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AC Generator Design Question

Discussion in 'Electronic Basics' started by Randy Gross, Nov 1, 2003.

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  1. Randy Gross

    Randy Gross Guest

    Greetings:

    I've begun the construction of a small A.C. generator with 8 poles and a 3
    phase stator. Instead of igniting wound poles with D.C., I've decided to
    use permanent magnets. I don't know the field strengths of these magnets
    but, they are Magnetron magnets 2 1/4" in diameter by 3/8" thick, not the
    best but cost effective.

    My problem is determining the number of turns (20 awg magnet wire) per pole
    to achieve the 120vrms output. I can do this by trial but, that would mean
    assemble - disassemble until I reach the goal. Each phase will be wound
    with a continuous strand, not individual coils.

    Does someone have a formula for calculating turns that can speed things up?
    Is it 15v or is it 30v North and 30v South per set of poles?
     
  2. The open circuit voltage is proportional to the magnet field strength
    , the speed and the number of turns. If the first two are fixed, the
    number of turns is all that you need to find. Wind one (or a few)
    turn and measure the voltage produced, then scale the winding up to
    produce the desired voltage. The voltage will sag, almost linearly
    with current, so you will want to produce a bit extra (or figure out
    that factor with the one turn winding with a second test for short
    circuit current).
     
  3. Randy Gross

    Randy Gross Guest

    With this plan I'd say the generator is as good as done.

    Thanks John.

    Randy Gross

    <>...

    <snip>

    :
    : The open circuit voltage is proportional to the magnet field strength
    : , the speed and the number of turns. If the first two are fixed, the
    : number of turns is all that you need to find. Wind one (or a few)
    : turn and measure the voltage produced, then scale the winding up to
    : produce the desired voltage. The voltage will sag, almost linearly
    : with current, so you will want to produce a bit extra (or figure out
    : that factor with the one turn winding with a second test for short
    : circuit current).
    :
    : --
    : John Popelish
    :
     
  4. Guest

    The faster the coils move the more the voltage output and the more
    turns you have, the more the output.

    The output will "droop" when you connect the load more or less
    depending on its efficiency. Trial and error is probably your best
    bet.


    Robin
     
  5. Randy Gross

    Randy Gross Guest

    Experimenting with electricity is truly fascinating. The more you learn,
    the more there is. Thanks guys, I'm in a better position now to make
    informed decisions.

    Randy Gross

    wrote in article
    <>...
    : > Greetings:
    <snip>
    : > Does someone have a formula for calculating turns that can speed things
    up?
    : > Is it 15v or is it 30v North and 30v South per set of poles?
    :
    : The faster the coils move the more the voltage output and the more
    : turns you have, the more the output.
    :
    : The output will "droop" when you connect the load more or less
    : depending on its efficiency. Trial and error is probably your best
    : bet.
    :
    :
    : Robin
    :
     
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