Adel Zein El Dein

This paper investigates the impact of soil replacement around a ground grid on its performance, with a focus on replacing the base soil with a lower-resistivity material and analyzing the influence of the replaced layer’s area and thickness. The study explores the effects of soil replacement on critical parameters such as total ground resistance, earth surface potential (ESP), current density, and electric field distribution under line-to-ground fault conditions. Key soil properties, including water content, thermal and electrical conductivity, heat capacity, density, and relative permittivity coefficient, are also considered to assess their role in optimizing the grounding environment. Despite extensive research on grounding system performance, most existing studies have assumed homogenous soil models or ideal conditions, overlooking the complex variations in real soil properties and environmental factors that critically affect fault performance. Traditional design methodologies often fail to address the effects of non-uniform soil composition, moisture variations, and localized resistivity changes, leading to suboptimal safety and performance in practical installations. This gap necessitated the proposed research, which systematically investigates soil replacement strategies as a practical and scalable solution to enhance grounding system efficiency under realistic conditions. This paper addresses a detailed investigation of how targeted soil replacement strategies influence grounding system behavior under realistic fault conditions. It introduces a practical framework that integrates both environmental and electrical soil properties to enhance performance evaluation and design accuracy. The results demonstrate that replacing high-resistivity sand with low-resistivity clay significantly reduces total ground resistance. For a 1-meter-thick replaced layer, resistance decreased from 8.4 Ω to 3.17 Ω (a 62.3% reduction) when sand was replaced with clay, whereas replacing clay with sand increased resistance to 11.5 Ω (a 37% increase) at 1.5 meters of thickness. Similarly, ESP values dropped substantially when clay was introduced as a replacement layer, enhancing current dissipation and reducing surface potential risks. Moreover, expanding the replaced soil width from 25 meters to 50 meters resulted in further ground resistance reduction, with values decreasing from 3.3 Ω to 3.17 Ω when replacing sand with clay, while resistance increased from 2.5 Ω to 8.4 Ω when replacing clay with sand. The study also revealed that a 50% replacement of sand with clay improved current density uniformity and enhanced grounding efficiency compared to full replacement scenarios. The findings show that replacing the cover soil layer achieves greater improvements in reducing ground resistance and enhancing current dissipation compared to the base layer. Increasing the thickness and area of the replaced soil further improves current density uniformity, reduces surface potential, and significantly boosts the safety and efficiency of grounding systems, especially in high-resistivity soils.

In this paper, the study of the homogeneous resistivity and two‐layer soil influences on the performance of the electrodes of grounding systems subjected to lightning strikes is carried out considering soil ionization. The study is done on the behaviour of the ground electrodes while the resistivity of the soil is altered from small to high value in the case of homogeneous soil, while the study is obtained on two‐layer soils in the case of diverse values of the reflection factor. In the suggested algorithm for two‐layer soils, each layer has its resistivity and dielectric constant, where the dielectric constant and soil resistivity depend on the lightning frequency. The field resulting from lightning strikes, which causes soil ionization, has been studied, and the results have been used to understand the behaviour of ground rods under the influence of lightning strikes. The credibility of the results has been strengthened by comparing it with what others have obtained recently. The article's novelty can be summarized in the investigation of the performance of the electrodes of grounding grids that are installed in high soil resistivity of uniform and two‐layer soils containing the impacts of soil ionization, lightning frequency, soil resistivity, and permittivity variations.

One important objective of this article is to present a novel approach to study the current density and ground surface potential around the area surrounding earthed and isolated systems in the event of a line-to-earth fault. The present study is done in the case of uniform and two layers of soil. The contact and arc resistances of the line-to-ground faulty conductors are considered. A grounded system is usually implemented with rods and/or grounding grids, the impact of both on step and touch potentials and current density are investigated, discussed, and adapted. The methods of the calculations are based on the electrical concepts, the charge simulation method, and the image method for the grounding system. The results obtained are in agreement with that reported by others, with the benefits of the proposed algorithm for its ease of application, simplicity, and it does not need complex computer programs or a long time in calculations. 3-D dimensions contours of the current density and the electric potential on the earth’s surface around the faulty point in case of homogeneous and two layers of soil are presented, whether the network is grounded or isolated. Comparing the results obtained with those reported by the others, differences of 2.2% in the Ground Potential Rise, 2.46% in the current density, and 0.5% in the fault current passes into the isolated system are recorded. These values in the differences are within the acceptable limits.

