Answer / iamdon

No.
The speed of synchronous machine can be changed by either varying
the supply frequency or varying the no of poles.

Synchronous machine runs at synchronous speed which is given by
(120*f/P),
where f=supply ferquency and P=no of stator poles.
Once the machines is designed it is not possible to alter the P but
f could be changed through cycloconverter. However in some
synchronous machines the no of poles could also be changed.

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