Synchronous Motor |
Induction Motor |
|---|---|
| Synchronous motor construction is complicated. | Induction motor construction is simpler, particularly in case of cage rotor. |
| This is Not self starting. | This is self Starting |
| Separate DC source is required for rotor excitation. | Rotor gets excited by the induced e.m.f so separate source is not necessary. |
| The speed is always synchronous irrespective of the load | The speed is always less than synchronous but never synchronous. |
| In synchronous motor speed control is not possible. | In induction motor Speed control is possible through difficult. |
| As load increase, load angle increases, kipping speed constant at synchronous. | As load increases, the speed keeps on decreasing. |
| By changing excitation, the motor p.f can be changed from lagging and leading. | It always operates at lagging p.f. and p.f. control is not possible. |
| It can be used as synchronous condenser for p.f. improvement. | It cannot be used as synchronous. |
| Motor is sensitive to sudden load changes and hunting results | Phenomenon of hunting is absent |
| Motor is costly and requires frequent maintenance | Motor is cheap, especially cage rotors and maintenance free. |
