Miller CP-250TS converted to single-phase - Page 5
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  1. #81
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    DaveKamp,
    I have found some info that might help you out. I have been working on my convert also and found that the welder was designed to be Spray Transfer only and was later revised with a Z inductor for short arc and they call that model the CP252ts it has the inductor in it. I found that the inductor for the CP252ts is kind of expensive around 800 new so I took an iron pipe about 2" diameter and made me a temporary inductor of about 30 turns of my - lead wire. I have found an online supplier of Grey Iron Rod 40 and have ordered some 1.5" and 2" solid rod and this should make a real nice inductor. I also found that sense the machine will go down to about 18 volts about 30000 uf of capacitance really helps out if you want to weld aluminum and it helps with the weld on other material also but not as much as the inductance. I also setup the slope coils to max inductance also. Hope this helps I also found that the .045 and larger wire works better in this machine than .035 before I added the inductor also.

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    Thumbs up Awesome tip!

    Thanks for the tip, Dan-

    I've been reading and re-reading the slope section on this pig, and don't recall seeing any reference to ANY kind of transfer, and in considering history, I can understand why- they were probably hadn't come up with any result EXCEPT spray. In any event, I believe you're right- a good chunk of UNIFIED inductance was my next plan. I've been tossing around different ways of building a compact 400A reactor, and decided that it'd be really hard to make it fit INSIDE the case, unless I was to excise the three-phase unit. Post your conversion- I wanna see what you've done!

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    DaveKamp
    I will try to make it out in the shop this weekend to take some pictures I have been working 12 hour days for a while and we have a new baby boy that is 2 months old so I spend a lot of time with him when I am off. I found that Speedy Metals sells grey cast iron rods which should be great for an inductor here is their web sight Round Cast Iron | Cast Iron Rod | Cast Iron Supply & Suppliers | Metal Industrial Supplies I was using my father in laws mig gun and wire feeder to test my CP250 out and I have now moved it to my shop and have been working on getting my 10e feeder and my Bernard mig gun gun working here of course no one localy sells parts in my area. I will take some pictures when I can.

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    Default Miller Dimension 302 Welder 60 series

    Hello Dave,
    I have been reading your excellent informational articles converting from 3 phase to single phase power and have a question?
    Is this welder Miller Dimension 302 convertable to run on single 220v from the three phase 220v?
    Would it be better to run it on a rotary phase converter instead?
    If that is the case how big a converter would I need?

  5. #85
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    Hi Dave; Did you fire up the welder yet? I see in your schematic the capacitors are connected effectively in series which will tend to half their value. I'm wondering if your getting the output you desired?
    Frank
    Last edited by Froneck; 05-16-2011 at 11:31 AM. Reason: mispelled word

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    Default Hi Guys!

    Sorry, between work, and neck surgery, I've not only been out-of-pocket, I've also been out-of-the-shop and not lifting anything heavy.

    I did stumble upon Scott Henion's writeup on his output reactor experiments, and when I get an opportunity, I'll do similar output reactance... note that his writeup features converting the 3-phase internal 'slope' reactor to a single-phase output filter reactor... which mimics the design of the CP-200 setup I first started my single-phase experiments on.

    I'm betting that his reactor mods, along with my single-phase input, will yield a pretty strong horse. It'll be a while before I can do it, but look for it in the future.

    Bull- the Dimension MIGHT be suitable for the H_K conversion, but I haven't looked at any diagrams... nor have I tried it, so I won't say either way... I'd rather try, and post... but if you've read this, and the SRH-333, and the CP-200 thoroughly, and have a solid understanding of what's happening in this mod, there's no reason why you couldn't give it a shot... if you do, I encourage you to write it up... and if I can help 'ya out, I certainly will!

    Hi Frank! The LINE side caps are yeah, essentially series'd... however... they're doing phase shift in a variable reactance condition... the output side caps... I set 'em up to get what I could get, with what I could get... (did that make sense?)

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    was startin' to worry about you dave
    glad to see u back around
    if you need a hand let me know

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    Talking Sorry...

    Sorry, Kev... I've been runnin' like crazy with this company project... but fortunately, we're ahead of schedule, and lookin' like we'll have it well wrapped up by early August... nearly 2 months early.

    In other news, rapture has been postponed until further notice, citing mathematical errors produced by a first-generation Pentium processor running WIN98 with Excel 2007. Tonight's episode of Dante's Divine Comedy will not air, instead we'll be featuring Jay Leno and Dennis Miller providing commentary on the greater works of Edgar Allen Poe!

