FYI: Wire sizes..

[fcfcfc]

Hi: In trying to figure out the "proper" wire size for gen coils, I found it ambiguous as to why recommended wire sizes for low voltage DC wiring were so different from 115-230VAC recommended ratings. Since I do not like confusion especially when it comes to technical areas, I sought out to understand this. To keep this somewhat short the following are reasons you might find substantial variances in recommended wire sizes at the same amperage:

Use voltage (power loss concerns not so much heat concerns)

Open air or in bundles (heat buildup)

Insulation type for non-bare ratings. (high temp or low temp insulation)

Conductor type (copper, aluminum or other)

Normal environmental temp. (Alaska outdoors or under the hood of your car in

                             Florida)

Just these few "conditions" can change widely the recommended wire size for a given use amperage.

So, if you find yourself looking at what appears to be different ratings for the same wire size, keep these variables in mind. The link below is a decent link for bare copper. They list the "open air" rating and reference the bundling issue which would be allot like gen coils that tend to "trap" heat.

.....Bill

http://www.powerstream.com/Wire_Size.htm

[blueyonder]

 thanks for posting this link.

  i will try and read every word. ive already read the power humor page .

   that cheered me up great.

  i dont know much about copper wire . but hope to have a better understanding .

  i have a lot in commom with copper wire but only the thick stuff.

[Flux]

"Hi: In trying to figure out the "proper" wire size for gen coils, "

That is what I thought last time I replied to you.

Why on earth are you looking at factors that determine wire size for normal electrical circuits?  

That reference you give is fine in context but don't give people ideas that you can apply this to machine windings. I don't care what you do, but don't confuse others please.

Flux

[TomW]

flux;

Wondered the same thing myself, just hoped someone would point it out.

I think it is just another example of the current obsession with math and numbers that seems to have infested the board.

Math is the language we use to describe electrical relationships but, in the real world, it seems to seldom work out with the exacting precision that some would have you believe. Usually a fair bit of "windage" between the mathematical model and the real world application. A valuable tool, indeed, but not something to get too hung up over.

I suspect some math is involved in a fair bit of your input, however.

As always, your input is invaluable.

Cheers.

TomW

[fcfcfc]

Hi: I will say one thing, some of you are wonderful at taking the things people post and pulling them out of context and twisting them just to have something bad to say. Are you so easily threatened and insecure....

I did not say the chart was "THE ONE AND ONLY" piece of info used to determine coil size!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I think the simple truth is some of you have been up in the mountains to long and need to come down and take an English course and reading comprehension....

If you have that much hostility inside, get laid....

[finnsawyer]

Back in the slide rule days getting the answer for a circuit design to within 10% was considered adequate.  Today with computers you can crunch the numbers down to the tenth decimal place, which doesn't change the fact that the thing must work in the real world.  A certain amount of understanding of the relationships that affect the design must exist in the designers mind. While such an understanding for the engineer develops as a result of his course of study, it doesn't exist for those that would be characterized as lay people, most of those who frequent this site.  Consequently, the ratings given for wire or other components should be put into context at all times.  That is, what type of use goes with the rating.  This ideal, of course, will seldom be met in practice here.

[wooferhound]

The biggest point that should be made here is that

 - Wire gauge amperage ratings are closely related to the temperature that they are used in -

That is very important to the success of our projects !!

[Flux]

That chart was for wire in general and as such it is useful.

It has nothing to do with wire or anything to do with coils. That is a different ball game and using such information for coils is plain crazy. The wire used for coils is a different thing with different insulation, the current densities it is worked at would be ridiculous for normal applications. I did give you the benefit of the doubt in case you were worrying about connecting cables. When you confirmed my suspicion that you were talking about the wire used to wind coils I thought I ought to make it obvious to another newcomer also involved in that post. Your information was entirely confusing to anyone worrying about machine windings. If it had been advice on connecting a wind generator to batteries or inverter wiring or something I wouldn't have commented.

