120 amp max welder needs only a 20amp breaker

[tautech]

True things are built to a price but with a Mig there is the feature of being able to weld until the wire spool runs out, theoretically. Stick welders on the other hand get a forced break each time you have to replace the electrode.

I run my big 400 A 3 phase stick welder on a 20 A breaker, an ordinary one will trip in seconds @ 400 A but if you use a D curve motor rated breaker that permits a significant current overload for a fixed duration I can weld @ 300 A long enough to consume a full 5mm rod. By the time you've chipped and brushed the weld and replaced the rod the duty cycle starts over. 

BTW, in case you wonder why I have a 400 A welder....it was only $200 on a trolley and with longer than normal leads so couldn't resist buying it.    Transarc 400 IIRC.

[CaptainNomihodai]

Inverter type welders is where the future is, so much grunt for their size and weight not to mention better efficiency.

While this is true, and oh how I would love to have a nice inverter TIG setup, there's something to be said for the simplicity and durability of a good transformer. About a year ago I noticed that my open circuit voltage was too high. It took me about 30 seconds to figure out that the "suppressor" (just a resistor across the output terminals) had failed open. If I've got a Dynasty or Synchrowave (sorry, I speak Miller, not sure what the rest of the world has) that fails, fixing it would probably take a lot of help from people on this board. My current welder was built before I was born and, barring intentional damage or something catastrophic, will be working after I die. That being said, it also weighs significantly more than I do and would probably win in a fight, and uses enough electricity to power a small country, so ... tradeoffs.

It's unlikely you'll find a capacitor in there.  Usually it's transformer, rectifier and choke.  The transformer does the 20A->120A transformation, hence the name.  The rectifer gets you DC and the choke is used for smoothing.  If it was just a capacitor, as soon as the wire made contact all the energy stored in the capacitor would get dumped into the stickout and blow the wire to bits.

In addition to what people have mentioned about MIG machines having caps on the secondary, some machines will also have capacitors for power factor correction. Unlikely here, though, this one sounds like a big box store model.

I have a lovely old adjustable AC CigWeld arc welder I inherited from my dad, its just a huge transformer on wheels. I would like to have a play with DC welding, would a heavy enough (200A) bridge rectifier stand up to this kind of abuse/use? Obviously would need to be sufficiently cooled. The welder's maximum output is 160A, but I have never measured it's voltage (and wont until the rain outside stops)

Yes. I open up my Miller and there are just 4 gargantuan diodes. I don't see why a sufficiently large bridge rectifier would be any different.

I run my big 400 A 3 phase stick welder on a 20 A breaker, an ordinary one will trip in seconds @ 400 A but if you use a D curve motor rated breaker that permits a significant current overload for a fixed duration I can weld @ 300 A long enough to consume a full 5mm rod. By the time you've chipped and brushed the weld and replaced the rod the duty cycle starts over. 

BTW, in case you wonder why I have a 400 A welder....it was only $200 on a trolley and with longer than normal leads so couldn't resist buying it.    Transarc 400 IIRC.

3 Phase, so that's 20A per phase on that breaker right? I've tripped 20A single phase breakers with a big angle grinder before...
I'm not sure what I'm more jealous of, that you got that monster welder for such a steal (though, I can't think of a situation where I would actually need 400A), or your apparent access to 3 phase.

[james_s]

While this is true, and oh how I would love to have a nice inverter TIG setup, there's something to be said for the simplicity and durability of a good transformer.

That is a valid point. I saw a guy once who had an arc welder that looked like it had been dredged up from the bottom of a lake after being run over by a truck. The thing still worked somehow.

[tautech]

I run my big 400 A 3 phase stick welder on a 20 A breaker, an ordinary one will trip in seconds @ 400 A but if you use a D curve motor rated breaker that permits a significant current overload for a fixed duration I can weld @ 300 A long enough to consume a full 5mm rod. By the time you've chipped and brushed the weld and replaced the rod the duty cycle starts over. 

BTW, in case you wonder why I have a 400 A welder....it was only $200 on a trolley and with longer than normal leads so couldn't resist buying it.    Transarc 400 IIRC.

3 Phase, so that's 20A per phase on that breaker right?

Yep.

I've tripped 20A single phase breakers with a big angle grinder before...

D curve motor rated breakers and available in single phase versions too.
Breakers to weaken with age, particularly if they've been tripped a good few times. A sparkie mate replaces a few that give trouble and then troubles are gone.

I'm not sure what I'm more jealous of, that you got that monster welder for such a steal (though, I can't think of a situation where I would actually need 400A), or your apparent access to 3 phase.

TBH I rarely use it over 200 A but it's sure nice to know the extra grunt is there when and if you need it. 

3 pase is something that I would be reluctant to be without as so much older 3 ph gear is available at low pricing as the market for them is smaller. If you have 3 ph there are bargains to be had.

[moz]

TBH I rarely use it over 200 A but it's sure nice to know the extra grunt is there when and if you need it. 

Heysoos! I had a 180A TIG that I think I only ran at 180A once (welding 25mm reinforcing rod). Albeit I mostly build bicycles, the only real jobs I do bigger than that are the usual "I have a workshop so I can build things for my workshop" stuff. Then I sold it to MakerSpace because I barely use it, and if it's in there I can go and have access to a much better workshop than I can fit in my shed (or afford/justify).

I have a 15A breaker that I plug in when I want to run the welder, the rest of the time I leave the 25A breaker in. Purely because the wiring in this house is a joke but I'm still saving up to fix it. 25A at random spots about the house, sure. 25A continuous to the far end of the property I am not so sure about. The loopback resistance on the garage circuit makes me doubt it's a single length of 2.5mm^2 cable the whole way (or it's running 100m of cable to cover 50m).

[Zero999]

While this is true, and oh how I would love to have a nice inverter TIG setup, there's something to be said for the simplicity and durability of a good transformer.

That is a valid point. I saw a guy once who had an arc welder that looked like it had been dredged up from the bottom of a lake after being run over by a truck. The thing still worked somehow.

Did it look like any of these transformers?


http://halbot.haluze.sk/?id=3555


https://expatinaddis.wordpress.com/

[james_s]

Yeah I think that's the one I was thinking of, that's nuts!