Salient pole rotor

Cylindrical rotor

1. Poles are projecting out from the surface

1. The unslotted portion of the cylinder acts as poles. Hence, poles are not projecting

2. The air gap is not uniform

2. The air gap is uniform

3. Diameter is high and axial length is small

3. Small diameter and large axial length is the feature

4. mechanically weak

4. mechanically robust

5. preferred for low-speed alternators

5. preferred for high-speed alternators i.e. for turbo-alternators

6. Salient pole rotor are used in hydro power plant.

6. Cylindrical rotors are used in thermal power plant.

7. For the same size, the rating is smaller compared to the Cylindrical type.

7. For the same size, the rating is higher than the salient pole type.