Electric generator
From Wikipedia, the free encyclopedia
Jump to navigationJump to search
This article is about electromagnetic power generation. For electrostatic generators like the Van
de Graaff machine, see Electrostatic generator. For devices to convert photons into electricity,
see photovoltaic panel.
U.S. NRC image of a modern steam turbine generator (STG).
In electricity generation, a generator[1] is a device that converts motive power
(mechanical energy) into electrical power for use in an external circuit. Sources of
mechanical energy include steam turbines, gas turbines, water turbines, internal
combustion engines, wind turbines and even hand cranks. The first electromagnetic
generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday.
Generators provide nearly all of the power for electric power grids.
The reverse conversion of electrical energy into mechanical energy is done by
an electric motor, and motors and generators have many similarities. Many motors can
be mechanically driven to generate electricity and frequently make acceptable manual
generators.
Contents
1Terminology
2History
o 2.1Faraday disk generator
o 2.2Jedlik and the self-excitation phenomenon
o 2.3Direct current generators
o 2.4Synchronous generators (alternating current generators)
o 2.5Self-excitation
3Specialized types of generator
o 3.1Direct current (DC)
3.1.1Homopolar generator
3.1.2Magnetohydrodynamic (MHD) generator
o 3.2Alternating current (AC)
3.2.1Induction generator
3.2.2Linear electric generator
3.2.3Variable-speed constant-frequency generators
4Common use cases
o 4.1Power station
o 4.2Vehicular generators
4.2.1Roadway vehicles
4.2.2Bicycles
4.2.3Sailboats
4.2.4Electric scooters
o 4.3Genset
o 4.4Human powered electrical generators
o 4.5Mechanical measurement
5Equivalent circuit
6See also
7References
Terminology[edit]
Early Ganz Generator in Zwevegem, West Flanders, Belgium
Electromagnetic generators fall into one of two broad categories, dynamos and
alternators.
Dynamos generate pulsing direct current through the use of a commutator.
Alternators generate alternating current.
Mechanically a generator consists of a rotating part and a stationary part:
Rotor
The rotating part of an electrical machine.
Stator
The stationary part of an electrical machine, which surrounds the rotor.
One of these parts generates a magnetic field, the other has a wire winding in
which the changing field induces an electric current:
Field winding or field (permanent) magnets
The magnetic field producing component of an electrical machine. The magnetic field of
the dynamo or alternator can be provided by either wire windings called field
coils or permanent magnets. Electrically-excited generators include an excitation
system to produce the field flux. A generator using permanent magnets (PMs) is
sometimes called a magneto, or permanent magnet synchronous generators (PMSMs).
Armature
The power-producing component of an electrical machine. In a generator, alternator, or
dynamo, the armature windings generate the electric current, which provides power to
an external circuit. The armature can be on either the rotor or the stator, depending on
the design, with the field coil or magnet on the other part.
