Driving a welder with an ST5

[veggie]

If you want it hot, I'd wire the two legs together.  Until we figure out the BS ST mod, It will be VERY unhappy about pulling that kind of load on only one side.

Perhaps a stupid question.....but here goes..

My junction box has two 120 plugs (pulls 120 from each leg in the dog house) and one 240 volt plug.
Is it possible to make make a "Y" cable for use with my welder that plugs into both of my 120V outlets and in effect, wires both of the 120 legs together?

veggie

[TimSR2]

It might make funny groans but it it will be OK to 20 amps. If you need more power rewire your head for full output at 120v . directions at utterpower. Easy to do. Then you will have 40 A @ 120. It is either in series or parallell . Can't be both at the same time. Possibly a S/P switch setup could be invented for this.

Sounds like you are going to have fun!

Tim

[TimSR2]

Parallel the  windings Jens. Not series.  You can have 240@21.8 amps , that is  2 @120 volt legs 180 degrees out of phase to each other. That is series connected. 120 or 240 volt loads supported.

OR you can wire it in parallell  for 43.6a at 120v.   120v loads only up to very high current levels. No 240v loads supported.

T

[potter]

If you are trying to use the head on 110 220 you are only going to get half your
output switch to 110 only to eliminate growl and get your max output.    

 Potter

[Crofter]

If you wish to use both legs of 120 they must be hooked the same polarity. The Y connector would be a dead short across 240 if the other ends of the 120 legs are hooked N to P for series connection.

You can pull 3 KW from one leg of an ST 5 with a 6-1 but you will be 500 watts over the rating for that leg and voltage will most likely be very low. Hook up in parallell and you produce 3KW at 1000 watts under each legs max rating and both welder and generator will be much happier!

The little "lunch box" inverter welders would be the real trick. With no transformer losses they make very efficient use of limited input power but they are pricy!

[bschwartz]

Jens,
With my now VAST experience pulling apart my ST gen head (haven't put back together...) may I suggest you open yours up, find the center tap, and split it and add your own second line.  Then you could parallel the coils if you wanted to.

[veggie]

Here's a better view of what I'm dealing with...

The ST5 is already wired to a sub panel with 240 and 120 outlets.
I prefer not to disturb this layout because of the other uses I have for this machine.
Rewiring the whole thing for 120 would mean upsizing the wire, plugs, breakers in the receptacle panel.

The pictures below show the wiring layout and how the 240 and 115 were separated.
(Note: The fuse blocks have since been replaced by breakers)

So....can I get get 120v 30A power without rewiring my ST5 (or the receptacle panel) by combining the two 120 outlets using a "Y" cable? Or will this create the dead short as crofter pointed out?
For TIG welding, my machine requires a 23A, 120 volt supply.
Any other options?, or am I s#*% outta luck ?

veggie

[bschwartz]

IF and only IF your head is wired as the diagram below, you should be able to make a Y cable.

If one leg of your head (say blue wire and one white taped) is U1 and U4 (or U3) and the other leg (red and white taped) is U2 and U3 (or U4) and currently U3 and U4 are the white taped wires, then connecting your red and blue wires (U1, U2) would put them in parallel.

Can You check for continuity to verify the separate windings?

[BruceM]

Veggie, If your connection to the panel is to remain intact, then you have no choice except to use a 240-120V step down transformer. This will cost you about 7% efficiency if you can find some suitable toroid transformers.

But since the welder will totally use your ST's output,  bringing out the wires to a switch box so that you can DISCONNECT the line to the fuse box, and create 120V just for the welder, might be a better solution.

[veggie]

BruceM,
Not trying to create an argument here...
But are you saying that bschwartz' idea for the "Y" cable would not work?
I need to be clear on this.

thanks,
veggie

[bschwartz]

Hmmm. Rethinking my earlier post.  If you have U3, U4 tied together, connecting U1, U2 might put them out of phase (wrong terms I'm sure) with each other.  On the St head, when bridging for 120V, they usually connect U1, U4 and U2, U3.

Although parallel, they would be backwards.

Maybe a Y cable would be bad.......

[veggie]

Now it's clear.

Thanks guys.
I like the idea of bringing the ST power into a switch box and then branching to the panel or the welder.

veggie

[bschwartz]

Jens, now you're just bragging 

[rl71459]

I believe it is seldom a mistake to buy a quality product! I bet you wont regret it.
I do own a ST12 and it has been good so far.... But I only use it as needed (Powerfailures)
also some fuel experimentation.  I will say they are inexpensive.... But a bit of a crapshoot
and a likely diy project.

Rob

[BruceM]

Veggie, Yes, I like Bschwartz's approach, I'm not very wordy this week as reading is a bitch right now.