Determination of Threshold Electric Field of Practical Earthing Systems by FEM and Experimental Work

• Published in: IEEE transactions on power delivery Vol. 28; no. 4; pp. 2180 - 2184
• Main Authors: Nor, N. Mohamad, Trlep, M., Abdullah, S., Rajab, R., Ramar, R.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; earth electrodes; Earthing systems; Electrical engineering. Electrical power engineering; Electrodes; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Exact sciences and technology; Finite element analysis; finite-element method (FEM); Grounding; Ionization; Power electronics, power supplies; Resistance; Soil; Studies; threshold electric field; Transient analysis; transients and nonlinear; {\rm E}_{\rm c}; Earth electrode; Earthing systems; System configuration; transients and nonlinear; Grounding; Computer simulation; earth electrodes; E; Resistivity; Outdoor installation; Power supply; Power electronics; Experimental study; Finite element method; threshold electric field; Electric field; Ionization; Comparative study; finite-element method (FEM)
• ISSN: 0885-8977; 1937-4208
• DOI: 10.1109/TPWRD.2012.2227511

In this paper, the results of an experimental study and finite-element method (FEM) of the impulse characteristics of simply built practical earthing systems consisting of 2, 3, and 4 rods are reported. These electrodes are installed at three outdoor test sites having nonuniform soil and different soil profiles to provide variation in the result analysis. The tests on these electrodes were intended to determine the nonlinear characteristics of earthing systems which can be seen from their voltage and current traces and reduction of their impulse resistance values. Two-rod electrodes in the highest soil resistivity profile showed the largest reductions in impulse resistance due to soil ionization compared with other earth electrodes. Computer simulations of all the nine earthing systems using the FEM are also conducted, which showed good agreement with the measured results. It was also found from FEM that threshold electric field Ec is dependent on the earthing systems configurations, soil profile, and impulse resistances.