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Motor and engines

  1. Jul 5, 2009 #1
    I was just thinking about replacing an engine with a motor in my genset but can't find the right match. It would be really great if someone can shed some light on the rationale btw. the two. How's the engines capacity rated and which motor capacity would be equivalent to a particular engine capacity? I hope the question's sounding pretty clear. I need to know the relation between an engine and a motor in terms of their capacities.
  2. jcsd
  3. Jul 5, 2009 #2
    If your engine has to run at a specific RPM (e.g. 3600 RPM) because the generator is a synchronous ac machine, we need to know that. We might be able to estimate the engine horsepower at that RPM if we knew the displacement, number of cylinders, etc., but the more detail the better. Does the engine have a nameplate?
    What is the nameplate and rated capacity of the generator? Is it running something that requires a high starting torque?
  4. Jul 5, 2009 #3


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    I usually use the words "engine" and "motor" virtually interchangeably. So could you be a bit more specific, what kind of engine do you wish to replace and what type of motor do you wish to replace it with?
  5. Jul 8, 2009 #4
    It's a diesel engine. And for the nameplate and the rating etc. gimme a day and I'l post more information. Is there some principle that governs that what capacity of a motor is a must to run a particular alternator to generate electricity? I mean if a diesel or gasoline driven engine is running an alternator to generate electricity from mechanical energy, a motor can be used as well, and that motor to be run by the electricity generated by the alternator rather than an external source.
  6. Jul 8, 2009 #5


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    No that cannot work. Just forget it as it violates conservation of energy.

    If you want to generate electricity from a prime mover that itself is powered by electricity then you are better off to use a more direct electrical conversion such as a transformer (if AC to AC is required) or a rectifier (if AC to DC is required) or a DC-DC converter etc, depending upon exactly what is your supply and what are your load electrical requirements.
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