On the Influence of Stator Slot shape on the Energy Conservation Associated with the Submersible Induction Motors

Problem statement: A good design of Submersible Induction Motor is required to maintain maximum efficiency level. This can be achieved in one way by optimum design of magnetic circuit. The magnetic circuit of an Induction Motor is formed by the combination of Stator core, Rotor core and air gap. In applications like Submersible Motor Pumps, the air gap cannot be minimized beyond 0.5 mm, because of the machining tolerance required, due to large core length. Now a day, the efficiency of such motor is improved by die-cast copper rotor. But the cost of such motor is more and sometimes the rotor core properties are getting changed due to high temperature during die- casting process. Approach: A new stator slot shape is proposed based on the results obtained from the iterations with Rotational Machine Expert (RMxprt) software and the performance is compared with that of the existing stator slot shape, for a 3-phase, 5 hp, 380 V, 2-pole motor The motor with both the stator slot shapes have been analyzed with the Rotational Machine Expert (RMxprt) software. Results: The magnetizing current of new design is 3.25 A, compared to the existing design of 4.67 A. The overall efficiency of the Submersible Induction Motor pump set is 5% more than that of the existing one. The discharge of the pump set has increased by about 80 liters per minute. Conclusion: The proposed stator slot dimension is suitable for more efficiency, less magnetizing current and a good power factor. This design modification does not require much cost and needs no complex manufacturing process.