In this article, an algorithm is proposed and used to study the influence of harmonics on the behavior of medium‐voltage underground cables in flat formation. The proposed algorithm is a thermal model based on the heat equilibrium of the thermal circuit nodes of the medium‐voltage cable system. The impact of harmonics on the temperature rise of the cable elements and the cable capacity is evaluated in this article. Also, the impact of harmonics on the derating factors of cable for different soil types is presented. Finally, the measurement of temperatures of cable cores is carried out experimentally and compared with the calculated results to validate the proposed algorithm. One of the algorithm merits is that several harmonic percentages can be taken into account for each cable phase individually, and the heat exchange between the cable phases and their sheath is also taken into consideration. From the obtained results, it is illustrated that the presence of harmonics has a remarkable influence on the cable core temperature; mainly, harmonics of the third and fifth orders may lead to dry zone formation around the cable. It is also observed that the presence of harmonics has an important influence on the cable current, especially when it is buried in soil that has high thermal resistivity during the summer season (suction tension = ∞). In summer, the cable core temperature reached 152.162°C, 139.053°C, and 133.375°C when lime, sand, and silty sand, respectively, are used as backfill materials, rather than 90°C in the normal operating condition of the 11 kV three‐phase single‐core cable. It is observed also that with the increase of the soil thermal resistivity, the ratio of /) reached about 1.2 times at 2.5 K m/W soil thermal resistivity. In addition, it is also observed that the impact of harmonics leads to a percentage reduction in the derating factor of the cable center phase by 11.88%–12.37% depending on the composition of the backfill materials.

The enhancement of the thermal properties of insulating oils has positively reflected on the performance of the electrical equipment that contains these oils. Nanomaterial science plays an influential role in enhancing the different properties of liquids, especially insulating oils. Although a minimum oil circuit breaker (MOCB) is one of the oldest circuit breakers in the electrical network, improving the insulating oil properties develops its performance to overcome some of its troubles. In this paper, 66 kV MOCB is modeled by COMSOL Multiphysics software. The internal temperature and the internally generated heat energy inside the MOCB during the making process of its contacts are simulated at different positions of the movable contact. This simulation is introduced for different modified insulating oils (mineral oil and synthetic ester oil) with different types of nanoparticles at different concentrations (0.0, 0.0025, 0.005, and 0.01 wt%). From the obtained results, it is noticed that the thermal stress on the MOCB can be reduced by the use of high thermal conductivity insulating oils. Nano/insulating oils decrease internal temperature and generate heat energy inside the MOCB by about 17.5%. The corresponding physical mechanisms are clarified considering the thermophoresis effect.

A lightning strike is considered one of the most risky natural phenomena that can lead to human harmful and the surrounding soil layers. To tackle this issue, this article investigates the influence of direct lightning characteristics in terms of human body safety. Specifically, such investigation is carried out on the effect of resistivities of two-layer soils on human safety when lightning stroke hits the towers of the high voltage transmission lines (HVTLs). The merit of the proposed study is that the soil ionization phenomenon is taken into consideration. Further, the study focuses on the current passing through the human heart, when step and touch (contact) voltages are generated by grounding potential rise, caused by direct lightning strikes transmission tower and the produced potential rise that a person could be exposed. Also, studying the effects of peak current and time of lightning strokes are investigated. Additionally, the paper presents the effect of different reflection factors on human safety. For validation purposes, the ATP program is used in the simulation of the grounding system as well as the human body model. Numerous simulations were accomplished in order to examine the behavior of the current passing through with the human heart. Based on the simulation results, it was concluded that the soil characteristics have superior influences on the contact and step potentials and, accordingly, the survival threshold.

