footprint area is obtained for the biggest lengths of the electrodes and the minimum distances between them, that are practicable in the given soil and with the technology available to the potential manufacturer. Similarly, the criterion of minimum total volume of the EGR leads also to the minimum distances between electrodes, but to their smaller lengths, within the range of considered lengths.