Synchronous Machines

Front

What is a synchronous machine?

Back

A synchronous machine is an AC rotating machine whose speed under steady state condition is proportional to the frequency of the current in its armature.

Front

What are the main uses of synchronous machines?

Back

Synchronous machines are commonly used as generators for large power systems, such as turbine generators and hydroelectric generators.

Front

What is the purpose of an excitation system in synchronous machines?

Back

The excitation system provides direct current to the synchronous generator field winding and performs control and protective functions essential for the power system.

Front

What are the advantages of brushless excitation systems?

Back

Brushless excitation systems offer savings in maintenance, no carbon dust contamination, no wear from electrical or mechanical contacts, and no consumable parts like brushes.

Front

What is synchronous impedance?

Back

Synchronous impedance is the ratio of the open-circuit emf to the short-circuit current of a synchronous machine, both values referred to the same field excitation.

Front

Why is the synchronous impedance method considered pessimistic?

Back

The synchronous impedance method gives higher values of voltage regulation than the actual value, making it a pessimistic method.

Front

What is the construction of a synchronous motor?

Back

A synchronous motor consists of a stator and a rotor. The stator has a three-phase winding, and the rotor is mostly of salient pole type.

Front

How does a synchronous motor start?

Back

Synchronous motors are started by mechanically coupling them with another motor or using a damper winding to provide initial torque.

Front

What is the principle of operation of a synchronous motor?

Back

The stator produces a rotating magnetic field, and the rotor is magnetized by DC supply. The rotor locks with the stator poles when it reaches synchronous speed.

Front

List three applications of synchronous motors.

Back

Synchronous motors are used in applications like reciprocating pumps, air compressors, and rolling mills.