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The widespread integration of high-speed trains has significantly enhanced the quality of human life. However, the intricate electromagnetic environment within carriages has raised notable concerns, especially for passengers with pacemakers. This work assessed the electromagnetic exposure of three-chamber pacemaker wearers with standed and seated posture by a traction transformer and its cable system. The analysis included evaluating the distribution of induced electromagnetic fields within passengers’ pacemakers and heart tissue, calculating the induced voltage on electrodes to determine the potential health risks. The results indicated that the B $_{in~max}$ , E $_{in~max}$ of the passengers’ heart tissue are $7.53~\mu $ T and 47.626 mV/m. All the B $_{in~max}$ , E $_{in~max}$ well within the basic limits established for public electromagnetic exposure set by the International Commission on Non-Ionizing Radiation. The Ein on the pacemakers of both passengers mainly appeared at the metal parts, and the B $_{in~max}$ of passengers’ pacemakers is $20.754~\mu $ T, which achieves the minimum requirements for pacemakers to anti-electromagnetic interference as specified by the International Organization for Standardization. The $U_{in~max}$ at the unipolar and bipolar electrodes of passengers are 0.409 mV and 0.005 mV, which are smaller than the perception sensitivity. The above results illustrated that the electromagnetic fields generated by the traction transformer are within the recognized accepted limits for passengers with pacemaker, and we recommended that individuals with heart diseases should try to choose a pacemaker with better anti-interference ability in bipolar pacing mode and keep a distance from windows as possible when riding on high-speed trains.

Whether for the estimation of circulating current in the parallel circuits of the stator winding, damper current in the rotor of a synchronous machine, or voltage oscillation in the stator winding, an exact calculation of induced voltage is always inevitable. However, even when using FEM software, this voltage estimation is a post-process calculation based on pre-calculated flux densities or vector potentials. Since the air gap flux density is the primer parameter used in analytical estimations, it is therefore desirable to have a general and programmable method for calculating induced voltages regardless of their origin based on the air gap flux density. The rotating Tensor and its projection function offer a suitable alternative for these kinds of estimations. In this paper, the projection function is used to present a general method of estimating induced voltage in rotating machines with different winding topologies. This has been done for integer and fractional multi-layer windings in different machines, as well as the damper bars in the rotor. The results are compared to FEM calculation.

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Copyright of Electric Drive for Locomotives is the property of Electric Drive for Locomotives Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The induced voltage pulsation in DC winding can generate various issues in five phase wound field flux switching (WFFS) machine such as DC current ripples, unsteady field excitation, deteriorates the DC power source and challenges for control performance of machine. In this paper, the simplest five phase WFFS machine having the 5 stator slots with 7, 6, 4 and 3 rotor poles are analyzed and investigated for open circuit DC winding induced voltage. The phenomena of the DC winding induced voltage is briefly analyzed and explained. Three reduction techniques i.e., rotor pole chamfering, rotor pole arc optimization and rotor pole axial pairing, are investigated and optimized to reduce the open circuit DC winding induced voltage and cogging torque for WFFS machine while the average electromagnetic torque is kept greater than 90% of its initial value. The Finite Element (FE) results show that the reduction achieved in peak-to-peak value of open circuit DC winding induced voltage is 70.84%, 73.65%, 70.13%, and 63.42% as compared to its initial values by performing the rotor pole chamfering for the five phase WFFS machine having the 7, 6, 4, and 3 pole rotors, respectively. For rotor pole arc optimization, DC winding induced voltage peak to peak value is effectively reduced to 60.18%, 74.91%, 64.74%, and 64.10% for the 7, 6, 4, and 3 rotor-poles machines, respectively, while its reduction for axially paired rotors is 42.70%, 68.05%, 68.64%, and 56.09%, respectively. The 5-stator-pole/6-rotor-pole five phase non-overlapped WFFS machine with the initial rotor, chamfered rotor, optimized rotor, and axially paired rotor are prototyped to validate the FE results.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] This paper carries out an experimental study on the coupling response characteristics of the internal cables of a metal mast when struck by lightning. [Method] A lightning induction coupling test platform is built for the cable system inside the mast. The induced voltages of the coaxial cables, two-core single shielded cables and multi-core double shielded cables are measured under four kinds of termination load characteristics (open circuit at both ends of core wire; end of core wire near to the ground connected to the load; end of core wire far from the ground connected to the load; and both ends of core wire connected to the load). From the perspective of time domain and frequency domain, an analysis is made of the influence of load characteristics on the induced voltage and shielding effects. [Results] The induced voltage of the cable reaches its maximum value when the far ground terminal is grounded by the load. When the near ground terminal is grounded by the load, the main frequency band of the induced voltage frequency response exceeds the lightning current, whereas they are similar under other load characteristics. Grounding the inner shielding layer can reduce the peak value of the induced voltage, but does not affect the main frequency band of the frequency response. The voltage peak value is most significantly reduced when both ends of the core wire are open-circuited or when the end of the core wire far from the ground is connected to the load (approximately 59.3% and 77.2% of the value when the inner shielding layer is ungrounded). In addition, the induced voltage peaks of the three types of cables exhibit considerable differences. However, the rise time and half-peak time of the induced voltage for each cable show insignificant differences. [Conclusion] This study reveals the influence of terminal load characteristics on cable coupling induced voltage when lightning strikes the metal mast of a ship, as well as providing basic data support for the subsequent calculation of the coupling effect.

