In its most basic definition. an electric generator is a machine that produces electricity. Generators produce about all of the electricity used by people. They supply the electric power that runs machines in mills. supply illuming. and operate contraptions in the place. There are two chief types of generators – alternating-current ( AC ) generators ( sometimes called alternators ) and direct-current ( DC ) generators ( besides known as dynamos ) . Both types of generator work on the same rules.
How A Generator Works ( Basic Principles )
A generator does non make energy – “energy can non be created or destroyed. merely changed from one signifier to another” ( Sir Isaac Newton ) . A generator changes mechanical energy into electric energy. Every generator must be driven by a machine that produces mechanic energy. For illustration. the big generators that provide electricity to Lae and the remainder of PNG are driven by hydro power. The mechanical device that powers a generator is known as a premier mover. To obtain more electrical energy from a generator. the premier mover must provide more mechanical energy.
Generators produce electricity by agencies of a rule discovered independently by two physicists in 1831 – Michael Faraday of England and Joseph Henry of the United States. Faraday and Henry found that they could bring forth electricity in a spiral of Cu wire by traveling the spiral near a magnet. This procedure is called electromagnetic initiation.
A simple generator ( see Figure 1 below ) consists of a individual cringle of wire turning in a magnetic field. Electricity is produced merely while the cringle is revolving. As the cringle rotates. the two sides “cut” the magnetic lines of force. This induces electricity into the cringle. One complete revolution of the cringle through the lines of force is called a rhythm. The frequence of the electromotive force or current. which is figure of rhythms in a 2nd. is measured in units called Hz ( one Hz equals one rhythm per second ) . The revolving cringle is connected to an outside circuit by either a brace of faux pas rings ( in an AC generator ) or a commutator ( in a DC generator ) . These connexions are the lone mechanical differences between AC and DC generators.
Alternating Current ( AC ) Generators
The simple generator shown in Figure 1 produces jumping current. in which the electricity flows on a regular basis in one way and so the other. in a cringle of wire. Slip rings and coppices on each terminal of the cringle of wire allow the generator to direct the current produced to the devices that use it.
How AC Generators Work
Practical AC generators are normally equipped with a little supporting generator called an exciter. The exciter supplies direct current for the electromagnets used to make the magnetic field in the generator. The armature of an AC generator consists of a Cu wire lesion in 100s of spirals around slots cut in an Fe ore.
Uses of AC Generators
AC generators are the chief generators in about all electric power workss. intending they provide the electricity we use every twenty-four hours. This is because jumping current can easy be increased or decreased ( utilizing a transformer ) . In this manner. the electromotive force can be increased significantly to coerce the current over long distances. and so lowered when needed by family contraptions etc. A Serbian applied scientist named Nicola Tesla was responsible for planing many of the devices today that usage jumping current. including polyphase Ac generators ( generators with more than one stage ) . the electric motor. and transformer systems for altering the electromotive force of jumping current. Tesla’s innovations made it possible to bring forth electric current far from the topographic point where the current is to be used.
Direct Current ( DC ) Generators
Direct current generators differ from AC generators in that a commutator is used alternatively of slip rings ( see Figure 4 ) . The commutator sections rotate with the cringle. and do contact with two fixed coppices. When the cringle turns. the commutator segments come alternately in contact with each coppice. Because of this. the current flowing in each coppice is ever in the same way. Therefore direct current flows from the generator to the outside electric circuit.
Uses of DC Generators
DC generators are used by the electroplating industry and mills that industry aluminum. Cl and other industrial stuffs which need big sums of direct current for their production. DC generators are besides used in vehicles. trains and ships driven by diesel-electric motors.
§AC – jumping current – an electric current in which the electricity flows on a regular basis in one way and so the other. normally change by reversaling 120 times per second.
§Armature – a spiral of wire lesion around an Fe nucleus. placed between opposite poles of a magnet in an electric motor or generator.
§Current – a flow of electricity through a wire. or the rate or sum of such a flow. normally measured in amperes.
§DC – direct current – a steady electric current that flows in one way merely.
§Electromagnet – a piece of soft metal that becomes a strong magnet when an electric current is passed through wire coiled around it.
§Electromagnetic Induction – the production of an electromotive force in a circuit by fluctuation of the magnetic field with which the circuit is connected.
§Electromagnetism – magnetic attraction produced by a current of electricity.
§Electromotive Force – the sum of energy derived from an electric beginning per unit of current passing through the beginning. Electromotive force is normally measured in Vs.
§Generator – a machine that changes mechanical energy into electrical energy and produces either direct or jumping current ; besides known as a dynamo.
§Magnetic Field – the infinite around a magnet in which its power of attractive force is effectual ; infinite around an electric current in which the magnetic force of the current is felt.
§Prime Mover – the first agent that puts a machine in gesture. such as air current or hydro-power.
§Voltage – the strength of electrical force. measured in Vs.
§Watt – a unit of electric power equal to the flow of one ampere under the force per unit area of one V. to one J. or to 1/746 HP.
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Alan Storen & A ; Ray Martine2000
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Physicss 132 Notes: The Electric Generator
P. Rubin – Richmond University1999
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