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Power line magnetic field deviations for three different definitions of current unbalance
Danka Antic, Anamarija Juhas, Miodrag Milutinov, 2019, professional article

Abstract: An estimation procedure of the public's exposure to the low-frequency magnetic field generated by overhead power lines, according to the international standards, implies measurement and an extrapolation. It is necessary to measure both the magnetic field around the lines and the current in the lines simultaneously. The extrapolation procedure implies the calculation of the maximum magnetic field that will occur when the line current achieves its maximum. The calculation relies on a proportion between the current in the power line and the magnetic field around the power line, which is valid only when the currents are balanced. Unfortunately, the standards do not cover the unbalanced cases. The relation between the current unbalance and magnetic field could improve the estimation procedure. In the literature, several different definitions of the current unbalance could be found. In this paper, a comparison of three different definitions of current unbalance and their relation to the deviation of a magnetic field are considered. The magnetic field is calculated in the vicinity of the bus bar. The same procedure could also be applied around overhead power lines. The definitions for the current unbalance used in this paper are derived from the existing definitions of the voltage unbalance. Only one of these three definitions considers phase unbalance. The relationships between current unbalance and the maximum deviation of the magnetic field are found to be proportional.
Keywords: magnetic field, power delivery, measurement, public exposure assessment
Published in DKUM: 22.12.2023; Views: 437; Downloads: 3
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Electric and magnetic field measurements for high voltage transmission lines : the case of Turkey
Mehmet Zeki Çelik, Mehmet Murat Ispirli, Yusuf Öner, Bülent Oral, 2019, professional article

Abstract: A power system is a facility that creates low-frequency electromagnetic fields (EMF) with its highvoltage level and high electric current capacity. In this respect, these electromagnetic fields need to be significantly evaluated from the aspects of both those who are exposed to the fields due to the structure of the facility during their daily lives and those who are exposed to the fields due to their occupation. In this study, the transmission lines and substations in the power system of Turkey are evaluated on account of electric and magnetic field measurements. Firstly, the people living in general public zones near the transmission line or substation were examined. In another part of the study, measurements were made in the occupational exposure of the staff in the energy zone. The results obtained from measurements are compared with the limit values provided by the International Commission on Non%Ionizing Radiation Protection (ICNIRP). The measurements were performed by NARDA EFA-300 electromagnetic field measurement. The closest point to the ground was determined as the reference point for the measurements performed on transmission lines. The results for different distances were obtained by performing measurements following those reference points with fixed distances.
Keywords: electric field, ELF, electromagnetic filed, ICNIRP, magnetic field
Published in DKUM: 05.12.2023; Views: 361; Downloads: 5
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The properties of the material gadolinium and the working agent used in the installation of magnetic refrigeration devices
Dorin Botoc, Jurij Avsec, Adrian Plesca, Georgel Gabor, Rusu Ionut, 2020, professional article

Abstract: Much remains to be done to understand better and thus achieve better control over magnetic materials to maximize their magnetocaloric properties and performance, specifically for gadolinium. A clear path forward is highlighted by thorough experiments coupled with theory, in which the latter is tested and re%ned against the former, thus resulting in discoveries of new and improved materials and bringing near-room-temperature magnetic refrigeration technology to fruition in the near future.
Keywords: Gadolinium, heat transfer, magneto-calorific, magnetic field
Published in DKUM: 01.12.2023; Views: 355; Downloads: 4
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Assessment of human exposure to electric and magnetic fields near transmission lines using FEMM
Bojan Glushica, Blagoja Markovski, Andrijana Kuhar, Vesna Arnautovski Toseva, 2023, original scientific article

Abstract: The intensity of ELF electric and magnetic fields near transmission lines is of particular interest in environmental and equipment protection studies. The use of numerical tools is the most efficient method for their assessment. In this paper, we numerically compute the electric and magnetic fields near different configurations of high-voltage transmission lines using the open- source software FEMM 4.2. Computed fields are compared with reference levels related to human exposure to electromagnetic fields. The accuracy of the applied method is validated with published, numerically computed and measured results.
Keywords: finite elements method, transmission lines, electric field, magnetic field, electromagnetic computation
Published in DKUM: 11.10.2023; Views: 443; Downloads: 6
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Assessment of magnetic fluid losses out of magnetic properties measurement
Miloš Beković, Irena Ban, Anton Hamler, 2010, published scientific conference contribution

Abstract: In this paper an improved measurement system for experimental assessment of magnetic fluid losses is presented. When fluid is exposed to AC magnetic field, three different losses mechanisms are active; relaxation, hysteresis and resonance mechanism. In this paper not individual contributions where studied but combine acting which can be determine as specific power losses (SPL). SPL of the sample is obtained for a variety of amplitudes and frequencies of magnetic field with presented method of measurement of field parameters where results revealed f H2 dependence for fixed temperature of the sample. Temperature dependence of SPL is examined with calorimetrical measurements, where heating of magnetic fluid at fixed value of applied field and various frequencies is examined and results revealed linearly decreasing temperature dependence.
Keywords: magnetic fluid loss, magentic field, hysteresis loop
Published in DKUM: 30.06.2017; Views: 1384; Downloads: 413
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Ecological alternatives to the reduction and oxidation processes in dyeing with vat and sulphur dyes
Mojca Božič, Vanja Kokol, 2008, review article

Abstract: This article gives a summary of the most commonly used ecologically unfriendly processes for the reduction and oxidation of vat and sulphur dyes. It also describes the new alternatives that are in the development stage and could be important in the near future. Sodium dithionite as the dominant reducing agent produces large amounts of sodium sulphate, and also toxic sulphite and thiosulphate as by-products. Consequently, high amounts of hydrogen peroxide and alkali are required for the treatment of effluents, which add to the cost of the process. Attempts have been made to use organic biodegradable reducing agents, enzymes, catalytic hydrogenation, and also indirect or direct, electrochemical reductive methods that employ a redox mediator (electron-carrier). The reduction has also been carried out via the dye radical molecule or, in the case of indigo, by direct electrochemical reduction using graphite as the electrode material. Physical techniques, for example using ultrasound, magnetic fields or UV have been shown to be effective only when used to accelerate methods using classical reduction and oxidation processes. However, although these methods offer some environmental benefits, there is still no satisfactory alternative reducing and/or oxidising agent available today.
Keywords: textile dyeing, vat dyes, sulphur dyes, reduction, oxidation, catalysis, ecology, organic agents, electrochemistry, ultrasound, magnetic field, UV application, biotechnology
Published in DKUM: 01.06.2012; Views: 3061; Downloads: 117
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Experimental system for determining the magnetic losses of super paramagnetic materials; planning, realization and testing
Miloš Beković, Anton Hamler, 2012, independent scientific component part or a chapter in a monograph

Keywords: magnetic losses, experimental system, magnetic field
Published in DKUM: 01.06.2012; Views: 1919; Downloads: 43
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