page_title: Commutator (electric)
section_title: The commutating plane
hierarchical_section_title: Commutator (electric) / The commutating plane
caption_attribution_description: English: Dynamo - commutating plane definitions
context_page_description: A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit. It consists of a cylinder composed of multiple metal contact segments on the rotating armature of the machine. Two or more electrical contacts called "brushes" made of a soft conductive material like carbon press against the commutator, making sliding contact with successive segments of the commutator as it rotates. The windings on the armature are connected to the commutator segments.
  Commutators are used in direct current machines: dynamos and many DC motors as well as universal motors. In a motor the commutator applies electric current to the windings. By reversing the current direction in the rotating windings each half turn, a steady rotating force is produced. In a generator the commutator picks off the current generated in the windings, reversing the direction of the current with each half turn, serving as a mechanical rectifier to convert the alternating current from the windings to unidirectional direct current in the external load circuit.
context_section_description: The contact point where a brush touches the commutator is referred to as the commutating plane. To conduct sufficient current to or from the commutator, the brush contact area is not a thin line but instead a rectangular patch across the segments. Typically the brush is wide enough to span 2.5 commutator segments. This means that two adjacent segments are electrically connected by the brush when it contacts both.
caption: Commutating plane definitions.[7]
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