Electrical earthing in troubled environment

Abstract

Practical challenges of electrical earthing in both steady and transient states have been revisited. By analyzing the cases based on theoretical and practical aspects, engineering guidelines are proposed to develop suitable solutions. Less complicated cases can be approached with various electrode configurations such as multiple ring, antenna, crow-foot and centipede arrangements. Distributed earthing arrangements treated with backfill materials are suitable for the sites with extremely high resistive soil. Clay based backfill materials such as bentonite-mix give corrosion and erosion protection for the electrodes in highly acidic, alkaline, saline and sulfur-rich environments apart from reducing the low frequency resistance. On-rock sites such as transmission and communication towers are better approached with concrete-based earthing systems in both cases of power and lightning protection earthing. Extreme cases of soil instability have been identified and discussed. The suitability of vertical and horizontal electrode components as well as copper and steel electrodes under various soil conditions is also discoursed. For most cases, we recommend all types of earthing systems to be integrated, however, properly coordinated system of Surge Protective Devices (SPDs) should be incorporated in such integrated earthing system.

A method for the evaluation of fault current distribution in complex high voltage networks

“…Very high values of the EPR have been found that request the realization of specific measures [16,17] for the reduction of the dangerous touch and step voltages.…”

Lightning protection techniques for roof-top PV systems

“…Earth electrodes are permitted to be installed inside the structure through the basement, or by using natural elements inside the structure as the ring conductors for the type B earthing systems as well [3]. However there are several criteria to be satisfied for such usage [2].Earthing under pathological soil conditions has been addressed in [4][5][6] B…”

“…It is recommended for services to enter the LPZ at one location and connect to bonding bar at one point, if it is not possible there should be different bonding bars which finally interconnected together. Moreover, by shielding of internal lines, the mutual induction effect would be minimized, also routing electrical and signal lines together will minimize the induction loop and passing them close to the natural components of the structure that is earthed as well [4][5][6][7], [5][6][7][8].…”

Modeling of electrical resistivity of soil based on geotechnical properties

“…The electrical resistivity of geo-materials has attracted the attention of the researchers since 1912 when Schlumberger used the electrical resistivity measurements to characterize the subsurface ground (Griffiths & King, 1965). Since then, the need to understand the behavior of electrical resistivity of soils has been extended to different areas such as design of electrical earthing system, monitoring moisture content for agriculture applications, electro-osmosis consolidation and drainage of soils, and assessing the homogeneity of compacted clay liner (Laver & Griffiths, 2001;Lim et al, 2013;Rhoades et al, 1976;Abu-Hassanein et al, 1996;Tabbagh et al, 2002;Brillante et al, 2015;Jones et al, 2011;Al Rashid et al, 2018).…”