Electric Field Emissions Research Articles

Reduction of Electric and Magnetic Field Emissions caused by Overhead Power Lines

Calculations and measurements of magnetic and electric fields of overhead power lines existing in Slovenia show that electromagnetic field emissions on the border of overhead power line right of way could be too high. The allowed electromagnetic field emissions defined by Slovenian government in 1996 are very strict especially for newly constructed overhead lines. For that reason some modification should be applied for newly constructed overhead lines. This paper proposed a few solution of aforementioned problem regarding arrangements of overhead power line conductor.

Reduction of the Environmental Impact of Electric Field Generated by High Voltage Power Transmission Lines

The growing interest in the negative environmental impact of overhead power lines of high and extra-high voltage stems from the increasing ecological awareness of societies. Consequently, a number of respective legal restrictions have been issued and actions have been undertaken to reduce this impact, especially in the electric field of the power frequency. The aim of this paper is to analyze the possibilities of reducing the width of electric field influence zones by changing the design parameters of power lines and defining the spatial distribution of its conductors. This analysis was carried out using the developed and experimentally verified models for determining the electric field and audible noise in the power line environment. The computational models were used to analyze the width of the electric field influence zones of 400 kV lines and the noise levels at the borders of these zones. The research focused on single and double circuit 400 kV power lines. It was revealed that a reduction in electric field emissions is accompanied by an increase in noise emission. However, the analyses confirmed that the width of the electric field influence zones can be significantly reduced if the most important design and construction parameters of the line are properly selected. The obtained conclusions are valid not only for 400 kV lines, but also set directions to follow when changing the parameters of high voltage transmission lines of other rated voltages (above 100 kV).

Anomalous subsurface VLF electric field emissions related to Nepal earthquakes (M = 7.8, M = 7.3), and their generation and propagation mechanisms

Anomalous subsurface VLF electric field emissions related to Nepal earthquakes (M = 7.8, M = 7.3), and their generation and propagation mechanisms

Electric field measurements at the plasma frequency around comet 67P by RPC-MIP on board Rosetta

Context. The Mutual Impedance Probe (RPC-MIP) carried by the Rosetta spacecraft monitored both the plasma density and the electric field in the close environment of comet 67P/Churyumov–Gerasimenko (67P), as the instrument was operating alternatively in two main modes: active and passive. The active mode is used primarily to perform plasma density measurements, while the passive mode enables the instrument to work as a wave analyzer. Aims. We are reporting electric field emissions at the plasma frequency near comet 67P observed by RPC-MIP passive mode. The electric field emissions are related to Langmuir waves within the cometary ionized environment. In addition, this study gives feedback on the density measurement capability of RPC-MIP in the presence of cold electrons. Methods. We studied the occurrence rate of the electric field emissions as well as their dependence on solar wind structures like stream interaction regions (SIRs) and coronal mass ejections (CMEs). Results. We are showing that strong electric field emissions at the plasma frequency near 67P were present sporadically throughout the period when Rosetta was escorting the comet, without being continuous, as the occurrence rate is reported to be of about 1% of all the measured RPC-MIP passive spectra showing strong electric field emissions. The Langmuir wave activity monitored by RPC-MIP showed measurable enhancements during SIR or CME interactions and near perihelion. Conclusions. According to our results, Langmuir waves are a common feature at 67P during the passage of SIRs. Comparing the plasma frequency given by the RPC-MIP passive mode during Langmuir wave periods with the RPC-MIP active mode observations, we conclude that the measurement accuracy of RPC-MIP depends on the operational submode when the cold electron component dominates the electron density.

On the propagation of VLF electric field emissions associated with earthquakes in the middle layer of the earth crust

An ensemble of elementary radiators is generated on the basement rock because of the applied stresses in the preparation zone of the earthquakes in the earth crust. Considering such an ‘ensemble’ as the source of electromagnetic signals, the strength of the electric field is estimated at different distances and frequencies lying in range (3 – 27 kHz) at three different conductivities of the crustal layers (10-8, 10-9, 10-10 S/m). The results of the computation are presented in this paper. Moreover, propagation distances for the seismogenic VLF emissions have also been calculated in the frequency band (3 – 27 kHz) at the conductivities lying in the range (10-8 - 10-10 S/m) within the limit of detectability of measuring instruments (10-7 V/m). It is observed that these distances increase with the decrease of conductivity of the middle layer of crust. Furthermore, theoretical results of comptations are verified from the experimental observations of the seismic event that occurred at the distance of 698 km from the observing station at Chaumuhan Mathura (Geographic lat. 27.490N, long. 77.670E). In addition to this, generation and propagation mechanisms of seismo-electromagnetic radiations have also been discussed briefly.

