New Welder Day - Miller CP 302 - Possible single phase conversion?

Pete Deal · Nov 22, 2020

I saw a pretty nice looking wire feed on the HGR site and succumbed to temptation. I have a Miller 252. The new purchase is a CP 302 with a S-75D wire feeder. The CP 302 is a little over kill but I like the idea of separating the wire feed from the power supply for a little more portability. I also have an engine driven welder I could use the wire feed with so it will give me a lot of flexibility. Assuming it's not all burned up inside, which with HGR you never know (I have not picked it up yet).

I've read many of the single phase conversion threads and am not afraid to try it. My question is to those who have converted a similar power supply (cp 300, 302 etc) how has it worked out for you? Other than the up front effort does the welder work well as a single phase machine once you get these details worked out?

I do have a phase converter that ought to be up to the task of driving the welder so that's an option too. I would prefer if it was single phase though.

I_AM_MACHINE · Nov 22, 2020

Pete,

Use this link to the three phase to single phase conversion: Haas-Kamp conversion for Miller CP-300, and CP-302 200-230-460

I've done this conversion and it works spot-on. Peter Haas and Dave Kamp I'm sure will chime in momentarily

Regards,

Kevin

Pete Deal · Nov 22, 2020

Thanks Kevin I did see that link and spent quite a bit of time going over it and will likely spend quite a bit more. There was not much follow up on these conversions though after people have used them a while so that's what I'm after.

I've been pouring over the CP-302 schematic and it looks pretty simple inside. I just got done resurrecting's a mouse infested Miller Pipe Pro 304, which is an engine driven inverter. Quite a bit more going on in that. I look forward to messing with the transformer machine.

DaveKamp · Dec 6, 2022

Any progress on it, Pete? The 302 is basically the updated 300, primarily they went to SCR control, rather than a contactor. Other than that, the 302 was the 300's successor intended to hold the market for robotic continuous duty market, rather than the 'home garage' and 'commercial' realm... or in short, it's a BEAST...

Pete Deal · Dec 7, 2022

Yes and no. I did the conversion and messed with it for a while. The weld voltage drop was 10 or so volts and I never could get it to weld nicely. I messed with capacitor values etc. I wound up putting it back to 3 phase and running it off my phase converter and it welds great this way.

ksimolo · Dec 24, 2022

Strange - my 3 different conversions ran better on the conversion than on 3-phase.

Pete Deal · Dec 24, 2022

ksimolo said:
Strange - my 3 different conversions ran better on the conversion than on 3-phase.

Mine didn’t but I certainly wanted it to work.

William Payne · Jan 3, 2023

How many amps can you feed it? 3 phase or single phase when you get into high amperage at low input voltage the current draw is extreme. Some people use lower amp breakers and say "Its ok as long as you don't weld at high amps". I don't agree with that mindset as why buy a high amperage machine if you are going to gimp it.

Pete Deal · Jan 3, 2023

It was on a 50 amp breaker. If a higher amperage breaker would have worked I’ll never know. Done fooling with it. It’s working nicely on a 3 phase 30-40 amp breaker now ( can’t remember which).

DDoug · Jan 3, 2023

William Payne said:
How many amps can you feed it? 3 phase or single phase when you get into high amperage at low input voltage the current draw is extreme. Some people use lower amp breakers and say "Its ok as long as you don't weld at high amps". I don't agree with that mindset as why buy a high amperage machine if you are going to gimp it.

Because you got the machine for little money......

William Payne · Jan 3, 2023

DDoug said:
Because you got the machine for little money......

Absolutely. Been there done that. What I am more getting at is its better to do what you have to do to give the machine what it wants and get to use the machine to its fullest then gimp the machine and only get to use it half way. Its like having a race car you can't drive.

DDoug · Jan 3, 2023

William Payne said:
Absolutely. Been there done that. What I am more getting at is its better to do what you have to do to give the machine what it wants and get to use the machine to its fullest then gimp the machine and only get to use it half way. Its like having a race car you can't drive.

Do you have a place like HGR in New Zealand ?

William Payne · Jan 3, 2023

DDoug said:
Do you have a place like HGR in New Zealand ?

No, I wish we did. It is luck of the draw here in New Zealand. We have a website that is basically our version of ebay. Stuff shows up on there. Plus used machinery dealers. The dealers are a pain, only because when you go to a liquidation auction they will bid against you and if they win they will go on to sell it at a substantial mark up through them.

I have started importing stuff as I can buy things over seas and even with shipping it is cheaper than buying here.

Also what often is cheap here has been terribly looked after and abused.

DDoug · Jan 4, 2023

William Payne said:
No, I wish we did. It is luck of the draw here in New Zealand. We have a website that is basically our version of ebay. Stuff shows up on there. Plus used machinery dealers. The dealers are a pain, only because when you go to a liquidation auction they will bid against you and if they win they will go on to sell it at a substantial mark up through them.

I have started importing stuff as I can buy things over seas and even with shipping it is cheaper than buying here.

Also what often is cheap here has been terribly looked after and abused.

So why the negative comments towards the OP ?
Most welders are not used at more than 65% of their rated output.

William Payne · Jan 4, 2023

DDoug said:
So why the negative comments towards the OP ?
Most welders are not used at more than 65% of their rated output.

Negative? what negative? My comment was just to do what gets him the most out of his welder so that he can use it as fully as he can. I spend a lot of time on welding forums and many people do this they buy a welder for cheap that they can't power. My answer is always the same which is to give it as much power as you can.

The highest amp welder I own is a 400 amp Syncrowave 350LX and I have maxed it out before. That Syncrowave is single phase well actually L1 L2 N and I run it at 400volts supply and it is on a 63amp breaker. If it was running at 220-240 it would need a 100 amp breaker.

Without knowing the original posters electrical service my advice is to give it as much as you can. The Miller cp302 has more modest current draw at 3-phase but may draw a lot when converted to single phase.

Either way the original poster has his welder working and is happy, which is what matters most he now gets to enjoy using his welder.

Search

Largest Manufacturing Technology Community on the Web

Search

New Welder Day - Miller CP 302 - Possible single phase conversion?

Pete Deal

Stainless

I_AM_MACHINE

Aluminum

Pete Deal

Stainless

DaveKamp

Titanium

Pete Deal

Stainless

ksimolo

Aluminum

Pete Deal

Stainless

William Payne

Aluminum

Pete Deal

Stainless

DDoug

Diamond

William Payne

Aluminum

DDoug

Diamond

William Payne

Aluminum

DDoug

Diamond

William Payne

Aluminum

Similar threads