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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 76 (1958), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The existence of magnetic anisotropy in electrical steels has long been known to designers of electrical machines. However the effect of this anisotropy in real devices has not to date been studied in any great depth. Finite element modeling software is proving useful for designing such electrical machines, however, the material models which form the heart of the process are based on limited data and indeed often make incorrect assumptions regarding the anisotropic nature of the machine core. This article discusses shortcomings of present anisotropic material models, suggests what is needed to overcome these shortcomings and presents one such two-dimensional magnetic test system capable of generating the materials data required. The method by which the data is obtained is described and measured results are presented, indicating some of the features of the system. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Grain oriented 3% silicon iron is widely used as magnetic core material in power devices. It is usually assessed on the basis of its magnetic losses when magnetized as single strips or in the Epstein square. When material is built into cores and magnetized, some flux passes normal to the plane of the laminations and increases the losses of transformers and rotating machines. Pairs of strips were placed together and magnetized at 50 and 60 Hz at ac longitudinal flux densities from 1.0 to 1.8 T and the normal flux density, BN transferred between them was calculated from the emfs induced in search coils located between the strips. Static domain structures were observed using a colloidal technique. Values of BN have been correlated with the domain structures, grain size, and boundary effects. BN was found to be dependent on the static wall spacing in adjacent grains and varied between 0.5 and 3.0 mT with a repeatability better than ±5%. Most large grains had low surface magnetic charge at their boundaries and BN was low. The opposite was found where the flux was transferred between small, not so well oriented, grains. This large normal flux transfer between poorly oriented small grains causes small additional losses in laminated cores.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5379-5381 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been previously shown that the building factor of three-phase transformer cores can be improved by using materials with different permeabilities for limbs and yokes. This paper presents results of a comprehensive experimental study of the effect of using conventional, high-permeability, and domain-refined grain-oriented 3% silicon iron in various parts of a small three-phase, three-limb stacked laminated transformer core. It is shown that the core building factor can be improved using certain mixtures of material and that the absolute core loss can be minimized only by using combinations of materials with suitable permeability and texture. The operating flux density and joint geometry are shown to be important factors in controlling the degree of improvement obtained. The results obtained from the models are used to predict the losses in a range of larger transformers and their costs of operation are compared by considering the capitalized cost of losses and the cost of the core materials. It is shown that it is possible to reduce the cost of operation, particularly at low or medium flux density levels, by using suitable mixtures of low- and high-permeability steel in the transformer yokes and limbs.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 18 (1983), S. 1657-1665 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The preceding paper described the general process by which the magnetic properties of electrical steels can be improved by a surface diffusion technique. This paper describes detailed effects of adding aluminium or silicon to non-oriented and grain-oriented silicon-iron. The addition of silicon proved more difficult and surface porosity tended to increase the power loss of grain-oriented steel whereas a paste containing aluminium powder was effective on all the materials although it was found that the powder size was critical. A reduction of 10% at 1.5 T in well oriented silicon-iron was achieved using the aluminium powder and an improvement in stress sensitivity of the magnetic properties also resulted.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 12 (1977), S. 187-191 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The a.c. magnetostriction of conventional grain-oriented 3 1/4% silicon-iron and more highly oriented silicon-iron has been measured from room temperature up to the Curie point using high temperature strain gauges. Curves of magnetostriction plotted against flux density showed that a definite change in the magnetization process occurred at about 300° C extending to 400° C for both types of material. This was considered to be due to the onset of magnetic annealing, considerably modified by the effect of the coating on the materials. From the experimental results the magnetostriction constant λ100 has been calculated using a predicted domain structure and was found to agree well with single crystal values apart from within the 300 to 400° C region.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 18 (1983), S. 1650-1656 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A method of adding either aluminium or silicon to electrical steel sheet from a coating applied to its surfaces is described. This is done in order to improve the a.c. magnetic properties of the material through the setting up of a controlled resistivity gradient through the thickness of the material. A paste containing the chosen element in powder form mixed with sodium silicate solution is applied to the steel, which is then heated to such a temperature as permits diffusion of the element into it. Suitable control of the amount and distribution of the element can yield reductions in iron loss, magnetostriction and stress sensitivity of the material. In this paper the controlling parameters are discussed in detail; a subsequent paper will describe a series of experiments carried out on a range of materials using both silicon and aluminium pastes.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 5 (1970), S. 463-469 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effects of heat-treatment in a magnetic field or under an applied stress have been studied in this investigation. Magnetic properties (magnetostriction and power loss in particular), measured along the rolling direction in grain-oriented silicon-iron were unaffected by magnetic annealing, but their stress-sensitivities were improved by annealing under tension. Magnetic annealing was found to be effective in non-oriented silicon-iron and also in grain-oriented material if it was annealed with the field applied along directions other than the rolling direction. The magnetic annealing results can be explained largely on the basis of the Néel-Taniguchi theory of directional ordering of atom pairs. The changes obtained by annealing under stress showed that directional order only plays a minor part. The magnetic changes could be explained by assuming that during heat-treatment under stress a process of magnetostriction strain relief occurs, forming a residual internal stress. Other alloys similar to silicon-iron showed no more response to magnetic annealing or annealing under stress than silicon-iron.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 9 (1974), S. 217-222 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The magnetic properties of grain-oriented 3 1/4% silicon-iron, as used in laminated transformer cores, are extremely sensitive to mechanical stresses. Power loss and magnetostriction (the cause of core vibration and noise) are most affected by compressive stresses. The theoretical effects of different types of stress on the domain structures of silicon-iron are correlated with measurements made on single laminations and transformer cores. The ways in which stresses can arise in cores and possible methods of avoiding or eliminating them in practice, are discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 29 (1890), S. 580-580 
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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