MOTOR – 21091

A motor converts electrical or chemical energy into mechanical energy.Electric motors are commonly used in robots. They can operate from alternating current (AC) or direct current (DC), and can turn at a wide range of speeds, usually measured in revolutions per minute (rpm) or revolutions per second (rps). Motors range in size from the tiny devices in a wristwatch to huge, powerful machines that can pull a train.

All motors operate by means of electromagnetic effects. Electric current flows through a set of coils, producing magnetic fields. The magnetic forces result in rotation. The greater the current in the coils, the greater is the rotating force. When the motor is connected to a load, the force needed to turn the shaft increases. The more the force, the greater the current flow, and the more power is drawn from the power source.

The illustration is a functional diagram of a typical electric motor.One set of coils rotates with the motor shaft. This is called the armature coil.The other set of coils is fixed, and is called the field coil. The commutator reverses the current with each half-rotation of the motor, so that the shaft keeps turning in the same direction.

The electric motor operates on the same principle as an electric generator.In fact, some motors can be used as generators.