adjustable ac motor controller

Discussion in 'General Electronics Chat' started by seesoe, May 2, 2009.

  1. seesoe

    Thread Starter Active Member

    Dec 7, 2008
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  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I don't find that type currently listed on their site, but from the Bodine's history web site:

    :)

    You might want to look at their excellent motor manual: http://www.bodine-electric.com/TechTools/

    All references to "shunt wound" seem to be DC motors, but in the description it says:
    Which implies an AC source.

    I'm not a motor-head so maybe others can be of more help.

    Ken
     
  3. PRS

    Well-Known Member

    Aug 24, 2008
    989
    35
    To vary the speed of an induction motor like yours you might vary the amplitude of the voltage feeding it. I could not see your linked motor; when I tried, I got an 'error on page' report.

    If it is a small motor you might use a voltage divider type of pot. But if the current is substancial (> 1 Amp), you might want to use a rheostat which is a variable transformer and does not waste power as does a pot.
     
  4. seesoe

    Thread Starter Active Member

    Dec 7, 2008
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    does this motor require a cap?
     
  5. loosewire

    AAC Fanatic!

    Apr 25, 2008
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    Go to the acc blog,there an ajustable curcuit video just posted.
     
  6. seesoe

    Thread Starter Active Member

    Dec 7, 2008
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    which link was broken?

    do you mind posting a link to the acc blog, i couldn't find it?

    im still at a standpoint on this project, im not sure where to start or look...
     
  7. seesoe

    Thread Starter Active Member

    Dec 7, 2008
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    i found out that the motor is 1.6 amps
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    seesoe,

    You might try emailing or calling the people at Bodine Electric to find out if this motor can be made variable speed.

    Ken
     
  9. seesoe

    Thread Starter Active Member

    Dec 7, 2008
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    i got in contact with the guy i bought it from. he said that it came off of a working conveyor belt that had an adjustable speed controller on it.

    he said something from Boston Gear, so i looked up their site and i found these, i guess that is what he is talking about.
    http://bostongear.com/products/electric/ac.html

    however i think that is way over kill than what i need...
     
  10. awright

    Well-Known Member

    Jul 5, 2006
    84
    7
    Speaking in broad generalities, a common AC induction motor is not safely variable by means of a pot or transformer. Some special purpose AC induction motors can be varied by varying the voltage, but these are specially designed for such service and normally drive loads whose power demands are sharply reduced with reduced operating speed, such as fans.

    A conveyor does not have that characteristic and would not normally be equipped with a motor capable of speed control by voltage reduction.

    The speed of an induction motor is primarily determined by the frequency of the power source, not it's voltage. Starving the motor of voltage to slow it down forces it to operate at high slip (the difference between the speed of rotation of the magnetic flux {normally EXACTLY 3600 or 1800 RPM for a two or four pole motor on 60 Hz power} and the speed of rotation of the rotor). Unless the motor is designed to operate at high slip, such operation with constant torque demanded by the load will lead to overheating and possible destruction.

    The inverters you linked to avoid this problem by reducing both the frequency of power applied to the motor and the voltage.

    I suspect that you have simply selected the wrong motor for your application if you are unwilling to purchase a variable frequency inverter. If you shop around on ebay or in salvage stores you may find an inverter at quite a reasonable price.

    awright
     
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