磁気異方性ダンパウェッジの電磁気的基礎特性

概要

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A magnetically anisotropic conductor was applied to the damper-wedge which acts as a slot wedge and damper bar in electrical rotating machinery. This conductor is composed of copper clad steel wires of 1.6mm diameter, which are aligned in the same radial direction. This means permeability in the direction of the wires, i.e. the thickness direction of the damper-wedge, is larger than the permeability perpendicular to this direction, and electrical conductivity is good. In order to evaluate the electromagnetic characteristics, a trial damper-wedge, 1.2m in length and with a steel space factor of 40% to total volume, was manufactured and mountained in a stand-still model iron core. Test results were as follows when the magnetically anisotropic damper-wedge was employed.(1) As the magnetic flux flowed well in the radial direction, the flux distribution at the core slot portion was flattened. Consequently, the ripple amplitude became small and the average flux density increased compared with cases when the non-magnetic or magnetic isotropic conductor are used.(2) The damper-wedge had a smaller skin effect for AC current than a conventional copper damper bar. The losses concentration for the damper system was relieved, so that better machine performance under heavy load condition would be obtained.