induction motor to generator

Discussion in 'The Projects Forum' started by Hk606, Oct 19, 2014.

  1. Hk606

    Thread Starter New Member

    Oct 19, 2014
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    I have a 115/230 V 1.1 KW 1.5 Hp single phase duel capacitor single speed induction motor I want to use as a generator. I can't seem to find the answer to my questions. The motor is now wired for 115 volt. As i want the output to be 115volt
    Do I Choose a capacitor bank based on it being wired as a 115 volt motor. Being duel capacitor duel voltage is where information on the web is not to be found for converting to a generator.
    Thanks for veiwing
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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  3. Hk606

    Thread Starter New Member

    Oct 19, 2014
    17
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    I got this motor free really robust windings it came off a milling machine. I was going to use this one just as a small back up generator.
     
  4. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Your motor will work but it will be far from an ideal generator.

    First you will have to disconnect the start windings and reconfigure them to be independent of the run winding so they can work as a dedicated exciter winding.

    Second to get the right frequency you will need to run it at a speed proportionally above its ideal synchronous speed and it normally ran below it which means if it was a 1725 RPM motor you will need to run it around 1875 RPM to get a fairly stable 60 HZ frequency from it.

    Third is the trial and error method of finding the right value of capacitance to get the correct voltage in the load range you want.

    Also dont forget that your capacitors you will be using on the start winding will now be running in a continuous duty application so you can not use the old starting capacitor for the the exciter system. You will need dedicated motor run/PFC type for that.
     
  5. Hk606

    Thread Starter New Member

    Oct 19, 2014
    17
    1
    Thanks for the information. I'm just going to use it as a small back up doing some research online I can expect about 750 watts.
     
  6. crutschow

    Expert

    Mar 14, 2008
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    Doesn't an induction generators output have to connected to an external AC source (such as the mains) to provide initial excitation and stabilize its output frequency and voltage? In other words they only operate properly when connected to an AC source.
     
  7. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Most don't need to due to having enough residual magnetism to get themselves oscillating if the correct size of capacitor is on the exciter circuit.

    But to be fair some due and to get them to work as generators can take as little as a flash from a 6 - 12 volt battery across the exciter circuit capacitors for a second.

    All you got to do is get the electric pendulum swinging and physics takes over from there. ;)
     
  8. Hk606

    Thread Starter New Member

    Oct 19, 2014
    17
    1
    Yeah I ask for some math help on this site for capacitor calculation for the correct uf's I need for this project. I'm not very good with electrical calculation I'm afraid. hope I here something back. as at this point I'm stuck.
     
  9. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Unfortunately finding the right value of capacitance for the exciter circuit so that the output voltage will be in the right range for a specific load is pretty much trial and error.
     
  10. Hk606

    Thread Starter New Member

    Oct 19, 2014
    17
    1
    Thanks I suppose I'll try 250uf as it had two 250uf caps as a motor wish I knew at least a baseline to start. I don't want to fry the windings
     
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