Mohamad Nor, Normiza
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Effect of high resistivity soil under high impulse currents Syed Abdullah, Syarifah; Idris, Nur Farahi; Mohamad Nor, Normiza; Ahmad, Nurul Nadia; Mahmud, Azwan
Bulletin of Electrical Engineering and Informatics Vol 13, No 4: August 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v13i4.7287

Abstract

In this paper, experimental test results of several ground electrodes surrounded with gravelly soil medium subjected to high impulse currents were studied, to investigate the effect of confined soil surround electrodes. Ground resistance measurements were performed at low magnitude of voltage and current, where the results are compared to the impulse characteristics of ground electrodes. This paper shows a significant difference in the RDC values and impulse characteristics of ground electrodes when gravelly soil medium surrounded the ground electrode in comparison to the electrodes installed in natural soil. This indicates that the confined soil around the electrode has a major effect on the performance of ground electrodes, whether at steady state or under high impulse conditions. Equivalent circuit for each tested electrode was developed with personal simulation program with integrated circuit emphasis (PSPICE), where the effect of inductance was seen in the electrodes surrounded with gravelly soil.
Evaluation of steady-state ground resistance by field measurement and CDEGS computation Muhammad, Usman; Zaid, Hadee; Ahmad, Nurul Nadia; Mohamad Nor, Normiza; Aman, Fazlul
Bulletin of Electrical Engineering and Informatics Vol 13, No 5: October 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v13i5.7603

Abstract

In addition to the soil resistivity and size of the grounding system, grounding system configuration can influence the steady-state resistance (RDC) of a grounding system. The RDC of four to six configurations in three distinct soil conditions (sites 1 to 3) is measured using the fall-of-potential method and computed using the current distribution, electromagnetic fields, grounding, and soil structure analysis (CDEGS) simulation. The RDC value generally decreases as size increases, i.e., when more rods or tapes are added, except for a little variation subject to the electrode arrangement and soil resistivity. The 3 and 4-parallel configurations perform better on low resistivity soil (site 1), while the grid configurations (2×2- and 3-rod grids) are better on high resistivity soil (site 2). The difference between the measured and computed values at high soil resistivity sites (sites 2 and 3) is large, ranging from 18% to 66% for site 2 and from 35% to 53% for site 3. The difference is lower and more consistent at site 1, where five out of six configurations achieve less than 10%. At all sites, the difference between computed and measured RDCs generally decreases as the area of the electrode increases, except for some cases at site 2.
Comparing horizontal versus vertical arrangement on the ground resistance values Shamsul, Syakir Azim; Muhammad, Usman; Aman, Fazlul; Mohamad Nor, Normiza; Osman, Miszaina
Bulletin of Electrical Engineering and Informatics Vol 13, No 6: December 2024
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v13i6.7944

Abstract

It is important to compare the horizontal electrodes versus vertical ground electrodes particularly when there is limited area to extend the horizontal ground electrode and hard soil at the deeper soil in order to install the vertical rod electrode. Although all of these can be assessed by computational work, much work has shown that computed resistance values are different than measured resistance values and these computational softwares are not always available to the users. For these reasons, the aim of this paper is to address this shortfall by considering two sites with two-layer soil resistivity model where site 1 with upper layer higher than the lower layer and vice versa for site 2. For the same size of ground electrodes, vertical arrangement is found to have lower ground resistance values, despite higher soil resistivity at the lower layer soil. Soil compaction after backfilling the trench during the installation of horizontal electrode has been identified as the main factor that contributes to differences between the measured and computed resistance values.
Influences of impulse generators on the impulse characteristics of grounding systems Muhammad, Usman; Aman, Fazlul; Mohamad Nor, Normiza; Nadia Ahmad, Nurul; Osman, Miszaina
Bulletin of Electrical Engineering and Informatics Vol 14, No 3: June 2025
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v14i3.8467

Abstract

It is important to ensure the effectiveness of the experimental test set up and to accurately characterize grounding systems under high impulse conditions, the study on the effect of impulse generator is therefore needed. As with other experimental work, the test results may be influenced not only by the characteristics of the test load under study, but also the test arrangement, rating of the impulse generator and transducers. In this work, sources of this overshoot/spike observed in voltage and current traces of 1-rod, 3-rod, and 4-rod electrodes subjected to two impulse current generators of different rating: generating at maximum voltage and current of 100 kV, 1.5 kA, and 300 kV, 10 kA with the same response time of 1.2/50 μs are identified with the aid of simulation work.