28-08-2014, 02:30 PM
Regardless of size, all electrical generators, whether dc or ac, depend upon the principle of magnetic induction. An emf is induced in a coil as a result of (1) a coil cutting through a magnetic field, or (2) a magnetic field cutting through a coil. As long as there is relative motion between a conductor and a magnetic field, a voltage will be induced in the conductor. That part of a generator that produces the magnetic field is called the field. That part in which the voltage is induced is called the armature. For relative motion to take place between the conductor and the magnetic field, all generators must have two mechanical parts �� a rotor and a stator. The rotor is the part that rotates the stator is the part that remains stationary. In a dc generator, the armature is always the rotor. In alternators, the armature may be either the rotor or stator