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The harmonics and resonance of traction power supply systems (TPSSs) aggravate the electromagnetic interference (EMI) to adjacent metallic pipelines (MPs), which has aroused widespread concern. In this paper, an evaluation method on pipeline interference voltage under harmonic induction is presented. The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies. Then, an integrated train–network–pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP. It is revealed that the higher the harmonic current distortion rate of the traction load, the larger the interference voltage on an MP. Particularly, the interference voltage is amplified up to 7 times when the TPSS resonates, which is worthy of attention. In addition, the parameters that affect the variation and sensitivity of the interference voltage are studied, namely, the pipeline coating material, locomotive position, and soil resistivity, indicating that soil resistivity and 3PE (3-layer polyethylene) anticorrosive coating are more sensitive to harmonic induction. Field test results show that the harmonic distortion can make the interference voltage more serious, and the protective measures are optimized. [ABSTRACT FROM AUTHOR]

In 1873, J.C. Maxwell derived relations for current density and current in a solitary long cylindrical conductor supplied with variable current. According to Maxwell, the current density in a conductor increases towards the conductor surface. This phenomenon is called the skin effect. The skin effect affects in particular the inductance of a line formed by one or several long parallel conductors. A number of papers have been published regarding the skin effect and its effect on inductance. Another phenomenon, closely related to the skin effect, is the proximity effect, which refers to the dependence of the current density in a conductor on the proximity of other conductors through which a time-variable current is flowing. Many published papers deal with the calculation of current density in two conductors, using the method for calculating current density in a solitary conductor. All the phenomena given above can be analysed and quantitatively described based on the knowledge of current density in conductors, and therefore the method for calculating current density in a group of conductors is of fundamental significance. It follows from the analysis performed that the skin effect is not a general characteristic of current density in long conductors, except for in the solitary conductor. This conclusion affects the knowledge of the phenomena associated with the skin effect. [ABSTRACT FROM AUTHOR]

An analytical model of an E-core driverpickup coils probe located above a multilayer conductor containing a hidden cylindrical conductor is presented. The truncated region eigenfunction expansion (TREE) method is used to deal with the axial symmetry problem, and the closed-form final expression of the induced voltage in the pickup coil is derived. The changes of the induced voltage in the pickup coil due to the hidden cylindrical conductor are examined and calculated in Mathematica. Experiments and finite element simulations are performed and the results are compared with the analytical results, and they are in good agreement. [ABSTRACT FROM AUTHOR]

Abstract The harmonics and resonance of traction power supply systems (TPSSs) aggravate the electromagnetic interference (EMI) to adjacent metallic pipelines (MPs), which has aroused widespread concern. In this paper, an evaluation method on pipeline interference voltage under harmonic induction is presented. The results show that the Carson integral formula is more accurate in calculating the mutual impedance at higher frequencies. Then, an integrated train–network–pipeline model is established to estimate the influences of harmonic distortion and resonance on an MP. It is revealed that the higher the harmonic current distortion rate of the traction load, the larger the interference voltage on an MP. Particularly, the interference voltage is amplified up to 7 times when the TPSS resonates, which is worthy of attention. In addition, the parameters that affect the variation and sensitivity of the interference voltage are studied, namely, the pipeline coating material, locomotive position, and soil resistivity, indicating that soil resistivity and 3PE (3-layer polyethylene) anticorrosive coating are more sensitive to harmonic induction. Field test results show that the harmonic distortion can make the interference voltage more serious, and the protective measures are optimized.

