Electrical Machine First Order Short-Time Thermal Transients Model: Measurements and Parameters Evaluation

This paper deals with the measurements and parameters determination of a stator thermal model suitable to predict the winding thermal behavior during short-time thermal transient. A possible application of the proposed first order thermal network is the overcurrent limit prediction in electrical drives. Initially, a detailed description of the thermal model is reported with a deep discussion about its validity limits. Than the test methodology as well as the required measurements for the thermal parameters determination are presented and discussed. Two procedures for the thermal parameters determination are analyzed and compared. Finally, the accuracy of the thermal model and its parameters determination have been validate for five industrial induction motors with a rated power in the range of 4kW divided by 55 kW. Furthermore, the proposed short time thermal test allows the quick determination of the equivalent thermal resistance of the slot insulation system. The proposed thermal model shows an accurate prediction of the winding thermal evolution in thermal transient long up to 4 minutes.