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    Hi Dave and others,

    Just picked up a CP250-TS with a S52-E wire feeder for $350 and am starting my conversion.

    I've been pouring over this write up and Scott Henion's write up and in my novice brain it makes sense to do a hybrid solution using your primary wiring modifications and Scott's slope reactor modifications. Did you ever try that on yours?

    Also is the modified schematic on page 1 still valid? I see that later on you state that you switched the wiring to 208V on the primary which is no big deal, but later on in the thread you sized capacitors (55/5 x4, 2 for each leg). The drawing states 140-150uf.

    I too work overseas and I usually take the time when I'm on the road to do the research/purchasing phase of my projects. I'm attempting to size the capacitors to make it happen and would enjoy reading about your findings using Scott's reactor mod.

    Does the .045 wire work best with this setup? Reason I'm asking is I need a gun for mine, I'm looking at a 250A Tweco Weldmark that ships with a .030/.035 liner. If the .045 wire works best then I will order up the .045 liner.

    I'm just a hobbyist welder, I currently have a Lincoln SP125 plus but more often than not I find myself needing a bigger welder. I'm tired of borrowing a buddys MM 211 and think the CP250-TS will make a great addition to my equipment stable

    Thanks!!!

    Erik

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    Cool project. Not to be a simpleton and I may have missed this. But did you ever just try reversing the polarity?

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    .045 would be at the top end of a 250 machine
    .035 would be more in its "power band"

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    Ok .035 it is then

    Dave is very busy but answered all of my questions.

    60uf 370v x4 (2 per line) will work!

    I also emailed Scott Henion and made him aware if this thread, perhaps he can share his knowledge on his modifications and whether or not they will work.

    Thanks!!

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    Default Yep-

    Yeah, it's been a really busy year-and-a-half, and haven't gotten around to doing a reactor addition. My intention is to bypass the slope coils (make the secondary go straight to the rectifier stack) and then wire the slope coils in series, and use THAT for doing stabilization (and adjustability)... just haven't gotten to it yet.

    I've been using the TS, but primarily on the heavier stuff... when 'ya wind it up tight and run heavy spray, it settles down. I'm sure it'll push 45 wire pretty well, but going to thicker wire doesn't make up for the fact that it's 'antsy' at low power. I'm sure that Scott's mod will clear it up, just haven't done it yet.

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    Lightbulb Update- Another Go-Around...

    Hi All!

    Okay, I can't say wether it's a fit of inspiration, or desperation... winter is coming, and I need to get this TS buttoned up and out-of-the-path-of-progress....

    But I've been contemplating it for better part of a year now.

    I volleyed a few Emails with Scott Henion (How to Modify the CP-250TS for Single Phase and Short Arc Welding) which didn't really come to any forward progress.

    BUT...

    I went back and revisited the diagrams, and took some voltages, and found that there was something, somehow, missing.

    In earlier tests, I tried doing a delta-to-wye conversion on the secondary side, and it wasn't quite meeting what I expected... not as predictable as the CP-200.

    It also didn't respond to handle-position changes as I'd expected.

    And finally... I never did verify operation beforehand... so I had no authoritative way to identify wether it was actually in good health to begin with.

    Well, it wasn't. It'd sat for 9 years in a barn, at the residence of a gentleman who raised cattle.

    I went through, took measurements, and decided to break each connection, polish them clean, and reassemble them. Every brush, every rectifier plate, every binding post... and every connector on the slope coil.

    When scale was set to 18 OCV, NO load, using a Fluke 85:
    Initial voltage: 14.24
    After cleaning connections: 21.81.

    Fluke and welder's panel meters agree.

    That large of a change indicates to me that those connections had been so permeated by cow urine, that it was NEVER gonna maintain a proper arc.

    Now, I also disconnected the SLOPE coils altogether, as I have a future plan for them... but tomorrow morning, I'll perform an operational test, first setting it up with no capacitance, and again, with capacitance. I'll do the test without changing ANY adjustments, and then I'll make some test-beads under each circumstance to try to get the best stability.

    Next step, will be to set up the slope inductors in parallel with eachother, DOWNSTREAM of the rectifier stack, as an output inductor. My next step (if deemed necessary) will be to install yet more inductance in series, but I've got a gut feeling that somewhere along the line, it'll settle down and go short-arc without needing to install more. I believe just the series inductance of the slope coils AND the capacitance already in place, will put it in the short-arc domain.

