Research Output
Study of soil resistivity using wenner four pin method: Case study
Lightning generated electric field over land and sea at northern region of peninsular malaysia: Measuring setup
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Publication
Soil resistivity is usually measured at the selected site either for new installation or in the existing grounding system. In this paper, soil resistivity test has been done to study the soil resistivity around the 33 kV substation according to IEEE 81-1983 standard. A factory site located in Kulim Hi-tech, Malaysia has been selected to research on the soil resistivity. The soil resistance measured in this study is then be calculated in using the soil resistivity formula. The soil resistivity shows that the longer the distance between rods, the lower the resistivity of soil due to larger soil volume. The lowest soil resistivity around the substation is 3.454 Ω.m, which is on the left side of the substation with a distance of 5 meters between the rods followed by front side with 15.71 Ω.m, right side with 34.243 Ω.m and backside with 45.239 Ω.m. While the highest soil resistivity is 176.306 Ω.m on the right side of the substation with a 2-meter distance between each rod.
Publication
Lightning electric fields can be characterized based on its origins which include the preliminary breakdown, stepped leader, return stroke, subsequent return stroke, dart leader, dart-stepped leader, narrow bipolar pulses, cloud activity between strokes, regular pulse trains, K and M changes, and chaotic pulse trains. The aim of this work is to describe a lightning measuring setup suitable for characterizing lightning electric fields and their propagation when the measuring sensors are close to the sea. A location close to the sea in Northern Malaysia was identified and prepared for the study. Parallel plate and vertical whip antennas are used as the main sensors, which are connected to a high-speed digital storage oscilloscope through customized analog filter buffer circuits. Noise-distortion effects in the recorded data are filtered using MATLAB computer simulation before further analyses are carried out. The 1-D wavelet technique is used in the signal denoising process. Preliminary results show that the installed setup and denoising method is adequate and potentially efficient for the pre-processing of lightning electric field signals, and hence can be used for the detailed characterization study including the effects of sea on lightning characteristics and propagation.