A new type of energized diagnostic technique aimed at defects in the cross-bonded grounding system of power cables is proposed. Based on the equivalent model of a normal cross-bonded grounding unit, the equivalent models of 23 common cross-bonded defects were analyzed in depth, and a general matrix calculation model was summarized to provide the possibility of programming calculations. The programs were then written in Java for both a normal cross-bonded grounding unit and defective cross-bonded grounding units to form a software that can realize an energized diagnosis of defects in the cross-bonded grounding system of the transmission cable system. The software was applied to a 220 kV cable line with some defects in its cross-bonded grounding system for energized diagnosis, and the diagnostic result was consistent with the actual defect. It took only half an hour to remove the defects after the power failure. It was proven that the software can accurately diagnose defects in cross-bonded grounding system with shorter outage time and higher power supply reliability.

Accurate tracking involuntary head movements is fairly a challenging problem in MR imaging of the brain. Though there are few techniques available to monitor the head movement of the subject for a prospective motion correction, it is still an unsolved problem in MRI. In this theoretical study, we aim to describe an analytical investigation to track head movement inside an MR scanner by calculating the change in induced voltage in the head-mounted coils during the execution of time-varying gradients. We derive an expression to calculate the change in induced voltage in a coil placed in a time-varying gradient. We also derive a general equation to investigate the changes in the induced voltage in a set of coils mounted onto the head for the planar position and orientation of the coils. Each coil is considered as a magnetic dipole with location and sensitivity vectors. The changes of the vectors can track the head movement in the MR scanner by measuring the changes in the induced voltage in the coils. The dipole concept is valid for a wide range of coils. The changes in induced voltage in the coils are linear due to small changes in pose of the head. Movement parameters are estimated from the induced voltage changes. If the random noise voltage is less than 100 μ V, it does not significantly affect movement parameters because the change in induced voltage in the coils dominates over the small noise voltage. This method and array of the coils may provide a real-life solution to the long-standing problem of head motion during MRI. [ABSTRACT FROM AUTHOR]

Copyright of Electric Power is the property of Electric Power Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The electromagnetic and output performance characteristics of three (3) different types of double stator permanent magnet machines are quantitatively compared and presented in this study, in order to determine the most promising machine topology amongst the considered machine types, for potential practical applications(s). Two-dimensional (2D) and three-dimensional (3D) finite element analysis (FEA) methods are deployed in the computation of the performance metrics using ANSYS-MAXWELL software. The compared machines in this work are designated as: Machine 1, Machine 2 and Machine 3, respectively. The investigated machines have varying structural arrangements and two separate excitation sources. Machine 1 has its magnets situated in the outer stator with corresponding armature windings on both inner and outer stators. The magnets of Machine 2 are located in its inner stator while it has armature windings on both inner and outer stator parts. More so, Machine 3 is equipped with magnets in its inner and outer stators, though without armature windings on the inner stator section. The considered performance metrics include: inducedelectromotive force (induced-EMF), torque, power, demagnetization, losses and efficiency. The results show that the investigated Machine 3 has higher induced-EMF value and more sinusoidal electromotive force waveform than the other compared machines. Consequently, Machine 3 also has larger electromagnetic torque and power. Moreover, Machine 1 has the best flux-weakening potential, obtained from both the ratio of its maximum speed to base speed and the flux-weakening factor ( kp).

It urgently demands wellside remote and well advance detection technique in petroleum exploration and metallic minerals prospecting, as well as underground space detection. Combining the theory of three-component induction logging and transient electromagnetic field, a time domain electromagnetic tensor logging method was proposed. Based on the solution of the 9 components of alternating magnetic field in 3D induction logging, a transmission line algorithm was adopted to fastly solve Dyadic Green’s function. Hence, the theoretical formula was obtained for time domain electromagnetic tensor field by converting magnetic tensors into time domain. The attenuation versus time for all of the induced voltage components was analyzed by making use of a three-layered medium with a deviated well, and the tensor electromagnetic response characteristics of the target layer was obtained. Eventually, the effect of time domain electromagnetic tensor measurement was testified on the basis of downhole transient electromagnetic data. The results show that the attenuation curves for xz, yz, zx and zy components of induced voltage tensor have an electromagnetic feature excited by a vertical magnetic dipole, while the rest of components meet with the feature excited by a horizontal magnetic dipole; the voltage components related to z component can be used as preferred parameters for their significant resolution to the electrical interface of strata, while the others can be considered as auxiliary parameters; the low resistivity target layer can be clearly identified in the multi-channel curves and induced voltage tensor time sections, which provide an effective tool for the measured data processing and interpretation. [ABSTRACT FROM AUTHOR]

