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Synchronous Motor


Definition: The motor that runs at synchronous speed is understood because of the Synchronous motor. The synchronous speed is that the constant rate at that the motor generates the voltage. The Synchronous motor is employed for changing the voltage into energy.


Construction of Synchronous motor:-

The stator coil and also the rotor are the 2 main elements of the Synchronous motor. The stator coil becomes stationary, and it carries the coil winding of the motor. The coil winding is that the main winding as a result of that the electromotive force induces within the motor. The rotator carries the sector windings. Most field flux induces within the rotor. The rotor is intended in 2 ways in which, i.e., the salient pole rotor and also the non-salient pole rotor.

The Synchronous motor uses the salient pole rotor. The word salient means that the poles of the rotor projected towards the coil windings. The rotor of the Synchronous motor is created with the laminations of the steel. The laminations scale back the eddy current loss happens on the winding of the Synchronous motor. The salient pole rotor is usually used for planning the medium and low-speed motor. For getting the high-speed cylindrical rotor is employed within the motor.


Synchronous Motor operating:-

The stator coil and rotor are the 2 main elements of the Synchronous motor. The stator coil is stationary half, and also, the rotor is that rotating a part of the motor. The three-phase AC offer is given to the stator coil of the motor.

The stator coil and rotor each are excited severally. The excitation is causing the force field on the elements of the motor with the assistance of electrical current.

When the 3 section offer is given to the stator coil, the rotating force field developed between the stator coil and the rotor gap. The sector having moving polarities is understood because of the rotating force field. The rotating force field develops solely within the multiphase system. As a result of the rotating force field, the north and south poles extend on the stator coil.

The rotor is happy with the DC offer. The DC offers induces the north and south poles on the rotor. Because the DC offer remains constant, the flux induces on the rotor remains the same. Thus, the flux has a fastened polarity. The North Pole develops on one finish of the rotor, and also, the pole extends on another finish.

The AC is curving. The polarity of the wave changes in each [*fr1] cycle, i.e., the wave remains positive within the half-cycle and becomes negative within the half cycle. The positive and negative [*fr1] cycle of the wave develops the north and pole on the stator coil severally.

Why the synchronous motor isn't self-starting?

When the rotor and stator coil each have an equivalent pole on an equal facet, they repel one another. If they need opposite poles, they attract one another. This will simply be understood with the assistance of the figure shown below.synchronous-motor-circuit-diagram The rotor draws towards the pole of the stator coil for the primary [*fr1] cycle of the provision and repulse for the half cycle. Therefore the rotor becomes pulsated solely in one place. This can be the explanation as a result of that the Synchronous motor isn't self-starting.

The pulsating-of-rotors cause is employed for rotating the motor. The reason rotates the rotor at the synchronous speed. The synchronous speed is the constant speed of the motor whose price depends on the frequency and also the numbers of the pole of the device.

When the rotor starts rotating at their synchronous speed, the cause is disconnected to the motor. and also the DC offer is provided to the rotor as a result of that the north and pole develops at their ends

The north and south poles of the rotor and also the stator coil interlock one another. Thus, the rotor starts rotating at the speed of the rotating force field. and also the motor runs at the synchronous speed. The speed of the motor will solely be modified by dynamical the frequency of the provision.

Alternative Answer to this Question

Why synchronous motor isn't self-starting?

At a specific instant, rotor and stator coil poles can be of a similar polarity (N-N or S-S) inflicting a force on the rotor and also the terribly next instant it'll be N-S inflicting attraction. The inertia of the rotor, it's unable to rotate in any direction because of that enticing or repulsive forces, the rotor remains in standstill condition. Therefore synchronous motor isn't self-starting.

Here we have a tendency to use some mechanical suggests that that at first rotates the rotor within the same direction because the flux to hurry terribly about to synchronous speed. On achieving synchronous speed, a magnetic lockup happens, and also the synchronous motor continues to rotate even once the removal of external mechanical suggests that.

But the inertia of the rotor, it's unable to rotate in any direction because of repulsive forces, the rotor remains in standstill condition. Therefore synchronous motor isn't self-starting.

Here we have a tendency to use some mechanical suggests that that at first rotates the rotor within the same direction because the flux to hurry terribly about to synchronous speed. On achieving synchronous speed, a magnetic lockup happens, and also the synchronous motor continues to rotate even once the removal of external mechanical suggests that.


Methods of Starting of Synchronous motor

External prime Mover:- Synchronous motors square measure automatically in addition to another motor. It may well be either a three-part induction motor or DC shunt motor. Here, we have a tendency to don't apply DC excitation at first. It rotates at speed terribly about to its synchronous speed, and so we have a tendency to provide the DC excitation. Once your time, once magnetic lockup takes place to offer to the external motor is stopped.


Damper winding:- during this case, the Synchronous motor is of salient pole kind. The extra winding is placed in the rotor pole face. Initially, once the rotor isn't rotating, the relative speed between damper winding associate degreed rotating air gap flux is massive, and an electrical current is elicited in it that produces the specified beginning torsion. As speed approaches synchronous speed, rotor current and torsion square measure reduced, and at last, once magnetic lockup takes place, torsion additionally reduces to zero. Therefore during this case Synchronous motor initial runs as 3 part induction motor victimization extra winding, and at last, it's synchronous with the frequency.



Main features of Synchronous motor:-


  1. The speed of the Synchronous motor is not dependent on the load, i.e., the variation of the load doesn't have an effect on the speed of the motor.
  2. The Synchronous motor isn't self-starting. The cause is employed for rotating the motor at the synchronous speed.
  3. The Synchronous motor operates each for leading and insulating material power issues.
  4. The Synchronous motor also can be started with the assistance of the damper windings.

Read More About Electrical Motor


Explanation Of AC Induction Motor: Working Principle, Type, and details of AC Induction Motor



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