Earth Conductor Research Articles

Зависимость потенциала на рельсах от сопротивления заземляющего устройства тяговой подстанции и параметров рельсовой линии

Purpose: to analyse the dependence of the potential on rails on the track coordinate at different values of conductivity of the grounding device of the traction substation (g0 = 0 S, 10 S, 25 S, 50 S). Methods: the analysis was carried out on the developed substitution diagram of the traction rail network section using the method of nodal potentials. The calculation was implemented in Mathcad 15 mathematical package. Selection of initial data was carried out taking into account the values established in the current normative documentation. Results: an equivalent substitution scheme of the traction rail network on a double-track section has been developed, in which each homogeneous section of the rail line is replaced by an equivalent U-shaped quadrupole. This allows to transform an electric circuit with distributed parameters into a circuit with concentrated parameters. If it is necessary to simulate transverse or longitudinal asymmetry of traction current in a section, such a section is replaced by a three-wire substitution diagram in which the earth conductor is taken into account. To improve the accuracy of the modelling results, the inter-track jumpers are taken into account, and the number of nodal potentials is increased to 7. It is established that the highest modulus value of voltage on rails is observed near the traction substation. It has been determined that the voltage value on rails near the traction substation decreases when the conductivity of the earthing device increases. Practical significance: values of rail-ground potential at different values of conductivity of grounding device of traction substation for tracks of both directions of traffic — even and odd tracks — are determined. The value of conductivity of the traction substation grounding device at which it is safe for the personnel to stay on the rails near the traction substation has been determined. The obtained results can be recommended for practical use in railway transport.

FDTD Analysis of Electric Field and Step Voltage in a Clay‐Wall House Struck by Lightning

The density of lightning flashes is quite high in Rwanda and its neighboring countries in Africa. In rural areas of these countries, there are still many clay‐wall houses. Sometimes people in clay‐wall houses are fatally injured by direct lightning strikes to the houses. In this paper, the electric field in a clay‐wall house and the step voltage on the floor, associated with a direct lightning strike to the house, are analyzed using the finite‐difference time‐domain (FDTD) method. Also, the electric field and the step voltage in the same clay‐wall house but with a horizontal air termination conductor connected to buried vertical bar earth conductors or a square ring earth conductor via bare or insulated down conductors are analyzed using the FDTD method. It has been shown that installing these protection systems reduces the inside electric field and the step voltage on the floor particularly if insulated down conductors are employed. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Ensuring the Serviceability of 0.4 kV Electric Networks in Case of Breaks of the Combined Neutral and Earth Conductor

Breaks of the neutral conductor are among the most common failures in 0.4 kV networks. At present, to ensure the electrical safety of personnel, grounding loops with standard values of grounding resistance in compliance with Electrical Installation Code (PUE) are set up. Such grounding loops do not have any significant impact on the power quality indicators. Moreover, their construction is quite expensive and requires significant material costs. To maintain power quality parameters within the permissible limits, grounding loops with much lower resistance values are needed, which, however, are much more expensive. One of the ways for solving the problem under consideration is the use of natural grounding conductors for temporarily maintaining the standard electric power quality. The article addresses the problem of ensuring the electric power quality in case of breaks of the neutral conductor and a decrease of its conductance with reference to voltage unbalance. The ways of solving this problem are briefly outlined, in particular, by laying an additional conductor or using the TN-C-S grounding system. One of the alternative solutions to the problem considered is the use of natural grounding conductors, for example, a reinforced concrete foundation or a metal fence. The grounding resistances of such grounding conductors were calculated, the estimated values of which have confirmed the possibility of using them to comply with the PUE requirements. Practical recommendations for implementing the suggested proposals are given. One of them is to develop a device for monitoring the state of the neutral protective and main conductors. The key related issue of the problem considered is to ensure the electrical safety of both personnel and all people staying in the territory in which the grounding is temporarily used as the main neutral conductor. This issue will be addressed in the subsequent publications.

Analysis of Simultaneous Broken and Fallen to Earth Conductor Fault Condition in Power Systems

In power systems, analysis of critical faults, mainly, different types of simultaneous faults on transmission lines, is a sensitive issue. To identify the accurate fault place during a simultaneous fault condition, all major algorithms fail to provide the desired results. In this paper, an analysis of simultaneous faults called broken and fallen to earth conductor fault conditions is carried out. With the help of an equivalent sequence components network, generalized impedance equations are derived to determine the accurate fault place on the transmission line during the simultaneous broken and fallen to earth conductor’s fault condition. For authentication of the derived method, simulation has been done using MATLAB tool with two different medium transmission lines. Simulation outputs manifest the accuracy of the proposed generalized impedance equations by showing 98% accuracy for identifying precise fault places. The derived fault analysis method uses the sequential network formation technique, which can be easily understood by researchers.

