Heating of railway motors in service and on test-floor runs

M. R. Hanna: Mr. Luke has shown the difficulty of calculating accurately the temperature of the various parts of a motor when operating on an intermittent duty cycle. However I would like to point out that it is possible to obtain quite satisfactory results without any great difficulty by considering larger sections of the motor. In the case of inclosed or slightly ventilated motors we can consider the motor as a whole and in the case of well-ventilated motors we may consider the armature as a whole and each of the field windings as separate units.