What Is The Principle Of Synchronous Machine?


The principle of operation of a synchronous motor can be understood by considering the stator windings to be connected to a three-phase alternating-current supply. The effect of the stator current is to establish a magnetic field rotating at 120 f/p revolutions per minute for a frequency of f hertz and for p poles.



What is the principle of synchronous machine?

The principle of operation of a synchronous motor can be understood by considering the stator windings to be connected to a three-phase alternating-current supply. The effect of the stator current is to establish a magnetic field rotating at 120 f/p revolutions per minute for a frequency of f hertz and for p poles.


What is the V-curve explain?

V curve is a plot of the stator current versus field current for different constant loads. The Graph plotted between the armature current Ia and field current If at no load the curve is obtained known as V Curve.


What are V curves in synchronous motor?

V Curve of Synchronous Motor: V curve is a plot of the Armature current versus Field current for different constant loads. The armature current changes with the change in the field current.


What is the use of V and inverted V curves?

The graphs obtained by plotting the armature current and field current of a synchronous motor are called the V curves. Similarly, the inverted V curves give the relation between the power factor and field current.


What is the inverted V-curve?

The Inverted V Curve is a graph showing the relation of power factor as a function of field current.


What is difference between synchronous motor and alternator?

The main difference between Alternator and Synchronous motor is, Alternator is an electricity generating machine that converts mechanical energy into electrical energy in the form of alternating nature whereas a synchronous motor is an electricity consuming machine that converts electrical energy into mechanical energy


What is pitch factor in alternator?

Pitch factor: In an alternator, the factor by which the full pitch voltage is multiplied to get voltage generated in fractional pitch is called a pitch factor. Pitch factor is defined as, Pitch factor = Resultant emf of a short-pitched coil/ Resultant emf of the full pitched coil.


Is synchronous motor and generator same?

Almost all aspects of synchronous motor like construction, working, is similar to the synchronous generator but the difference is that generator converts mechanical power into electrical and motor converts electrical into mechanical.


What are types of rotors used in alternators?

There are mainly two types of rotors used in construction of alternator:

  • Salient pole type.
  • Cylindrical rotor type.


Is synchronous generator same as alternator?

Synchronous generators are also referred to as alternators or AC generators. The term "alternator" is used since it produces AC power. It is called synchronous generator because it must be driven at synchronous speed to produce AC power of the desired frequency.


What are the advantages of an induction motor?

Induction Motor Advantages:

They are maintenance free motors unlike dc motors and synchronous motors due to the absence of brushes, commutators and slip rings. Induction motors can be operated in polluted and explosive environments as they do not have brushes which can cause sparks.


How do you reduce synchronous speed?

However, with the invention of solid-state devices, the frequency of the current fed to the synchronous motor can be varied. We can control the speed of the synchronous motor by changing the frequency of the supply to the motor.


What is the efficiency of synchronous motor?

Synchronous motors can achieve efficiencies of >90% in some cases and are generally more energy-efficient than induction motors.


What are the special features of synchronous motor?

Main Features of Synchronous Motors

Synchronous motors are inherently not self starting. They require some external means to bring their speed close to synchronous speed to before they are synchronized. This motor has the unique characteristics of operating under any electrical power factor.


What is an AC synchronous machine?

A synchronous electric motor is an AC electric motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integral number of AC cycles.


Which type of rotor is used in synchronous motor?

Cylindrical, round rotors, (also known as non salient pole rotor) are used for up to six poles. In some machines or when a large number of poles are needed, a salient pole rotor is used. The construction of synchronous motor is similar to that of a synchronous alternator.


How do you calculate torque of a synchronous motor?

Torque in a Synchronous Motor

  1. Pm=2πNSτg60Watts(
  2. Pm=VIaCos(δ−φ)(
  3. τg=602πPmNS=9.55×PmNSN−m(
  4. τsh=9.55×PoNSN−m(


What is V-curve of synchronous motor?

A V-curve of a synchronous motor shows the relation between armature currents as ordinates and field currents as abscissas when the motor operates with a constant power input at rated terminal voltage.


Why are synchronous motors more efficient?

Synchronous motors generally have a higher power density than induction motors of comparable size, allowing them to provide more power at a smaller volume. This is great for size-constrained applications and is a reason to choose a synchronous motor over an induction motor.


What are the advantages of synchronous motors?

Advantages of Synchronous Motor

  • It operates at a constant speed (i.e., synchronous speed) from no-load to full-load.
  • Power factor of a synchronous motor can be easily controlled by changing the excitation of the motor.
  • For low speed (< 300 RPM) applications, synchronous motors are more economical than induction motors.


Dated : 12-Jun-2022

Category : Education

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