Evaluating the electrostatic discharge risk between small radius objects and charged planar insulating materials

In some industrial situations such as web processes, charging of large planar insulating surfaces can give risk of electrostatic discharges that could ignite flammable process materials such as solvent vapours. Charging of the material has for some years been evaluated using electrostatic field measurements to estimate surface charge densities. In a planar system, the threshold risk of an electrostatic discharge has been equated with a surface charge density of about 25 μCm-2 required to produce a field strength exceeding about 3 MVm-1, the breakdown field strength of air. It is known that where a small radius earthed conducting object approaches a charged insulator, intensification of the field strength occurs at the surface of the object. Similarly, the field strength is increased by the presence of a field meter near the surface. This paper investigates the effect of field concentration by an object near the charged insulator and the conditions leading to electrostatic discharges using analysis, electrostatic field modelling and experiments. The results are applied to understanding and quantification of the effect on measurements and safety factor indicated for evaluation of electrostatic discharge risk introduced by the earthed conductor in this situation.Initiation of a discharge to a spherical measurement electrode requires that the field strength at the surface of the electrode exceeds the breakdown field strength and other factors. This occurs at different induced charge levels on the electrode for different electrode diameter. Discharges could occur with electrode-target gap around 10–20 mm at lower charge density than with smaller gaps. The threshold of discharges occurring was reached at lower charge density for a smaller 16.6 mm diameter electrode, which might be important when evaluating ignition risk for Group IIC flammable materials. Conversely higher charge transfer was confirmed with 25.4 mm electrode above the threshold for discharges occurring.

Method of the Earth Fault Location in Power Distribution Network Besed on Mearing Earth Conductor Current

The copper foil shielding layer and armoring layer of the three-core cable and the grounding electrode of the distribution network constitute the grounding network of the distribution network. When a grounding fault occurs in the power grid, a regular ground current distribution is formed in the grounding network. .This paper analyzes the distribution law of the ground wire current in the arc suppression coil and resistance grounded distribution network: for the distribution network with the neutral point through the arc suppression coil and resistance grounded, the active component of the ground wire current of all cable segments without ground faults is Pass-through, that is, the active components of the ground current at the head and end of the cable are equal in magnitude and in the same direction; the sum of the active components of the ground current at the head and end of the ground fault cable segment is equal to the active component of the fault current at the ground fault point. According to this distribution law, this paper proposes a ground fault location method in which the neutral point is grounded by the arc suppression coil and resistance grounded grid, and its effectiveness is verified by simulation.

Research on cylinder Flexible Graphite Earth Electrode (FGEE) used to reduce tower earth resistance✰

The excellent performance of earth electrodes is the key to stable and safe operation of transmission lines. However, corroded earth electrodes in practical cases can increase the tower earth resistance. In this paper new Flexible Graphite Earth Electrodes (FGEE) are introduced to address the corrosion problem and its new wrapping method is proposed to reduce the tower earth resistance. The proposed earth resistance reduction method is effective by theoretical analyses. Lots of simulation work is conducted to analyze the effect of factors on both single-pile and multi-pile tower earth resistance. Comparisons are conducted on five commonly used types of tower earth-electrode network, including sole tower foundation, tower foundation with ring earth conductor or FGEE, tower foundation with both ring earth conductor and FGEE, and tower foundation with ring earth conductor and horizontal radial electrode of 20 m on four directions.. Besides, grounding tests on scaled foundation earth electrodes are carried out to verify the validity of the proposed method. Simulation results show that the tower earth resistance is reduced by 15~60% in 500~3000 Ω•m soil. For single-pile tower foundation, the lower the wrapping position, the smaller the earth resistance, and the earth resistance is negatively related to the wrapping radius, while down lead wire connection types have little influence on earth resistance; besides, all the three factors above have impacts on current density. For multi-pile tower foundation, earth resistance is negatively related to the distance between two piles and separate wrapping is a preferred type of wrapping. Moreover, among the proposed five commonly used grounding types, Type V is preferred. Finally, scaled laboratory test results indicate that the cylinder FGEE can effectively reduce the tower earth resistance.

Effect on Human Body of the Magnetic Field Induced by the High Voltage Transmission Line

The quality of electrical energy and the fight against energy losses are a crucial issue for electricity companies. The use of high voltage lines can limit energy losses for the transmission of electricity over long distances. But this solution has the disadvantage of the propagation of the electromagnetic wave which has a great influence on human health. The work presented in this study mainly deals with modelling problems that may be encountered by the community working in the field of low frequency electromagnetic fields. In order to model a power line, we are based on geometric data as well as phase and earth conductor data.

