18-05-2012, 04:42 PM
high speed system.
ASSIGNMENT-01.doc (Size: 21 KB / Downloads: 27)
> Why we cannot use saint pole type rotor where are need to deal with high speed system.
Salient pole type rotor is used almost entirely for slow moderate speed alternators (hydro generators). Since it is least expensive and provides ample space for the field ampere turns. Salient poles cannot be employed in high speed generators, such as turbo-generators, on account of very high peripheral speed and the difficult of obtaining sufficient mechanical strength. Such rotors have large diameters and small axial length.
In these machines .the air-gap is uniform so that the reluctance of the magnetic path is the same in all directions. Therefore the effect of armature reaction can be accounted for by one reactance the synchronous reactance. It is because the value of reactance is constant for all directions of armature flux relative to the motor.