110vt Inverter Stick welder wanted

What you probably don't understand is that most breakers are not fast acting devices until you get up to about 8x their rating (160 amps for a

20A breaker). Below that they are slow acting devices that allow for large amounts of over current for short but extended periods to allow for high current surges such as a motor starting. This is because the breaker is there to protect the wires in the wall and #12 wire doesn't melt the insulation at 21 amps. You can probably push 100 amps through it for a few second without it getting hot enough to cause any damage. The breakers use bimetallic strips that heat up and and bend. They don't trip until they get hot enough. So you can run high currents through them for short periods. They are designed so they can run forever at their rated load. A 20 amp breaker should never trip at 20 amps. But when you run 21 amps though it, it should eventually trip. But it will probably take an hour. You can run rates of 2x though these breakers for a few minutes. So a 20 amp circuit can support 40 amps for a couple of minutes. Then you have to let it (and the wires in your wall) cool down.

The small 110V welders that go over 90 amps (and almost of them now go a lot over 90 A) do it only on a very short duty cycle.

Look at the specs for the Millermatic 140 for example:

It produces up to 140 amps. And though I've never tired to measure the amperage output on any of these machines, I doubt those graphs are a lie. It goes up to 140 amps - and probably is able to go beyond that. But if you look at the duty cycle graph you see at 140 amps, it's below 10%. That means whatever current the welder is sucking at that point, it will only do it for 1 minute out of every ten.

But notice the "rated" output. That's only 90 amp at 18 V, and the table shows the welder will be sucking 20 A from the 110V line at that rating. So this means, that at 140 amps, it's going to be drawing something like 31 amps. That's only 1.5x the breaker load. Most breakers will allow you to draw that for a few minutes before tripping. And since the welder only has a duty cycle of about 10% at 140 amps, that means you can only weld for 1 minute out of every 10 at 140 amps. And a typical 20amp breaker will allow that.

But the reason it's "rated" at 90amps (I assume), is because that's the highest it can go and know for sure the breaker won't trip (there's where it's drawing 20 amps). It can do that even with a fast acting fuse protecting the branch circuit. So the duty cycle they publish at the rated load is only a function of how hot the welder itself can get before you damage it. When you go over the rated load however, it will work as advertised only if the wires in the branch circuit, and the breaker protecting it, will allow it it go that high for that long. They are trusting that you are connecting it to a branch circuit that has an effective high amperage duty cycle greater than the welder. Most will allow it to go longer than that, but since there's not published standards for what the duty cycle of a 20 amp branch circuit will allow, they can't officially rate the unit at anything over 90 amps. If you put one of these machines on branch circuit with a fast acting 20 amp fuse, you won't be able to get more than 90 amps out of it. But if you put it a branch circuit with a normal 20 amp breaker, you will be able to get 140 amps out of it with a duty cycle of about 10% which means you can run it for about a minute at 140 amps every 10 minutes.

I don't know how much these 110V machines have changed over the years so I don't know if the new 140 amp machines have any more power and current than the old 90 amp machines. It might just be the marketing folks pushing the engineering department to call the machine a 140 amp machine. But I suspect that the machines have actually been designed to intentionally over-current the line to take advantage of the surge ability of the breakers and the wires in the branch circuit when the older machines were not so bold to do that.

Then you should be able to use that high range for short periods on a normal 20amp circuit as well.

To test this BTW, I did a test on a 15 amp branch circuit in my home. I connected two hair driers pulling 12.75 amps each (measured with a meter) producing a total current of 25.5 amps on this 15 amp breaker. I ran them for about a minute and 45 seconds and the breaker still hadn't tripped. That's 1.7x the rated load for nearly 2 minutes. If it can do that for only 1 minute out of every 10, that would be more than enough for a 20 amp breaker to support a welder drawing 31 amps for 1 minute out of very 10 to produce 140 amps of welding current.

These 110 volt units very definitely should be able to produce a lot more than 90 amps of output on a 20 amp (and even a 15 amp) circuit. You just can't use them for very long without overheating both the welder, and the circuit breaker. But those low end units can't be used for very long at 90 amps either (only 2 minutes out of every 10 for the Millermatic 140 for example). I've never tried to measure any of the machines to see what they are really doing, so it could all be a lie. But there's no technical reason to believe they are lying. They are just pushing the typical branch circuits protected by normal slow acting breakers to their very limits.