Assessment of Electric Shock Hazard Coming From Earth Continuity Conductors in 110 kV Cable Lines

There has been a growing demand of electric power in many urban agglomerations. To address this demand, 110-kV power networks are regularly expanded inside and around cities in Poland. These power networks are often constructed as underground cable lines. The 110-kV cable lines are usually designed as three single-core cables laid in a common route. In case of long 110-kV cable lines, the cross-bonding method is applied to the connection of metal sheaths of these cables. Additionally, one or more earth continuity conductors are laid along the main cable line and earthed at both their ends. These earth continuity conductors can be uninsulated and can cause electric shock hazard (danger step voltages). The problem defined in this paper consists of an attempt to calculate the expected step voltages for different considered earth continuity conductor arrangements in 110-kV cable lines and to compare the obtained results to admissible values of the voltages found in an appropriate standard. Protection against electric shock, calculation of earthing resistance, and step voltages, as well as simulation studies in case of sample 110-kV cable lines have been described in the paper. The results show the analyzed layouts of 110-kV cable lines have significant impact on the values of voltages occurring in and around earth continuity conductors. The maximum values of earth electrode voltage (and in this way expected touch voltages), as well as step voltages occur in the layout of single cable line and single earth continuity conductor arranged in parallel.

Dynamics of the Velocity of Anodic Dissolution of the Material of Ferrosilide Anode Earth Conductors at Long Time Intervals

Dynamics of the Velocity of Anodic Dissolution of the Material of Ferrosilide Anode Earth Conductors at Long Time Intervals

Ensuring public safety through proper earthing in low-voltage networks

Electrical network should have proper earthing (grounding) system for its reliable operation and for the safety of operating personnel and connected customers. Good earthing provides a suitable return path for the fault current when a short circuit occurs in the network. In a low-voltage (LV) network mainly terra-terra (TT) and terra-neutral (TN) type network configurations are commonly used. Depending on the agreement between the network operator and the customer, earthing at a customer's point of connection (POC) is provided by a dedicated earth conductor, combined network cable (PEN conductor), or via a separate earth electrode. When an earth retour path is broken or interrupted, it will not be able to provide earth retour circuit and can cause dangerous fault voltage at various exposed parts of the conducting circuit. In this paper, various LV network configurations are discussed. Further, a practical monitoring based case study is presented to analyze the diversity of earth resistance values for different LV network configurations. Also, guiding rules are given to define safe value of circuit impedance and earth resistance path for various configurations. Finally, a proposal is given to optimize the safety needs at a customer's POC.

Energetics of disordered and ordered rare earth oxide-stabilized bismuth oxide ionic conductors

Rare-earth stabilized bismuth oxides are known for their excellent ionic conductivity at intermediate temperatures. However, previous studies have shown that their conductivity deteriorates during extended heat treatments at 500-600 °C, although the fluorite phase is maintained. In this study, the enthalpies of formation of quenched and aged ytterbia- and dysprosia-stabilized bismuth oxides were measured using high-temperature oxide melt solution calorimetry in 3Na2O-4MoO3 solvent at 702 °C. While a modest energy difference (-2 to -3 kJ mol(-1)) drives the kinetically slow aging transformation in the ytterbia-stabilized system at moderate dopant contents, no energetic driving force is detectable in the dysprosia-stabilized system. Although the small magnitude of the exothermic ordering energy suggests extensive short range ordering in both the quenched and aged samples, the anion configuration specific to the aged samples is nevertheless responsible for the significant decrease in conductivity.

Propagation of IG Current Underground Elucidated by Remanent Magnetization

SummaryIn our previous studies, we showed that the remanent magnetization of materials could be used to analyze lightning currents at ground level. In this study, using an IG (Impulse Generator) current as a model of lightning, we used remanent magnetization to investigate the underground propagation of IG currents. For this purpose, we dug a square hole with a side length of 80 cm and a depth of 13 cm and placed in it magnetic samples prepared using sea sand. After injecting an IG current of 530 A underground, the magnetization of these samples was measured.The directional distribution of magnetization was successfully used to analyze the circular magnetic field induced by the IG current and its transit point. Then the underground path of the IG current was determined to a depth of 12 cm. The current path was inclined by approximately 9° from the vertical direction, which may be attributed to a ground conductor being located east of the experimental area. To relate the magnetization intensity and the distance from the IG current, an inverse square relation was applied outside the area close to the transit point of the current.From the results obtained in this study, we conclude that the method using the remanent magnetization is useful for elucidating the polarity, intensity, and path of both IG and lightning currents underground. Further, the method of using remanent magnetization as a record of lightning currents may contribute to the development of an effective earth conductor for limiting damage caused by lightning. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 1–8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22484

