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In this paper, in order to make a clear principal cause in increasing iron loss of amorphous wound cores in processing, effects of bending stress on magnetic characteristics of a Fe-based amorphous wound core are clarified. The amorphous magnetic materials have been widely used as a core material of power transformers to reduce iron loss due to their excellent soft magnetic characteristics. However, the amorphous magnetic material has an issue that the building factor (B.F.) is very large in comparison with that of grain-oriented electrical steel sheets. The amorphous transformers usually use a wound core formed by stacking plural amorphous sheets in different lengths. Bending stress is, therefore, generated at each corner of the wound core in processing. Due to this bending stress, the magnetic characteristics of the wound core deteriorate. The deterioration of magnetic characteristics of the wound amorphous core is so large because of the large magnetostriction constant. As a result, the B.F. of this material becomes larger. In order to remove the residual stress, which is generated in the wound core including the bending stress, the amorphous wound core is usually annealed in a magnetic field, which is called “a magnetic annealing.” In this paper, the effect of the magnetic annealing on the magnetic properties is studied experimentally by evaluating some wound amorphous model cores. As a result, a suitable magnetic annealing condition is clarified and the iron loss of the wound amorphous model core is reduced by 65.7%. [ABSTRACT FROM AUTHOR]

A human-size magnetic shield of cylindrical structure (inner diameter: 92 cm, length: 220 cm) has been constructed with magnetic shaking enhancement. The weights of the magnetic materials used are 69 kg for Metglas 2705M amorphous tapes and 40 kg for Permalloy tapes and the total weight was about 250 kg. The shielding factor at the center was 4000 for a transverse magnetic field of 10 /spl mu/T, 1 Hz and residual dc magnetic field was as small as 1-2 nT when compensation for open ends was applied. The noise level of the shield measured, when open end compensation was off, by a SQUID magnetometer at the center of the shield was 54 fT//spl radic/Hz at 1 Hz and 23 fT//spl radic/Hz at 10 Hz. [ABSTRACT FROM PUBLISHER]