

Articles
by
N. Mohamad Nor 
Total Records (
2 ) for
N. Mohamad Nor 





N. Mohamad Nor
,
R. Rajab
and
K. Ramar


Much research has been published in the literature on the mathematical approaches to obtain the most accurate earth resistance and resistivity values. However, the published research only conducted the comparisons among the mathematical/computational techniques and so far none has conducted validation tests of these mathematical/computational methods against the real earth resistance measurement at real field sites. Thus, the main contribution of this research is to show the validity of the formulas available in the literature against the measured earth resistance value at field site. The earth resistance values at three field sites for the earthing systems consists of two, three and four rods were obtained with i) calculation, where the earth resistivity is first measured, which later interpreted into 2 layers earth and used to calculate for the earth resistance and ii) measurements using a FallofPotential Method. The results from this present study can help to validate the mathematical approaches in some published work against the measurement results. Also, this is the first time this kind of comparison study between the calculated and measured for two layers soil model is presented, which can help to improve the earth resistance formulas in a future, since the calculation of earth resistance is important especially at the preliminary earthing system designs. 





Ramdan E. Rajab
,
N. Mohamad Nor
and
K. Ramar


Problem statement: The twolayer soil model at low magnitude voltage is assumed to be accurate for the measurement and calculation of the earth resistance of a combined gridmultiple rods electrode. The aim of this study is to measure and calculate the earth resistance of a combined gridmultiple rods electrode buried in a twolayer soil and to confirm the simplicity and accuracy of the used formula. Approach: Soil resistivity was measured using Wenner four point method. Advanced earth resistivity measurement interpretation techniques which include graphical curve matching based on master curves and an advanced computer program based on a genetic algorithm are used in this study. Results: Based on the resistivity data, the earth resistance value was calculated using the formulas obtained from the literature. Measurements of the earth resistance of the earthing system were also conducted using the fall of potential method. Conclusion/Recommendations: A very good agreement was obtained between the measured and calculated earth resistance values. This research is the first time ever conducted where the measured earth resistance values are compared directly with the calculated earth values. 





