What is the ampacity of 24ga. wire?

[Jerry]

My next 14-11 duel rotor PMA will be using 400 turns for each of the 11 coils of 24 ga. wire per coil.

I'll be using 12" discs. With the same 15" speaker basket support as the 14-11 ceramic PMA.

I think I'll use a 1" shaft for this unit.

I'm just wondering about the amp capacity at 24 ga. I'll be using 14 wedge NEOs per disc (24 total) and 11 coils. No iron in the coil centers on this one.

I'm thinking an 8 ft tip to tip blade for this unit. Most likely my foam pipe blades?

This will be a 48 volt machine. This is why the high turns count. I'll be using the 3 amp diodes (44 of them) as in the ceramic 14-11 alt.

Like to see cut in around 200 rpm? DANO? This is my first build of a machine this big.

My little 8" duel rotor works so well with 250 turns of 22 ga. per coil for 24 volt use, So twice the turns count (500 turns) of 25 ga. would equal for 48 volt use.

However the littel 8" only has 12 magnets per rotor and 9 coils and has a much smaller diameter.

I'm thinking the larger diameter wire (24ga.) and more poles will allow slightly fewer turns and still get the 48 volt operation I'm looking for plus the added current of the larger wire ( 24 VS 25 GA).

I've seen over 1600 watts from the little 8" in a storm without any coil heating.

It will be interesting to see the upper limits of this unit.

Hope to have this genny flying this winter? The 40ft tower is waiting.

I'll post pictures as the build progresses. Thanks for any answers on the 24ga. ampacity.

                                     Jerry

[Flux]

Nearly impossible to give you a figure Jerry, it depends how well you can cool it .

Your wire is rated at about .4A at 1000A/sq inch. Typical ratings on transformers is 3000A/sq inch. Welding duty things can run at nearer 5000A sq inch.

At 5000 you are looking at 2 A and I suspect you won't get much above that except for very short time ratings. You have a lot of parallel circuits so you may get a decent output.

I am sure you will find the neos so much better than the ceramics and you will need far less turns. You may be able to use thicker wire.

Flux

[Jerry]

Thank Flux.

I was doing some # crunching and came up with about 1.8 amps max.

So I think I should be fine. I have the 24 ga. so I'll wind a test coil.

What about the cut in rpm and blade size?

Thanks again Flux.

                        Jerry

[Flux]

For 8ft with conventional blades then you need to cut in below 200 rpm. With plastic pipe blades you probably need to go a fair bit slower perhaps below 150 rpm.

Flux

[Jerry]

Sounds like then if I go with the 8ft pipe blades the 24 ga. may be a good choice.

If I go with a more conventional blade a larger ga. wire may work.

You know I'll try several scheems.

Thanks again Flux. I'm leaving this morning, be away from the board for a few days.

I'll get back to this discusion then.

                          Jerry

[ETech]

"My little 8" duel rotor works so well with 250 turns of 22 ga. per coil for 24 volt use, So twice the turns count (500 turns) of 25 ga. would equal for 48 volt use.

However the littel 8" only has 12 magnets per rotor and 9 coils and has a much smaller diameter.

I'm thinking the larger diameter wire (24ga.)"

Sorry, but you kept changing wire gauges in you description.

Just wanted to add that of the three wire gauges that you list 22, 24, and 25 AWG:

22 AWG has the greated current capacity and the largest diameter.

Followed by 24 AWG and then by 25 AWG.

You may know this already, but from your question it wasn't clear to me.

Good luck,

Etech

[Gary D]

 ETech, Jerry did a translation from a 24 volt to 48 volt stator. The 25 AWG wire at twice the turns would allow the same watts thru at 1/2 the amps.

 The only error I saw was in 14 magnets on each rotor needed to add up to 28 (not 24).

 It will be interesting to see what the total winding count for the desired cut in speed. Going from ceramic magnets to neo's (Ed's?) should be an eye opener.

 If I understand Flux correctly tho, the stator will only be safe up to around 1200-1300 watts (at 2 amps per coil). That is figuring the current turns and wire size at 58 volts. Jerry will definately need a furling system on this one.....

    Gary D.

                       

[bracken]

I'll second what every one else had said, with one exception.

The insulation, i am guessing you are using magnet wire with an enamel insulation, right? if you are using high temp stuff 180+ C, mil spec goes to about 240+ C with no cooling and expected continuous use i would keep it under about 1.5.

If you can give it at least min cooling you might be able to push it to 3 amps. Remember tight bends or kinks cause hot spots, burn off there insulation and start burning the wires next to it, before you know it your 200 turn coil now only has one turn!

Good luck!

Bracken

[Jerry]

Thanks for the correction Gary D. Good eye. Must have been to many #s for this old guy. You are correct. A total of 28 magnets not 24.

Gary do you have any idea at what mph furling should ocur on this unit?

I've never biult a furling machine. I'll probobly fly it without it and see what happens.

The littel 8" actuly did over 1600 watts in that storm.

                     Jerry

[Gary D]

 Jerry, have you tested a coil at 400 turns yet? There may be a bit of difference between ceramic's and the neo's. Hopefully you'll need less turns to get the cutin at 150 or so that Flux suggested. No sence jumping the gun until you get that test done... Hopefully you can get 2 strands in there per coil to get your wattage up while keeping a safe value diode wise...

            Gary D.

[Jerry]

Hi Gary D.

I've exstrapilated (sp?) the turns count from my littel 8" duel rotor machine that uses the same NEOs I'll be using in this new 14-11 NEO alt.

I refur to the ceramic 14-11 only because that coil count and magnet count worked so well. And I know its a very doable and good preforming configuation.

I built the 14-11 first just to confirm it was a good and viable scheem for NOEs as well befor I waisted 14 NOEs and a bunch of wire, diodes and time.

I refur to the 8" duel rotor NEO alt because it also works so well.

So now I'm combing the 2 ideas. The small wedge NEOs from the 8" 24 volt and the coil/magnet count from the 14-11 ceramic 12 volt and also the increase of voltage from the 24 volt 8" to this new 14-11 NEO 48 volt.

In the 8" 24 volt the wire ga. is 22 at 642.6 circular mills. To double the turns count I would need wire half the circular mills or 25 ga. at 320.4 circular mills.

Since the magnet and coil count is larger in the NEO 14-11 with larger 12" rotors the vilosity will be greater with a higher poles count for a given rpm. Therefor higher voltage.

There should be enough of an increase to allow even larger mills wire with fewer turns.

Thats why I'm thinking 24 ga. at 404 circular mills. Yes its posable the wire ga. might even go larger then that. I'll know once I've done some coil testing. Keep in mind each coil will be producing the 48 volts. Neat thing about this aragement, if any coil or brige opes up the unit will continue to make power airly smoothly.

1 coil goes out power is reduced by 1/11th and ECT. At this small wire ga. it would be posable for a short to simple burn the 3 amp diodes open or a coil open with not much of an interruption of operation.

However there were no burntouts of any kind on the 8" version even at 80 plus mph with no furling.

I'll go with Fluxes sugjested 150 rpm cutin for the pipe blades.

The littel 8" withstood over 1600 watts in a storm. No reason why this unit would be any diferant.

BTW I'm still using the littel 8" in some blade & wind tunnel tests. Its as good as day one. Its "Jerry Rigged" 9 coils 9 fullwave bridge rectifiers.

The 14-11 NEO will have 11 coils and 11 fullwave bridge rectifiers.

After checking on parts the blade may be 7.5ft.

                             Jerry