AC Generators

AC Generators

  

A basic generator consists of a magnetic field, an armature, slip
rings, brushes and a resistive load. The magnetic field is usually
an electromagnet. An armature is any number of conductive
wires wound in loops which rotates through the magnetic field.
For simplicity, one loop is shown. When a conductor is moved
through a magnetic field, a voltage is induced in the conductor.
As the armature rotates through the magnetic field, a voltage
is generated in the armature which causes current to flow. Slip
rings are attached to the armature and rotate with it. Carbon
brushes ride against the slip rings to conduct current from the
armature to a resistive load

An armature rotates through the magnetic field. At an initial
position of zero degrees, the armature conductors are moving
parallel to the magnetic field and not cutting through any
magnetic lines of flux. No voltage is induced.

The armature rotates from zero to 90 degrees. The conductors
cut through more and more lines of flux, building up to a
maximum induced voltage in the positive direction.

The armature continues to rotate from 90 to 180 degrees,
90 cutting less lines of flux. The induced voltage decreases from a
maximum positive value to zero.

The armature continues to rotate from 180 degrees to 270
degrees. The conductors cut more and more lines of flux, but
in the opposite direction. voltage is induced in the negative
direction building up to a maximum at 270 degrees.

The armature continues to rotate from 270 to 360 degrees.
   Induced voltage decreases from a maximum negative value to
zero. This completes one cycle. The armature will continue to
rotate at a constant speed. The cycle will continuously repeat as
long as the armature rotates