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    in messing with a little 250 Linde (in the same class as your little friend) this weekend. i noticed that the "inductance knob" had very hansom effects on the bead. it went from kinda shty (at lowest setting) to damn nice (at highest setting).

    so

    the inductance factor is hear-by deemed as "quite significant" on these little old welders by yours truly

    also
    no place for cow piss in a welder i am sure

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    Talking I agree!

    Okay, so the slump coil connections were clearly a problem... cleaning 'em up brought OCV well above the scale indications, which means I'm not chasing my tail on THAT anymore.

    With filter capacitor NOT connected, it'll operate in spray-mode nicely at about 300A... way too much for most needs, and I don't think a spool of 035 would last too long at that, but someday I very-well-may need that kind of ability... but today, I want it to work calmly in short-arc transfer.

    Reconnected the filter cap, and it DID calm down substantially... not spraying fits of hot metal pellets everywhere... but it's still stacking up, rather than puddling.

    I've reconfigured the slump inductors to work in parallel DOWNSTREAM of the rectifier bridge... gotta make some suitable busbars to carry 400A, then bypass through the inductors and see how it does. The concept here, is that although the slump coils' reactance is low, by moving it DOWNSTREAM of the rectifier array means the coils are dealing with substantially lower ripple, hence, they'll smooth it out a whole lot. Stay tuned!!!

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    Default Update

    Okay, so I had some time home, and put in a few hours in the shop.

    I disconnected the slump coils from their original configuration altogether, and found that the performance below 300A was essentially unchanged.

    The slump coils don't really have much inductance... they're wound around a 3-phase core, using copper that is about 1/4" square. Doesn't look to be useful for much more than AC-side (before the rectifiers), but it MAY be that it won't take much inductance to settle the big bird down in the 150A range... SO... as an experiment, I tied all the inductors together in parallel, then connected 'em via busbars to the output. One of the possibilities, is that by moving the inductors DOWNSTREAM of the bridge rectifier, that the frequency-based products would be much higher, hence, the inductor's value would have greater impact. Prior to the rectifier bank, the inductors are being fed with 60hz waveforms. AFTER, it's DC with ripple in the 3-phase realm... so three times that figure... and the next point- the ripple will be LOWER.

    Well, It WAS noticeable, but not nearly enough. I'd put 'em in series, but I don't feel satisfied that the conductors have enough capacity to carry full weld current.

    As noted above, Wippinboy (Kevin) adjusted the inductance very low on his Linde, and found that it would exhibit similar characteristics... meaning, it'd weld fine at the higher levels, starting at spray mode, but as we got out of the spray mode realm, it'd get yukky.

    There's an interesting factor of magnetics in play here... that is, when a magnetic element exists in a circuit, it's properties of action are not necessarily linear. How they perform at high power (say, when the TS is operating in spray mode at 350A) is drastically different from what you'll get when running at a very LOW level (i.e. 100A). It's a function of the inductor's core, and how closely coupled the inductor's WINDINGS are. Basically, it's the situation of farting in a hurricane. This not only happens in a simple inductor, it also happens in common transformers- the coupling efficiency varies based on the amount of power being carried through, because the magnetic fields of the windings don't build up enough to effectively act upon the core. In the case of welding, this would explain why the TS is pretty happy blasting out high-current, but doesn't like being small.

    So the conclusion here, is that paralleling the slope coils DOWNSTREAM is still not enough inductance... substantially more is in order.

    Which brings me to Dan Bennett's notes. Sorry I didn't acknowledge it Dan- I didn't ignore it, I was just still on the track of tryin' to make it fly without adding an external component.

    Since you got good results from as 2" grey iron pipe with 30T of welding wire, I'm gonna make an experimental inductor, and I've been pondering what would be a good-quality 'junk pile' alternative to the OEM external unit. Obviously, we don't have inductance numbers from which to go off of, but we can take a guess.

    I came up with some stuff that I THINK might do the trick, and since it can be connected into the welding leads, I'm gonna button up my CP and move it out of the garage and into the small workshop for the winter (that's where most of my welding is done anyway).

    For my first experiment, I'll use some pretty common junk:

    Some old window sash weights: Grey iron, about 1.5" diameter, and 10" long, recently removed from our house during some remodeling...
    Some old overhead aluminum service wire, also recently removed from the house when I ran a bunch of the farm-overheads through underground conduits.

    The iron may be pretty good... I'm sure that the magnetic properties of these weights is not 'consistent', but it's dense. Will probably take some messing-with to get it 'right'.

    Copper would be better for the windings, particularly, some 1/2" square copper, coated with enamel, wrapped on a form, with enough airspace to cool between... but the average guy won't be able to obtain or afford something like that.

