Salient pole rotors have large diameter and shorter axial length. They are generally used in lower speed electrical machines, say 100 RPM to 1500 RPM. Flux distribution is relatively poor than non-salient pole rotor, hence the generated emf waveform is not as good as cylindrical rotor.

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Hereof, what is non salient pole rotor?

Non-salient pole rotors are cylindrical in shape having parallel slots on it to place rotor windings. Damper windings are not needed in non-salient pole rotors. Flux distribution is sinusoidal and hence gives better emf waveform. Non-salient pole rotors are used in nuclear, gas and thermal power plants.

Subsequently, question is, what is meant by salient pole alternator? Salient Pole Synchronous Alternator: Salient Poles are laminated in order to reduce eddy currents. They are used in hydraulic turbines or diesel engines. Salient pole generators will have typical speed about 100 to 375 rpm.

Moreover, what are the advantages of cylindrical rotor for a turbo alternator?

Advantages of Cylindrical rotor over salient pole rotor A better mechanical balancing of the rotor is obtained. Noise less running is possible as the surface of the rotor is smooth cylindrical shape. The winding provided in the rotor is a distributed one like DC armature. Hence a better cooling surface is available.

What are the different types of rotor of alternator?

There are mainly two types of rotors used in construction of alternator: Salient pole type. Cylindrical rotor type.

Salient Pole Type

  • They have a large horizontal diameter compared to a shorter axial length.
  • The pole shoes covers only about 2/3rd of pole pitch.
  • Poles are laminated to reduce eddy current loss.
Related Question Answers

What does salient pole mean?

Definition of salient pole. : a magnet pole that projects toward the armature of an electric machine — compare consequent pole.

How many types of rotors are there?

Read More. For induction motors, there are two types of rotors: (1) squirrel cage and (2) wound rotor. Of these two types there are many variations.

What does non salient mean?

1 prominent, conspicuous, or striking. a salient feature. 2 (esp. in fortifications) projecting outwards at an angle of less than 180°

How does a rotor work?

The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator. Its rotation is due to the interaction between the windings and magnetic fields which produces a torque around the rotor's axis.

Which 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.

What is reluctance power?

Reluctance power is the additional power developed in synchronous motor or synchronous generator due to saliency of the rotor. The amount of this power may not be great but its main advantage lies in increasing the synchronising power and thereby improving the stability of the machine.

Why synchronous motors are not self starting?

Key Point : As a result, the average torque exerted on the rotor is zero. And hence the synchronous motor is not self starting. This is because the speed with which rotating magnetic field is rotating is so high that it is unable to rotate the rotor from its initial position, due to the inertia of the rotor.

What is damper winding?

Definition of damper winding. : a short-circuited squirrel-cage winding placed in the pole faces and around the pole shoes of synchronous machines, the currents induced in the winding by the periodic variations in synchronous speed having the effect of a damper. — called also amortisseur.

How many types of alternator are there?

The five different types of alternators include:
  • Automotive alternators – used in modern automobiles.
  • Diesel-electric locomotive alternators – used in diesel electric multiple units.
  • Marine alternators – used in marine applications.

What is meant by turbo alternator?

Turbo-alternators are basically hydrogen cooled cylindrical rotor alternators used to generate electric power in generating stations. They have only 2 poles and are run by a 3000 rpm turbine for 50 Hz machine and 3600 rpm for 60 Hz machine.

What is saliency in synchronous machines?

(1) Salient pole machines develop some extra power due to saliency. This is called reluctance power. Thus, due to saliency, a synchronous motor can run at light load even without field energized, like a reluctance motor.

Which rotor is used in thermal power plant?

Cylindrical pole high speed rotors are used in high speed gas and steam turbine generators which operate at 1,000rpm and above. This rotor is used in applications where a distributed winding is required. The rotor body is made from laminations with slots to take the windings.

Why cylindrical rotor alternators have small diameter and large core length?

At higher speeds, rotor diameter has to be decreased to keep centrifugal forces in check in cylindrical rotor machine and vice-versa for salient-pole machine. Hence A has to be kept constant. where rotor radius and axial length. Thus cylindrical rotor will have a longer axial length in contrast to salient-pole rotor.

What is the work of alternator?

An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.

How does a car generator work?

The battery provides electricity needed for the starter motor to start the car. When the car is running, the alternator generates energy to feed the electrical system and charge the battery. The alternator used to be called a generator, and it works in a similar way. The output of an alternator is direct current (DC).

What are the advantages of salient pole type construction used for synchronous machines?

Advantages of salient-pole type construction are : They allow better ventilation. The pole faces are so shaped that the radial air gap length increases from the pole center to the pole tips so that the flux distribution in the air-gap is sinusoidal in shape which will help the machine to generate sinusoidal emf.

What is synchronous speed?

In a motor, synchronous speed is the speed at which the magnetic field rotates. Depending on motor design, the actual mechanical speed may be equivalent (synchronous motor) or slightly smaller (asynchronous motor). The synchronous speed is a function of:The electrical frequency used, typically 60 Hz or 50 Hz.

What is meant by two reaction theory?

Two Reaction Theory was proposed by Andre Blondel. The theory proposes to resolve the given armature MMFs into two mutually perpendicular components, with one located along the axis of the rotor of the salient pole. It is known as the direct axis or d axis component.

What is synchronous reactance?

The Synchronous Reactance (XS) is the imaginary reactance employed to account for the voltage effects in the armature circuit produced by the actual armature leakage reactance and by the change in the air gap flux caused by the armature reaction.