Welding Tips and Tricks

I'm thinking about getting a new 3 phase Millermatic® 350P Aluminum, but my shop doesn't have incoming 3 phase from the power plant. We have a 10 horse rotary phase converter which puts out plenty of power for our machinery but it's not "pure" 3 phase. It's pretty close, but it doesn't fire at exactly 120 degrees apart per leg. How close do modern 3 phase welders need to be to pure 3 phase? I don't really want to have to put out another 5k (at least) for an electronic converter if I don't have to.


Thanks!

Other Steve

Ohh, good question!

I've work in shops with these phase converters, but never ran a modern digital welder on them. I'm sure there's some tolerance in the machine for phase variance, as even the power comapny can't get it "perfect".

I'd contact Miller directly with this question.

Steve S

Actually, with a good-quality phase-converter, you might get more accurate phasing than from the mains, simply from the short cable runs from source to equipment.

I'll be interested to see what you find.

Steve S

I wrote to Miller, I'll copy their answer here when I get it.

Some warranties on machinery, especially anything CNC, will be automatically voided if a static converter is used, but a static converter is about the lowest you can go. I used to use a static converter on a grinder and a bandsaw, pretty simple machines, and somedays it was hell to get them started. If the converter didn't click in at just the right moment, they might only run at a third or less of what they were supposed to. I've never had a problem with the rotary converter on any machinery as long as it doesn't exceed the rated horsepower.


Other Steve

Here's the answer I got from Miller...

As a general comment We do not recommend the use of phase converters on our
equipment as it can drastically affect the arc performance. With that said the
Millermatic 350P or 350P Aluminum can run on single phase or three phase power
with no problems.


David McLaughlin
Service Technician, Integrated MIG Systems

Miller Electric Mfg. Co. An ITW Welding Company
N855 Mayflower Drive, Appleton, WI 54913 Phone: 920-954-3499 Fax: