Commutator

Definition

A commutator is a rotary switch in electric motors and generators that periodically reverses the current direction between the rotor and external circuit. It ensures unidirectional torque in DC machines by switching the current as the rotor turns.

5 Must Know Facts For Your Next Test

1. Commutators are essential for converting AC to DC in electric motors.
2. They consist of a cylinder composed of multiple metal contact segments on the rotating armature of the machine.
3. The brushes, usually made of carbon, maintain sliding electrical contact with the commutator segments.
4. Wear and tear on brushes and commutators is a common maintenance issue in machines using them.
5. Proper functioning of a commutator ensures continuous torque output in one direction.

Review Questions

• What role does a commutator play in an electric motor?
• How does a commutator maintain unidirectional torque in DC machines?
• What are common materials used for brushes that contact the commutator?

Related terms

Rotor:

The rotating part of an electrical machine, which interacts with the magnetic field to produce motion or electricity.

Brushes:

Conductive materials, often made from carbon, that maintain electrical contact with moving components like the commutator.

Torque:

\(Force \times Distance\) resulting in rotational motion; critical for evaluating performance in motors.