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. |
