Constructional Details of Salient Pole Alternator

     TYPES OF ROTORS:


The two types of rotors are used in alternators.
  •  Salient pole type
  •  Smooth cylindrical type.

SALIENT POLE TYPE:


  Digital-computer program for design-analysis of salient, wound pole alternators (NASA technical note)
  • It is used in low and medium speed alternators.
  •    It has a large number of projecting poles having their cores bolted or dovetailed onto a heavy magnetic wheel of cast iron (or) steel of good magnetic quality.
  •     It has large diameters and short axial lengths.  
                  Ex: water turbine (or) Diesel engine.
  •  The poles and pole –shoes are laminated to minimize heating due to currents.
  •    In large machines, field windings consist of rectangular copper strip wound on edge.
  •    They are built with vertical shaft.
  •    The stator slots on pole shoes are skewed to reduce tooth ripples. the ventilation is increased by providing fan blades.


   
    


















SMOOTH CYLINDRICAL TYPE:
  •     It is used for steam turbine-driven alternators which run at very high speeds.
  •     Hence turbo –generators are characteristics by small diameters and very long length.
  •     The cylindrical construction of the rotor gives better balance and quiter operation and also less   windage losses.

DIFFERENCE BETWEEN SALIENT AND CYLINDRICAL TYPE OF ROTOR


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