Thought the lover had bad intentions, everyone expected to protect them me
winding and
a magnetic field. But
there is one
important
difference between
the two. Whereas
in DCgenerators, the
armature rotates
and the field system
is stationary, the
arrangement in
alternators is just
thereverse of it. In
their case, standard
construction
consists of armature
winding mounted
on a stationary
elementcalled stator
and field windings
on a rotating
element called
rotor. The details of
construction are
shown infigure1
The stator consists of a cast iron frame, which supports the armature core, having slots on itsinner
periphery for housing the armature conductors. The rotor is like a flywheel having alternate N and S
polesfixed to its outer rim. The magnetic poles are excited (or magnetized) from direct current supplied
by a dcsource at 125 to 600 volts. In most cases, necessary exciting (or magnetizing) current is obtained
from a smalldc shunt generator which is belted or mounted on the shaft of the alternator itself. Because
the field magnets arerotating, this current is supplied through two slip rings. As the exciting voltage is
relatively small, the slip ringsand brush gear are of lightconstruction. Recently, brushless excitation
systems have been developed in which a3-phase ac exciter and a group of rectifiers supply dc to the
alternator. Hence, brushes, slip rings andcommutator are eliminate