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Miller DeltaWeld 451 Haas-Kamp conversion issues...

CADman_KS

Aluminum
Joined
Dec 6, 2014
I have successfully converted a both a Lincoln CV-400 and DC-400.

I recently landed a Miller DeltaWeld 451. After looking at the schematic, and some of the other conversions floating around here and on the internet, I deduced that IF it was going to work, it would actually be a pretty simple conversion.

I did the conversion per the attached schematic, which is identical to the CP-300 conversion schematics that others have used, at least on the transformer side, so I figured that it would work.

Well, it doesn't work, and part of the reason that it doesn't work, I think, is because I'm not getting 240V across the middle transformer, and I cannot figure out why.

In the schematic that I attached, I get 240V(ish) across A-B AND E-F when I probe them on the back panel. However, I was only getting around 11.5V across C-D when I probed it. At that point, I only had 200MFD of caps in there, and I thought that was the issue, possibly, because it was supposed to have 256MFD. I added another cap, getting it to 250MFD, and the voltage went UP to 14V now, but it still won't weld.

The funny thing is that it will actually "weld" at times, but only for a 1/2 second or so, and then it quits, but most of the time when I pull the trigger, all it does, it just heat up the wire, and sometimes will actually melt the weld, but not weld.

What kind of voltage should I being seeing across that connection? I'm making the assumption that it should be 240V. I've checked all of the connections, and it appears that 120V is going to the cap banks, AND coming out, BUT when you test across the two, it is only the 11-14V.

I have a good feeling that this thing should be convertable, but just haven't gotten there yet.

Any ideas what I should try next, or what this issue could be with cap bank, or the voltage, etc????

Thanks!

DeltaWeld 451 Schematic AFTER conversion.jpg
 
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It looks like you got everything right... so that being the case, my first conclusion is that something ELSE is wrong... and it's probably something silly, most likely something that was wrong before you started.

Whip out your Harbor-Freight IR thermometer and put a load on it, let it work for fifteen seconds, then poke the laser around. Anything getting hot? Anything NOT warming up?

Remember- in a capacitive-reactance circuit, Low voltage across the capacitors means that the coil reactance is LOW... they're carrying current. When reactance is HIGH, they WON'T be carrying much current, and the capacitor terminal voltages will be higher.

You might have a shorted winding in the center coil set. Perhaps a jumper is in the wrong place, or factory wired the terminals wrong (seen that).

The coil consists of more than one set of windings in parallel and series... isolate them out one at a time and try it without, to narrow down a bad winding.

A short in the center coil would cause it to pull more current than the capacitors carry, which would keep a shorted coil from overheating, but you'd probably see it getting warm on the IR.
 
It looks like you got everything right... so that being the case, my first conclusion is that something ELSE is wrong... and it's probably something silly, most likely something that was wrong before you started.

Whip out your Harbor-Freight IR thermometer and put a load on it, let it work for fifteen seconds, then poke the laser around. Anything getting hot? Anything NOT warming up?

Remember- in a capacitive-reactance circuit, Low voltage across the capacitors means that the coil reactance is LOW... they're carrying current. When reactance is HIGH, they WON'T be carrying much current, and the capacitor terminal voltages will be higher.

You might have a shorted winding in the center coil set. Perhaps a jumper is in the wrong place, or factory wired the terminals wrong (seen that).

The coil consists of more than one set of windings in parallel and series... isolate them out one at a time and try it without, to narrow down a bad winding.

A short in the center coil would cause it to pull more current than the capacitors carry, which would keep a shorted coil from overheating, but you'd probably see it getting warm on the IR.

I currently don't have an IR thermometer, BUT, I have tried changing the capacitors to the other coils, and it acts exactly the same, so I know that it's not in the coils. In fact, it does "weld", or should I say, manages to melt the wire for a second or two, with any two coils hooked up. BUT, it doesn't weld right, because that third coil is never getting enough voltage.

One thing that I haven't tried, that's easy to test is current flowing thru the capacitor bank. I'll check that and report back what I find.

You're correct that it IS something super simple, but I can't for the life of me see what it is...
 
So, I don't know if this helps or not, but I took some more measurements today.

First off, I included a schematic of where I took these current values at, so hopefully that's clear.

Across the right side coil, these were the values that I got with the amp clamp:

XYZ
Leg 16.59.39.3
Leg 26.59.39.3

I don't know why the input is less than the legs, but it is. I did NOT do the A,B,C,D on this coil. I forgot.

Then I moved it all back to the center coil, and these were the values that I got:

XYZ
Leg 16.59.39.3
Leg 26.59.39.3

ABCD
4.625.05.05.3

I don't really know what they should be, or what I should be expecting there, BUT at any rate, the X and Y values were the same from coil to coil, so I have to assume that I either have two BAD coils, or two GOOD coils, because the values are the same. No matter which position I'm in, the voltage across A/B-C/D is ALWAYS 235ish on the coil NOT hooked up to the capacitors, and the coils hooked up to the caps will measure somewhere between 10V-14V ALWAYS.

