Generators and Alternators
Name: holly s vaughn
Date: Around 1993
I was wondering if I could get a very simplified (almost elementary)
description of how generators and alternators work.
Hopefully this information will still be useful to you. I must qualify the
answers that I will give by saying that I am a mechanical engineer and thus
may not have as strong an understanding of alternators and generators as my
electrical counterparts, however, I will do my best.
As I understand it, alternators and generators both work basically the same
except that the alternating current produced naturally in a rotating machine
is rectified in a DC alternator within the commutator or brushes. What you
are trying to do with an alternator is generate electricity from shaft
power. Either you provide a magnetic field in field windings (the stator)
by passing current through the windings or you provide the magnetic field
with magnets attached to the rotor. Because of the mutual inductance that
occurs as a conductor moves relative to a magnetic field, the motion of the
rotor can be used to essentially "push" the electrons along, thereby
inducing a current. When you attach the alternator to a load (bank of
resistors, starter motor, batteries for charging, etc.) then current begins
to flow and does work.
At times like this, I wish that I could draw you a picture. Just remember
that mutual inductance between the magnetic field and a current carrying
conductor that is moving relative to the field is at the heart of it.
david r munoz
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Update: June 2012