Ionosphere Sounding for Pre-seismic Anomalies Identification (INSPIRE): Results of the Project and Perspectives for the Short-Term Earthquake Forecast

The INSPIRE project was dedicated to the study of physical processes and their effects in ionosphere which could be determined as earthquake precursors together with detailed description of the methodology of ionospheric pre-seismic anomalies definition. It was initiated by ESA and carried out by an international consortium. The full set of key parameters of the ionospheric plasma was selected based on the retrospective analysis of the ground-based and satellite measurements of pre-seismic anomalies. Using this classification the multi-instrumental database of worldwide relevant ionospheric measurements (ionosonde and GNSS networks, LEO-satellites within situprobes including DEMETER and FORMOSAT/COSMIC ROC missions) was developed for the time intervals related to selected test cases. As statistical processing shows, the main ionospheric precursors appear approximately 5 days before the earthquake within the time interval of 30 days before and 15 days after an earthquake event. The physical mechanisms of the ionospheric pre-seismic anomalies generation from ground to the ionosphere altitudes were formulated within framework of the Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model. The processes of precursor’s development were analyzed starting from the crustal movements, radon emission and air ionization, thermal and atmospheric anomalies, electric field and electromagnetic emissions generation, variations of the ionospheric plasma parameters, in particular vertical TEC and vertical profiles of the electron concentration. The assessment of the LAIC model performance with definition of performance criteria for earthquake forecasting probability has been done in statistical and numerical simulation domains of the Global Electric Circuit. The numerical simulations of the earthquake preparation process as an open complex system from start of the final stage of earthquake preparation up to the final point–main shock confirms that in the temporal domain the ionospheric precursors are one of the most late in the sequence of precursors. The general algorithm for the identification of the ionospheric precursors was formalized which also takes into account the external Space Weather factors able to generate the false alarms. The importance of the special stable pattern called the “precursor mask” was highlighted which is based on self-similarity of pre-seismic ionospheric variations. The role of expert decision in pre-seismic anomalies interpretation for generation of seismic warning is important as well. The algorithm performance of the LAIC seismo-ionospheric effect detection module has been demonstrated using the L’Aquila 2009 earthquake as a case study. The results of INSPIRE project have demonstrated that the ionospheric anomalies registered before the strong earthquakes could be used as reliable precursors. The detailed classification of the pre-seismic anomalies was presented in different regions of the ionosphere and signatures of the pre-seismic anomalies as detected by ground and satellite based instruments were described what clarified methodology of the precursor’s identification from ionospheric multi-instrumental measurements. Configuration for the dedicated multi-observation experiment and satellite payload was proposed for the future implementation of the INSPIRE project results. In this regard the multi-instrument set can be divided into two groups: space equipment and ground-based support, which could be used for real-time monitoring. Together with scientific and technical tasks the set of political, logistic and administrative problems (including certification of approaches by seismological community, juridical procedures by the governmental authorities) should be resolved for the real earthquake forecast effectuation.

Towards the Prediction of SpaceWire Radiated Emissions Employing an LVDS Signal Emulator

The majority of the past and current ESA’s, NASA’s, and JAXA’s science missions utilize broadly SpaceWire (SpW) Links, with Low Voltage Differential Signaling (LVDS) for the physical layer, to transfer mission data. Electromagnetic Compatibility (EMC) and Electromagnetic Interference (EMI) problems caused by harnesses’ radiated emissions remain a constant open issue in every mission due to the scientific payload sensitivity. A common cause of radiated emissions from shielded cable bundles can be traced to the currents flowing on the shield of the harness. This work aims to present a complete methodology for predicting the Electric field emissions in the case of an operating SpW link, while it can be expanded to any shielded cable which utilizes LVDS. The physical and protocol layer of the link are implemented via a developed LVDS Signal emulator, handling both the characteristics of the signals at the outputs of the LVDS line drivers and the effects of their transmission across the link along with the termination scheme, in order to calculate the common mode current flowing on the shield. The radiated emissions can then be estimated considering the ground material and a detailed harness topology, employing traveling wave antenna theory. The validity of this approach is assessed by comparing the predictions with actual link radiated emissions measurements. Simulation results are in good agreement with the measurements, rendering this methodology a fast tactic for the pre-compliance procedure for the early design stage of the science space mission.