I wouldn't expect it to be likely if you follow the published duty cycle (but easy to go over the limit because no ones times how long they weld for).

Good question. Did they change the windings on the transformer or add another tap to allow you to actually pull the extra current? Or did the

120 always produce 145 amps but they just didn't feel it was ok to admit it since it was for such a short duty cycle and risked tripping the breaker if people didn't follow the duty cycle limits?

Checking the spec sheets for the current Handler 125:

and the Handler 140:

They both have current voltage curves for the 4 tap settings and though the graphs are drawn differently, they look identical to me. All they did was cut the graph short at 125 amps for the Handler 125 and extend them out to the 140 point for the Handler 140. So I would say they are identical machines. Even the duty cycle is identical. Again, all they did was draw the lines further on the graph to reach the 140 amp point.

The real difference in these machines seems to be that the 140 comes configured for mig or flux core where as the 125 is only configured for flux core. You have to buy the mig conversion kit to turn the 125 into the

140. The welding power looks identical in both of these current machines.

But what machines were they selling 10 years ago and what did the voltage current curves look on those machines? Have they added a higher amperage range settings on these new machines, or has the increase in ratings been totally a marketing game?

Soon, the marketing folks will probably force engineering to produce 400 amp 110V units that can only tack weld for 5 seconds once an hour when the ambient temp is below -50 deg. :)

I don't know what "true welding output" is, but I have no reason to doubt the mfr's published volt-ampere curves.

The "rated" output may be what they can deliver with 20 amps of input, since the plug supplied on the cord is rated for 20 amps and fits a standard 20-amp receptacle.

My experience has been that the welder's overheat thermal protection trips before the 20-amp breaker does.

That's true.

Iggy - you've got something wrong here - you have said what you have said about Gunner without realising you have made the mistake by getting the voltage way wrong - the one you use in your power calculation.

The voltage you are quoting is probably "Open Circuit Voltage". And Constant Current welding machines go to much OCV's than this - I know that many give you a good tingly buzz and OCV's around 90V are reported for some welding machines.

The "arc running" voltage is lower. Here are some of my own actual readings, working with a friend who is a welding technician / instructor at a technical college:

"All 2.5mm diameter:

+-------------------------------------------------------+ |7018 |Bohler EV50 |22V |72A| |---------+---------------------------------+-------+---| |6013 "R" |straight rutile |25V |62A| |---------+---------------------------------+-------+---| |6013 "RC"|Zodian Universal rutile-cellulose|21V |76A| |---------+---------------------------------+-------+---| |6010 |Foxcel |30V |62A| |---------+---------------------------------+-------+---| |6010 |Foxcel - wet |28V |64A| |---------+---------------------------------+-------+---| |6011 |Arcos Nu5 |20V-25V|62A| |---------+---------------------------------+-------+---| |6011 |Arcos Nu5 - wet |30V-35V|63A| +-------------------------------------------------------+

Welding machine was Murex Transtig AC/DC 250HF on polarity DCEP set to 20% on the 20A-320A range."

Say 22V for non-cellulosic rod

(15A x 110V)/22V = 15 x 110/22 = 15 x 5 = 75A

That 75A can only be the welding current if the welding machine is

100% efficient - which cannot be the case.

Now this is the stuff you will know, Iggy...

Reputedly, copper-and-iron tranformer weldign machines are about 50% effient - which squares with how often you blow the fuse when welding away with a buzz-box. (that's because 50Hz to 60Hz would need an infeasibly massive transformer to be efficient(?))

A inverter "silicon" welding machine is reckoned to be over 90% efficient - which squares with the fact that here in the UK you can lay down loads of heat in your welds without blowing the fuse ever. (and this is because "chopped" at around 20000Hz even a tiny transformer is very effcient for weldign currents)

So Gunner with an inverter welding machine is surely going to be happily welding away with 2.5mm (3/32nd-inch) rods off this weedy domestic supply...

Isn't that right?

Richard Smith

I think that you are 100% correct.

i