To improve welding efficiency and elongate the life by laminating a silicon steel plate which contains a given component of Si, and has a given thickness and an insulation film of a given thickness, and storing it in a insulating case at a given fill factor.
When a silicon steel plate is laminated and filled in a core of an impeder, the Si content of the silicon steel is 5-8 mass %. The welding efficiency is improved by deciding the plate thickness of the silicon steel to 0.1 mm or less. Also, for the purpose of obtaining the enough insulating property between the laminated plates, an inorganic system or organic system insulating material having the heat resistance at 800°C or more, is coated on the surface of the silicon steel plate, so as to form an insulating film with the thickness of 2 μm or more. Phosphate magnesium and the like can be applied as the inorganic system insulating material, and epoxy resin and the like as the organic system insulating material. Furthermore, the fill factor at the time when the silicon steel plate is laminated and stored in the insulating case (the ratio of the core sectional area against the sectional area of the space in the case) is 50% or more.
TANAKA NOBUKI
TOYOOKA TAKAAKI
ITAYA MOTOAKI
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