Temperature rise within the rotor of squirrel cage induction machines with solid iron and laminated rotors during run up and standstill

The electrical and thermal behaviour of induction motors with solid and laminated rotors is compared. In particular, temperature rises within the rotor during standstill and run ups are investigated. The investigation is based on a finite difference time-stepping method, which takes the motion of the rotor into account. The calculation method is verified by comparison with measurements on a 22 kW induction motor. The temperature rise depends upon the position of the rotor bars compared with the stator winding during standstill. Differences up to 50% occur on account of the position. Specialities in the temperature distribution are elaborated for the solid iron rotor and are compared with the results of laminated induction motors.