International Journal of Applied Electromagnetics and Mechanics - Volume 48, issue 2-3

Article Type: Editorial

DOI: 10.3233/JAE-151976

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 111-111, 2015

Authors: Ishihara, Yoshiyuki

Article Type: Research Article

Abstract: I have investigated the methods of measurement of the magnetic properties of Fe-based amorphous strip proper to establish a material specification standard. A single strip tester designed for the material was constructed and the effects of measurement conditions on the results were studied. I have found that the single strip tester method proposed is superior to the toroidal core method and the H-coil method is essential to avoid the effects of yoke.

Keywords: Fe-based amorphous strip, IEC standardization, single sheet tester (SST), H-coil method, magnetizing current method

DOI: 10.3233/JAE-151977

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 113-122, 2015

Authors: Appino, C. | Ferrara, E. | Fiorillo, F. | Rocchino, L. | Ragusa, C. | Sievert, J. | Belgrand, T. | Wang, C. | Denke, P. | Siebert, S. | Norgren, Y. | Gramm, K. | Norman, S. | Lyke, R. | Albrecht, M. | Zhou, X. | Fan, W. | Guo, X. | Hall, M.

Article Type: Research Article

Abstract: We discuss the results of an international comparison regarding the measurement of magnetic power loss and apparent power between 20 Hz and 100 Hz at magnetic polarization values ranging between 1.3 T and 1.8 T in grain-oriented steel (GO) sheets using the Single Sheet Testing (SST) and Epstein methods. This exercise, carried out in the framework of the activity of Joint Working Group IEC 68/WG1-ISO/TC17/WG16, was aimed at a solid assessment of the degree of reproducibility of the SST method, under its prospective adoption in the industrial practice as a reference method for the specifications of grain-oriented alloys. Five different …types of Fe-Si GO alloys were circulated among eleven different laboratories of metrological institutes and industry. The statistical analysis of the results shows close reproducibility properties of the SST and Epstein methods. It is obtained, in particular, that the power loss figures, measured by the participants at 50 Hz and the aforementioned peak polarization values are distributed around their reference value with relative standard deviation σ (P)SST = 0.88% and σ (P)Epst = 0.82% for SST and Epstein, respectively. It is obtained σ (S)SST = 2.20% and σ (S)Epst = 2.15% for the apparent power. For the industrially relevant case of polarization Jp = 1.7 T in the high-permeability P-type grades, these quantities amount to σ (P)SST = 0.48%, σ (P)Epst = 0.80%. By restricting the comparison to the European metrological laboratories (INRIM, NPL, PTB), the overall distributions narrow to σ (P)SST = 0.42%, σ (P)Epst = 0.55%, σ (S)SST = 1.19%, and σ (S)Epst = 0.82%. A qualitative interpretation of the main physical mechanisms and the measuring features underlying the lab-to-lab dispersion of the SST and Epstein results is discussed in this paper. It is concluded that the combination of good reproducibility and simple practical implementation make the SST method totally appropriate as a reference method for the definition of the material quality in the specification standards. Show more

Keywords: Grain-oriented Fe-Si, single sheet testing method, Epstein method, measurement comparisons

DOI: 10.3233/JAE-151978

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 123-133, 2015

Authors: Tanaka, Masaya | Hagihara, Hiroto | Takahashi, Yasuhito | Fujiwara, Koji | Ishihara, Yoshiyuki | Azuma, Daichi

Article Type: Research Article

Abstract: International standardization concerning Fe-based amorphous strip is necessary in the electrical industries with the demand for higher-efficiency transformers. Efforts to achieve pertinent standards are progressing in the IEC technical committee 68 (IEC/TC68). Especially, measurement standards for magnetic properties must be established before material standards. We have studied methods that could measure the magnetic properties correctly. We designed a single sheet tester for amorphous strip (AM-SST) based on the results of experiments, and an international round robin test (RRT) of amorphous strips with this AM-SST is proceeding among IEC/TC68 experts. We report preliminary results of the RRT.

Keywords: Fe-based amorphous strip, IEC standardization, single sheet tester (SST), H-coil method, magnetizing current method, round robin test (RRT)

DOI: 10.3233/JAE-151979

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 135-141, 2015

Authors: Pfützner, Helmut | Shilyashki, Georgi | Mulasalihovic, Edin

Article Type: Research Article

Abstract: In contrast to clear under-estimations through non-experts, modern transformers represent high-tech products of highest economic value. This is also true for the soft magnetic core of a transformer. It consists of highly grain oriented (HGO) silicon iron that is surface-treated by stress coating and laser scribing, yielding domain refinement through most intelligent physical mechanisms. Considering a single individual core package, it reveals a complex 2-dimensional flux distribution that is characterized by ``flux along rails'' due to the high effective anisotropy of HGO materials. It impedes effective numerical modelling since being linked with non-linearity, hysteresis and stress effects from surface treatments. …Experimental modelling faces problems of scaling-down and from imperfect clamping, but it yields clear indications for the existence of significant rotational magnetization that should be restricted through further research. The core packages are in - non-clarified - interaction to each other which means that a core has to be considered as a 3D system. This complicates attempts of modelling in further ways. However, high potential exists for further core improvements with respect to lower building factor and lower audible noise. The challenge will be to reduce both characteristics in synchronous ways. Show more

