Difference between Single Phase and Three Phase Induction Motor

The differences between single phase and three phase induction motor are explained on the basis of very important practical factors such as power source, starting mechanism, starting torque, cost, operational reliability, power factor, size, maintenance, structure, and uses.The following table presents the key differences between single-phase induction motor and three phase induction motor.

The main difference between single phase induction motor and three phase induction motor is that single phase motors are NOT self-starting so they require some starting mechanism while three-phase motors are self-starting. Furthermore, single phase motor requires ONLY single phase supply so they produce an alternating magnetic field whereas three phase motor requires three phase supply so they produce rotating magnetic field.

Single phase IM is mainly utilized in household applications like in fans, refrigerator, grinder, and Air Conditioner. Three phase IM is primarily used in various industries, factories such as paper mills and for traction purposes.

Difference between Single Phase and Three Phase Induction Motor

Characteristics	Single Phase induction Motor	Three Phase Induction Motor
Power Source	Single Phase (1-phase) Only	Generally requires more than a single phase power source (like 3-phase supply).
Starting Mechanism	They are NOT self-starting.	They are self-starting.
Efficiency	Low as only one winding has to carry all the current	High because three winding are available to carry the current
Types	Shaded pole Split Phase Capacitor Start Inductor Run Capacitor Start Capacitor Run	Squirrel cage type Slip ring type or wound induction motor
Cost	Cheaper	Quite Expensive
Slip (s)	There are two slips: Forward slip (s) Backward slip (2-s)	It has only forward slip
Size (for same power rating)	Larger in size	Smaller in size
Power Factor	Low	High
Repair & Maintenance	Easier to repair	Difficult to repair and maintain
Structure	Simple and easy to manufacture	More complicated to construct because of extra components involvement
Starting Torque	Low	High
Operational Reliability	More Reliable	Less Reliable
Motor Rotation	There is no mechanism to change the rotation.	Can be changed easily by changing the phase sequence in stator.
Uses	Frequently used for lighter loads. such as: Blowers Vacuum cleaner fans Centrifugal pump Washing machine Grinder Compressor	Extensively employed in industrial and commercial drives since they are more rugged and economical in terms of operational efficiency.