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Re: problem with magnet wire

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  • eo.lien
    Hi, Tim Thank s a lot i understood all (i m french and some time s it s hard to understand technique explanations) But this one is percfect for me.So i will
    Message 1 of 8 , Apr 1 1:11 AM
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      Hi, Tim
      Thank's a lot i understood all (i'm french and some time's it's hard to understand technique explanations) But this one is percfect for me.So i' will take a 1.6 mm² and will adapt the gap and turn per coil to have a good compromise between low rpm start and keep the maximum of security from burning in case of overspeed.

      Thank's a lots that's a really easy understanding answer and sorry again if i start on a mistake and took some of your time.

      I will give you news when i'll have do it .

      Best Regards and good continuation for you too (keep that mental that's the best one!!)

      Fred
      (really happy to understand weel) :)

      --- In axialflux@yahoogroups.com, "Tim Greiner" <casey51234@...> wrote:
      >
      > Fred-
      >
      > Nothing says you can't put an equal numbers of turns using a bigger gauge wire compared to smaller. You will have more weight of wire. You will have a slightly bigger gap between the magnets, so increasing the turns a little (like 88 instead of 85) would compensate for that. It is the number of turns that determine voltage at RPM (along with magnet strength). More turns makes the same voltage at a lower RPM or more voltage at the same RPM. The load you connect determines wattage (if the wind is strong enough). The wire gauge influences effiency (smaller is better because the magnetic gap can be smaller) and lifetime (bigger wire runs cooler).
      >
      > You could build a 180 watt machine using 1.29, 1.4 or 1.6mm dia wire and the same magnets, with the same voltage per RPM. The bigger wire would need a couple more turns. The 1.29 would be almost melting down (5amps with 5.2 maximum), the 1.6 safest, 1.4 in the middle.
      >
      > Note there is a "max amps" column in AWG.txt, your controls should keep current below that value. Check the gauge you select, if you use the 1.6mm make sure you don't exceed 8.2 amps (almost 300 watts).
      >
      > Ultimately the choice is yours, and some of this is art, not science. Good luck.
      >
      > Tim Greiner
      >
      > --- Fred wrote:
      > >
      > > hi Tim, thanks again , i know that if i change any caracteristic of alternator that will change all results (but thanks for explanations).That's why i ask for a confirmation about size of wire and yes i made a mistake when i told about 200w effectivly that's for 180 W but i stay on a valu of 200w after reading a french site who did it and told about 200 watts in theory .
      > > So i understand well that if i use bigger diam of wire i will have more power and less chance to meltdown generator in overspeed situation but if i use bigger diam i will put less turns and lose low speed starting like tha's sid in axial flux hp alternator page4 and that's not intressed me.
      > >
      > > About piggot's book a spoke about "how to built a wind turbine axial flux alternator 8 foot and 4 foot diameter machine" and in the section cold small machine supplement (at the end of book p46) that's write " coils contains 85 turns of #16 wire (1.4 mm²) for 12 volts"So that's why i ask for details because awg#16 is not equal to 1.4mm but equal to 1.2908 like that's write in AWG.txt.The result is that i don't understand nothing now about what size of wire and number of turns to keep low speed production.
      > >
      > > So to make simple:
      > > If a choose to make like M Piggot's said in his book for a 4 foot diam . I have to make coil with 85 turns of what size ???
      > >
      > > 1) 1.29 or 1.44 mm²?
      > > 2) and if i put 85 turns of 1.4mm² will i have low speed production again (with less chance to meltdown in over speed situation) or no??
      > >
      > > sorry for taking your time with mistake Tim
      > >
      > > Fred
      > >
      > > ---Tim Greiner wrote:
      > > >
      > > > Fred-
      > > >
      > > > The wire size was calculated from your information that you were going to have 200 watts at 12 volts. That gives 16.7 amps total,5.6 amps per phase (three phases) and then looking up the recommended size from this chart:
      > > >
      > > > http://tinyurl.com/cyphta
      > > >
      > > > which is in this groups "files" section, called "AWG.txt". 1.8mm is more conservative as far as waste heat produced and when you overspeed there is less chance of a meltdown. I don't know which Piggott book you're speaking of but if it is this one:
      > > >
      > > > http://tinyurl.com/chewvk
      > > >
      > > > (which is found in the "files" section as "axial flux hp alt.pdf" he was trying to get 180 watts, not 200. Every time you change a portion of an alternator, something needs to adjust- wires are sized to the amount of current going through them so if you increase the current they need to get bigger.
      > >
      > > > The same thing happens with turns in the coil- the 85 you are planning will not be anywhere near what you need if you are changing other things like the number of magnets. The alternator will put out the specified voltage at a certain RPM if it is built exactly to the plans, but reducing the number of magnets to 1/3 means you will have to spin it three times as fast to get the same output, or wind the coils with three times the turns. If you're building a direct drive wind machine, the RPM isn't going to be any different.
      > > >
      > > > Tim Greiner
      > > >
      > >
      >
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