Synchronous motor always runs at constant synchronous speed irrespective of the load and variable power factor operation. As seen earlier its power factor can be controlled by controlling its excitation. For over-excitation its power factor is leading in nature, which is very important from the power factor correction point of view.
Applications of Synchronous Motors
We use synchronous motors where we need almost constant speed in the operation.So applications of synchronous motors list goes like this, we use them in,
- Machine tools,
- Motor generator sets,
- Synchronous clocks,
- Stroboscopic devices,
- Timing devices,
- Belt driven reciprocating compressors,
- Fans and blowers,
- Centrifugal pumps,
- Vacuum pumps,
- Pulp grinders,
- Textile mills,
- Paper mills line shafts,
- Rolling mills,
- Cement mills etc.
Some more uses of synchronous motors:
Not only for the above purposes we also use synchronous motors for power factor correction.You might have known about synchronous condenser[If not read here].Also used as phase advancers and phase modifiers for voltage regulation of the transmission lines. This is possible because the excitation of the synchronous motor can be adjusted as per the requirement.
Disadvantages of synchronous motor :
The disadvantages of synchronous motor are their higher cost, necessity of frequent maintenance and a need of d.c. excitation source, auxiliary device or additional winding provision to make it self starting. Overall their initial cost is very high.