Turbine rated speed varies mainaly on the factors of Generating frequency and means of coupling to generator (viz trough a gear box or directly coupled and no.poles in generator). For exmple a 50hz...
Turbine shaft material has its own natural frequency, when turbine rotates on such a speed that frequency of shaft become close to its natural frequency, machine causes noise & high vibrations...
Steam (under pressure) comes into contact with the blades of the turbine through which it is flowing and, by the direct application of force, causes the blades to move, turning the turbine shaft. The...