Helicity-dependent terahertz photocurrent and phonon dynamics in hybrid metal halide perovskites.

We report the discovery of helicity-dependent ultrafast photocurrent generation in organic-inorganic perovskite by measuring terahertz (THz) electric field emissions in the time-domain. We find signatures of the circular photogalvanic effect (CPGE) where right circularly polarized light and left circularly polarized light lead to different photocurrent generation. The direction of photocurrent is also resolved by measuring the polarization of the emitted THz pulses. Furthermore, we observe distinct wavelength-dependent, coherent phonon dynamics using THz pump-induced differential reflectivity, indicative of multiple exciton resonances. Both the CPGE and exciton fine structure, together with theoretical simulations, provide compelling and complementary evidence for the existence of Rashba-type bands in perovskite.

Capacitive Power Transfer System with Reduced Voltage Stress and Sensitivity

This paper introduces a DC–DC buck converter on the secondary side of the capacitive power transfer system to reduce the voltage and electric field across the interface, and to reduce the circuit Q, and thus the system sensitivity. The system is mathematically analyzed to study the improvement in sensitivity and voltage stress. The leakage electric field emissions around the plates are investigated by simulation. The analytical and simulation results show that by reducing the duty cycle of the buck converter at a constant output power, the voltage across the plates can be significantly reduced and the circuit becomes less sensitive to the variations in parameters. Experimental results demonstrated that Q and the voltage stress over the capacitive interface are reduced by changing the duty cycle of the buck converter. For delivering 10 W of power, the maximum voltage stress across one pair of the coupling plates is reduced from 211 V in the conventional system without using a DC–DC converter, to 65 V and 44 V at duty cycles of 30% and 20%, respectively. The system achieves an end-to-end power efficiency of 80% at an output power of 10 W and a duty cycle of 30%.

Six-Plate Capacitive Coupler to Reduce Electric Field Emission in Large Air-Gap Capacitive Power Transfer

This paper proposes a six-plate capacitive coupler for large air-gap capacitive power transfer to reduce electric field emissions to the surrounding environment. Compared to the conventional four-plate horizontal structure, the six-plate coupler contains two additional plates above and below the inner four-plate coupler to provide a shielding effect. Since there is a capacitive coupling between every two plates, the six-plate coupler results in a circuit model consisting of 15 coupling capacitors. This complex model is first simplified to an equivalent three-port circuit model, and then to a two-port circuit model which is used in circuit analysis and parameter design. This six-plate coupler can eliminate the external parallel capacitor in the previous LCLC topology, which results in the LCL compensation and reduces the system cost. Due to the symmetry of the coupler structure, the voltage between shielding plates is limited, which reduces electric field emissions. Finite element analysis by Maxwell is used to simulate the coupling capacitors and electric field distribution. Compared to the four-plate horizontal and vertical structures, the six-plate coupler can significantly reduce electric field emissions and expand the safety area from 0.9 to 0.1 m away from the coupler in the well-aligned case. A 1.97 kW prototype is implemented to validate the six-plate coupler, which achieves a power density of 1.95 kW/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a dc-dc efficiency of 91.6% at an air-gap of 150 mm. Experiments also show that the output power maintains 65% of the well-aligned value at 300 mm X misalignment, and 49% at 300 mm Y misalignment.

Optimization of electric and magnetic field emissions produced by independent parallel overhead power lines

This paper presents a method for determining optimal arrangements of parallel independent overhead power lines aimed to decrease electric and magnetic field emissions. The Genetic Algorithm (GA) is used to find the optimal placement of conductors. The Monte Carlo approach implemented in GA allows consideration of uncertain phase shifts between independent overhead power lines. The results and practical aspects of the proposed methodology are illustrated on two different configurations of both independent 400 kV singlecircuit and double-circuit overhead power lines.

