What is a salient pole rotor?

What is a salient pole rotor?

What are Salient Pole rotors? Salient pole rotors are large in diameter and shorter in length. They are typically used in lower speed electrical machines (100 RPM to 1500 RPM). Salient pole rotors normally require damper windings to avoid oscillations of rotors during operation.

What is salient pole type?

In salient pole type of rotor consist of large number of projected poles (salient poles) mounted on a magnetic wheel. Construction of a salient pole rotor is as shown in the figure at left. The projected poles are made up from laminations of steel.

What do you mean by salient and non salient pole rotor?

Based on the construction the rotor of an electrical machine is classified into two types. They are, Salient pole type or projected pole type rotor ( low speed, more number of poles, kaplan turbines ) Non-salient type or smooth cylindrical type rotor ( high speed, 2 or 4 poles, pelton wheel )

What is 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.

Why salient pole rotor is laminated?

A salient pole rotor is made from steel laminations to minimize loss of electric current. This is because the rotor is subject to magnetic field changes. Poles with the same dimensions are assembled to the necessary length via stacking laminations.

What is XD and XQ?

To determine the direct axis reactance (Xd) and quadrature axis reactance (Xq) of synchronous machine.

What is salient pole rotor made of?

A salient pole rotor is made from steel laminations to minimize loss of electric current. This is because the rotor is subject to magnetic field changes. Poles with the same dimensions are assembled to the necessary length via stacking laminations. There is a non-uniform air gap in a salient pole rotor.

What are the advantages of salient pole type of 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 salient pole generator?

A Salient Pole Synchronous Generator, as shown in Fig. 4.29, is distinguished from a round rotor machine by constructional features of field poles which project with a large interpolar air gap.

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.

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.

What is the slip test?

The slip test is a simple no-load test, which is used to determine the direct-axis and quadrature-axis synchronous reactances of a salient-pole synchronous machine. In this test, a small voltage at rated frequency is applied to the 3-phase stator winding of the synchronous machine.

Where is salient pole used?

Where is the salient pole rotor used? About the salient pole rotor speed, it is mainly used for low- and medium-speed output because of its mechanical instability at higher speeds. It is used in hydropower plants. It is also used in water turbine-powered in low-speed generators.

What are the advantages of salient pole alternator?

Right Answer is: D Advantages of salient pole machine are: It develops an extra power called reluctance power due to saliency. It is more stable because it has a higher synchronizing power. Adaptability to low and medium speed operations, hence used in hydro power plants.

What are the advantages of salient pole rotor?

Which type of rotor is best for alternator?

Smooth cylindrical type rotor is generally used for high speed alternators or turbo alternators.

What are the advantages of salient pole type construction?

What is hunting in machine?

Hunting is the phenomenon of oscillation of the rotor about its steady state position or equilibrium state in a synchronous motor. Hence, hunting means a momentary fluctuation in the rotor speed of a synchronous motor.

Why damper windings are used in salient pole generators?

Main Purpose of damper winding in the generator Prevents hunting (momentarily speed fluctuations) in the alternator, Increases the transient stability. Provides high starting torque to the synchronous motor.