generator


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generator,

in electricity, machine used to change mechanical energy into electrical energy. It operates on the principle of electromagnetic inductioninduction,
in electricity and magnetism, common name for three distinct phenomena. Electromagnetic induction is the production of an electromotive force (emf) in a conductor as a result of a changing magnetic field about the conductor and is the most important of the
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, discovered (1831) by Michael Faraday. When a conductor passes through a magnetic field, a voltage is induced across the ends of the conductor. The generator is simply a mechanical arrangement for moving the conductor and leading the current produced by the voltage to an external circuit, where it actuates devices that require electricity. In the simplest form of generator the conductor is an open coil of wire rotating between the poles of a permanent magnet. During a single rotation, one side of the coil passes through the magnetic field first in one direction and then in the other, so that the induced current is alternating current (AC), moving first in one direction, then in the other. Each end of the coil is attached to a separate metal slip ring that rotates with the coil. Brushes that rest on the slip rings are attached to the external circuit. Thus the current flows from the coil to the slip rings, then through the brushes to the external circuit. In order to obtain direct current (DC), i.e., current that flows in only one direction, a commutator is used in place of slip rings. The commutator is a single slip ring split into left and right halves that are insulated from each other and are attached to opposite ends of the coil. It allows current to leave the generator through the brushes in only one direction. This current pulsates, going from no flow to maximum flow and back again to no flow. A practical DC generator, with many coils and with many segments in the commutator, gives a steadier current. There are also several magnets in a practical generator. In any generator, the whole assembly carrying the coils is called the armature, or rotor, while the stationary parts constitute the stator. Except in the case of the magneto, which uses permanent magnets, AC and DC generators use electromagnets. Field current for the electromagnets is most often DC from an external source. The term dynamo is often used for the DC generator; the generator in automotive applications is usually a dynamo. An AC generator is called an alternator. To ease various construction problems, alternators have a stationary armature and rotating electromagnets. Most alternators produce a polyphase AC, a complex type of current that provides a smoother power flow than does simple AC. By far the greatest amount of electricity for industrial and civilian use comes from large AC generators driven by steam turbines.

generator

[′jen·ə‚rād·ər]
(computer science)
A program that produces specific programs as directed by input parameters. Also known as generating routine.
(electricity)
A machine that converts mechanical energy into electrical energy; in its commonest form, a large number of conductors are mounted on an armature that is rotated in a magnetic field produced by field coils. Also known as dynamo; electric generator.
(electronics)
A vacuum-tube oscillator or any other nonrotating device that generates an alternating voltage at a desired frequency when energized with direct-current power or low-frequency alternating-current power.
A circuit that generates a desired repetitive or nonrepetitive waveform, such as a pulse generator.
(mathematics)
One of the set of elements of an algebraic system such as a group, ring, or module which determine all other elements when all admissible operations are performed upon them.

Generator

A machine in which mechanical energy is converted to electrical energy. Generators are made in a wide range of sizes, from very small machines with a few watts of power output to very large central-station generators providing 1000 MW or more. All electrical generators utilize a magnetic field to produce an output voltage which drives the current to the load. The electric current and magnetic field also interact to produce a mechanical torque opposing the motion supplied by the prime mover. The mechanical power input is equal to the electric power output plus the electrical and mechanical losses.

Generators can be divided into two groups, alternating current (ac) and direct current (dc). Each group can be subdivided into machines that use permanent magnets to produce the magnetic field (PM machines) and those using field windings. A further subdivision relates to the type of prime mover and the generator speed. Large generators are often driven by steam or hydraulic turbines, by diesel engines, and sometimes by electric motors. Generator speeds vary from several thousand rotations per minute for steam turbines to very low speeds for hydraulic or wind turbines. See Diesel engine, Hydraulic turbine, Motor, Prime mover, Steam turbine, Wind power

The field structure of a generator establishes the magnetic flux needed for energy conversion. In small generators, permanent magnets can be used to provide the required magnetic field. In large machines, dc field windings are more economical and permit changes in the magnetic flux and output voltage. This allows control of the generated voltage, which is important in many applications. In dc generators the field structure must be stationary to permit a rotating mounting for the commutator and armature windings. However, since the field windings require low voltage and power and have only two lead wires, it is convenient to place the field on the rotating member in ac generators. See Electric power generation, Electric rotating machinery, Windings in electric machinery

generator

A machine that converts mechanical power into electric power.

generator

1. Physics
a. any device for converting mechanical energy into electrical energy by electromagnetic induction, esp a large one as in a power station
b. a device for producing a voltage electrostatically
c. any device that converts one form of energy into another form
2. an apparatus for producing a gas

generator

(1) Software that creates software. See application generator and macro generator.

(2) A device that creates electrical power or synchronization signals.
References in periodicals archive ?
Some of the tables and figures provided in Global Portable Generator Market Report 2015 research report include:
A generator, operating inside the home, had exploded, he said.
Never use a generator in a garage or any area with a partial enclosure.
However, if you need to power your critical systems for an extended period of time a generator is a must.
That's precisely what occurred in 1995, when Wagner, then a graduate student at Berkeley, and his fellow student Ian Goldberg cracked the random-number generator used by the Netscape web browser to secure online transactions.
A lot of people who work here know people who know people," Jasper said, "so when we needed extra generators, somehow they were able to find them.
As a major component in simplifying the overall design process, the System Generator for DSP tool now also allows designers to insert ChipScope Internal Logic Analyzer (ILA) probes directly into the system model to debug and verify internal signals within the FPGA at or near system operating speeds.
In the telling, it never occurs to them that if retailers weren't brow-beaten by politicians like our attorney general, they might be able to raise their prices enough to induce faraway stores to sell or transport their generators to the afflicted area, thus alleviating the scarcity at least a little bit and eliminating all these road trips.
Most electricians and electrical contractors can install Generator InterlockKit, which retrofits to any existing panel and requires no additional wall space.
These technologies help control the speed of generator engines automatically, making the generators highly energy efficient.
However, once the generator is shut down, pushing the reset button will "clear" the indicator whether the air filter restriction has been corrected or not.
And you're having to stack two or three of these things (Capstone generators) together just to get the same power as a diesel generator,'' Quealy said.

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