Influence of foundation on pillar grounding system's characteristics

Abstract

Purpose

The purpose of this paper is to estimate influence of the pillar concrete foundation approximated by a semiconducting semi‐sphere on the pillar grounding system.

Design/methodology/approach

Unknown current distributions and impedance of pillar grounding system, which consists of a ferro armature modelled as a single electrode inside concrete foundation, ring electrode and two earthing conductors, are determined in this paper. Concrete foundation is approximated by a semi‐spherical semiconducting inhomogeneity. The expressions for electric scalar potential are formed using the quasi‐stationary image theory, including a recently proposed Green's function for the point source in the presence of a semiconducting sphere. Based on the quasi‐stationary antenna model, unknown currents are determined solving the system of integral equations using the moment method and polynomial approximation for current distributions.

Findings

The influence of inhomogeneity is not negligible for real values of specific conductivity of the inhomogeneity domain. The same goes for earthing conductor influence, especially the one on electric scalar potential distribution on the ground surface.

Practical implications

Besides the analyzed system, the model is applicable for solving for example a grounding system in the vicinity of large holes in the ground (pond and small lake) filled with water, treated as semi‐sphere or near vertical container (silage and reservoir) having semi‐spherical basis with a lower one buried in the ground.

Originality/value

Obtained results give possibility to analyze influence of semiconducting ground inhomogenities, which can be treated as semi‐spherically shaped ones, on grounding system. It results in better accordance of projected and real grounding system's characteristics.

Citation

Cvetkovic, N.N. and Rancic, P.D. (2009), "Influence of foundation on pillar grounding system's characteristics", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 28 No. 2, pp. 471-492. https://doi.org/10.1108/03321640910929335