controlling the generator output voltage is to vary the current through
windings of the electromagnets and thus vary the strength of the field.
When we use rotating mechanical devices to produce the large amounts of current
needed for practical uses, we find that the mechanical devices produce essentially
reverses itself and flows the other way through the conductor. The simplest source
of mechanically produced ac energy is the ac generator. It produces this energy by
a combination of electromagnets and rotating coils of wire.
a. Basic Ac Generator. The basic ac generator is made up of an electromagnet
The coil of wire
then spins between these two pole pieces to develop a voltage as a result of the
The ends of the coil of
wire are brought out to sliprings so that the voltage developed by the coil may be
conveniently attached to circuits that will use the voltage.
The circuits so
connected are collectively called the load. The sliprings of a basic ac generator
are shown connected to a galvanometer in figure 16. This instrument will measure
the amount and direction of the current developed by the generator.
Generation of ac voltage.