Low-speed machine
This term allows two interpretations:
Low-speed machines were for some time regarded as the best solution for power generators. Two-pole generators require a drive motor with no less than 3000 rpm for the generation of three-phase or AC current with 50 Hz. The service life of a combustion engine is longer if it is operated at low rotational speed, which meant that the speed was inevitably reduced. The speed required todrive the alternator was obtained through a transmission. The likelihood of a longer service life stood therefore against the increased costs caused by the additional transmission. Low-speed machines for small power generators are only rarely used today.
Rotary-current motors in their eight- and ten-pole versions are also known as low-speed machines.
How it all begann...