Simplified numerical based method for calculation of DC ground electrode resistance in multi-layered earth
Ng, Chong Kiat
The main focus of this thesis is to develop an efficient method for handling DC grounding problems involving earth non-homogeneity. A numerical technique has been employed using a commercial 'Finite Element Method' (FEM) package called 'ANSYS 5.5'. Due to the large scale of the problem domain a technique known as ''substructuring'' has been used. Classical analytical solutions were utilized to establish the accuracy of the numerical solutions. It is shown that an error of no worse than 10% in the estimation of the ground resistance can be guaranteed with only a few exceptions, which are pointed out in the thesis. A technique for reducing a problem involving two-layered earth to a homogeneous earth is proposed. This procedure can be extended to cover for cases involving multi-layered earth. The effects of inclined earth layers have been considered and suggestions for handling such situations are proposed.