This document compares salient pole and cylindrical pole synchronous machine rotors. Salient pole rotors have projecting poles, larger diameters, and shorter axial lengths. They are used for lower speeds from 100-1500 RPM and require more poles. Cylindrical rotors are drum-shaped with parallel slots for windings, have smaller diameters but longer axial lengths. They are used for higher speeds from 1500-3000 RPM and typically have 2-4 poles. Cylindrical rotors have better flux distribution and output waveform but salient pole rotors may require damper windings to prevent oscillations.

1. SYNCHRONOUS
MACHINE COMPARISION
BETWEEN
SALIENT POLE
AND
CYLINDRICAL
POLES
MACHINE

2. ELECTRICAL MACHINE
Syllabus
 Introduction of Machine
 Classification of Machine
 Construction of DC, Induction & Synchronous machine
 Working Principle of
 DC Machine
 Synchronous machine
 Induction machine
 EMF Equation of
 DC Machine
 Synchronous Machine
 Comparison Between Salient And Cylindrical Poles
 …….

3. SALIENT POLES ROTOR SYNCHRONOUS MACHINE
 In salient pole type of rotor consist of large number of
projected poles.
 The rotor winding is provided on these poles and it is
supported by pole shoes.
 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.
 As the rotor speed is lower, more number of poles is
required to attain the required frequency. (N = 120f / P).
Typically number of salient poles is between 4 to 60.
 Flux distribution is relatively poor than non-salient
pole rotor, hence the generated emf waveform is not
as good as cylindrical rotor.
 Salient pole rotors generally need damper windings to
prevent rotor oscillations during operation.
 Salient pole synchronous generators are mostly used
in hydro power plants.
Diameter
Axial length

4. CYLINDRICAL POLES ROTOR SYNCHRONOUS MACHINE
 Non-salient pole or Cylindrical rotors are cylindrical in
shape having parallel slots on it to place rotor windings.
 It is made up of solid steel. Sometimes, they are also called
as drum rotor.
 They are smaller in diameter but having longer axial
length.
 Cylindrical rotors are used in high speed electrical
machines, usually 1500 RPM to 3000 RPM.
 Number of poles is usually 4 or 2.
 Windage loss as well as noise is less as compared to
salient pole rotors.
 Their construction is robust as compared to salient pole
rotors.
 Damper windings are not needed in non-salient pole
rotors.
 Flux distribution is sinusoidal and hence gives better emf.
 Non-salient pole rotors are used in nuclear, gas and
thermal power plants.
Diameter
Axial length

5. TRICK TO REMEMBER SALIENT AND CYLINDRICAL POLES

6. SALIENT POLES ROTOR
 Salient rotors have non uniform air gap
 Salient pole rotors have large diameter
 Salient rotors pole have shorter axial
length.
 They used for lower speed electrical
machines, say 100 RPM to 1500 RPM.
 Salient rotors have more number of
salient poles is between 4 to 60.
 Flux distribution is poor hence the
generated emf wave is not sinusoidal.
 Salient rotors need damper windings to
prevent rotor oscillations.
 It mostly used in hydro power plants.
 Cylindrical rotors have uniform air gap
 Cylindrical rotors have smaller diameter
 Cylindrical rotors have longer axial
length.
 It used for high speed electrical
machines,1500 RPM to 3000 RPM.
 Cylindrical rotors have less number of
poles is usually 2 or 4.
 Flux distribution is sinusoidal and hence
gives better emf.
 Cylindrical rotors have damper windings
are not needed
 It used in nuclear, gas and thermal
power plants.
CYLINDRICAL POLES ROTOR

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