MOTORSThe Electric Motor

Motors

A motor is a rotating device which converts electrical energy into mechanical energy.

A d.c. motor operates from d.c. only. All d.c. motors have commutators (a metal ring which is split into halves. It reverses the current direction in the coil on each half cycle –

ensuring that the motion of the coil is continuous).

Current Flow

Current flow is such that the north pole of the coil is next to the north pole of the permanent magnetic field. Likewise, the south pole of the coil is next to the south pole of the magnetic field.

The Magnetic Field Of the d.c. Motor The magnetic field of the coil opposes that

of the permanent magnetic. Repulsion takes place. Since the permanent magnet is fixed and the coil moveable, the coil rotates. As the coil rotates it north pole is attracted to the south pole of the permanent magnet.

At the instant when two unlike poles are about to line up, the commutator changes the polarity of the coil. Repulsion takes place and the coil continues to rotate.

The Action of a d.c. Motor When the current is switched on the

coil rotates in the direction shown. The commutator reverses the direction of the current flow every half a revolution so the armature continues in the same direction.

Improvement of the d.c.motor Using an electromagnetic in place of

the permanent magnetic. Using more than one loop in the coil. Winding the coils around a soft iron

core (armature).