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Ramiel
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Massive transformers
This idea here is really more like MadPhysics...
My gR4nD 1dEa!!!!1
primarily the grand idea was to have one multi-transformer, if you will. it works like this:
Here it is adapted for rapid electrolosys.
I am the first to say that this is a pretty dangerous device, that sort of power is enough to zap someone dead many times over i believe. Therefore
would also be making a grounding thingie.
Do you think this device will work? will it induce correctly and work essentially like three transformers in series?
On a slightly different topic, does anyone know how to limit current into a circuit? I think i would need to do that so the device didn't coverheat
eh?
ps. If it does work and no-one has thought of it before, then it's copy-left. If someone patents it, I will hunt them down, kill them, (eat them?)
revoke the patent and make it copy-left.
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Organikum
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???? ! ??
This makes no sense to me sorry. I plain don´t understand what function the middle two windings have. I suppose a kind of stepping up. I also suppose
that this cannot work on a common iron-core.
After the negative part has to follow a constructive one:
What you want can easily be achieved by rebuilding the transformer of a microwave. You rip away the output windings and rewind the coil with
something usable for the more current coming, say 10 to 15 windings of 1-2cm diameter wire. Wire? Not wire anymore thats more cable. I have a link
somewhere as it was made this way for a homemade electro welder, I will dig it up.
Limiting current? Your design doesn´t need this. It will blow every fuse at once. The law of Mr Ohm might be helpful, something like: more resistance
less current? Some lightbulbs in line before the transformator might give a easy regulation......
ORG
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Organikum
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here it is, the transformer....
thats the way it is done:
| Quote: | | Microwave oven transformers are step up transformers. That means that the voltage at the secondary winding is higher than the primary. In microwave
ovens, the primary accepts standard house current, 120 volts. The secondary voltage is typically 4000 volts. The secondary winding must be removed and
a low voltage winding put in its place. The new secondary winding has a typical open circuit voltage of 10 volts. Under an arc welding load, this
voltage will drop to between 2 - 4 volts, and up to 250 amps. You will use #6 single conductor wire for the new secondary winding. Many people ask
exactly how many turns I put on this new secondary, and I always say as many as you can fit! If you must know, I got 12 to 15 turns on each
transformer. |
from this page:
http://www.dansworkshop.com/Homebuilt%20arc%20welder.shtml
Hey this is worth a look - the guy buildt a electro furnace for melting aluminium too!
This should be hot enough to fulfill the most perverted dreams ;-)
mine at least
ORG
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lucifer
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Sorry to say ramiel, but this transformer will not work, the red and blue windings are shorted and there four will also short the black winding,
result a blown fuse.
What kind of transformer are we talking of, it looks like a three phase transformer.
Also the turn ratio’s are wrong.
You will get 68V on the output (if red and blue are open)
With only 35 turns on the primary it should really be a very big transformer.
Or it will still blow the fuse
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Ramiel
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It looks like it will not work because of those many annoying laws of physics. But just imagine that there was a way for the wires to induce only
those coils parralell to them, and the top two coils were ~3500 and ~1000 coils. That might work, no?
I had a look on hv4 for MO transformers, and that looks like the right way.
I looked at that dan's workshop site while I was searching about for furnace designs, the only problem is that the plans for the furnace cost money.
I was thinking of purchasing it anyway (then i could give it to the community i guess).
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Organikum
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microwave transformers
They are for free and rewinding is easy. You can make an connection at winding 10/12/14/16 for example and have various voltages output available this
way.
What advantages has the hv4 MO transformer? A link to this or short description would be appreciated - I always love to see better concepts for
something.
thanks
ORG
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Ramiel
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"MOTs and MOTs"
"MOT coilers unite"
Oh no! what have i done? i've linked to another forum and stolen posters. noooo
nbk2000 spare my soul!
Caveat Orator
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axehandle
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I can't think of any reasons for having more than 2 different transformers:
1) An ATX power supply. An old one can give +12V at 9A and +5V at 30A, new ones typically more. And they are dirt cheap, or free.
2) A Neon Sign Transformer of respectable power. I've got one capable of 9kV at 60mA, which comes to 540W of power. This one wasn't cheap
though, but not that expensive either. Approx. 200 Euro including VAT, with a 3 year warranty =)
(3?) A bridge rectifier connected directly to the mains in case you REALLY want to electrolyze the hell out of something.
Edit: Actually you'd probably want to reconsider point 3. When electrolyzing using a salt bridge made out of toilet paper impregnated with
KNO3(!), I lost patience with the slow rection at 5V, and connected the electrodes to a full-wave rectifier driven directly from the mains (220V AC).
The paper boiled and carbonized. Perhaps a little too much power
[Edited on 2004-2-12 by axehandle]
[Edited on 2004-2-12 by axehandle]
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Organikum
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to 3.