The induced voltage and current were measured while changing the contact resistance of gloves and the resistance between the shoes and ground, respectively, to evaluate the human impact of the voltage induced by overhead power lines. The major parameters were extracted using a formula, and the results were compared using a simulation tool. When exposed to an electric field of 4kV/m, an induced voltage between the human body and the ground of approximately 600 V was generated. The maximum value and duration of the discharge current varied according to the change in the gloves and shoe resistance. In addition, the induced voltage-reduction effect through the shielding wire was also confirmed. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The calculation method of ground synthetic field intensity at different altitudes is presented. With the increase in altitude, the ground synthetic field strength gradually increases, leading to a corresponding increase in the relative voltage between the human body and the metal greenhouse under the power line. • A transient electric shock dynamic simulation method that takes into account altitude is proposed in this study. The formula for electron ionization and adhesion coefficient, which varies with altitude, is obtained through fitting. It is found that under the same contact gap distance, the electric field intensity and streamer radius of the discharge gap increase with higher altitudes. Additionally, the average streamer speed also significantly increases at higher altitudes, resulting in a faster shock to the human body. • The higher the altitude, the greater the transient electric shock current that flows through the human body via the metal greenhouse and the contact gap beneath the UHVDC transmission line. This results in a larger amount of transient electric shock energy being received by the human body, leading to a stronger sensation of electric shock and causing serious pain. However, it is important to note that this level of pain is still far from causing death to the human body. Aiming at the issue that existing research methods for human transient electric shock do not take into account the altitude factor, resulting in deviations in transient electric shock calculations at high altitudes, a dynamic simulation method of the electric shock process considering actual environmental factors is proposed. The study investigates the characteristics of line-induced voltage at different altitudes. Based on this, a dynamic model of the electric shock process is established and the formula for model parameters is fitted with altitude. This allows for analysis of streamer propagation characteristics and transient electric shock current at different altitudes. The effectiveness of this method is verified by comparing it to existing experiments. Finally, an evaluation of human transient electric shock at different altitudes is conducted. Previous studies have identified metal greenhouses as the primary sites of transient electric shock phenomena under UHVDC lines, and these structures have been utilized as the focus of research. The research reveals that as altitude increases, there is an increase in relative voltage between the human body and metal greenhouse, reaching 3261.3 V at an altitude of 4000 m; however, this relative voltage growth decreases with higher altitudes. The electron ionization coefficient increases rapidly while the adhesion coefficient increases slowly with elevation. Under a constant contact gap distance, there is faster reception of electric shock by the human body with increasing altitude. Additionally, there is a larger amount of transient electric shock energy received by the human body; its maximum value being 5.358 mJ - although this is far less than the human death threshold of 25 J and will not cause death to humans. [ABSTRACT FROM AUTHOR]

In recent years, many accidents occurred in the operation of pipe corridors at home and abroad. Especially with the entrance of power cables, gas and thermal pipelines, the risk factors of the pipe corridors were greatly increased. Pipeline damage and operators suffered injuries and deaths caused by electromagnetic interference of the pipeline in the corridor were the most important safety hazards for the safe operation of urban underground comprehensive corridors. In order to find out the influencing factors and laws of electromagnetic interference of high voltage transmission lines in the pipe corridor, and to provide technical support for the construction of corridors, the professional analysis software CDEGS was used to simulate the influence of the high voltage transmission lines in the corridor on the electromagnetic interference of the pipeline in the corridor. Results showed that the induced voltage and induced current on the pipeline increased with the increase of high voltage line voltage and soil resistivity, and firstly decreased rapidly and then slowly decreased with the increase of the distance between the pipeline and the high voltage line. The pipeline specifications had little effect on the induced voltage and induced current. As the resistivity of anti-corrosion layer increased, the induced voltage first increased and then tended to be stable, whereas the induced current decreased first and then tended to be stable.

