Driving a welder with an ST5

[veggie]

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

Bruce,
OK now I'm confused again (not hard to do ).
Bschwartz said that his suggestion for the "Y" cable might not work.
The easiest fix for me is a "Y" cable.
Will it work or not ?  

veggie

[BruceM]

Veggie, what you need is a switch box that lets you:

1. Switch your ST head wiring between 120V (parallel) and 240V.
2. Disconnects the 240V connection to your main power panel when 120V is selected, the 120V being just for shop welding power.

This is going to take some fancy ganged switches or perhaps some DIN rail circuit breakers which can have their switch levers ganged via music wire.  I don't know the best way of doing this-  maybe Shipchief would?

There is no doubt that this is doable following the wiring diagram provided with the ST head.

In this case, careful labeling of the wires before extending them from the genset to the switch box should eliminate most chances of polarity reversal.  You will be extending 4 wires (one pair for each 120V coil set), your switch box will put them either in series (240) or parallel (120).  A temporary inline fuse for one winding set for initial test is a good insurance policy.

The attachment shows a switched setup- egads, it takes 6 switches, which would have to be ganged and break before make types. 

Plan B-  make up a cable from the 4 coil wires that plugs (Sermos?) into one of two sockets; one is for your existing 240V feed, the other for your 120V welding supply.  Each socket would then make the proper winding configuration. 

Plan B is a lot cheaper and simpler.

[mobile_bob]

i think you could also use a reversing contactor set to allow for the interconnections, with a simple flip of a toggle switch
a reversing contactor is both electrically and mechanically interlocked so that there is no way of getting both cross connected

they can be had fairly reasonably used and surplus off of ebay, although the large sizes can be quite pricey.

i got a schematic somewhere outlining this system for 60 and 120volt operation, should be an easy adaptation to
do the 120/240 series/parallel thing as well.

just an option

bob g

[veggie]

Bob & Bruce,

Thanks very much for those explanations. Most helpful.
In the meantime, I contacted the manufacturer of my welding machine.
Seems that may people are successful in welding with this machine when powered by a 15 amp wall outlet.
Although it's rated for much higher amperage, this unit can stick weld 1/8" to 1/4" material when using 3/32 rods as long as the stick amps is set to 80A.
I will give this a try first before doing any ST5 rewiring.
This will pull the max from one leg of my ST, but I can apply a bit of load to the other leg to balance things out.
If that does not work, I will pursue the ideas brought forth here.

Thanks again,
veggie

[bschwartz]

The ST-5 being rated at 5KW is 2500w per leg.  At 120v, that would be 20A.  I suspect it could handle quite a bit more than that for the short period of time that you are welding.  It may groan and make ugly noises, but I suspect that it would work just fine.  Although I haven't used my stick welder on the ST, I have used the 120v wire feed miller 130 without issues.

[mobile_bob]

another option or two

there are countless web articles on building welders with microwave transformers, they appear to work quite well
there is also a website illustrating the use of a hd automotive alternator as a welding generator, it to appears to work well.

of the two, i would probably explore the use of an automotive alternator, because it operates as a 3phase low ripple dc
power source, so it should make a nice clean welder..

then of course there is looking at your local craiglist or welder supplier for a used portable welder, such as a miller, or lincoln
often times these can be bought very reasonably and are real welders capable of doing series work, much more so
than a 120v cracker/buzzbox welder. they also have built in generator capability which gives you a layer of redundancy.
i have seen good machines going for a couple hundred up to whatever you wanna spend, 500 should get you a good machine
that is ready to go to work.

just a thought fwiw

bob g