Table of Contents
What affects the synchronous speed of an alternator?
The synchronous speed is the speed of the revolution of the magnetic field in the stator winding of the motor. Thus, an AC machine in which the rotor moved at a speed and built a constant relationship between the frequency of the voltage in the armature winding and the number of poles is called a Synchronous Machine.
Why should an alternator run always at synchronous speed?
Some motors are designed to operate at synchronous speed. The reason for this is if the armature turns exactly at synchronous speed, then the magnetic field of the stator windings no longer cuts the rotor windings. Under this condition, no current would be induced to the rotor windings.
Is alternator a synchronous generator?
The rotating magnetic field induces an AC voltage in the stator windings. Since the currents in the stator windings vary in step with the position of the rotor, an alternator is a synchronous generator.
Why alternator is also called synchronous generator?
In case of alternator, the RMF speed matches the rotor speed, since the rotor field circuit generates a constant magnetic field, hence it is also called synchronous generator.
Why is synchronous speed constant?
In the synchronous motor, rotor too have a DC excitation, so it produces a constant flux forming the electromagnetic poles on rotor which initially are stationary. Even on loading, the speed is always constant but the torque angle (between stator and rotor magnetic poles) may vary.
What happens when you load a synchronous motor or generator?
Loading either a synchronous motor or generator will result in a drop in speed for both. In the case of the motor as the speed drops the electrical torque will increase as the load angle increases until electrical and mechanical load torque are balanced and the motor will run synchronously again but at a larger lagging load angle than before.
What is the synchronous speed of an alternating machine?
It is the speed at which the electromotive force is produced by the alternating machine. The Synchronous Speed is given by the relation shown below. The above equation (1) shows that the rotor speed N bears a constant relationship with the field poles and the frequency of the generated voltage in the armature winding.
What is the difference between synchronous generator rotor and field winding?
In a synchronous generator, a DC current is applied to the rotor winding producing a rotor magnetic field. The rotor is then turned by external means producing a rotating magnetic field, which induces a 3-phase voltage within the stator winding. Field windings are the windings producing the main magnetic field (rotor windings
What is meant by synchronous machine?
A machine which runs at synchronous speed is called synchronous machine. Thus, an AC machine in which the rotor moved at a speed and built a constant relationship between the frequency of the voltage in the armature winding and the number of poles is called a Synchronous Machine.