In the first part of this thesis, I examine the theory and the application of the first order thermal model of an induction motor. This model is based on the power dissipation of the asynchronous machine and the heat transport processes. The point of this model is measuring the coil currents of the motor and calculating the stator temperature using the measured datas.
In the second part, I intruduce my measurement set-up that can be used for measuring the coil currents and the stator temperature of the selected induction motor. The load of the motor is variable: the motor is driving a car alternator, which is loaded with light bulbs. The number of the bulbs (and of course the load of the induction motor) is controllable with relays.
In the third part, I introduce the NI CompactRIO and LabVIEW platforms, and describe my VIs which are implementing the first order thermal model and the overload protection based on that model.
In the fourth part, I present the measurement results: the thermal transient behaviour of the asynchronous machine on constant nomiminal load, the results of the linear system identification, and the thermal behaviour of the motor with variable load (with a diagram that shows both the measured stator temperature and the calculated temperature using the thermal model).
Finally, I describe a lesson plan which can be used in the electrical engineer BSc and MSc courses to demonstrate the thermal transient behaviour and the thermal model of the induction motor.