ROTOR STRUCTURE OF DINAMO-ELECTRIC MACHINE

PROBLEM TO BE SOLVED: To provide the rotor structure of a dynamo-electric machine which increases the amount of cooling air. SOLUTION: A length of an RT bar out-of-groove portion 10b on a side opposite to a cooling fan is reduced, so that the fan effect of the out-of-groove portion is reduced. The axial length of an RT bar out-of-groove portion 10a on the cooling fan side is increased, so that the fan effect of the out-of-groove portion is increased. The axial lengths of the RT bar out-of-groove portions are controlled, so that the length on the opposite side to the cooling fan is not more than 1/3 of that on the cooling fan side. The circumference of the RT bar out-of-groove portion on the opposite side to the cooling fan is covered with the axially extended portion of an end ring, so that the fan effect of the out-of-groove portion is reduced. The RT bar out-of-groove portion on the cooling fan is constituted to be widened in the radial direction, so that the fan effect of the out-of-groove portion is increased. The RT bars with their out-of-groove portions which are widened in the radially are placed at intervals in the circumferential direction.