International Journal of Applied Electromagnetics and Mechanics - Volume 44, issue 3-4

Article Type: Editorial

Abstract: Guest editorial to the 12th International Workshop on 1&2 Dimensional Magnetic Measurement and Testing (2012) special issue.

DOI: 10.3233/JAE-141785

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 243-243, 2014

Authors: Fiorillo, F. | Beatrice, C. | Son, D. | Ahlers, H. | Groessinger, R. | Albertini, F. | Liu, Y.P. | Lin, A. | Patroi, E. | Shull, R. | Thomas, O. | Hall, M.J.

Article Type: Research Article

Abstract: We present the results of an international comparison regarding the magnetic properties of hard magnets, measured using the Vibrating Sample Magnetometer. The comparison involved eight different international laboratories, plus two laboratories using the SQUID magnetometer. It was directed, in particular, at the determination of the hysteresis loop parameters of hard ferrite and magnetic tape samples. It was carried out in the framework of the activity of the IEC TC68 Working Group 2. The statistical analysis of …the obtained results was performed according to standard rules (e.g. ISO and EURAMET guidelines). The standard deviation around the mean of the laboratories best estimates is found to be s ∼ 1% in anisotropic ferrites for all the measured quantities: coercive fields H_{cJ} and H_{cB} , high-field polarization J_{800 k} , polarization at remanence J_r , maximum energy product (BH)_{max} . Isotropic ferrites show larger dispersion of the best estimates of J_r and H_{cB} (∼ 3%) and (BH)_{max} (∼6%). For the quantities measured in the magnetic tapes (magnetic moment under applied field H=400 kA/m m_{400 k} and at remanence m_r , squareness S = m_{400 k}/m_r , H_{cJ} ) s is found to fluctuate around 2%. In all cases, the relative expanded uncertainty of the reference value (weighted mean), associated with a 95% confidence level, is at most ± 1.5%. Show more

Keywords: Magnetic measurements, Vibrating Sample Magnetometer, hard magnets, measuring uncertainty

DOI: 10.3233/JAE-141786

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 245-252, 2014

Authors: Sievert, J. | Yang, H. | Zhang, P. | Ge, H.

Article Type: Research Article

Abstract: The standardized Epstein frame is a magnetic circuit for the normative measurements of magnetic properties of electrical sheet steel following the Wattmeter method. It was designed for convenient practical use in industry rather than as an accurate physical representation of magnetic power loss of the material. In principle, the Wattmeter method is based on the use of a homogeneous ring sample as the magnetic circuit. The double overlapping corners of the Epstein frame constitute a significant …divergence from the topology of the homogeneous ring, and, thus, are the source of a substantial systematic error. This paper applies the simple method of summation of the reluctances of the complete magnetic circuit (CRS) for the determination of this error. The results for various types of electrical steel and for the frequency range of 40 Hz to 100 Hz are considered. Results of variations of the Epstein strip stacking scheme are also recorded. Show more

Keywords: Electrical sheet steel, Epstein method, systematic error

DOI: 10.3233/JAE-141787

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 253-258, 2014

Authors: Pfützner, Helmut | Shilyashki, Georgi | Palkovits, Martin | Galabov, Viktor

Article Type: Research Article

Abstract: In principle, single sheet testers (SSTs) or Epstein testers (ETs) determine iron losses p through the time integral over the field H and the time derivative of the induction B. Both quantities should be determined in equivalent ways, i.e. considering an identical quasi-homogeneously magnetized sample section. Partly, this condition is fulfilled by H-coil methods. However, the so far used very small coils do not meet the demand of equivalence. At least outside of Japan, most labs …prefer apparatuses where H is assumed to be proportional to the magnetization current i. But exact proportionality does not exist due to the periphery – the yoke of SST and the corners of ET, respectively. Usually, the periphery is considered through a constant effective magnetic path length l_M based on the peak induction B_p . But in fact, l_M varies during the period, i.e. it is a function of B(t) and thus also of time. Our novel "PLC method" is characterized by path length consideration. We consider dynamics of length through a "path length function" Λ (B) which is determined for each grade of material in a calibration process by means of a large, rigid H-coil. Considering Λ [B(t)] by software, routine measurements on similar materials can be based on the "corrected" current i(t)/Λ (t). First results are presented for HGO SiFe investigated in an ET. Here, Λ proves to be above 1 for low B and below 1 for very high B. As a final target, application of the method for both ETs and SSTs should yield almost identical loss values that are close to "true" ones. Show more

Keywords: Iron loss measurements, Epstein tester, single sheet tester

DOI: 10.3233/JAE-141788

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 259-270, 2014

Authors: Yamamoto, Ken-ichi | Yanase, Shunji

Article Type: Research Article

Abstract: Changes in permeability and magnetic losses in non-oriented electrical steel sheets resulting from compressive stress have been investigated using a single-sheet tester. A compressive stress of up to 20 MPa is uniformly applied normal to the sheet surface. It is demonstrated that a stress beyond 5 MPa can decrease magnetic losses, including both hysteresis loss and eddy current loss.

