Features and Applications of Synchronous Motor

Features of Synchronous Motor

1. The synchronous motors run only at synchronous seed.

2. By varying its excitation, its power factor can be varied.

3. As it can be operated at leading power factor, it is used as a power factor correction device.

4. They are not self starting and requires an additional facility to make it self starting.

5. Under no load and over excited condition it can be used as a synchronous consdenser.

Review Question

1. Write a note on features of a synchronous motor.

Applications of Three Phase Synchronous Motor

The important characteristics of the synchronous motor is its constant speed irrespective of the load conditions, and variable power factor operation. As seen earlier its power factor can be controlled by controlling its excitation. For overexcitation its power factor is leading in nature, which is very important from the power factor correction point of view.

Due to constant speed characteristics, it is used 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.

The synchronous motors are often used as a power factor correction device, 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.

The disadvantages of synchronous motors 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.

Review Question

1. State the applications of synchronous motors.