Development of single point feed circularly polarized coplanar antenna

AbstractA single point fed circularly polarized coplanar antenna is proposed. The antenna consists of a rectangular slot loop of 1λ (wavelength) and the earth conductor. The antenna has orthogonal surface currents and appropriate phase differences suitable to generate circularly polarized waves. The antenna design method is studied and the design parameter table is obtained for several applications. Antenna performance was measured and examined with numerical simulation results. Finally, an application for XMSR was examined with a car body model. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 96(1): 33–42, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11425

TN-C-S계통에서 PEN도체 단선이 인체안전에 미치는 영향

In electric power supply systems, an earthing system determines the electric potential of the conductors related to that of the Earth`s surface. The choice of earthing system has implications for the safety of the power supply systems. There are considerably different regulations for earthing (grounding) systems in each country. A protective earth(PE) conductor ensures that all exposed conductive surfaces are at the same electric potential as the earth surface. This paper deals with that when PEN conductor of TN-C-S system is disconnected, dangerous touch voltage causes personnel body to be harmed and human being`s property to be damaged seriously. For this reason, this paper explains how serious problems can occur when the fault current flows. As a consequence, we can understand how we can design earthing system properly to ensure the personnel safety against earth faults. The result shows the way that TN-C-S system can be applied safely in Korea.

Optimal cable assembly for reducing conducted electromagnetic interference in the traction system

The present work deals with a method of modelling a traction system in PSpice with the consideration for optimal cable arrangements for reducing conducted electromagnetic interference. Multiconductor transmission line (MTL) theory is adopted to model the cable which connects the pulse-width modulation (PWM) source inverter and the motor. A simple decoupling transformation method is proposed and used to transform the MTL into several single transmission line, which can be easily modelled in PSpice. The PWM controlled voltage source and induction motor are also included in this model. Thus, the full model for a traction system is realised in PSpice. From system simulation, the voltage oscillation in the cable is observed and the conducted electromagnetic noise in the system is studied. The relationship between the frequency of the noise and the length of feeding cables are also demonstrated in this work. In order to mitigate the high-frequency noise, a cable system with a fourth parallel earth conductor is proposed and the noise level is indeed reduced by this technique. This modelling procedure for traction system can be used for any specific application like the electrified railway traction system.

A new transmission system using the Protective Earth conductor for Narrow-Band PLC

A new transmission system using the Protective Earth conductor for Narrow-Band PLC

Propagation of IG Current Underground Elucidated by Remanent Magnetization

Summary In our previous studies, we showed that the remanent magnetization of materials could be used to analyze lightning currents at ground level. In this study, using an IG (Impulse Generator) current as a model of lightning, we used remanent magnetization to investigate the underground propagation of IG currents. For this purpose, we dug a square hole with a side length of 80 cm and a depth of 13 cm and placed in it magnetic samples prepared using sea sand. After injecting an IG current of 530 A underground, the magnetization of these samples was measured. The directional distribution of magnetization was successfully used to analyze the circular magnetic field induced by the IG current and its transit point. Then the underground path of the IG current was determined to a depth of 12 cm. The current path was inclined by approximately 9° from the vertical direction, which may be attributed to a ground conductor being located east of the experimental area. To relate the magnetization intensity and the distance from the IG current, an inverse square relation was applied outside the area close to the transit point of the current. From the results obtained in this study, we conclude that the method using the remanent magnetization is useful for elucidating the polarity, intensity, and path of both IG and lightning currents underground. Further, the method of using remanent magnetization as a record of lightning currents may contribute to the development of an effective earth conductor for limiting damage caused by lightning. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 185(4): 1–8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22484

Physical Interpretation of Impedance Formulas for Conductors Enclosed in a Cylindrical Tunnel

Based on a comparison of earth models and conductor impedance equations, a physical interpretation of the self and mutual impedance for conductors enclosed in a cylindrical tunnel with peripherally infinite homogeneous earth is put forward. The inherent relations between Carson's formulas and Tylavsky's formulas are revealed through a rigorous mathematical justification. A new concept of complex radius, which is similar with the complex depth, is introduced to explain the simplified approximate impedance expressions.

Development of Single Point Feed Circularly Polarized Coplanar Antenna

A single point feeded circularly polarized coplanar antenna is proposed. The antenna shape composes rectangular slot loop antenna of 1λ (Wavelength) and the earth conductor. The antenna shows orthogonal surface currents and appropriate phase difference to generate the circular polarization wave. Antenna design method is studied and the design parameters table is obtained for several applications. Moreover, antenna performance are measured and examined with the numerical simulation results. Finally, the application for XMSR was examined with the car body model.