In this paper, the effect of rotating magnetic fields on hydrogen generation from water electrolysis is analyzed, aiming to provide a research reference for hydrogen production and improving hydrogen production efficiency. The electrolytic environment is formed by alkaline solutions and special electrolytic cells. The two electrolytic cells are connected to each other in the form of several pipes. The ring magnets are used to surround the pipes and rotate the magnets so that the pipes move relative to the magnets within the ring magnetic field area. Experimentally, the electrolysis reaction of an alkaline solution was studied by using a rotating magnetic field, and the effect of magnetic field rotation speed on the electrolysis reaction was analyzed using detected voltage data. The experimental phenomenon showed that the faster the rotation speed of the rotating magnetic field, the faster the production speed of hydrogen gas. [ABSTRACT FROM AUTHOR]

In cable fire test,a fire source is essential for the fire performance evaluation. Most of the existing fire sources for power cable are based on chemical fuel,which is unable to represent the cable fire caused by fault arc. Therefore,to simulate the ignition of power cable by fault arc,a fire source based on electrical arc is developed in this work. Firstly,the induced voltage on the metal armor layer is theoretically analyzed when the 110 kV cable has the ground wire stolen or the cross interconnection wires on both sides are stolen. Voltages can reach thousands of volts. Secondly,the pre-breakdown voltage and sustained voltage of the metal-to-ground arc in power cable and the Jacob's Ladder arc are compared. It is found that the breakdown characteristics of both arcs are similar for applied ac voltage with frequencies of 50 Hz and 20 kHz. Thirdly,a fire source based on Jacob's Ladder arc is proposed for the ignition of power cables. Experimental results show that the 110 kV cable can be successfully ignited by this fire source,and the flame is able to spread both vertically and horizontally. Finally,the conclusion is that the high frequency Jacob's Ladder arc can simulate the characteristics of the fault arc and effectively ignite the 110 kV cable.

In 1873, J.C. Maxwell derived relations for current density and current in a solitary long cylindrical conductor supplied with variable current. According to Maxwell, the current density in a conductor increases towards the conductor surface. This phenomenon is called the skin effect. The skin effect affects in particular the inductance of a line formed by one or several long parallel conductors. A number of papers have been published regarding the skin effect and its effect on inductance. Another phenomenon, closely related to the skin effect, is the proximity effect, which refers to the dependence of the current density in a conductor on the proximity of other conductors through which a time-variable current is flowing. Many published papers deal with the calculation of current density in two conductors, using the method for calculating current density in a solitary conductor. All the phenomena given above can be analysed and quantitatively described based on the knowledge of current density in conductors, and therefore the method for calculating current density in a group of conductors is of fundamental significance. It follows from the analysis performed that the skin effect is not a general characteristic of current density in long conductors, except for in the solitary conductor. This conclusion affects the knowledge of the phenomena associated with the skin effect.

Imaging of magnetic nanoparticles with ultrasound utilizes ultrasound excitation and electromagnetic receiving. At present, the size of magnetic nanoparticles (MNPs) for the imaging method is required to be no less than 100 nm, which limits its application in human bodies. To overcome the limitation of particle size, imaging of MNPs with ultrasound based on saturation magnetization is proposed. The relationship between the concentration of superparamagnetic pear-shaped MNPs and the induced voltage under saturation magnetization is derived based on the classical Langevin theory of paramagnetism. A 3D simulation model is constructed and numerical research is carried out under the saturated magnetic field provided by the Helmholtz coil. The concentration image is reconstructed by point-by-point scanning. Numerical studies show that the induced voltage is rich in the concentration information of superparamagnetic pear-shaped MNPs, proving the feasibility of the method. The maximum induced voltage, which enhances the imaging effect, occurs under the minimum radius of the detection coil containing the region of interest. MNPs under 20 nm still meet the imaging requirements in the proposed method. This research pushes the imaging of MNPs with ultrasound based on saturation magnetization a further step forward to practical applications in the biomedical field. [ABSTRACT FROM AUTHOR]

