Advantage and Disadvantage of synchronous condenser on power factor improving

Advantage and Disadvantage of synchronous condenser on power factor improving 

principle of operation 

A synchronous motor takes a leading current when over-excited and, therefore, behaves as a capacitor. An over-excited synchronous motor running on no load is known as synchronous condenser. When such a machine is connected in parallel with the supply, it takes a leading current which partly neutralizes the lagging reactive component of the load. Thus the power factor is improved.

Advantages

1. By varying the field excitation, the magnitude of current drawn by the motor can be changed by any amount. This helps in achieving steepless control of power factor.
2. The motor windings have high thermal stability to short circuit currents.
3. The faults can be removed easily.

Disadvantages

1. There are considerable losses in the motor.
2. The maintenance cost is high.
3. It produces noise.
4. Except in sizes above 500 kVA, the cost is greater than that of static capacitors of the same rating.
5. As a synchronous motor has no self-starting torque, therefore, an auxiliary equipment has to be provided for this purpose.