- Single phase induction motors are in very wide use in industry especially in fractional horse-power field,
They are extensively used for electric drive for low power constant speed apparatus such as machine tools, domestic apparatus and agricultural machinery in circumstances where a three-phase supply is not readily available,
- There is a large demand for single-phase induction motors in sizes ranging from fraction of horse-power upto about 5 H.P.
Though these machines are useful for small outputs, they are not used for large powers as they suffer from many disadvantages and are never used in cases where three-phase machines can be adopted.
The main disadvantages of single-phase induction motors are:
- Their output is only 50% of the three-phase motor, for a given frame size and temperature rise.
- They have lower power factor.
- These motors do not have inherent starting torque.
- More expensive than three-phase motors of the same output.