So, I don't think that I have any bad coils from these crude measurements that I've taken. Also, if I do have wiring messed up, it has to be messed up on both the center and right coil. That is really hard for me to diagnose, because all of the tags with the wire descriptions on them are faded, and you can't read the numbers on there.

Man, I am really stumped with this whole thing. What really stumps me even further is that the forum user that got his 450 working used the EXACT same schematic that I did, and his works and mine doesn't. It's at times like this that I wish I had access to true 3PH so that I could test it out. I'm working on that, and may have a place that I can test it at, but I have to load the beast and take it there. While that may provide me with answers, it would still be a LOT of work...

DeltaWeld 451 Schematic AFTER conversion AMP draw.jpg
 
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Did you ever get this working?

I'm picking up a years old project to convert a Dimension 452 with nearly the same circuit as your 451 (I let the project sit because I've got another welder working fine with an HK conversion so I haven't needed it), and I am having exactly the same symptoms.

Right now I'm suspecting bad caps (I don't have a good cap meter ATM).

One thing that's not clear from your posts above - are your jumpers set for 230 or 460?

Thanks,
Erik
 
No, I never did. In fact, in trying to build a rotary phase converter to run it in right now. It IS a BIG motor!! ;)
 
I checked my caps with an LCR meter, they seem to be ok.

So, for experimentation purposes, I reduced the caps on each side of the center coil to 1 30uF can. Then I tried stick welding again, and it worked a bit better... I actually got some ok (although not great) beads laid down. I had to remember how to stick weld and balance the amps setting with my electrode size and travel speed, but it worked well enough to do a few joints on pieces of scrap metal I had lying around - mostly 1/4" plate. It was easiest to keep the arc lit with 5/32 rod and about a 130 amp setting.

I also tried a little bit of rectangular tubing - about 11 gauge - and blew some holes in it.

I then tried 60 uF on each leg and also got working settings, but only for a narrow range of the dial. Higher amps than the 30uF caps though.

In summary, I think there's a narrow range of caps values that work for this machine for a given amps setting. I'm going to theorize about it elsewhere, but I think this machine "will" work for an H-K conversion, but unless I want to swap caps at the same time I change amp settings it's not practical to use.
 
I checked my caps with an LCR meter, they seem to be ok.

So, for experimentation purposes, I reduced the caps on each side of the center coil to 1 30uF can. Then I tried stick welding again, and it worked a bit better... I actually got some ok (although not great) beads laid down. I had to remember how to stick weld and balance the amps setting with my electrode size and travel speed, but it worked well enough to do a few joints on pieces of scrap metal I had lying around - mostly 1/4" plate. It was easiest to keep the arc lit with 5/32 rod and about a 130 amp setting.

I also tried a little bit of rectangular tubing - about 11 gauge - and blew some holes in it.

I then tried 60 uF on each leg and also got working settings, but only for a narrow range of the dial. Higher amps than the 30uF caps though.

In summary, I think there's a narrow range of caps values that work for this machine for a given amps setting. I'm going to theorize about it elsewhere, but I think this machine "will" work for an H-K conversion, but unless I want to swap caps at the same time I change amp settings it's not practical to use.

I tried lower cap values as well, and it didn't make a difference for me. In fact, didn't really change it at all. My problem also is that I'm not 100% sure that it was totally working before I started. I would still like to have 3 phase in my shop, so I'm working on that. Hopefully my 50HP motor is big enough. Hopefully, I can get my 50HP motor spinning!!!
 
Hopefully, I can get my 50HP motor spinning!!!

If all you're trying to do is test it out, you can actually start it spinning manually (IE a pull cord).

You can get a third phase generated that's somewhat usable by just powering two phases of the motor then pull starting it. Caps will still help balance it, but it'll work :)
 
If all you're trying to do is test it out, you can actually start it spinning manually (IE a pull cord).

You can get a third phase generated that's somewhat usable by just powering two phases of the motor then pull starting it. Caps will still help balance it, but it'll work :)

LOL!

I actually tried that, but it's hard to get a 50HP turning! I didn't have a bug enough breaker either, so that was another issue. I have a bigger breaker now, but haven't installed it yet...
 
Life got in the way of my rotary 3-phase project, and that's taken a back burner. But, I had renewed interest in seeing if I can get a Miller 451 going on the HK conversion, so I resurrected it today out of the pile of welders that I have. :)

Well, to my surprise, nothing has changed in almost two years. DRAT...

There is still something about this that doesn't seem quite right, and I just can't quite put my finger on it. It's almost like it's only using one set of the coils or something. I'm going to spend some more time with it, now that I have it drug out, and if I can't get it going, I have a person of interest that is willing to possibly buy the unit converted back to 3-phase, so I might do that, and sell it to him.

Has anyone else ever got one of these going on the HK conversion, successfully???
 








 
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