5 Describe the fundamental differences between a single phas

5. Describe the fundamental differences between a single phase induction motor and a 3 phase squirrel cage induction motor in terms of construction, feeding, speed and price. On what basis you would decide which type to purchase?

Solution

CONSTRUCTION:   The construction of the stator of asynchronous motor is similar to that of three phase squirrel cage induction motor except there are two dissimilarity in the winding part of the single phase induction motor.

Firstly the single phase induction motors are mostly provided with concentric coils. As the number of turns per coil can be easily adjusted with the help of concentric coils, the mmf distribution is almost sinusoidal.

Except for shaded pole motor, the asynchronous motor has two stator windings namely the main winding and the auxiliary winding. These two windings are placed in space quadrature with respect to each other.

The construction of rotors of both the motors are similar.

PRICE: The single phase induction motors are cheaper for smaller ratings, Based on your objective of using the motor like optimum performance if u want, then you can buy the single phase which is at lower price and also maintainance is easy.

SPEED: A three phase induction motor is basically a constant speed motor so it’s somewhat difficult to control its speed. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. single phase induction motor rotes at a speed less than the synchronous speed