The field-to-line coupling problem of the transmission line (TL) excited by external fields can be analyzed by adopting the electromagnetic (EM) reciprocity theorem. In this article, according to the frequency-domain expression of the test current along the line in the case of the TL is terminated by the mismatched loads, the time-domain formula, consisting of the original excitation, and multiple reflected waves caused by the loads, is derived. Furthermore, the analytical expression of the induced voltage is obtained based on the EM-reciprocity theorem. The correctness of the proposed method is verified by the numerical results generated by utilizing full-wave method. [ABSTRACT FROM AUTHOR]

The electromagnetic and output performance characteristics of three (3) different types of double stator permanent magnet machines are quantitatively compared and presented in this study, in order to determine the most promising machine topology amongst the considered machine types, for potential practical applications(s). Two-dimensional (2D) and three-dimensional (3D) finite element analysis (FEA) methods are deployed in the computation of the performance metrics using ANSYS-MAXWELL software. The compared machines in this work are designated as: Machine 1, Machine 2 and Machine 3, respectively. The investigated machines have varying structural arrangements and two separate excitation sources. Machine 1 has its magnets situated in the outer stator with corresponding armature windings on both inner and outer stators. The magnets of Machine 2 are located in its inner stator while it has armature windings on both inner and outer stator parts. More so, Machine 3 is equipped with magnets in its inner and outer stators, though without armature windings on the inner stator section. The considered performance metrics include: induce-delectromotive force (induced-EMF), torque, power, demagnetization, losses and efficiency. The results show that the investigated Machine 3 has higher induced-EMF value and more sinusoidal electromotive force waveform than the other compared machines. Consequently, Machine 3 also has larger electromagnetic torque and power. Moreover, Machine 1 has the best flux-weakening potential, obtained from both the ratio of its maximum speed to base speed and the flux-weakening factor (kp). [ABSTRACT FROM AUTHOR]

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the development of 1000 kV UHV transmission technology and the shortage of line corridor resources, UHV will inevitably cross the building area. Although many scholars had studied the power frequency electromagnetic field under UHV AC transmission line, it is very difficult to accurately calculate the electric field strength and induced voltage, which cannot be applied in engineering. At present, there is no relevant literature to study the problem of induced electricity in buildings with a large number of steel frame structures under the line and the estimation method of induced electricity in buildings. By summarizing and analyzing the simulation data, the estimation method of induced voltage and induced current density of steel frame buildings under UHV lines was proposed. An auxiliary calculation system was developed. The calculated values of the software were compared with the measured values, which accuracy of voltage and current can reach 91.5% and 92.7%, and fully meet the engineering needs.

When lightning strikes an apartment building, transient voltages are generated or induced in electrical and telecommunication wires in the building. The transient voltages may cause malfunctions or failures of electronic or telecommunication appliances. Therefore, it is necessary to know the spatial distribution of voltage, generated by typical lightning, in the building. Although there are several works studying lightning‐generated voltages in buildings, they do not consider the presence of concrete that accommodates steel structures. In this paper, lightning‐induced voltages between wires in a simplified apartment building struck by lightning are computed using the finite‐difference time‐domain (FDTD) method, taking into account the presence of reinforced concrete. On the basis of the computed results, the effect of the presence of concrete is discussed. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In this paper, impact of the causality of frequency-dependent models of soil on the effective area of grounding grids buried in single and two-layer soils is studied. In the analyses, the computationally efficient multi-conductor transmission line method is used. The simulation results show that the causality plays an important role on the effective area so that it can decrease or increase the effective area in comparison with the non-causal model. This reduction or increase depends on the low-frequency resistivity of dispersive soil and current waveform. The relative error due to non-causality is considerable only for the subsequent stroke current, whereas for the first stroke current, it is low enough to be ignored. In addition, the burial depth effect on the effective area in causal and non-causal-dispersive soils is investigated. With the aim of more accurate design, comprehensively predicting formulae for effective area versus low-frequency resistivity of soil, burial depth and current waveform under causal assumption are proposed. Finally, importance of effective area based on causal and non-causal models on the lightning-induced voltage on the soil surface is investigated. [ABSTRACT FROM AUTHOR]