Novel Double Clamp Methodology to Reduce Shielded Cable Radiated Emissions Initiated by Electronic Device Switching

A new “double clamp methodology” (DCM) is proposed that can suppress a cable's peak radiated emission in a band centered around noise frequency $(f_{{\rm{noise\,pk}}})$ that is generated by common-mode (CM) electrical noise current flowing in any product containing pulsed switching devices connected to a shielded cable. DCM is a cable grounding technique that clamps or terminates a shielded cable in two places. The first shield clamp at the switching device output uses traditional well-known cable termination techniques, e.g., 360° low inductance shield connection to ground. A second shield clamp can be placed at a predetermined cable length from the first, where the cable resonant frequency is known to have ultralow CM impedance at noise frequency $f_{{\rm{noise\,pk}}}$ . The cable loop between shield clamp terminations sets up a resonant low impedance at $f_{{\rm{noise\,pk}}}$ that diverts CM current to the ground plane inside the product, so CM current entering a shielded cable is reduced as well as radiated electric field emissions. Analytical and measurement techniques are provided to determine the correct cable clamp length. Experimental test results confirm DCM effectively controls CM noise current and resulting peak radiated emissions by 12 dB⋅µV/m (∼4×), without external suppression components added.

Ion density and temperature variations at altitude of 500 km during moderate seismic activity

Ionospheric ions (O+ and H+) and temperature (Ti) as precursory parameters to seismic activity have been analysed from year 1995 till 1998, using SROSS-C2 (average altitude range of ∼500km) satellite measurements for moderate magnitude earthquakes. The details of seismic events during this period are downloaded from United State Geological Survey (USGS) and National Earthquake Information Centre (NEIC) website. 13 seismic events of moderate magnitude (M=4–5.5) from 1995 to 1998, using SROSS-C2 satellite measurements have been analysed. During seismic affected period, considerable decrease in the density of heavier ion - O+ and increase in the ion temperature (Ti) is observed during all the selected events. Lighter ion - H+ doesn’t show any significant change. Electric field and electromagnetic emissions generated due to seismogenic activity could be the plausible initializing agents responsible for change in ion concentration and temperature values during these events.

Novel multi-objective optimization method of electric and magnetic field emissions from double-circuit overhead power line

Summary This paper proposes a novel method for determining optimal arrangements of overhead double-circuit power line conductors aimed to reduce electric and magnetic field emissions. Extremely low frequency electric and magnetic field optimization problems have multiple objectives. Multiple-objective optimization allows the simultaneous optimization of two or more conflicting objectives and determination of mutually non-dominated solutions. The multi-objective optimization technique used in this paper is based on Genetic Algorithm to obtain a set of mutually non-dominated solutions (Pareto optimal set) for the two objectives: the electric and magnetic field strengths near overhead double-circuit power line. Also, additional assessment criteria were defined for the selection of several decision scenarios from the Pareto optimal set. The results and practical aspects of the proposed methodology are demonstrated on two typical 400-kV double-circuit overhead power lines. The efficiency of the proposed multiple-objective optimization method is compared with the existing one based on single-objective optimization function. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of EMI Reduction Techniques on a PRBS Generator Board

In this article, several EMI characterization and reduction techniques have been investigated and their effectiveness is demonstrated using the developed test boards. The sum and difference outputs of the hybrid (expressed in dBm), that is placed at the output of the TEM cell, are be used to make relative comparisons between the electric and magnetic far field emissions. This data is used to compare the effectiveness of the EMI reduction techniques.

Ground observation of electromagnetic emissions related to clusters of earthquakes

Ultra-low frequency (ULF) and very low frequency (VLF) data obtained from three ground-based experiments at Agra station (latitude 27.2° N, longitude 78.0° E) in India, namely measurement of ULF magnetic field emissions using a three-component search coil magnetometer, the vertical component of VLF electric field emissions with a borehole antenna, and the phase and amplitude of fixed frequency VLF transmitter signals using an Absolute Phase and Amplitude Logger (AbsPAL) receiver, were analysed in search of possible precursors of two major seismic activities that occurred in Sumatra (Indonesia) during the post-tsunami period between January and April 2005. These two major seismic events occurred as clusters of earthquakes during 27–29 January and 28–30 March 2005. The results show that, apart from the borehole antenna, all the experiments showed precursors due to these clusters of earthquakes. Such precursors were not seen in the case of isolated large-magnitude earthquakes. Furthermore, the precursory duration was influenced by a magnetic storm that occurred about a week before the clusters. The mechanism of ULF propagation to long distances between Sumatra and Agra and perturbations in the ionosphere before the clusters are discussed.

