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Define electrical components.

  1. Aug 11, 2009 #1
    What is the difference between,

    - Alternators
    - Generators
    - Dynamos

    - Rotors
    - Stators
    - Armature
    - Field

    - Commutators
    - Brushes.

    My mind is filling up with terms and im struggling to make sense and define the difference between each!

    your help is appreciated.
  2. jcsd
  3. Aug 11, 2009 #2


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    You really need to look at a diagram. Always try Wikipedia.

    Try this:

    Alternators produce power from a stationary winding while a rotating field coil produces magnetic field.

    - Rotors rotate
    - Stators stay still
    - Armature produces power
    - Field produces magnetic field

    - Commutators are the part of a rotating armature that brushes make contact with. They are for producing DC from a rotating armature or for making a motor work from DC.
    - Brushes are sometimes graphite blocks that make contact with an armature.

    http://en.wikipedia.org/wiki/Commutator_(electric [Broken])
    Last edited by a moderator: May 4, 2017
  4. Aug 11, 2009 #3
    - Armature produces power

    - Commutators are the part of a rotating armature that brushes make contact with. They are for producing DC from a rotating armature or for making a motor work from DC.

    you said the armature produces the power, but is stationary.

    then you say that the commutator is located on the rotating armature.

    sorry if im being stupid.
  5. Aug 11, 2009 #4


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    Staff: Mentor

    Another wikipedia article that should help:


  6. Aug 11, 2009 #5


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    Science Advisor

    Normally, the armature and the rotor are the same thing. The bit that spins around in a motor or generator.
    In the special case of a generator that has the power coming out of the stationary part, the armature is the stator.

    Armature just means the bit that power comes out of in a generator. It doesn't have to be rotating. If it does rotate, and produces DC it will have a commutator and brushes.

    Did you read the Wikipedia references Berkeman and I sent you? What did you think?
  7. Aug 12, 2009 #6
    ok got it...

    now whats the difference between

    - asynchronous generator (induction)

    - synchronous generator

    and what is synchronous speed / frequency?

    do asynchrounous generators allow wind turbines to produce 50hz electricity even when the gearbox isn't spinning this fast?

  8. Aug 12, 2009 #7


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    Science Advisor

    All generators are synchronous with the driving engine. They produce an exact number of cycles of output for each rotation caused by the drive.

    However to get certain exact speeds of rotation and hence get an exact standard electrical output, the drive engine has to be regulated precisely.

    This is from one of the Wikipedia references I sent you:

    The output frequency of an alternator depends on the number of poles and the rotational speed. The speed corresponding to a particular frequency is called the synchronous speed for that frequency. This table [6] gives some examples:
    Poles RPM at 50 Hz RPM at 60 Hz
    2...... 3,000........ 3,600
    4...... 1,500........ 1,800
    6...... 1,000........ 1,200
    8...... 750........... 900
    10..... 600 .......... 720
    12..... 500 .......... 600
    14..... 428.6........ 514.3
    16..... 375 .......... 450
    18 .... 333.3........ 400
    20 .... 300 ........... 360
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