MillerMatic 212 turns itself off

[Willvis]

I don't think it would work well if you disconnected the neutral. You must return the power somehow.

I suppose technically speaking the neutral is at the transformer and that is the return of power? Single phase is actually split phase where one leg of the 3 phase power from the power company goes into a transformer that has a center tap on the secondary winding. The center tap is the neutral. Thats how you end up with two hots and a neutral coming into your house. The two hots are 180 degrees out of phase from each other and give 240v between them or 120v from one hot to neutral. Actually technically I dont think the neutral in the transformer is the return to power at all? Its AC right so the "power" goes back and forth 60 times a second (or 50 in Europe). But ya I dont think the neutral is needed at all other then for providing 120v? Because you can take a voltage off any 2 legs of 3 phase aswell. Ahhh electricity is confusing lol.

But to answer your "question" no you dont need the neutral at all for anything that is strictly 240v. They add it into the range and dryer circuits so that 120v can be used for the controls and stuff.

[aPoundFoolish]

Are you using some kindof pigtail adapter? That 10-50 didnt come standard on the machine so you either changed the plug or are using an adapter. Me thinks you got a hot and neutral crossed and your only inputing 120 into the machine.

The machine was used when I bought it so likely the previous owner attached the 10-50 cord so it would work with his outlet.

I'll verify how the cord connects to the machine and post pics.

I appreciate everyone giving their thoughts... what I thought would be a simple matter has turned into quite the international mystery....

[Franz©]

The purpose of the Neutral wire is to carry the imbalance current between the phase wires. Neutral doesn't come into play on a 240 volt load unless there are independent 120 volt loads on the circuit.

Example if phase a is delivering 22 amps and phase b is delivering 10 amps, the Neutral carrys 12 amps. If both phases are carrying 22 amps the Neutral carrys nothing.

I got 10 bucks says the instant problem is a miswired receptacle on the wall.

[ryanjones2150]

No way I'd take that bet.

[Franz©]

No way I'd take that bet.

Cluck cluck, you already folded last week when my badge outweighed your bugles.

[Willvis]

The purpose of the Neutral wire is to carry the imbalance current between the phase wires. Neutral doesn't come into play on a 240 volt load unless there are independent 120 volt loads on the circuit.

Example if phase a is delivering 22 amps and phase b is delivering 10 amps, the Neutral carrys 12 amps. If both phases are carrying 22 amps the Neutral carrys nothing.

I got 10 bucks says the instant problem is a miswired receptacle on the wall.

Ah yes thats right and in some cases like a sub panel you can run a smaller neutral because of that. Also when I was thinking neutral on the power lines I was thinking what we have on the road here which is 3 phase + a neutral. But doing a bit or reading and it seams usually the main distrubution lines dont carry a neutral.

[Franz©]

Ah yes thats right and in some cases like a sub panel you can run a smaller neutral because of that. Also when I was thinking neutral on the power lines I was thinking what we have on the road here which is 3 phase + a neutral. But doing a bit or reading and it seams usually the main distrubution lines dont carry a neutral.

Oh good, lets begin with the reality you Canadians don't even have electricity, you have HYDRO. Then you have industrial voltage of 575, not 480 like we have.

That established, 3Ø can be in either Star a/k/a Y or Delta. Star employs a Neutral at the centerpoint. Delta has no neutral and grounding any of the 3 legs making contact with Ground really screws things up in terms of voltage on the other 2 legs. Delta Primary, Distribution or transmission voltage is pretty normal since it eliminates the need to carry Neutral which saves money.
Delta Primary can easily be connected to a transformer bank connected Star at the secondary. Normal procedure is to pick the ground leg up from Mother Earth at the bottom of the pole or use Station Ground if the system has one.

So, you're looking at 3Ø Delta primary running down the road because Alberta Hydro saved on wire, connected to the primary side of the transformer. The secondary side of the transformer is connected Y/Star and you have 575 volts.
Of course the secondary could also be connected Delta with 1 transformer centertapped to station ground to give you 575/240/120.
We won't bother with Wildcat or open Delta secondarys because Hydro disfavors that connection.

I still got 10 bucks says the problem this thread started with is the wall receptacle is miswired.

[aPoundFoolish]

New development: I swapped the cord on my 240v compressor and plugged it in to the same outlet as the welder and, curiously, the compressor works fine on that circuit.

