Heating of an induction motor at reversing duty

This work attempts to find values of thermal resistances for the heating simulation of an induction motor by measurement on this motor. This article works with the assumption of a special case in that it is not possible to bring up an external load torque on the shaft. Nevertheless it should be possible to measure temperatures according to the insulation class of the motor. These claims can be met by the reversing duty of the induction motor with different periods and duty factors. The very useful measurements of rotor temperatures were realised by a measurement transmission with silver slip rings. The base of the equivalent thermal network is a four body model. The thermal capacities were specified by measurement of the different masses and by calculation from drawings. The different losses are broken down by calculation in different parts and used as input for the equivalent thermal network in which only the thermal resistances are unknown. A set of several different measurements (and equations) are available which allow the specification of the thermal resistances.