Editing Steam turbine (section)

==Direct drive==
[[File:Dampfturbine 5 MW mit ELIN Generator.jpg|thumb|A direct-drive 5 MW steam turbine]]
[[Electricity generation|Electrical power stations]] use large steam turbines driving [[electric generator]]s to produce most (about 80%) of the world's electricity. The advent of large steam turbines made central-station electricity generation practical, since reciprocating steam engines of large rating became very bulky, and operated at slow speeds. Most central stations are [[fossil fuel power plant]]s and [[nuclear power plant]]s; some installations use [[Geothermal energy|geothermal]] steam, or use [[concentrated solar power]] (CSP) to create the steam. Steam turbines can also be used directly to drive large [[centrifugal pump]]s, such as [[feedwater pump]]s at a [[thermal power plant]].

The turbines used for electric power generation are most often directly coupled to their generators. As the generators must rotate at constant synchronous speeds according to the frequency of the electric power system, the most common speeds are 3,000&nbsp;RPM for 50&nbsp;Hz systems, and 3,600&nbsp;RPM for 60&nbsp;Hz systems. Since nuclear reactors have lower temperature limits than fossil-fired plants, with lower steam [[Vapor quality|quality]], the turbine generator sets may be arranged to operate at half these speeds, but with four-pole generators, to reduce erosion of turbine blades.{{sfn|Leyzerovich|2005|p=111}}