Author Topic: wire gauge thickness does it matter  (Read 3811 times)

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brianschanafelt

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wire gauge thickness does it matter
« on: January 10, 2008, 11:13:19 PM »
I recently bought some 17 gauge magnetic wire to build one of hugh piggotts wind turbines. but the book call's for either 16 gauge wire or 18 gauge wire two in hand. i was just wondering why cant i just add a couple more or less turns per coil. but i am not shure how many turns i need for each coil. if anyone might know this information or could tell me who or where i might find that.    thanks!


Resectioned because its a common question Newbies could benefit from.

« Last Edit: January 10, 2008, 11:13:19 PM by (unknown) »

tecker

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Re: wire gauge thickness does it matter
« Reply #1 on: January 10, 2008, 06:44:21 PM »
Don't sweat it 2 awg 17 will be compatable
« Last Edit: January 10, 2008, 06:44:21 PM by tecker »

richhagen

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Re: wire gauge thickness does it matter
« Reply #2 on: January 10, 2008, 10:34:30 PM »
The voltage generated as output for a given rpm is a linear function of the number of turns of wire you have in the coil.  Adding more turns reduces the cut in speed, and effects the matching of the blades power curve to the alternators output power curve.  The current carried in the wire, and the voltage drop from (delta V = I * R) is a function of the resistance in the coil of wire.  Thicker wire has lower resistance, and for a given voltage across it, more current will pass through the wire.  Also a result is that since the thicker wire has less resistance, for a given current, there is less heat generated in the coil (Power = square of current multiplied by the resistance).  Flux or some others can probably explain this much more clearly, but basically by tampering with the thickness of the wire in the cable, and the number of turns, you are changing the operational parameters  of the machine.  That being said, there is a bit of wiggle room with these things, and other parameters that can be adjusted to help compensate for some types of changes.  Still for a first turbine, I for one would recommend following the specifications as closely as possible if you want to duplicate the performance.  Rich
« Last Edit: January 10, 2008, 10:34:30 PM by richhagen »
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brianschanafelt

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Re: wire gauge thickness does it matter
« Reply #3 on: January 10, 2008, 11:47:19 PM »
thank u for the info. i wound my coils today because i couldn't wait. so i looked at the book and it said that i could use 80 turns of 16ga or 150 for 18ga so i split it in half or about half and i got 135 turns for 17ga. so i wound then and the specs for the coil weight, width, height, lenth all match the specs so i hope that everything works out well thanks again brian schanafelt
« Last Edit: January 10, 2008, 11:47:19 PM by brianschanafelt »

Flux

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Re: wire gauge thickness does it matter
« Reply #4 on: January 11, 2008, 02:18:28 AM »
You haven't given enough information about what the correct winding should be.

What you have done is not likely going to get you off to a good start.


I assume the 80 turns would have been for 12v and 150 turns for 24v.


What you have will stall at 12v and will have a high cut in speed at 24v but you might get away with it in a good wind area.


Not a wise move for a first attempt.


Flux

« Last Edit: January 11, 2008, 02:18:28 AM by Flux »

tecker

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Re: wire gauge thickness does it matter
« Reply #5 on: January 11, 2008, 04:16:15 AM »
I find the only factor that really matters is the thickness of the coils with whatever plastic is involved .Dan's rule of thumb is a good one (make sure the stator with plastic is roughly the thickness of your magnet). The overall air gap will have to include any mechanical problems so will usually end some what less than the thickness of both magnets . Ampacity wise the two AWG 17 s locks you into the 10 amp  range per phase delta remembering around .15 per 100 feet for the two conductors. Making connectons for star delta outside of the casting is a good idea  here.
« Last Edit: January 11, 2008, 04:16:15 AM by tecker »

Hoskald

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Re: wire gauge thickness does it matter
« Reply #6 on: January 11, 2008, 04:23:39 AM »
Flux,

as an example, 10' dia bladeset, tsr 5 - 6, 24v. How would you calculate the turns per coil?  What is the best way to determine cut-in?


Thanks,

Hos

« Last Edit: January 11, 2008, 04:23:39 AM by Hoskald »

Flux

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Re: wire gauge thickness does it matter
« Reply #7 on: January 11, 2008, 06:17:22 AM »
Blades tsr 5-6 would probably be happy at tsr 7 at cut in.

say you aim for cut in at 7mph ( 10ft/sec). you have a tip velocity of 70 ft/sec.


Divide by circ of blade tip  70/3.14 x 10  gives 2.3 rps or 134 rpm. This seems reasonable. That would be your cut in rpm.


I can't possibly help with turns, wire size or anything else without knowing the details of magnets, disc size, air gap etc. These thinga are all inter related.


Flux

« Last Edit: January 11, 2008, 06:17:22 AM by Flux »

Hoskald

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Re: wire gauge thickness does it matter
« Reply #8 on: January 11, 2008, 07:30:35 PM »
Sorry about that...24 1" x 2" x 1/2" magnets, 12" rotors(2) dual rotor setup. I'm thinking maybe 1/4" airgap.
« Last Edit: January 11, 2008, 07:30:35 PM by Hoskald »

Flux

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Re: wire gauge thickness does it matter
« Reply #9 on: January 12, 2008, 02:26:21 AM »
Air gap is the distance between magnets on opposite discs, 1/4" with mechanical clearances would give you a stator about 1/8" thick. If you mean 1/4" clearance between stator and magnets then with N40 grade neo you haven't got a lot of magnet to spare with a lower speed 10ft machine,but it will be ok if you can limit the output safely to about 600W.


Assuming a stator 5/8 thick total and a gap of 3/4" between magnets then you would be looking at about 80 turns of #15 as a starting point using N40 magnets.


What are the blades? does the tsr 5-6 imply some commercial product. If so then I can only assume your figures are correct. For those magnets and a good robust machine in a good wind area I would have been looking at blades with tsr7.


For those slower blades I would look at what Dan ( Otherpower) is doing with larger round magnets for 10ft. You may manage with those rectangular magnets at N50 with about 70 turns of #14 and have a better margin. Much depends on your ability to get things to furl properly and control the top end output and the wind area.


Flux

« Last Edit: January 12, 2008, 02:26:21 AM by Flux »

Hoskald

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Re: wire gauge thickness does it matter
« Reply #10 on: January 12, 2008, 10:34:47 AM »
Thanks!  And I was thinking clearance, not total gap.


How do you calculate the wire gage and turns from the mag information?


About the blades, it's a simple design and given my current skills I am assuming they will come out in the range of tsr 5 to tsr 6. The design is set to 5.5.


Thanks for the very useful information!


Cheers,

Hos

« Last Edit: January 12, 2008, 10:34:47 AM by Hoskald »

brianschanafelt

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Re: wire gauge thickness does it matter
« Reply #11 on: January 12, 2008, 09:12:06 PM »
I figured in for the wind and i have on a decent day 10 to 17 mph and on a windy day 20 to 45 and up.
« Last Edit: January 12, 2008, 09:12:06 PM by brianschanafelt »