Abstract: A twin-shaft concentric motor includes first and second stators arranged concentrically to each other; and first and second rotors formed between the first and second stators, the rotors being rotatable independently of each other. The twin-shaft concentric motor may also include first and second stator partition walls and first and second rotor partition walls for maintaining a vacuum side and an atmospheric side separated, respectively, so that the stators are located under atmospheric pressure while the rotors are located under vacuum pressure.

Abstract: A magnetic slot wedge inserted in each slot of a stator core of a dynamo-electric machine so as to close an opening of each slot for preventing coils embedded in each slot from getting out of each slot is disclosed. The slot wedge includes a first thin non-magnetic sheet such as a polyester film having the thickness of several ten microns or an aromatic aramid paper, an amorphous sheet bonded to one of two faces of the first non-magnetic sheet opposite the other face facing a coil side in the condition that the wedge is inserted in each slot, and a second thin non-magnetic sheet bonded to the amorphous sheet so as to cover it. Each non-magnetic sheet has such dimensions that each non-magnetic sheet is projected from both ends and both side edges of the amorphous sheet.

Abstract: A slot insulating magnetic wedge inserted into the vicinity of the center of an opening portion of a stator slot, the slot insulating magnetic wedge being contacted with an inner surface of the stator slot of a motor. The slot insulating magnetic wedge comprises a non-magnetic insulating thin leaf shaped material and a magnetic material layer laminated on at least one surface of the non-magnetic insulating thin leaf shaped material, the electric resistance of the magnetic material layer being in the range from 10 .mu..OMEGA..cm to 200 .mu..OMEGA..cm. The magnetic material layer comprises an amorphous magnetic alloy thin film, a Fe-based magnetic alloy thin ribbon having ultra fine crystalline particles, a crystalline magnetic alloy thin ribbon, a crystalline or amorphous magnetic alloy thin film produced by thin film forming technologies, or the like. The magnetic material layer with the electric resistance in the range from 10 .mu..OMEGA..cm to 200 .mu..OMEGA..

Abstract: A rotating electric machine provided with coils of various phases constituting 3-phase armature winding which are divided into first and second groups or circuits. A first circuit formed of selected sub-groups of coils of various phases is energized at the start of the electric rotating machine. A second circuit is formed of the remaining coils of various phases which are so connected as to generate an induced electromotive force having an equal magnitude to that which is produced in the first circuit. Said second circuit is connected in parallel with the first circuit to be energized at the full drive of the rotating electric machine.