First of all, it must be clear that the generator is only an integral part of the generator set. Power generation equipment using superheated steam is called steam turbine generator set, which consists of steam turbine and generator. The steam turbine converts the thermal energy of steam into the kinetic energy of the rotor, and then drives the generator rotor to generate electricity.

As for why superheated steam is used, you should first know two concepts: saturated steam and superheated steam. Simply put, superheated steam is reheated on the basis of saturated steam. The characteristic of saturated steam is that its temperature is at the boiling point, and once it is cooled, it will condense into water (for example, water vapor at standard atmospheric pressure 100℃ is saturated steam). On the other hand, superheated steam will not. Superheated steam is still gas after doing work and cooling. This can effectively protect the steam turbine, because the influence of condensed water is very unfavorable to the safety of the unit.

In detail, do you want to look at the knowledge about engineering thermodynamics? I'm just talking in general terms.

PS: I design power plants.