I am having the local 3 phase installed in my shop. I suspect it is around 400 volts.

Would a 3 phase welder be better than my 220 stick welder? Will I notice any difference? Do 3p come in AC and DC? If so whih is better.

Most of my welding is on I beam, angle etc. Not huge but not small either.

Hey Phil, Probably 380 50Hz. It will be AC. Three phase welder are a "little" more stable due to the overlapping phases. Will you notice the difference? Probably not. "Big" welder are usually three phase.

overlapping Phases ? HUH ? single is 180 degrees, and 3ph is out 120 degrees, what over lap ?

Gee Steve, way to make a guy feel bad(grin). I'm talking about about the sine wave of AC. Single phase goes from +240 to 0 and down to -240, 60 times per second. With three phase you have three overlapping sine waves 120 degrees apart. After going thru the transformer using three phase in, you don't have a zero point in the output, right? I think that's right. Even with a proper bridge rectifier, the single phase oscillates and has a zero point whereas the three phase overlaps each other. makes a more stable, smooth arc.

Because they all cycle at 180 degree and in three phase they are shifted 120 degrees, there has to be an overlap, right?

Edited June 11, 200917 yr by nakedanvil

Found this:

When polyphase AC is rectified, the phase-shifted pulses overlap* each other to produce a DC output that is much

Edited June 11, 200917 yr by nakedanvil
* my emphasis

Stewart Marshall describes the difference between single phase and three phase as being akin to the difference between a single cylinder engine and a multicylnder engine.
With welding machines there is a notedly smoother and more consistant arc.

I am having the local 3 phase installed in my shop. I suspect it is around 400 volts.

Would a 3 phase welder be better than my 220 stick welder? Will I notice any difference? Do 3p come in AC and DC? If so whih is better.

Most of my welding is on I beam, angle etc. Not huge but not small either.

May I add Philip, If you are talking about 3ph. stick welders on the US / Euro market today + or - a few years...I think you will find the major manufacturers have all scaled down thier product lines to a few 3 phase DC rectifier type welders in the 300 to 600 amp. range.
If you are talking the "oldies but goodies" 3 ph welders circa 1940's thru 80's You will find 3ph welders can be had in the AC transformer type, AC-DC transformer-rectifier type, and the motor-generator types.
ALL 3ph welders operate SUPERIOR to thier single ph counterpart. The higher the input voltages i.e. 380v-460v, the bettter, but even on lower voltages 3 ph. stick welders are "THE BONB" compared to any single ph welder. They have electricaly controled amperage and fine voltage adjustment of welding current.
I have used all types in the past 35+ years...if you could specify the year /make/type 3ph welder you are getting, perhaps myself and /or the other welders on I forge can give you more information.:cool:

Edited June 12, 200917 yr by alfonso

As an Electrician, I get picky about terms, To many are confused enough without misuse of technical words adding confusion. Not trying to make anyone feel bad. I have never heard or used the term overlap as being applied to phase relationships before, as that term implies repetition of an effect. I do agree the 3ph sine weaves leave no Zero, I also agree 3ph has a higher potential. But I can still plot the sine waves as distinct and not duplications on the scopes.

Just trying to understand what you were referring to, as many cultures, even geographical areas of the same culture use terms differently.

As for Phillip's question, I didn't comment on his power supply, as I have NO CLUE what the power is in China. I applied but did not get the 2 year post to Beijing a few years back, so no work for me there. It may or may not be the best choice over there. I would think after speaking with Phillip a few times, that having a self contained genny/welder unit would be best, for many reason and applications.

Edited June 12, 200917 yr by steve sells

My bad! I guess I had brain flatulence on the AC/DC question and thought he was talking about the service. Duh! Otherwise, what question did I fail to answer, Alfonso?

While I agree most "welders" can tell the difference, most non-welders can't even tell when they have the wrong polarity. Some can't even tell the difference between AC and DC. But I did tell him it can be smoother.

Phillip is actually IN China and I presumed he was getting a locally made machine. They use 220 and 380 50Hz. I've never noticed any difference between running my three phase machines on 240 or 480, just a different tap on the primary, the machine and the output is absolutely identical. My single-phase AC/DC welders have electronic amperage control but I've heard of "fine voltage adjustment of the welding current", current is ampreage. A modern single-phase welder like a Miller Syncrowave is mighty smooth and "most" people wouldn't be able to detect any difference from a three-phase machine.

SteveSells: What do you think, am I missing something. I can't see why or how it would make a difference running a three-phase machine on 240 or 480. Just the primary taping isn't it? Should be the same output, right? What's your take?

Nakedanvil, Steve Sells...I did not mean to sell you short, I should have read the your posts more completely. I guess his questions were answered, and I edited my posting.

I get my "progressive bi-focal" upgraded glasses next week just after my 53 rd. birthday. I better stay away from the computer til then before I get a punch in the eye! Peace and prosperity to all.

Alfonso, sorry if I got testy. That happens easy in forums where there is no "body language" goin' on. I'll try not to be so sensitive (sniff, sniff, boohoo). Now that I know you're just a young'un I'll be more understanding.

Rather you didn't edit a post that has been responded to. Makes subsequent posts sound irrelevant and all weird.

Edited June 12, 200917 yr by nakedanvil

SteveSells: What do you think, am I missing something. I can't see why or how it would make a difference running a three-phase machine on 240 or 480. Just the primary taping isn't it? Should be the same output, right? What's your take?

nope you covered it well, even your explanation of overlap was clear.

3 phase is 3 ph, the power factor is volts x amps. Only real difference is the size of the supply line bringing power to the welding unit. Because the 240v using 40 amps is the same power as 480v at 20a, but wire size is determined by the amperage.

OK. Thank you all. I don't know what Chinese 3 phase is as far as voltage is cincerned but as Anyang hammers work OK in UK and USA on 3 phase I suppose it can't be too far from what you use there. Once I have got the oney in place and have finished my brief vacation I can go shopping. A locally sourced welder will fit the local # Phase of that I am sure. Beyond that- well this is a land of constant adventure believe me!

Steve: Yeah, it sure is nice to be able to use small wire with the higher voltages. Copper ain't cheap.

Philip: The machines they sell here use motors that are for export only (most of the time). Local supplier should be able to help you out.