The metal shield and metal armor layers of single-core cables on high-speed railroad power penetration lines are usually grounded by common equipment protectors. This grounding method brings a continuous circulating current between the metal shield and metal armor layer compared to the subequipment protection grounding. In order to quantitatively study the circulating current condition of the through line and its influence on the reliability of the railroad power through line, the induced electric potential and circulating current generation mechanism of the single-core cable of the through line and its influencing factors were firstly analyzed in depth. Then, based on the cross-sectional structure of the single-core cable and the location of the traction network and cable in the roadbed section, a traction power supply model was established and simulated for the interlayer-induced potentials and circulating currents due to the two grounding protection methods under no load, single train operation, and heavy load four-train operation of the line. Finally, three actual sections of the Shanghai–Kunming and Nan–Kunming high-speed railroads in China were selected to collect and analyze the loop flow data with no load and with vehicles passing through, and finally the loop flow law of single-core cable for railroad electric through traffic was derived. The analysis shows that when the metal sheath of a single-core cable is grounded by ordinary equipment, the circulating current generated does not exceed 1% of the core current, which meets the relevant safety standards, but the induced voltage in the case of large loads will exceed 50 V safety voltage. [ABSTRACT FROM AUTHOR]

This paper investigates a linear generator (LIG) for application in high speed maglev train. Its configuration and working principle are introduced in detail. The mathematic models of magnetic field and induced voltage are established by the equivalent magnetic circuit method and the law of electromagnetic induction respectively, through which the characteristics of LIG and impact factors are analyzed preliminarily. An analytical and numerical method is proposed to analyze the characteristics of LIG further, in which the finite element model is applied to calculate the magnetic field accurately and the analytical model is used for the induced voltage calculation in a discrete way. The relationships of induced voltage amplitude and speed, induced voltage frequency and speed are clarified, providing the basis for the design of power supply system on vehicle. Finally, the experiments for the magnetic field and induced voltage are carried out on the performance test bench of magnet and real vehicle respectively to validate the analysis results.

An analytical model of a driver-pickup coil probe, consists of a cylindrical ferrite core, located above a layered conductor is presented. The truncated region eigenfunction expansion (TREE) method is used and the solution region is truncated with a certain radius around z axis. First, the magnetic vector potential of each region of filamentary coil problem is derived and solved with variables separation method using boundary and interface conditions, and then the rectangular cross-section coil problem is solved with superposition method. The expression of induced voltage in pickup coil is obtained and can be calculated with software such as Matlab or Mathematica. Using the proposed analytical model, the influence of the excitation frequency and excitation current in the driver coil on the responses of the pickup coil is examined. Experiments are performed, and the changes of voltage induced in the pickup coil due to the conductor are measured at different excitation frequencies and excitation currents. The analytical calculation results agree with the experimental results very well, verifying the correctness of the proposed analytical model. [ABSTRACT FROM AUTHOR]

This paper deals with the method of shaping the magnetic field distribution in the air gap of a synchronous machine. The main goal is to obtain a specific distribution of the magnetic field in the machine's air gap to enable easier powering, to increase the torque and power density, or to limit the content of higher harmonics in the induced voltage and torque. This method can be applied for both the electrically excited machines and permanent magnets excited machines. The problem has been reduced to solving a modified system of algebraic equations obtained by the finite element method. The presented examples show the effectiveness of the proposed method both in shaping the contours of the air gap and the magnetization of permanent magnets placed on the rotor. The method can particularly be used in the design of the high-speed synchronous machines. [ABSTRACT FROM AUTHOR]

This work presents the results of research on the influence of strong external electromagnetic fields on the operation of JED spark caps activated by transformer systems. The tests were carried out in order to determine the conditions of safe use of JED caps installed in control systems of generators producing electric current pulses using the principle of an explosive magnetic field cumulation [1]. For this purpose, the measurements of the voltages induced in the transformer JED spark cap actuation system were performed using sinusoidal external current with an amplitude of 10 kA for a period of 15 microseconds. This current flowed at a distance from d = 10 mm to d = 40 mm from the axis of the ferrite cores of the applied transformers: a closed core with an outer diameter of 20 mm, an inner diameter of 10 mm and a height of 10 mm and an open core with a diameter of 6 mm and a length of 25 mm. The transformers used in Air Force Institute of Technology (AFIT) were placed alternately parallel and perpendicular to the axis of the current conductor. In the case of a transformer with a cylindrical open core perpendicular to the current axis, the induced voltages significantly exceeded the values at which the caps were activated (about 2 kV) and became lower than these values at d of about 40 mm. Toroidal closed cores provided induced voltages of up to 200 V (10 times lower) for all configurations tested. The measurements were performed using a system and methods developed at AFIT.