From the basic
principles of electricity generation by Michael Faraday, supply authorities
have been able to generate electricity from various fuel sources.
If a single wire is passed through a magnetic
field, a small pulse of electricity will be produced. However, it would not
be possible to generate enough electricity to light the tiniest light bulb
with this method.
If the magnet revolves inside a coil of
wire, then energy of motion is transformed into electric energy, and an
electric current will flow through the wire.
In power stations, a powerful electromagnet
(rotor) is mounted on a shaft supported between bearings. This rotates
inside a cylindrical iron shell (stator) containing slots through which the
conductors are wound.
The current produced by this type of
generator flows momentarily in one direction through the conductors and then
it reverses and flows in the opposite direction, this cycle is repeated
continuously. This is called "alternating current", generally shortened to
the abbreviation "A/C."
The A/C. used throughout Victoria flows
alternatively in each direction 50 times each second. This frequency gives
some idea of the speed the coil must turn. In technical terms, the unit of
frequency is the Hertz (i.e.. 1Hz = 1 cycle per second).
A current that continuously flows in one
direction is called a "direct current", or abbreviated as "D/C" An example
of direct current is the power supplied by a battery. Direct current is used
for electroplating processes, railway and tramway systems and other motor
driven applications where a smooth and wide range of speed control is
required.
Since D/C transmission systems involving
long distances are generally not economical, all electricity generated at
power stations is A/C. If D/C use is preferred, the electricity is
transmitted as A/C to the place of use, then is converted into D/C by means
of devices called converters or rectifiers.
