Investigative Study of Vertical Electrodes Encased in Concrete/Mortar with Various Sizes of Air Voids

Hanis Hamizah Hizamul-Din,Dzulkafley Abd Samad,Muhd Norhasri Muhd Sidek,Normiza Mohamad Nor

doi:10.3390/en14092659

Hanis Hamizah Hizamul-Din, Dzulkafley Abd Samad + Show 2 more

Open Access

https://doi.org/10.3390/en14092659

Copy DOI

Journal: Energies	Publication Date: May 6, 2021
Citations: 1	License type: CC BY 4.0

Affiliation: Multimedia University, Universiti Teknologi MARA

Abstract

Ionisation can occur in the soil when high impulse currents are subjected to grounding systems. This occurrence is generated by a difference in the dielectric strength value between the soil and air voids. Several published works investigating the ionisation process in soil have seen that the degree of ionisation is dependent on several factors, among them soil resistivity, ground electrode size and impulse polarity. The effects on soil resistivity, such as the moisture content in soil, soil grain size, type of soil and its temperature, have been studied; however, the effect of the size of air voids in soil has not been extensively presented. This study considered four rod electrodes—a conventional rod electrode, conventional electrode with porous concrete (PC), conventional electrode with concrete mixed with a foaming agent (FC) and conventional electrode with concrete (NC)—to provide variations in the size of air voids. Resistance values, RDC, were measured for all these electrodes, and we found that the conventional rod electrode had the lowest value. A detailed evaluation of these rod electrodes under high impulse conditions revealed that similar current rise and discharge times were seen in all electrodes; however, PC, with the largest size of air voids, had the lowest impulse impedance (Zimp value) for the current magnitudes below 2 kA.

Highlights

Published: 6 May 2021A vertical rod electrode is normally driven to the required depth, horizontally or vertically extended, in plurality to other electrodes, to achieve a low resistance value
Four tested ground rod electrodes were used during the course of this study: conventional electrode (CE), conventional electrode encased in mortar with foaming agent (FC), conventional electrode encased in porous concrete (PC) and conventional electrode encased in mortar (NC)
Investigations of soil ionisation were carried out on four rod electrodes: conventional rod electrode, conventional rod electrode encased with porous concrete (PC), conventional rod electrode encased with concrete mixed with foaming agent (FC) and conventional rod electrode encased with concrete (NC)

Summary

Introduction

A vertical rod electrode is normally driven to the required depth, horizontally or vertically extended, in plurality to other electrodes, to achieve a low resistance value. This paper is directed towards differentiating the air voids in the soil, with the rod electrodes encased in concrete and mortar with various sizes of air gaps, and investigating the effects of these electrodes at low voltage and high impulse currents. Despite much work that has been carried out on concrete or conductive material encased rod electrodes, helping to reduce the resistance values, no study has considered air voids in concrete or other materials used in grounding systems It was observed in [8]. Since concrete or other hard materials were applied in studies mentioned earlier [9,11] and used in grounding installations, rod electrodes encased in concrete and mortar can be considered in this present study to investigate the effect of air voids on soil characteristics under high impulse conditions

Ground Rod Electrodes under Tests

Impulse Test Arrangement

Results

Conclusions