Here are photos of the welder and the the machine's 10-50 plug. Inside, the two hots (black/white) connect to the main switch at the front of the case and the ground is attached to the case at the bottom. Everything seems secured. I'm leaning towards just replacing the power cord on the welder since it does seem a bit old and worn out to me.

[Franz©]

Since you had it opan why didn't you check the voltage inside the machine?

Should have 240± across black & white at the switch inside the machine.

If not, go back to the wall and see if you have 240 on the corresponding terminals of the receptacle.

I been at the trades more than 50 years and I only recall cords going bad in a few instances where they were improperly installed to begin with.

Anything is possible though. If you do have a broken wire in the cord you can meter out the red for integrity and substitute red for the broken conductor if it's good.

[Broccoli1]

Strange that the 10-50 has a neutral but no ground? Isnt that sortof a safety issue not having a ground? Anyways I dont think the machine knows or cares about that. Neutral is tied to ground in the pannel anyways. From a pure electrical view all you need is the 2 hots. The neutral and or ground could be disconected and a welding machine will work. I also dont think 247 volts is too high, Im pretty sure mine reads around there some times. You could check the frequency but thats set at the power plant so I dont see how that could be wrong. Are you sure it worked fine at the dealer lol?

This was primarily used for 3-wire 120v/240v appliances and since that wire carries current it has to be called a neutral.

It is also the path for a ground fault- as you mentioned it is bonded with the Ground at the panel.

3-wire 120v/240v installations are no longer allowed- existing ones can still be used but all new construction uses the 4-wire receptacles.

When the 10-50 is used as a 240v only circuit that third wire is now a ground.

Confoosed ?

[Franz©]

I were confoogled till a nice man in a cheap suit sat me down and splained it was all about making money without working for it.

First you invent a possible problem where no problem worthy of statistical notation exists.
Then you whip up concern about this devastating potential problem.
Then you convince some drunk politician it's a big problem and he needs to get behind it.
Then you write proposed legislation and declare yourself an expert in the emerging field.
Make reference to all the new jobs it will create.
Once the legislation/regulation comes into place, since you're the Expert, you get the Executive administrator job
You get paid at every step along the way

[ryanjones2150]

Probably just a way to sell more wire.

This is a strange problem, so you'll need to use smart trouble shooting moves and check everything again, yourself, and redo the connections if you need to.

Then again, maybe the repair shop you took it too was wrong. Try plugging your machine into another outlet and see what happens.

[mongobird]

I had a similar problem with a well circuit. The well was a 3 phase pump, and a single phase 240 inverter to create the 3 phase, variable voltage, variable frequency power for the pump. It would run for a while and kick out.

The panel box is a Murry equivalent.

I ended up using a commercial power monitor, and eventually found a glitch. When I investigated, I found physical evidence.

One side of the 240 breaker had a looser spring in the contacts to the blades in the panel box. There was signs of arching at that point. I cleaned up the blade, and replaced the breaker, and 7 years later have not had a hicup.

This is not likely your problem, but no amount of having electricians inspecting things, and the factory doing diagnostics on the inverter found the problem. I first verified that there was a glitch, and then went and looked at everything until I found it.

Oh, for the record, my normal 240 volts is 249. I have solar inverters, and I am also on a high capacity run. My power meter and all the inverters have voltage readouts, and they all agree within a volt. 99% of the time my line voltage is 248-250.

[aPoundFoolish]

I appreciate everyone's advice, I haven't measured the voltage across black & white at the welder's switch because I ran out of time, but I'll post an update this weekend. Depending on what I get I may swap the cord, if for no other reason that i'll have to redo the connections and then I'll be starting with a fresh 10-50 plug instead of the old worn out one I've got now. I only have one 240v outlet at this location to work with, so unfortunately I can't try plugging it in elsewhere easily.

At least I know the power I'm getting is good enough to run a heavy compressor... now if I could just get it to the MM212, she's starving for juice!

[Noel]

I were confoogled till a nice man in a cheap suit sat me down and splained it was all about making money without working for it.

First you invent a possible problem where no problem worthy of statistical notation exists.
Then you whip up concern about this devastating potential problem.
Then you convince some drunk politician it's a big problem and he needs to get behind it.
Then you write proposed legislation and declare yourself an expert in the emerging field.
Make reference to all the new jobs it will create.
Once the legislation/regulation comes into place, since you're the Expert, you get the Executive administrator job
You get paid at every step along the way

That's what I like about you Franz... your eyes are open enough to see how the game is played.