I have a miller cp 300. It is wired for 3 phase power. I need to hook it up to 230 volt power. How do I do this correctly.

talk with an electrician but I think that if you have 3 phase motors on 480 volts you will need an inverter that will handle 480 volts
as it stands now you only have 230 volts for 3 phase and that means that there is insufficient power to run the motors
however in cases such as this , a long talk with an electrician could save lots of money

On 230 volts you have 3 wires 2 are 115 volt and the third wire is ground. As long as you hook the ground wires together correctly the other wires don't matter. Usually the ground wire is either white or green. The black wires are hot (115 volts).

The CP-300 and CP-200 were never designed to run on single phase. You can buy a 3-phase generator (see military surplus) or a phase converter. You will need a pretty big one - like one rated for 20hp to use the full potential of the welder. That is also pretty expensive - say $1000. However, if you have a shop, you can buy used 3-phase equipment sometimes significantly cheaper than 2-phase stuff. So you buy that expensive converter and save money on all the other equipment you will buy. Or sell it. Or scrap it - some older welders had big copper wound transformers - a few hundred bucks worth of copper.... some had aluminum though... Good luck.

Theoretically yes, but it would be a great deal of work and would draw a little over 6 times the current it did when on three phase power.

It would entail replacing the fan motors, connecting the 6 windings of the 3 phase primary in phase and in parallel. Plus adding a 115 circuit " tapping off half of the 220 single phase" incoming power for some aspects.

The control board would also need modifications as well. because it uses 3 current sense transformers and you would need to rework that circuit to compensate.

The short answer if you were wanting to set one up for home use- just invest in a "Sidekick" They did have a 240 volt single phase version, and if you consider the time invested to change something over that could trip the 200 amp service breaker, if you value your time- the money for a Sidekick would be well worth it.

If you want proof- open up the primary side of the Deltaweld and look at all of those connections you have before you- you would not be using 1/3 of them, and you would need to take the time to make sure the 6 windings were in phase otherise the transformer burns out- it may burn out anyway because the current draw increase beacause all the low impedance windings are now in parallel on a nominally lower voltage- just the potential of fire from that arrangement makes the money spent for a Sidekick to be considered "cheap insurance."

The wiring diagram is on the outside of the
motor case, on most motors,on the label

Also on the inside of the wiring connection
cover

Hello,
Look for a "Phase Converter" at Harbor Freight or look in You Tube for info on building one. If you have a lot of welding to do, I would get a better quality converter than they have at HF.

you can't, the S-22P8 it's not a volt sensing wire feeder, it requires 24V or 115 with an adapter. FOr CV machines only.

There is no neutral on 3 phase. They are all power wires. If you try hooking up a 3 phase motor to single phase power it won't work.

Well John Henery I'm new to this type of correspondence,but I'll give it a try!

#1 Disconnect from power & remove the 10 bolts holding the cover.(There should be diagams by each of the 3 jumper sets to be changed.)
#2 Standing at the front look to the rear left ,and you should see 4 studs. (Dotted line=buss jumper)
x----x x----x x x----x x
240V 480V

#3 At the front center down low there will be 4 more studs.
x----x x----x x x----x x
240V 480V

#4 On the right rear there is a vertical board with 10 studs.
x x x x x x
| | |
| | |
x x x x--------x x
| | |
| | |
x x x x--------x------x
|
|
x x
(240V) (480V)


As far as your no power problem look at the main power switch. Of the wires that go to the welder, 3 will go to the power board, and 2 to the control board. When you hook the power cord to the house power you need to make sure to use the 2 cord conductors that will also feed the control board.

I do have an operator's manual for a 300SM, contact me at [email protected] ,and I'll get you a copy.

Tom