This article presented the characteristics of the grounding electrodes in uniform and two layer soils when subjected to lightning including the impacts of soil ionization with frequency, soil resistivity, and permittivity variations. The critical breakdown field strength of two layer soils with different values of the reflection factors was presented. The transient probabilistic grounding potential rise and the transient impedances of the horizontal and vertical electrodes were investigated in uniform and two layer soils including the effect of soil ionization with frequency. Finally, the influences of resistivity and permittivity variations which have substantial impacts on the electric field at the occurrence of the soil ionization were considered. Moreover, transmission line approach (TL) with the aid of ATP has been used to compute the transient grounding voltages. The results indicated that the reflection factor has a significant impact on the equivalent radius of the grounding electrode. It is also observed that the peak values of the lightning induced voltages decreases sharply when the soil ionization phenomenon considering the variations in soil resistivity and permittivity with the stroke frequency changes. Furthermore, the impedances of the burial electrodes that have negative reflection factors were lower than that in case of positive reflection factors.

The electric and magnetic fields of overhead high voltage transmission lines are still a critical problem for new construction because of their biological effects on the human body. This issue has been a subject of scientific interest and public concern for the risk of the electric and magnetic fields on living organisms. Accordingly, the overhead transmission lines are considered a source of such this risk due to their high electric and magnetic fields in the populated areas. Because of the recent concerns that electric besides magnetic fields, generated by overhead transmission lines, electric power researchers have been trying to find effective methods for the mitigation of the electrical and magnetic fields to be in the range of acceptable limits. Researchers have been trying to find transmission line geometries that will reduce these electric and magnetic fields. Therefore, in this article two novel methods of reducing the electric and magnetic fields are discussed, one is to change the position of the center phase to optimize the delta configuration and the other is to use more than two shielding wires with calculating the currents in these wires. The obtained results of the two proposed methods are compared with the electric as well as magnetic fields, and the right-of-way values of the present conventional configuration. Additionally, this article presents a case study carried out on an Egyptian 500 kV high voltage overhead transmission line for the mitigation of magnetic and electric field intensities.

Dye solution temperature influences the elimination efficiency of water-soluble and anionic acid dye. Acid Blue 25 dye, using a gas–liquid electrical discharge system, was successfully investigated. The results showed an increase in the percentage of dye decolorization from 91.16% to 96.12% when the dye solution temperature was increased from 278 K to 308 K. However, the initial dye decolorization percentage was decreased with the further increase in dye solution temperature from 318 K to 358 K. The 2D simulation model was introduced to consider the influence of temperature and the electric field generated by corona discharge plasma in air and water. Results also showed a great match between the experimental and the simulation results. The reaction rates of dye degradation were analyzed using the Arrhenius equation. Furthermore, pseudo-zero-, pseudo-first-, and pseudo-second-order models were used to determine the reaction kinetics. The best fit for the experimental data would follow the pseudo-first-order model. Finally, electrical energy per order, energy yield, and experimental degradation data were calculated to investigate the cost analysis.

This article proposes using a metallic plate to be installed above the underground power cable route to mitigate the maximum cable conductor temperature and the ground surface magnetic flux density surrounding the cable route and underground cable de-rating factor. The article presents a case study containing a single-circuit 145 kV, three-phase individual cables in flat formation. The impacts of the mitigation plate dimensions such as plate width, thickness, the distance between the underground cables and the plate used in the mitigation, and the plate material are investigated. Three kinds of materials are examined in this article, namely aluminum, steel 100, and steel 500. Moreover, the optimal design dimensions of the metallic plate for the case under study were estimated. It is concluded that the shielding factors of the magnetic flux density and cable core temperature with aluminum are greater than steel 100 and steel 500. In addition, the de-rating factor, which is the ratio of the current capacity of the underground cable with shielding plate and that without shielding plate at the same cable core temperature, is increased to be 1.28 with the use of shielding Aluminum plate, rather than 1.18 and 1.17 in case of using Steel 500 and Steel 100 shielding plates, respectively. Finally, the proposed algorithm was validated by comparing its results with the experimental measurements obtained by the others, indicating good agreements.