Electric generator

In electricity generation, a generator is a device that converts motion-based power (potential and kinetic energy) or fuel-based power (chemical energy) into electric 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 the power for electrical grids. In addition to electricity- and motion-based designs, photovoltaic and fuel cell powered generators use solar power and hydrogen-based fuels, respectively, to generate electrical output. The reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators are very similar. Many motors can generate electricity from mechanical energy. 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 which together form a magnetic circuit: 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 a permanent magnet synchronous generator (PMSG). Armature: The power-producing component of an electrical machine.