Definition of a Split Ring Commutator

Written by jennifer gigantino | 13/05/2017
Definition of a Split Ring Commutator
Split ring commutators are found in many kinds of electrical generators. (power plant image by MAXFX from

A split ring commutator is a device found in a motor that reverses the direction of electrical current every half-turn of the armature. This allows the armature to spin consistently in the same direction.


Simple electric motors work on something called the catapult, or motor, effect. A wire is wound around a central block, called an armature, which rotates around a spindle through its centre. Electrical current flows in opposite directions through wires on either side of the armature, causing it to rotate.


The split ring commutator keeps the armature rotating in one direction by switching the direction of the current every half-turn. This helps turn electrical energy into kinetic (rotational) energy to power devices such as clocks, power drills, water pumps and even industrial robots.


The split ring commutator is made from two pieces of copper that do not touch each other. One sits on either side of the spindle going through the armature. A piece of carbon is placed against the copper to conduct the electricity to the armature. When the armature spins, the carbon brushes against the copper pieces. This keeps the armature spinning in the same direction.

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