Experimental assessment of end region cooling arrangements in induction motor endwindings

In this study the impact of different end region cooling arrangements on the endwinding heat transfer is analysed and discussed. An experimental approach to solving the problem has been adopted; two special prototypes have been built and a test bench has been assembled. Open drip proof `ODP` and total enclosed fan-cooled `TEFC` frames have been taken into account. In addition, the cooling effect of the fins, always present in the induction motor cage end rings, has also been analysed. The study reports in detail the set-up of the test procedures and the obtained results. Particular care has been devoted to the determination of the heat transfer coefficients concerning the thermal transfer between endwinding and the external frame. The obtained results are of basic importance for the determination of the thermal resistances between endwindings and end caps to be utilised in thermal networks usually adopted in thermal model analysis.