Editing Rectifier (section)

==== Motor-generator set ====
{{Main|Motor-generator|Rotary converter}}
[[File:Rotierender Umformer.jpg|thumb|A small motor-generator set]]
A ''motor-generator set'', or the similar ''rotary converter'', is not strictly a rectifier as it does not actually ''rectify'' current, but rather ''generates'' DC from an AC source. In an "M-G set", the shaft of an AC motor is mechanically coupled to that of a DC [[Electrical generator|generator]]. The DC generator produces multiphase alternating currents in its [[armature (electrical engineering)|armature]] windings, which a [[commutator (electric)|commutator]] on the armature shaft converts into a direct current output; or a [[homopolar generator]] produces a direct current without the need for a commutator. M-G sets are useful for producing DC for railway traction motors, industrial motors and other high-current applications, and were common in many high-power DC uses (for example, carbon-arc lamp projectors for outdoor theaters) before high-power semiconductors became widely available.
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