Keywords: Magnetic losses, permeability, electrical steel, compressive stress

DOI: 10.3233/JAE-141789

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 271-278, 2014

Authors: Soinski, Marian | Pluta, Wojciech | Zurek, Stan | owski, Adam Kozł

Article Type: Research Article

Abstract: Instrument current and voltage transformers remain the basic apparatus used in measurements of energy in electrical grid. Increasing importance of distributed energy sources necessitates more precise measurements of consumed as well as generated electrical energy. Both types occur in low voltage network where the main focus is on current transformers for electronic-type electrical energy meters. These current transformers should fulfil many requirements for precise electrical energy measurements. This paper presents a modern …system for measurement of various metrological features of current transformers. Show more

Keywords: Current transformer, phase error, amplitude error, nanocrystalline cores

DOI: 10.3233/JAE-141790

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 279-284, 2014

Authors: Kutsukake, Akifumi | Kido, Yukihito | Ikeda, Tetsu | Kanada, Tsugunori | Enokizono, Masato

Article Type: Research Article

Abstract: A study is carried out based on the evaluation of IEC-standard. Two measurement results on N.O. magnetic steel sheets, one from S-SST (Stress load type single sheet tester developed in our research laboratory), another is from SST based on the IEC standard regulation, are compared and discussed. As a result of the measurements, both magnetization curves coincide mostly, but magnetic power loss determined by IEC method is larger than that achieved by S-SST. The differences between …them may be caused by magnetic field strength evaluation for each measurement method, magnetizing current method for IEC-type-SST and H-coil method for S-SST. The effective magnetic path is regulated in IEC but actually this may be variable according to the type of magnetic sheet, the structure of the SST and of applied magnetic field strength. In order to discuss this point, a virtual magnetic path length is introduced by using the applied magnetic field strength. Show more

Keywords: Magnetic property, electrical steel sheet, single sheet tester, H coil method, magnetizing current method

DOI: 10.3233/JAE-141791

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 285-293, 2014

Authors: Ghalamestani, Setareh Gorji | Vandevelde, Lieven | Dirckx, Joris J.J. | Guillaume, Patrick | Melkebeek, Jan A.A.

Article Type: Research Article

Abstract: Magnetostriction, which refers to the deformation of the core material of transformers and electrical machines, is a main contributor to the total noise. In this work, a technique is proposed to calculate the magnetostrictive deformations of the core of the aforementioned devices. This technique is based on finite element approach with an artificial neural network model of the magnetostrictive behaviour of the core material. The strain measurements are carried out by using a dual heterodyne laser …interferometer setup. The proposed technique is then applied to a single-phase test transformer core. As a validation, the vibration of the magnetised core of the same setup is measured by using a laser scanning vibrometer. Show more

Keywords: Magnetostriction, transformer, finite element, neural network, vibration measurement

DOI: 10.3233/JAE-141792

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 295-299, 2014

Authors: Rekik, Mahmoud | Hubert, Olivier | Daniel, Laurent

Article Type: Research Article

Abstract: The research presented in this paper is motivated by the design of electrical devices submitted to mechanical stress. It aims at studying the magnetic behaviour of ferromagnetic materials submitted to biaxial stress. It deals with the evolution of the magnetic susceptibility, coercive field and magnetic losses with respect to stress, magnetic field level and frequency. These quantities are of primary importance in the design of rotors for high speed rotating machines. The work is focused …on the magnetic behaviour of a standard grade of Iron-Silicon alloy under the form of thin sheet. Non conventional experiments are performed on cross-shaped samples in order to apply biaxial stress representative of the loadings experienced by rotors of rotating machines. These experiments are performed on a multiaxial testing machine, ASTREE. The magnetic loading is applied using a single U-yoke. The measurement of magnetic induction, magnetic field and strain is conducted by the means of needle-B sensor, H-coil sensors and Digital Image Correlation (DIC) respectively. Both anhysteretic and dissipative responses to magneto-mechanical loadings are considered. The results allow to identify the more critical stress configurations for this material. Show more

Keywords: High speed rotating machines, biaxial stress, iron-silicon alloy, anhysteretic behaviour, dissipative behaviour, coercive field, power losses

DOI: 10.3233/JAE-141793

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 301-315, 2014

Authors: Wakabayashi, Daisuke | Enokizono, Masato

Article Type: Research Article

Abstract: Vector magnetic properties and two-dimensional magnetostrictions of electrical steel sheets under alternating and rotating magnetic flux conditions were measured. Based on the measured database, magnetic characteristic analyses of motor and transformer model cores have been carried out and distributions of two-dimensional magnetostriction have been estimated. The proposed method has been verified with a ring specimen in comparison of the analyzed result with the measured one.

Keywords: Vector magnetic property, two-dimensional magnetostriction, electrical steel sheet, motor, transformer, E&S model

DOI: 10.3233/JAE-141794

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 44, no. 3-4, pp. 317-330, 2014