Keywords: Transformer cores, silicon iron, flux distributions, anisotropy, 3-D effects

DOI: 10.3233/JAE-151980

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 143-151, 2015

Authors: Yamamoto, Ken-ichi | Hamada, Toshiyuki | Yanase, Shunji

Article Type: Research Article

Abstract: The magnetic properties of grain-oriented electrical sheets were measured under compressive stress applied in the thickness direction using a single-sheet tester with two H-coils. This apparatus can apply uniform stress throughout the specimens. Decreases in both the permeability and magnetic losses are observed in the specimens under normal stress of 20 MPa. This normal stress can reduce both hysteresis and the eddy-current losses.

Keywords: Magnetic losses, permeability, electrical steel sheet, normal stress

DOI: 10.3233/JAE-151981

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 153-158, 2015

Authors: Carrander, Claes | Engdahl, Göran

Article Type: Research Article

Abstract: The magnetic properties of a power transformer core are generally held to be quite similar to those of the core steel itself. Due mainly to it being rare and practically difficult to acquire a transformer for testing and verification, testing of large units is usually only performed concerning no-load losses. However, other parts of the magnetic hysteresis loop are more sensitive to variations in material and geometry and could be used for more detailed diagnostics. This paper shows that measurements of magnetic hysteresis can be performed with good results on large power transformers. Methods to compensate for capacitive currents and …to calculate the effective magnetic length of the core are shown and the results are compared to standard material measurements. The results show good agreement with Epstein frame measurements on annealed samples. Show more

Keywords: Power transformers, magnetic hysteresis, core steel, magnetic length, epstein, SST, magnetic properties

DOI: 10.3233/JAE-151982

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 159-162, 2015

Authors: Piotrowski, Leszek | Chmielewski, Marek | Augustyniak, Bolesƚaw | Maciakowski, Paweƚ | Prokop, Karolina

Article Type: Research Article

Abstract: In the paper we describe a novel apparatus for the measurement of the Barkhausen noise (BN) angular dependence, which in turn may be indicative of the stress induced anisotropy of magnetic properties. Such dependence can be further used for the stress distribution evaluation. The change of magnetization direction in the material is obtained by varying the magnetic flux density in two perpendicular yokes of the apparatus. We present here, as an example, the application of the apparatus for the determination of the stress distribution in the welded plates. It is to be stressed that, thanks to the very short time …of measurements achieved with the presented apparatus, it is very straightforward to obtain the spatial distribution of the stress over relatively big area of the plates in question. The whole measurement process as well as obtained data post processing is computer controlled and a stress distribution (based on 5 × 5 measurement matrix) for a single plate may be determined in less than an hour. Show more

Keywords: Barkhausen effect, material characterization, stress anisotropy, welding

DOI: 10.3233/JAE-151983

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 163-170, 2015

Authors: Manh, Tu Le | Caleyo, F. | Hallen, J.M. | Perez-Benitez, J.A. | Espina-Hernández, J.H.

Article Type: Research Article

Abstract: This paper presents experimental evidence of the correlation between the magnetocrystalline energy (MCE) and the Barkhausen noise (BHN) signal in three API 5L steel samples. The angular dependence of the MCE in each sample was determined using the r.m.s. values of the BHN signal in the time band from saturation to remanence, for angular positions ranging from 0 to 180 degrees, in 10-degree steps. The angular dependence of the average MCE of each steel was also estimated from the set of individual grain orientations measured by Electron Backscatter Diffraction (EBSD). The average MCEs determined from the BHN measurements and predicted …from the measured EBSD microtexture data show a relatively good concordance. This agreement is explained by considering the influence that magnetocrystalline energy has on the free pole charges that appear at grain boundaries as the material goes from saturation to remanence and therefore on the irreversible nucleation and growth of domains of reverse magnetization responsible for the BHN activity in this band. Show more

Keywords: Magnetocrystalline energy, Barkhausen noise, pipeline steels, EBSD

DOI: 10.3233/JAE-151984

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 171-179, 2015

Authors: Owzareck, Michael

Article Type: Research Article

Abstract: The measurement of the material properties of soft magnetic composites is yet a technical challenge because of the high magnetization currents in the saturation region [1]. If in an initially closed magnetic circuit an external air gap is introduced, the normal magnetization curve inclined more and more and flattened. This effect is referred to as shear. In powder composite materials this effect is called internal shear, since air gaps caused by the isolation of the individual powder particles. The high magnetization currents and magnetic field strengths occur because of this internal shear. The high magnetic field strengths cause a high …apparent power demand for the measurement sample. In this work two advanced test method for measuring the normal magnetization curve of powder composites are presented and compared with each other. With this measuring method it is also possible to perform magnetic measurements in the saturation region. The normal magnetization curve is required for finite elements calculations and analytical calculations up to the saturation. Show more

Keywords: Magnetic measurement, soft magnetic composites, normal magnetization curve, toroidal core

DOI: 10.3233/JAE-151985

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 48, no. 2-3, pp. 181-186, 2015