    I considered using aluminum strips, even old car coil springs, but I think this combination (being cheap and easy) is really the best start. I'll probably give myself a bit more 'real estate' on the core by machining and bonding two of the weights together, and clean up the OD so it's a consistent wrapping surface.

    In the meantime, I found another CP-200, and converted it... (hee hee... so I'd have a gas-gun in the garage!!!)

    Stay tuned!

  18. #98
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    Anyone need an Airco CV-450?

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    Default Re: Transformer Wiring & Equations

    Dave,

    I recently found your post with interest in your experiments to run a three phase welder on single phase power, as I have one that I was going to build a rotary phase converter to power it.

    This is in no way intended to be negative, only as constructive comments for you and others following this post.

    A delta connected transformer forms a triangle with each point of the triangle being a phase connection tying the windings together. There is a definite order in which these windings are connected and must be maintained, “A-B-C”, to provide proper phase sequence in the primary as well as the secondary windings. The secondary will mimic the primary but in the opposite direction. Although the physical transformer is laid out in a straight line, electrically it should still form a triangle.

    The original diagram shows a transformer connected with a delta primary and delta secondary otherwise known as a delta/delta.

    Now if we look at your after diagram. We will label the two incoming lines as L1 and L2. L1 being the top one and we will call this phase A. L2 being the bottom one and this will be phase B. We will label the six primary transformer connections as T1 thru T6 from the left to the right. As presently wired: T1=phase B, T2=A, T3=C, T4=C, T5=A and T6=B. The transformer coils are wired out of sequence, from right to left starting with T6 we have B-A-C-C-A-B not forming an electrical triangle, but two opposing triangles. If we swap the T4 and T6 connections this will bring it back into proper sequence on the primary as well as the secondary. Leaving the capacitors primary connections the same. Now if we look at the order of the corrected phase connections from right to left starting with T6 we have C-A-B-C-A-B forming a properly connected delta primary with all of the phases in sequence and electrically forming a completed triangle. In return the secondary will now be in sequence also. The A-B-C sequence can be forwards (A-B-C) or backwards (C-B-A) as long as the sequence is repeated in order.

    In three phase power each phase is separated by 120 degrees, in single phase power each phase is separated by 180 degrees. When we insert a capacitor we will get a phase angle shift of up to 90 degrees depending on the circuits resistance and capacitance, the current will lead the voltage. This 90 degrees would place it in the center between phases A and B. So it appears that if we assumed that you were getting the full 90 degrees on each of the C legs the middle coil of the transformer is seeing zero phase shift from the two C legs. However the transformers coil is presenting some resistance so the phase shift would be slightly less than 90 degrees in each of the C phases giving some opposing phase shift, but I would suspect not much as the resistance would be low. Or maybe the C phase feed from the A phase is at or about 90 degrees and the C phase feed from the B phase is at or about 270 degrees. This would change the whole scheme above. Hard to say for sure what is happening with the transformer as wired without putting an oscilloscope on the primary and secondary. But some cancellation is most likely taking place. Perhaps this could be causing part of your problems. It certainly is not working efficiently.

    I found this same problem to be present in your two previous projects CP200 (A-B-C-C-B-A) and SRH-333 (A-B-C-C-B-A).

    Also lets revisit the capacitance equations: 2 * π * F * V * C = I, capacitance in farads. However, most capacitors are in microfarads so that is 2 * π * F * V * C / 10^6 = I. About 20 or so years ago I found this to be long and laborious. So I decided to see if I could shorten it, realizing that it contained four parts that never changed: 2, π, F, 10^6. So if we arrange these to:

    10^6 / 2 * π * F = K.

    K = Constant

    1000000 / 2 * 3.1416 * 60 = 2653.58 or rounded to 2653

    Now with 2653 as the constant the equation becomes much simpler to use. The two things that I find myself trying to determine the most is amperage and capacitance (in microfarads).

    C * V / K = I

    K * I / V = C

    C = Capacitance in microfarads
    V = Voltage
    I = Amperage
    K = Constant = 2653 for 60 Hertz

    In the use of the above equation it appears that you divided the three phase amperage by three (18.6 / 3). This would be wrong each of the three phase would have the same amperage (think in wattage). Now since you are splitting each phase into two parallel wires you may divide by two only.

    I hope this will be of some help.

    Randy

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    Default Re: Transformer Wiring & Equations

    1000000 / 2 * 3.1416 * 60 = 2652.58 or rounded to 2653

    Ok I had a typo.


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