Experimental study of the cooling of a closed type electric motor

The present study aimed at the optimization of the external surface of an induction motor of closed type and is carried out experimentaly by considering, in parallel, the thermal aspects and flow distribution around the motor casing. Three non intrusive methods of investigation are used: determination of wall temperature fields by infrared thermography, flow visualization by laser sheet and measurement of velocity distribution by laser Doppler anemometry. The results obtained on an already commercialized motor display important overheating of several zones at the casing surface, and have led to the design of a new configuration of motor casing. The study of a prototype motor, equipped with the modified casing, shows a significant improvement of the casing irrigation, and consequently an appreciable decrease in surface temperatures.