There are a lot of people coming here with little knowledge and looking for a starting point. They will not be able to distinguish wire information intended for electrical circuits from data on magnet wire meant for coils, especially when you refer to windings.

There is nothing wrong with giving information and links as long as it is relevant to the task in hand. Information given at random and out of context just causes confusion.

Flux

[TomW]

fc;

You used the chart out of context. Period. End quote. Accuracy is important, especially to the new folks who are probably confused already.

No need to get all hostile because you misunderstood the purpose of the chart.

I happen to be a flatlander. And those guys up the mountain happen to be close personal friends so insulting them will not sit well with me. Not that they need my protection.

Insulting folks who are trying to square away your misconceptions is counterproductive don't you think?

Did you [at least] get my point about the math simply being the language we describe things with and not rigid result predictors? Not to mention that it is an integrated system and changing any one piece affects the entire device. Plus, as woofer mentioned , ampacity is all about removing the heat from the wire. Thats why they list different amperages for different uses. Its the cooling that dictates the ampacity. Just some free information to further your education because I truly wish to see accurate information posted here, even for folks who irritate me.

My only insecurity is that this site will become over run with academics and leaches and become useless to the doers it was meant to serve [make your electricity from scratch].

We are all different and it is quite easy to misinterpret written words regardless of how well thought out or worded.

Carry on.

And you are welcome.

T

[DanB]

Hi Bill -

It's about like everyone else said, and of course we realize it was an honest mistake...  but ths chart is not useful for coils of wire in alternators.  For power transmission the goal is to keep the voltage drop low - 'bundled' I shoud assume mean a couple/three wires bundled together with insulation around them or something.  Open air is just that (power lines  - that sort of thing) and chassis wiring I would assume means wires inside things like amplifiers, power inverters etc.  In all those cases you don't want things getting too hot.

In alternators we're often pushing the limits (sometimes too far) and running very hot with losses in the windings pushing 50% at times - these rules on this site don't address that application.

[fcfcfc]

Hi: I misunderstood nothing. The whole point of the posting was to bring to light that different charts can give different amp recommends based on different parameters. If you really had read it you would see I mention heat, internal and external, insulation, wire type etc.. all as factors and to quote myself:

"Just these few "conditions" can change widely the recommended wire size for a given use amperage." Gee, what does change widely mean..??. sounds to me like something that can make a BIG difference. Did it ever to occur to you to take, just maybe, a base chart like that which does have validity at a certain set of conditions, and using you VAST experience with PMA gens, create a base multiplier which could be used in conjunction with those base current ratings and call it a PMA amperage recommendations table. Such a table could easily use amps, volts and watts to guide first time users to zero in on coil AWG wire ratings and the like, without having to create a new post everytime.

You assume that because the post doesn't read the way you would have written it, the author must be lacking knowledge or be embracing ignorance... How arrogant and defensive.... and down right unfriendly...

[TomW]

fc;

You seem to be over thinking the plumbing. I usually leave that to the armchair crowd.

Just my opinion.

As far as the wire charts are concerned, you win.

So now show us what your going to do with the information. Anxious to see how you apply the information in hardware.

Best of luck with it.

TomW

[rossw]

There have been enough answers and posts to this, some have touched on what I believe to be the most important difference, others haven't.

Simply put, in the real world, people want to keep costs to a minimum for a given job.

With "mains" applicatons, that's 240V AC (in my part of the world, 110/120 in other parts). Under those conditions for a given CURRENT, the permissable voltage drop is several volts. Running a 240V motor drawing 10 amps, its not the end of the world if you only have 230V at the end of the run.

Most of whats done here is working at substantially lower voltages - often 12V.

If you tried to pull the same 10A at 12V, and lost 10V because of line resistance, the 2V you've got left isn't much damn good!