If you dont use an saltwaterheostat or other ballast between your mains and the bridge rectifier you will probably only blow your fuses.
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axehandle
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Organikum: Nope, only got some toilet paper to almost catch fire. But I won't do it again, I'm a one mistake learner.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
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rikkitikkitavi
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In most EU countries cheap (chinese made) welding transformer can be bought for around
50-90 €, they have a low voltage winding of around 20-30V, capaple of sustaining a good 6-800 W continously.
Most of them also have a current limit function by adjusting the iron core, but it will not work as a fuse.
/rickard
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jimwig
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Number 6 copper wire will not hold 250 amps for any lenght of usable time.
The highest rating for that wire is around 80 amps and that's free air single conductor.
250 amps would require around 4/0 Cu or several smaller wire sizes in parallel.
Take a look at the buzz box welder/transformers sometime and tell me you see anything short of large copper secondaries on the transformer. These are
rated at 225 amps and that's only for intermittent use. Duty cycle around 15%.
So if you want to do welding or more like use it as a supply for electro stuff you had best check the wire sizing.
Oh somelthing I saw recently in an old Popular Mechanics magazine. When you are winding using silicon iron laminations and they are closed - meaning
you cannot wrap the wire around and around - use a shuttle cock like is used on a loom. Wrap your wire onto the shuttle and pass it through over and
over. Great idea in those old mags.
JimWig
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rikkitikkitavi
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duty cycle 15 % *225 A => 33 A *25 V = 800VA aprox.
But unfortunately it is a little bit lower in reality , since the actuall output reduces a bit since the duty cycle /power is not linear.
if you can measure the wire size, aprox 3 A/mm2 cross section is ok with no cooling.
Good idea about the shuttle cook. It is a hell to rewind an E-I core.
/rickard
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Organikum
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rewinding cores
If you are to rewind the low voltage side of a transformer like from a MOT it is much easier to use Cu or Al SHEET (with an isolating layer or
painting - is understood) to wind the low voltage - high amperage side. The sheet is much easier and closer to fold and you will have almost no noise
generated from loose windings (whats nervy like hell). As almost no space is wasted like with round wire you can use more cmxcm effective and go for a
higher load this way.
"laminar transformer"?
Not sure on the name.
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jimwig
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rikkitikkitavi
a bit more on duty cycle. what is meant here is that a total of 15% of the time used welding can actually be the rated max current through the unit.
TRX.
this is not rms or pulsed - the unit still delivers the selected output current just not a 100 per cent of the time. otherwise it burns up. overheats.
Out of welding 100 minutes only 15 of those minutes can be at full power with a down cycle for cooling else you loose your insulation on the windings.
it melts..
So its a time factor not a power factor.
disipating the heat via fan etc would probably improve the duty cycle somewhat.
But now that I think about it if 800va output could be set (that's about 20 amps) or so then maybe a 100% duty cycle could be achieved.
But that would only be enough current to weld tin cans maybe.
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Marvin
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jim, rickard is correct, the time factor derives from the power factor, not the other way around. His math applies to a system where its being used
to supply power continuously, and still be within operating tolerences.
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Hermes_Trismegistus
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or..
| Quote: |
disipating the heat via fan etc would probably improve the duty cycle somewhat.
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Submerging the whole shebang in a tub of oil would work even better.
Silicone transformer oil is best, but peanut oit works in a pinch.
The larger the mass of oil the longer the duty cycle. The oil will usually mix itself via convection
as a temporary measure to really increase the heat capacity, pre- freezing the oil or adding frozen stones to the tub will also help.
Oil is cheap, so use lots and a suitabley large and heat resistant container. It the container is metal it will also dissipate heat to the surrounding
atmosphere faster, but yer gonna want to ground it, just in case (get it......in case).
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axehandle
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<b>or...</b>
Submerge the entire thing in Fluorinert(r), cooled by liquid nitrogen running through pipes in the coolant intermediary. 
Someone once did that to successfully overclock a Pentium II by a factor of 10...
Edit: <b>Yes</b>, I'm post-whoring right now.... the 250 limit is sooooo close....
[Edited on 2004-3-4 by axehandle]
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rikkitikkitavi
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but you have to cool the oil in some way, otherwise you end up with a hot transformer in warm oil. compare to the cooling flanges/tubes on large power
transformers. And actually, a large pot filled with oil doesnt provide much more cooling surface compared to the transformer, and the oils adds
another heat transfer resistance, especially when it is not forced circulated.
Ciruclating the oil in a radiator might do it, but then it becomes much more complicated.
Also, it is the inner (primary) winding that will be hottest , regardless of cooling method. Oil will not improve this since it will not contact the
primary winding.
