Impact of the Fan Design and Rotational Direction on the Thermal Characteristics of Induction Motors

Low manufacturing cost and high reliability make the induction machine suitable for different constant and variable speed applications. For machines operating in hazardous environments, the fully enclosed type is used, with limited access to the stator and rotor. Indirect air cooling method is usually employed with fins casing and an attached fan. Thus, the fan design is crucial as being the only resource to remove heat away from the machine. A poor thermal management of the electrical machine can lead to a machine failure and reduce the machine lifespan. Some machines are operating for bi-directional operation, which means the performance of the machine should be reviewed under both conditions. This paper focus on the impact of the fan cooling on the thermal profile of a 5.5 kW induction machine under bidirectional operation. Comparative studies using CFD simulations have been carried out to identify the effect of different fan types when operating at particular conditions. The performed work provides an understanding of the air flow under bi-directional operation, which notes the importance of the fan design and rotational direction in induction machines.