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{{merge to|magneto (generator)|date=October 2013}}
A '''permanent magnet synchronous generator''' is a generator where the excitation field is provided by a permanent magnet instead of a coil.
 
Synchronous generators are the majority source of  commercial electrical energy. They are commonly used to convert the mechanical power output of steam turbines, gas turbines, reciprocating engines, hydro turbines and wind turbines into electrical power for the grid.
 
In the majority of designs the rotating assembly in the center of the generator—the "rotor"—contains the magnet, and the "stator" is the stationary armature that is electrically connected to a load. A set of three conductors make up the armature winding in standard utility equipment, constituting three phases of a power circuit—that correspond to the three wires we are accustomed to see on transmission lines. The phases are wound such that they are 120 degrees apart spatially on the stator, providing for a uniform force or torque on the generator rotor. The uniformity of the torque arises because the magnetic fields resulting from the induced currents in the three conductors of the armature winding combine spatially in such a way as to resemble the magnetic field of a single, rotating magnet. This stator magnetic field or "stator field" appears as a steady rotating field and spins at the same frequency as the rotor when the rotor contains a single dipole magnetic field. The two fields move in "synchronicity" and maintain a fixed position relative to each other as they spin.<ref>{{cite book|last=von Meier|first=Alexandra|title=Electric Power Systems: A Conception Introduction|year=2006|publisher=John Wiley & Sons, Inc.|location=Hoboken, New Jersey|isbn=978-0-471--17859-0|pages=92–95}}</ref>
 
They are known as synchronous generators because f, the frequency of the induced voltage in the stator (armature conductors) conventionally measured in [[hertz]], is directly proportional to RPM, the rotation rate of the rotor usually given in revolutions per minute (or angular speed). If the rotor windings are arranged in such a way as to produce the effect of more than two magnetic poles, then each physical revolution of the rotor results in more magnetic poles moving past the armature windings. Each passing of a north and south pole corresponds to a complete "cycle" of a magnet field oscillation. Therefore, the constant of proportionality is <math>\frac{\text{P}}{120}</math>, where P is the number of magnetic rotor poles (almost always an even number), and the factor of 120 comes from 60 seconds per minute and two poles in a single magnet; <math>f \left(\text{Hz}\right)=RPM\frac{\text{P}}{120}</math>.<ref>{{cite book|last=von Meier|first=Alexandra|title=Electric Power Systems: A Conceptual Introduction|year=2006|publisher=John Wiley & Sons, Inc.|location=Hoboken, New Jersey|isbn=978-0-471-17859-0|pages=96–97}}</ref>
 
In a permanent magnet generator, the magnetic field of the rotor is produced by permanent magnets. Other types of generator use electromagnets to produce a magnetic field in a rotor winding.  The direct current in the rotor field winding is fed through a slip-ring assembly or provided by a brushless exciter on the same shaft.
 
Permanent magnet generators do not require a DC supply for the excitation circuit, nor do they have [[slip ring]]s and contact brushes. However, large permanent magnets are costly which restricts the economic rating of the machine. The flux density of high performance permanent magnets is limited. The air gap flux is not controllable, so the voltage of the machine cannot be easily regulated. A persistent magnetic field imposes safety issues during assembly, field service or repair. High performance permanent magnets, themselves, have structural and thermal issues. Torque current MMF vectorially combines with the persistent flux of permanent magnets, which leads to higher air-gap flux density and eventually, core saturation. In this permanent magnet alternators the speed is directly proportional to the output voltage of the alternator.
 
==See also==
* [[Alternator]]
 
==References==
{{Reflist}}
 
[[Category:Alternators]]
[[Category:Electrical generators]]
 
[[de:Erregersysteme für Synchronmaschinen#Permanentmagneterregung von Synchronmaschinen]]

Latest revision as of 21:07, 20 November 2014

Clients like to help them-selves. They can get what they want when they want them not when somebody else is able to provide them. That is where e-business can definitely make a difference, by stretching your existing customer-service techniques within the Web. Web-based or on line service allows your visitors to discover what they need at the contact of a button, anytime of the day or night. Whether its actual orders or account details, they will enjoy a much better level of service, making it easier for them to do business with you. All inside a secure web environment.

But as a customer you are probably wondering why it"s better to opt for o-nline printing than the conventional printing service. Well for starters, on line printing service lets you order and create documents with just a couple clicks of the mouse. In case you fancy to learn new resources on dfma process, there are many databases people should pursue. The web-based publishing company may get your order, produce them and deliver them right in the comfort of your house. The efficiency, comfort and simplicity that are offered by on line printing can present a great deal of benefits to you. All you have to accomplish is do some comparison-shopping until you see the lowest bid, when you"re looking for the lowest value for your print job. You will need not produce quote words to get the supplier that most readily useful appeal to your printing requirements.

Say for instance you have a poster that requires to be published as soon as possible and in large quantity. After exploring through the web you find this website that offered an incredibly low price to you. Good! Not just will you spend less but you"ll even be able to monitor the progress of your print job without the hassle of missing phone calls from the sales person. When you are having trouble with your style and you also have the advantage of having many choices in paper, ink, layout and typefaces.

But reported by users there are always two sides in a coin, if there is a yin theres always a yang. So even when on the web publishing has its benefits, of course it"s its down-sides. To begin with, going online on your publishing requirements requires one to do-it ahead if time. You"ve to start that on the web search as early as today if you need your poster printed by the following month. Understand that printing and supply may take a couple of days so do it in advance. Moreover, there"s lack of personal connection with owner and lack of get a handle on over the job once you select online publishing. The Web is your only way to track the development of your print job. So that you need to have lots and lots of faith for your printer. When you are able to trust your printer, you"ll have less fear of not having your print job the way you want them to become.

Nonetheless, today"s technology has taken lots of options as it pertains to print jobs. Online printing has offered clients and printers alike a brand new way of doing business. That is why; often the very best service is not any service..Accudynamics

240 Kenneth Welch Drive
Lakeville, MA 02347
Phone: 508-946-4545

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