/rickard
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axehandle
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That's why I suggested Fluorinert. (Even though I did so mainly in jest.) Its viscosity is much better for penetrating between wires. It's
horribly expensive though, but completely electrically inert. Combined with, say, water cooling and some mechanical stirring, it would work like a
charm. The world's most efficient and most expensive welding transformer.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
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rikkitikkitavi
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but the problem is the liquid (regardless of type of liquid) penetrating between the wires. There will be very little circulation regardless of the
circulation- or liquid for that matter. Smaller transformers have the winding so closely wound that liquid wont flow through easily, or might even
not, if the winding is impregnated.
large transformer has the windings shaped to cooling liquid can easily flow through.
Sometimes the core itself has cooling channels.
iof course fluorinert is a jest, I guess it is over the top for most of us...
whats the current price, 500US$/liter or so?
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Hermes_Trismegistus
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Big sigh!
| Quote: | Originally posted by rikkitikkitavi
but you have to cool the oil in some way, otherwise you end up with a hot transformer in warm oil. compare to the cooling flanges/tubes on large power
transformers. And actually, a large pot filled with oil doesnt provide much more cooling surface compared to the transformer, and the oils adds
another heat transfer resistance, especially when it is not forced circulated.
Also, it is the inner (primary) winding that will be hottest , regardless of cooling method. Oil will not improve this since it will not contact the
primary winding.
/rickard |
Nooo.....but then again, it's unlikely that anything you do (on the cheap) will turn this ugly little surplus transformer setup into a
High-Perfomance, internally cooled and jacketed wonder of modern science.
Will it?
I also didn't say it was perfect, just better than air.
Any liquid is better than air at cooling a substance regardless of the final transfer involved.
(because the molecules are closer together)
Having a hot transformer in warm oil is better than having a glowing transformer in air any day.
If you are driving so much power through a transformer that the heat doesn't even have time to dissipate from the internal windings to outer
portions of the transformer. Then you are just putting WAY too much power through it and you should look into modifying your setup.
Circulation through convection is significant.
At five bucks a gallon, a five gallon bucket filled with cold corn oil, will absorb one HELL of a lot of heat energy.
That will lengthen your duty cylce tremendously.
You don't have to cyle it through a radiator to make it worthwhile. Having a ten minute duty cycle and then having to wait half an hour is hugely
better than having a 3 minute duty cycle and having to wait forty five minutes.
and you'll be far less likely to push it too far and if you really wanted, you could drop in a copper coil around the edges and run cold water
through it for cooling. It would be unlikely to increase your duty cycle significantly, but would decrease the down time greatly.
What I would find easiest though, would be to simply buy some more oil, attatch a strap, and yank the transformer out and plunk it down in the other
bucket of oil.
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rikkitikkitavi
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yes , the oil will increase duty cycles if it is allowed to cool in between. I m not killing your idea, I have played with it myself , my point is
rather that it is difficult to say that it is going to increase capacity this and that...
I would think though that by using a fan, the simplest cooling is achieved...
/rickard
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Hermes_Trismegistus
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Experience.
Having run large HID transformers in an extremely hot humid enviornment for
12-18 hours a day I often ran into overheating problems.
There are situations in which having your power interrupted for even short periods of time while the transformers cooled enough to restart caused
serious problems.
This was my solution. It worked. I was able to run them for longer and they cooled faster.
Fans were my initial idea, and they worked up to a point, then the heat they produced and the amount of electricity they consumed became a problem.
using 8 1KW transformers in each room during a heatwave was difficult. I arranged five boxfans in a circle around the square rooms so that each blew
air in the same direction.
We jokingly called it (the first one the Cyclone room. As a teenager I liked to chatup the oldtimers at the local spot.
For those of you who've been around the scene and know what I'm talking about, I was in the headshop across the street from marc
emery's old bookstore where they were challenging the laws by openly selling clones.
anyway, an oldtimer was nice enough to sit me down and explain the difference between the heat capacity of wet and dry air and the way heat energy is
transmitted through gasses and solids verses through fluids.
and the difference between kinetic and radiant heat transfer.
I didn't retain alot of it, but kept enough to find that a clean five gallon steel tar bucket filled with oil was a magic trick for transformer
cooling. It also kept the thing from rusting.
Another sweet trick/but more time consuming and temporary, was to lay the transformer on a brick or a cinderblock that had soaked in water for a
couple days and then lay another on top. making sure the longest steel surface touched the largest flat cement/clay surface.
(also making sure the brick was wet but not dripping)
and replacing every four hours, that coupled with air cooling was pretty damn effective. (if I was using cinder blocks I found arranging them so the
air blew through the holes was better but dried them way faster.
good luck
[Edited on 5-3-2004 by Hermes_Trismegistus]
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rikkitikkitavi
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ok, i guess it worked fine for you
actually wet and dry air has almost the same heat capacity, so using a fan shows no difference...
wet cinderblocks+fan, hmm sounds a lot like evaporative cooling, very efficient..
/rickard
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