PURPOSE: To provide ease of magnetic shield installation without degrading the stray loss reduction effect by using a thick magnetic material magnetic shield in the vicinity of a nonmagnetic material magnetic shield and passing leakage flux through the thick magnetic shield for it to be absorbed.
CONSTITUTION: Magnetic material magnetic shields 4a, 4b using a stacked-layer Si steel plate are arranged at the side of a long arm 3a where the magnetic shield installation is easily made, while a nonmagnetic material magnetic shield 5 using steel is directly installed at the side of a short arm 36 where the installation is difficult. This makes the installation of the magnetic shield easy and also makes its installation simple in structure as compared to the installation of the magnetic material magnetic shield along the entire side wall of a tank. Since the magnetic material magnetic shields 4a, 4b having the superior stray loss reduction effect are arranged on a larger part of the tank wall (i.e., the long arm side 3a) and leakage flux ρ repelled by the nonmagnetic material magnetic shield 5 is absorbed by passing it through the thick magnetic shield 4b near the shield 5, the reduction of stray losses can be achieved.
KATADA KUNIO
KUDOU UICHI
KIKUCHI SHIGEO
