A generator is a machine that produces electrical current by moving a wire in a magnetic field. Energy is needed to move the wire. This may come from steam, wind, moving water, or, in the case of the small generator called a dynamo that may be found on some bicycles, from the movement of human legs! Dynamos produce just enough electrical energy to power the lights of a bicycle, but this energy is not stored. If the cyclist stops pedaling, the lights dim and go out.
The windmills of a wind farm can power generators to produce electricity for hundreds of homes.
Electric Generator also called dynamo, any machine that converts mechanical energy to electricity for transmission and distribution over power lines to domestic, commercial, and industrial customers. Generators also produce the electrical power required for automobiles, aircraft, ships, and trains.
The mechanical power for an electric generator is usually obtained from a rotating shaft and is equal to the shaft torque multiplied by the rotational, or angular, velocity. The mechanical power may come from a number of sources: hydraulic turbines at dams or waterfalls; wind turbines; steam turbines using steam produced with heat from the combustion of fossil fuels or from nuclear fission; gas turbines burning gas directly in the turbine; or gasoline and diesel engines. The construction and the speed of the generator may vary considerably depending on the characteristics of the mechanical prime mover.
Nearly all generators used to supply electric power networks generate alternating current, which reverses polarity at a fixed frequency (usually 50 or 60 cycles, or double reversals, per second). Since a number of generators are connected into a power network, they must operate at the same frequency for simultaneous generation. They are therefore known as synchronous generators or, in some contexts, alternators.