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Welding Shop

DC welder amp draw


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  #1  
Old 07-23-2007, 09:54 PM
Ray Griffiths Ray Griffiths is offline
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Question DC welder amp draw

I have a Lincoln AC/DC 125/225 welder. When welding on DC (+), the amperage is shown as a bit more than half the AC amperage.

Here's the question, when welding at 105 DC amps, how many amps does the welder actually draw? The 220v circuit I have is 30 amps, but the breaker kicks if I use it much.

FYI, I'm running this off one of two generators: a 12 kw attached to a 80 hp engine or a 5 kw driven by a 6 hp engine. (I'd like to use the smaller, but don't think it has the oomph to do the job.)

Thanks,
Ray
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Old 07-23-2007, 11:20 PM
Franz Franz is offline
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Default Re: DC welder amp draw

Input current is directly porportional to output current on a transformer welder. The nameplate on the welder shows maximum current draw at maximum output.

Welders do use a high inrush current when the arc is started, and that is probably a big factor in tripping your breaker. In order to know the actual current draw, you'll need to employ an Amprobe type current meter on the input side of the machine because nobody I'm aware of publishes a current chart for machines.
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Old 07-24-2007, 11:59 AM
Ray Griffiths Ray Griffiths is offline
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Default Re: DC welder amp draw

Thanks Franz,
Just FYI, the circuit breaker primarily trips when I've been welding a long bead. I kind of figured reading the current would be best. I guess part of the question I had is whether DC current (set say at 95 amps) is a greater current draw than AC current set at 95 amps. Using AC I can set the amperage lower than I need on DC. Don't know the answer, which is why I'm asking.
Ray
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Old 07-24-2007, 09:50 PM
Franz Franz is offline
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Default Re: DC welder amp draw

There is, as the nameplate clearly shows, a substantial loss of power, in watts, when going thru the rectifier to convert AC to DC.

If you ever look at the output of any of the low end AC/DC machines on a scope, you'll get sick looking at what the manufacturer calls DC.

For my money if you can't weld steel with AC you ought to hang the helmet in the shop and go to bolting. I've had a lot of "weldors" come in looking for jobs over the years, and heard plenty about their "certifications". 4 out of 5 of them just walked away when they were pointed to the old Lincoln AC 225 in the corner and told to go weld the 6 pieces of 1/4" plate into a cube. In my book if you can't do that you got no business callin yourself a weldor.
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Old 07-24-2007, 11:14 PM
Redwing Redwing is offline
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Default Re: DC welder amp draw

Quote:
Originally Posted by Franzİ View Post
There is, as the nameplate clearly shows, a substantial loss of power, in watts, when going thru the rectifier to convert AC to DC.

If you ever look at the output of any of the low end AC/DC machines on a scope, you'll get sick looking at what the manufacturer calls DC.

For my money if you can't weld steel with AC you ought to hang the helmet in the shop and go to bolting. I've had a lot of "weldors" come in looking for jobs over the years, and heard plenty about their "certifications". 4 out of 5 of them just walked away when they were pointed to the old Lincoln AC 225 in the corner and told to go weld the 6 pieces of 1/4" plate into a cube. In my book if you can't do that you got no business callin yourself a weldor.


I agreed with you about "certifications" almost everyone very easy to get own certification to showoff what they can do before job. I have seen many of them came in at my old job, or at my currently shop.
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Old 07-26-2007, 08:29 PM
Rick McKay Rick McKay is offline
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Default Re: DC welder amp draw

Just out of curiosity, I did some testing on my Miller SRAC-2. It is a good old '50's vintage ac-dc 300 amp machine that I'm running on single phase 220. It's a very smooth welding old machine that hasn't given any of the three generations in my family any grief, even though it's seen hours and hours of service.

I measured the actual line amperage at the following welding currents in DC mode:

stinger at 65volt dc (open circuit) line current @ 220v
300 amp dc 80 amp ac
200 amp dc 50 amp ac
100 amp dc 35 amp ac

My readings were taken with an induction reading ammeter, and the readings are approximate, not exact, but they give you an idea as to my welders amp-draw.

I have a 60 amp breaker feeding my welder and there have been times when I've been air-arcing at full amperage, and my breaker has tripped. I have purchased a new 100 amp breaker, but it hasn't been a big enough nuisance yet to change it.


Hope this info is useful,

Rick
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Old 07-27-2007, 01:58 PM
John Tozzi John Tozzi is offline
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Default Re: DC welder amp draw

Quote:
Originally Posted by Franzİ View Post
There is, as the nameplate clearly shows, a substantial loss of power, in watts, when going thru the rectifier to convert AC to DC.

If you ever look at the output of any of the low end AC/DC machines on a scope, you'll get sick looking at what the manufacturer calls DC.

For my money if you can't weld steel with AC you ought to hang the helmet in the shop and go to bolting. I've had a lot of "weldors" come in looking for jobs over the years, and heard plenty about their "certifications". 4 out of 5 of them just walked away when they were pointed to the old Lincoln AC 225 in the corner and told to go weld the 6 pieces of 1/4" plate into a cube. In my book if you can't do that you got no business callin yourself a weldor.
I thought my friend was going to cry when I dusted off his old AC225 and ran a roll of dimes with it. He told me it was junk and didnt weld worth a damn, I just laughed. As a wise old man once told me " A shoddy craftsman blames his tools".
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Old 07-27-2007, 10:26 PM
Franz Franz is offline
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Default Re: DC welder amp draw

It's probably been 30 years since I did much welding with my Toumbstone, sort of became addicted to the short naps I get burning rods with the Lincoln Verticle Rotarys, but I'd venture to say I can still run overhead with the
Toumbstone after a rod or two to get my hand back in.

Now of course we all know that Toumbstone machine ain't worth a flat damn in today's world of wire squirters with digital readouts so all you gotta do is read the chart on the machine and set accordingly. Hell, my newest wire squirter is a 1980 Miller MM 200. I'm ashamed to admit I manage to weld steel with that machine running Co2, and I have no idea how I accomplish it given that there are no digital readouts. I can get some nice naps in running that machine.

I do thoroughly enjoy the people who come along wanting to know how many volts to set the machine to, and how many inches per minute, and what gas mix to use. They're particularly fun when I tell them they should get a cylinder of C-32 for better contact tip cooling and less spatter. Generally takes about a month for them to ask what suplier can blend that gas for them. I don't bother tellin em any more that potter's clay works much better than spraycan antispatter, or that drywall mud is just as good as the $15- tube of heat paste. Why bother, they know more than I do.
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Old 07-28-2007, 11:07 AM
John Tozzi John Tozzi is offline
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Default Re: DC welder amp draw

I bought a brand spankin new Miller for my rig truck, now it is in the shop. I don't know how I am going to pay the bills with my old grey Lincoln .
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