This, in a nutshell, is why "mains" ratings for cables is so different - the permissable drop (which is dissipated as heat in the cable) is much less of an issue than in our field. While we might not be too concerned that the cable has got to 50 or 50 degrees C, the fact we're "wasting" 90% of our power IS a problem.

YMMV, and of course my opinion isn't worth a damn

[DanB]

Hi Bill -  I tried to understand the best I could and in my one comment I thought I was being reasonably nice.

'I misunderstood nothing.'

Forgive me then for misunderstanding you.  It would also seem that everybody else misunderstood  you so perhaps the blame is not on us for being defensive - arrogant.. unfreindly... needing to learn english/get laid etc.  I find often times that people accuse others of having problems that they themselves struggle with ;-)

Good thing I've had my 2nd cup of coffee this morning before commenting or I would shut down your account for being so thin skinned and arrogant on this one.  You've put up a lot of postings and the same people that you are accusing now (OK.. because they were confused by your posting) have spent many hours to help you and answer your many questions.  

You said 'reference the bundling issue which would be allot like gen coils that tend to "trap" heat.'

Which is simply not true.  Bundled wire for power transmission is nothing like wire used in alternator coils.  Perhaps we all misunderstood you and if that is the case then I would have to conclude that your posting was confusing and perhaps a bit misleading.  

 

[fcfcfc]

Hi: So am I anxious but it is going to be awhile... I still have more research to do. This is going to cost a bunch of thousands and I am not about to just wing this and hope for the best... I may end up putting the whole thing on a site somewhere and just drop a short post here with the link when the time comes. Then, if anyone here is interested in  the VAWT or the other green aspects of the building, they can just click on it....

[wpowokal]

Sorry I could not resist, thanks for a good laugh, I thought the northern winter was comming to and end.

I am not going to read all posts again but to adress your coment about recomended wire sizes for low voltage verses high (120/240v) simply relates to current verses voltage.

Heating is the killer, and that comes from current squared time resistance. A duel rotor coil would have to be concidered super bundled, as oposed to mains voltage cables being bundled, open air buried, laid in a tray etc.

Should one take the given resistance of a copper cable of a given cross sectional area (it is irelevent what it's use is) by virtue of the resistance per metre it will generate a given amount of heat (watts) relative to the current it is carrying.

It is quite an eye opener when one crunches the maths as to how much heat is generated in a say 1 Kw duel rotor at 1 Kw output, these losses have to be accounted for and can very quickly exceed 50% of output Kw.

To follow a proven plan or roll your own is an individual's choice. There in lies the reason desighning wind generators differs widly from mains cable runs, same basic principles very different applications, but IMHO one of the reasons this forum thrives, exchange of information, but it has to be factual (ie maths) or backed up by practical experience. I have used the information in your link along with much other data (fact) how much heat I believe a wind turbine stator can disipate is conjecture/experiment or proven desighn.

allan down under

[fcfcfc]

Hi:

Yes to all that you said. I think it should be possible though to come up with a baseline multiplier to use against a standard wire chart which would tell you, fairly close, the appropriate wire size to use. Actually, there is enough info. out there that one could design a spreadsheet that could give you all the basic coil answers. But again the reason for a board like this is not purely knowledge driven but socially driven, and the more it is automated the fewer the "social" interactions.

Regarding cooling, I have been thinking about putting some form of active cooling into my stator when I build it for those very power loss and protection reasons. Having thermally tripped sensors activating some form of cooling should not be very difficult considering the stator is the static part of the machine. My main motivation for doing this though, is more about protection for the gen then it is about a few extra kilowatts of power during high wind periods. I am trying to use the largest wire size I can in a delta config.. Using #11 square, which is almost identical to #10 round current wise, should allow me to keep fairly cool up to around 3 KW. I am still trying to work on these details but I really can not zoom in on this much better until I do the turbine wind tunnel tests and get some idea of the torque curve for the turbine at different wind velocities....