Electric generator parts and functions pdf
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- The Different Parts of a Generator
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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. A major reason for selecting alternating current for power networks is that its continual variation with time allows the use of transformers.
These devices convert electrical power at whatever voltage and current it is generated to high voltage and low current for long-distance transmission and then transform it down to a low voltage suitable for each individual consumer typically or volts for domestic service.
The particular form of alternating current used is a sine wave , which has the shape shown in Figure 1. This has been chosen because it is the only repetitive shape for which two waves displaced from each other in time can be added or subtracted and have the same shape occur as the result. The ideal is then to have all voltages and currents of sine shape. The synchronous generator is designed to produce this shape as accurately as is practical.
This will become apparent as the major components and characteristics of such a generator are described below. An elementary synchronous generator is shown in cross section in Figure 2.
The central shaft of the rotor is coupled to the mechanical prime mover. The magnetic field is produced by conductors, or coils, wound into slots cut in the surface of the cylindrical iron rotor. This set of coils, connected in series, is thus known as the field winding.
The position of the field coils is such that the outwardly directed or radial component of the magnetic field produced in the air gap to the stator is approximately sinusoidally distributed around the periphery of the rotor. In Figure 2 , the field density in the air gap is maximum outward at the top, maximum inward at the bottom, and zero at the two sides, approximating a sinusoidal distribution.
The stator of the elementary generator in Figure 2 consists of a cylindrical ring made of iron to provide an easy path for the magnetic flux. In this case, the stator contains only one coil, the two sides being accommodated in slots in the iron and the ends being connected together by curved conductors around the stator periphery.
The coil normally consists of a number of turns. When the rotor is rotated, a voltage is induced in the stator coil. At any instant, the magnitude of the voltage is proportional to the rate at which the magnetic field encircled by the coil is changing with time—i.
The waveform of the voltage will be approximately of the sine form shown in Figure 1. The rotor structure of the generator in Figure 2 has two poles, one for magnetic flux directed outward and a corresponding one for flux directed inward.
One complete sine wave is induced in the stator coil for each revolution of the rotor. The frequency of the electrical output, measured in hertz cycles per second is therefore equal to the rotor speed in revolutions per second. To provide a supply of electricity at 60 hertz, for example, the prime mover and rotor speed must be 60 revolutions per second, or 3, revolutions per minute.
This is a convenient speed for many steam and gas turbines. For very large turbines, such a speed may be excessive for reasons of mechanical stress. The required rotor speed for a frequency of 60 hertz is then 1, revolutions per minute. For lower speeds, such as are employed by most water turbines, a larger number of pole pairs can be used. Electric generator Article Media Additional Info. Article Contents. Print print Print. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies.
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Synchronous generators A major reason for selecting alternating current for power networks is that its continual variation with time allows the use of transformers. Get a Britannica Premium subscription and gain access to exclusive content.
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This article is for the design, materials, manufacture, testing, and commissioning of packaged stand-by diesel engine generators intended for permanent installation in industrial plants. Self-contained enclosure shall be provided for the diesel generator set. The enclosure shall be manufactured such that all part are accessible for inspection and minor maintenance without removal of the enclosure or enclosure roof. It shall include the following features:. The enclosure and all other items shall be designed and built by the supplier as an integral part of the entire diesel generator set, and shall perform without overheating in the environment specified.
Generators are extremely important for a variety of industries in order to provide power to remote and urban construction sites and to provide power in the event of a power outage. Generators are packaged units that provide electricity via an engine. The engine and various components turn a fuel source into usable electricity for a large number of applications. The engine is the workhorse of the generator. Generator engines are typically powered by either diesel or natural gas. The fuel turns the engine, and as the engine turns, various components, including the alternator and batte ry system, turn that mechanical energy into usable electricity for your equipment.
The synchronous electrical generator (also called alternator) belongs to the to the presentation of the basic components comprising a synchronous machine.
The rotor generates a moving magnetic field around the stator, which induces a voltage difference between the windings of that stator. This produces the alternating current AC output of the generator. The following are factors that you need to keep in mind while assessing the alternator of a generator:. This cycle continues until the generator begins to produce output voltage equivalent to its full operating capacity.
This is a popular alternative to using grid power generated from wind turbines or fossil fuels and a high voltage steam turbine in a power plant or power station. There are many types of generators out there, from petrol generators , portable generators and inverter generators. To home generators that may run on natural gas, standby generators for a power outage, and much larger industrial generators.
The Different Parts of a Generator
A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor , the alternating-current alternator , and the rotary converter. Today, the simpler alternator dominates large scale power generation , for efficiency, reliability and cost reasons. A dynamo has the disadvantages of a mechanical commutator. Also, converting alternating to direct current using rectifiers such as vacuum tubes or more recently via solid state technology is effective and usually economical.
Generators are useful appliances that supply electrical power during a power outage and prevent discontinuity of daily activities or disruption of business operations. Generators are available in different electrical and physical configurations for use in different applications. In the following sections, we will look at how a generator functions, the main components of a generator, and how a generator operates as a secondary source of electrical power in residential and industrial applications. An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output. Instead, it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. The modern-day generator works on the principle of electromagnetic induction discovered by Michael Faraday in
The electric generator was invented before the correlation between electricity as well as magnetism was discovered. These generators use electrostatic principles to operate with the help of plates, moving belts which are charged electrically as well as disks to carry charge toward an electrode with high potential. Generators use two mechanisms to generate the charge like the triboelectric effect otherwise electrostatic induction. So, it generates low current as well as very high voltage due to the complexity of insulating machines as well as their inefficiency. The power ratings of Electrostatic generators are low so they never utilized for electrical power generation.
The Generator, Exciter, and Voltage Regulation. Rev 1/11 components of the electrical generator, the exciter is a function of the voltage induced and the.
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.
A generator is a machine used to convert mechanical energy into electricity. Powered by a fuel source such as oil, gasoline, wind or moving water, generators create electrical current through electromagnetic induction. Generators widely serve as backup power sources for factories and hospitals, where the facility can set them up to work immediately if the main power goes out.