Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Generator Question.

  1. Oct 17, 2011 #1
    If you are turning a generator by hand that is directly wired to a electrical motor will it transfer the electrical energy produced by the generator to a electric motor more or less efficiently then with a pure mechanical system? assuming that the input energy is located away from the output such as a gear system on mechanical or circuitry/wires on electrical. So would there be more energy lose through the mechanical gears/belts or circuitry.
  2. jcsd
  3. Oct 17, 2011 #2


    User Avatar
    Gold Member

    This sounds like homework.

    What are your thoughts?
  4. Oct 17, 2011 #3
    Vertical axis wind turbine boat.... ive seen mechanical versions no electrical
  5. Oct 18, 2011 #4

    jim hardy

    User Avatar
    Science Advisor
    Gold Member
    2016 Award

    """ more or less efficiently ..."

    what's losses in a mechanical system? i'm no mechanical so don't know.

    rotating electric machinery has losses too
    friction, internal drag from windage, and electrical losses in copper and iron.

    this link has a table of motor efficiencies http://www.nema.org/gov/energy/efficiency/premium/ [Broken]
    click this line
    NEMA Premium Energy Efficient Product Specification and Definition
    and it'll open this pdf document


    as you see they run ~80% to 95% .

    square that number because you have similar sized motor and generator...

    then get an estimate from a mechanical type.
    Last edited by a moderator: May 5, 2017
  6. Oct 18, 2011 #5


    User Avatar

    Staff: Mentor

    If there is a complicated or large drivetrain involved, it may well be more efficient to convert to electrical and back to mechanical, but it depends on the specifics of the systems.
  7. Oct 18, 2011 #6


    User Avatar
    Science Advisor
    Gold Member

    Chain drive is pretty good.
  8. Oct 18, 2011 #7
    I dont think my question is understood.... But thanks for your time everyone.....
    I think the only way is to get two of the same motors, hook them up and give it a go...
  9. Oct 18, 2011 #8


    User Avatar
    Gold Member

    Please tell me you're not trying to get them to power each other...
  10. Oct 19, 2011 #9
    Why not? any electric motor can be used as a generator can it not?
  11. Oct 19, 2011 #10


    User Avatar
    Science Advisor
    Gold Member

    And both motor and generator are not 100% efficient. Power out of one will be less than the power put in. Total loss, the system will gradually (or rapidly) grind to a halt.
  12. Oct 19, 2011 #11


    User Avatar
    Gold Member

    Because it sounds like you're trying to make a perpetual motion device, hoping that each motor will generate power for consumption by the other.

    No offense to you, Grab, you are likely not aware of the uncountable number of people that have gone down this road ahead of you. This should be a mandatory lesson in grade school science. The number of person-hours wasted on people coming up with this exact idea and trying to bring it to life could be much better spent making some more meaningful contribution to society.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Generator Question.
  1. Generator questions (Replies: 1)