A traction power station is a power station that produces only traction current, that is, electric current used for railways, trams, trolleybuses or other conveyances. Pure traction power stations are rare and there are many more power stations that generate current for other purposes, such as standard three-phase alternating current (AC), in addition to traction current. Hydroelectric power stations, conventional thermal power stations and nuclear power stations can be used as traction power stations; wind and solar power stations for the production of traction current currently do not exist but could be used for this goal also.