Some Mobile Phone Associated Health Problems Among Mobile Phone Workers At Zagazig City, Sharkia Governorate.

Background: Although mobile telecommunications deliver enormous benefit to society, there are concerns whether its electric and magnetic field emissions are linked with cancer or other health hazards. Objectives: 1) determining some of the mobile phone(Mph) associated health problems. 2) identifying some of the risk factors associated with exposure to Mph. Subjects and methods: A comparative cross-sectional study was conducted on 125 workers in mobile phone shops at Zagazig City, Sharkia Governorate and non-exposed control group consisted of 119 Mph users group and 29 Mph nonusers group. All workers were interviewed using a pre-designed questionnaire including sociodemographic data, occupational history, Mph exposure & health complaints experienced during Mph working period and all workers were subjected to blood pressure measurement. Results: The results revealed that, the prevalence of sleep disturbances and tension was significantly higher in Mph workers (48.8% & 60.0%) compared to Mph non-users control group(17.2%, 31.0% and P

Ground Chamber Measurements of the Electromagnetic Emissions from the Hayabusa Ion Engine

DOI: 10.2514/1.19473 Radiated electric field emissions from the prototype model of the ion engine system of the asteroid explorer Hayabusa (MUSES-C) were measured in approximate accordance to MIL-STD-461C. The typical noise level exceeded the narrowband specification at frequencies less than 5 MHz. The microwave discharge neutralizer generates broadband noise and narrowband oscillations that have a fundamental frequency of about 160 kHz and are accompanied by its harmonics up to the fifth. Leakage of 4.25 GHz microwaves for plasma production and its second harmonic were 65 dB and 35 dB above specifications, respectively. The X-band receiver onboard Hayabusa measured the noise from the ion engine system at the uplink frequency of 7.16 GHz through a horn antenna. This susceptibility test showed that the microwave discharge ion thruster is unlikely to interfere with deep space microwave communication. Nomenclature d = neutralizer orifice diameter ID = electron emission current of the neutralizer l = anode distance from the neutralizer _ m = xenon flow rate P� = microwave power for plasma discharge of the neutralizer VD = voltage between the neutralizer and the anode in diode mode operation

Phenomena and mechanism of electric charges on spacers in gas insulated switchgears

The phenomenon of accumulated charges on solid insulator surfaces is one of the critical parameters to consider at the insulation design stage, for AC electric power equipment as well as for DC equipment, so it is important to investigate the characteristics and predominant factors underlying various charging mechanisms. Several researches related to this theme have been reported, but independently, and cross-sectional comparison and evaluation from a unified viewpoint are meaningful. In this paper, the resistance of solid insulator is first discussed, showing that the resistances found by diverse measurements are in a fairly good agreement under similar conditions of the temperature and electric field. Next, three kinds of electric charging mechanisms, i.e. volume conduction, surface conduction and electric field emission are characterized in terms of the time constant, applied voltage and charge distribution. Then, eight cases of recent measurements on the charging time are investigated and their charging mechanisms are classified. Electric field emissions are likely to occur with model spacers made in routine GIS manufacturing process at the electric field level used. Further, three examples in cases with metallic particles are introduced, of simulating charge from edge on the tank, spacer surface charging phenomena, and influence of charge on spacer surface flashover. It is expected that this paper wilt be helpful for understanding charging phenomena e.g. on insulation spacers in gas insulated switchgears

Identification of earthquake sources responsible for subsurface VLF electric field emissions observed at Agra

Employing USGS earthquake data for Indian region and very low frequency (VLF, 3 kHz) subsurface electric field data obtained by using a borehole antenna at Agra in India, statistical analysis has been carried out to identify the earthquake sources responsible for VLF data. The correlation coefficient between occurrence number of VLF noise bursts and earthquakes are calculated and level of null hypothesis tested. The results show that seismic activities occurring close to the observing station and the main boundary fault located at the southern base of Himalaya are the main sources of VLF emissions recorded at the station.