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Motor Powering Generator Efficiency

  1. Jun 25, 2014 #1
    What do I look for to determine the efficiency factor to know how many watts I can get out of a generator given a specific known HP sized engine?

    12.6 HP gives 9395 Watts from the standard HP to Watts conversion... however on a Markon generator, the spec sheet says that a 12.6 HP engine will provide 7500 Watts.

    I am sure that number is composed of data from days of testing, calculations, safety factors, etc. I wanted to see what I could calculate for a 9.9 HP engine but wasn't sure where to start. Is there an industry standard / assumed 80% efficiency factor?

    Any thoughts?

    Markon link for reference: https://www.cumminsgeneratortechnologies.com/www/en/referenceapplications/apu/MARKON_Brochure.pdf
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  3. Jun 25, 2014 #2


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  4. Jun 25, 2014 #3


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    You reach a price point for alternator efficiency. An extremely efficient alternator [~90%] would not be cost efficient. It is more practical to use a bigger motor.
  5. Sep 17, 2015 #4
    The most efficient system is for a high speed gas engine with a converter to deliver the electrical output as needed. This is because the size and weight for a given generator power go down with RPM. Conversion of the electrical output from the generator by electronic converter is over 90% efficient. The older gensets running at 1800 or 3600 RPM so they could put out 60 Hz is really old school thinking.
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