Difference between salient pole & cylindrical pole rotors:
We can define a synchronous generator or alternator as a machine which converts mechanical energy into alternating type electrical energy. It consists of a stator and a rotor. Stator consists of stationary armature windings and rotor consists of fielding winding. The rotor is two types
1.Salient Pole type
2.Cylindrical pole type
This textbook "Electrical Machinery by P.S. Bhimbhra" is the best in industry. Grab it now for very less price.
Depending on the type of rotor Synchronous Generator[Alternator] has been classified into two types:
1.Salient Pole Alternator:
- Poles are projecting out from the surface.
- The air gap is non-uniform.
- Diameter is high and the axial length is small.
- Mechanically weak.
- Preffered for low-speed alternators.
- Prime mover used are water, I.C. engines.
- For the same size, the rating is smaller than the cylindrical type.
- This rotor is also called as Projected pole type.
- This is preferred for low-speed alternators ranging from 125 r.p.m to 500 RPM
- Separate damper winding is provided.
2.Cylindrical Pole Alternator:
- Unslotted portion of the cylinder acts as poles hence poles are non-projecting.
- The air gap is uniform due to the smooth cylindrical periphery.
- Small diameter and the large axial length is the feature.
- Mechanically strong.
- Preferred for high-speed alternators
- Prime movers used are steam turbines, electric motors.
- For the same size, the rating is higher than Salient pole type.
- This rotor is also called as non-salient or non-projected pole type.
- This is preferred for high-speed alternators ranging from 1500 r.p. m to 3000 RPM.
- Separate damper winding is not provided.