1 vs. 3 phase

[lindsayb]

Hey everybody! I'm doing some research on welding products and am trying to understand the difference between 1 and/or 3 phase products. For example, looking at the Millermatic line: my basic understanding is that a 1 phase is made more for home hobby, light manufacturing work. 1 & 3 combined include those with some added power for slightly heavier applications while a 3 phase machine is for heavy duty apps. Any additional (and more in depth) info you can give is much appreciated. Thanks!
~Lindsay

[Sberry]

Residential power suppies are single phase. A lot of larger industry uses 3 especially where there are large motors involved and really heavy welding applications.

[Broccoli1]

A little more in depth as why the use of a 3 phase machine:

It is more efficient than single phase and allows for smaller wires and for smaller machines.

Easiest example is with the ol' water analogy

Filling a Bucket with water with one hose- Single Phase

Filling a Bucket with 3 hoses- 3-Phase

The Single Phase Hose would have to be rather large to keep up with the 3- Phase hose

Now for the Machine side:

Imagine a Water driven wheel BUT with only one paddle- Single phase
Same Water driven wheel but with 3 paddles- 3-Phase
--Both wheels produce 300 amps with each revolution--

The Single Paddle wheel will need to be constructed quite a bit bigger than the 3 Paddle wheel and the size of the Hoses as well.

[Broccoli1]

Here you can see the Amp input difference between running the machine on 1-Phase and 3- Phase as well as how the Amp Input requirements change with the Voltage used.

[Broccoli1]

here is a nudder link

http://www.millerwelds.com/education/basicelec/

[lindsayb]

So essentially, what you're telling me Broccoli with the water analogy... 3 hoses will fill a bucket in less time...but it's all the same amount of water. As in 3 hoses "water output" is the time it takes to fill the bucket...likened to the amount of amperage a 3 phase welding machine outputs. Does that make any sense? Clearly, I'm new to the world of welding, but I REALLY appreciate everyone's help. : )
~Lindsay

[Sberry]

just curious, why the concern with this particular question?

[Broccoli1]

So essentially, what you're telling me Broccoli with the water analogy... 3 hoses will fill a bucket in less time...but it's all the same amount of water. As in 3 hoses "water output" is the time it takes to fill the bucket...likened to the amount of amperage a 3 phase welding machine outputs. Does that make any sense? Clearly, I'm new to the world of welding, but I REALLY appreciate everyone's help. : )
~Lindsay

Bucket Fills in the same amount of time-

1ph = Bigger hose
3ph Hose= smaller hoses

Just makin' mud now

[Broccoli1]

I have yet to see / run a single phase stick or wire feed welder that will compete with a 3-phase machine!

Tig machines yes!

probably never will

[Burnt hands]

1 phase vs 3 phase

I would love to get 3 phase power in my garage but I doubt the local power company would be interested in installing a big transformer just for me.

Another advantage 3 phase gives is lower amperage draw for the equivalent output amps. Can be a help if you need to run equipment using a properly rated power cord.

Speaking of amperage draw, an interesting observation I made is when I had my home service upgraded from 60 amps to 200 amps. The electrician installed everything and I was at home when the electric company service technician installed a new meter.

I asked why he did not install a larger gauge wire from my house service entrance to the utility pole in the back yard. I went up a bit more than 3 times in amperage and the wire stays the same gauge?

Was told that even though the wire might get a bit warmer than before, it was in free air and this was allowed.

He also said that since the "warm" section was before my meter, the utility was paying to heat the air and not me so I shouldn't worry.

200 amps thru a clothesline sized wire - magic or priceless?

OK-it's been 14 years and no fires so far................

Another reason I would love to get 3 phase service installed at home, is that it is possible to run single phase equipment on one leg of a 3 phase service. Worked at a company who had only 3 phase power. All the 115 volt stuff was run off one phase and worked without any problems - even computers and TVs. I never knew until I asked one day.

Have your beer and pizza and enjoy both or did I mess up the saying.

[Broccoli1]

Another reason I would love to get 3 phase service installed at home, is that it is possible to run single phase equipment on one leg of a 3 phase service. Worked at a company who had only 3 phase power. All the 115 volt stuff was run off one phase and worked without any problems - even computers and TVs. I never knew until I asked one day.

Have your beer and pizza and enjoy both or did I mess up the saying.

Your House IS run off 1-leg of 3 -phase

[Burnt hands]

3 phase power

ok - who do I have to bribe to get the other 2 phases and how much will it cost me?

I can trade a slightly used welder.

Thought of buying a 1 to 3 rotary phase converter but isn't that a bit like buying a generator to run your electric lawn mower.

Duh, I just answered my own question - solution is to buy a 3 phase diesel generator.

3 phase power may end up not being a practical solution but when has this stopped us from dreaming.

Ed, thanks for the info.

[MAC702]

...Was told that even though the wire might get a bit warmer than before, it was in free air and this was allowed...

Still a common practice to this day. I've done many service upgrades, and overhead service is relatively cheap to upgrade because of this.

[Dmaxer]

I had a problem with the power to my home that manifested as failure of certain outlets in the house, but not others. To make a long story short, it turned out that one of the hot legs of my 240v service was being shorted by oxidation at the street connection and when the power company (finally) figured it out it was a quick fix. In the meantime, I replaced the main breaker with one I bought (175A) by hiring an electrician, because the power company originally said the problem was on my side of the meter. The breaker cost and labor was refunded eventually by the power company.

The electrician who installed the new breaker said, based on the wire gauge from the street, said I could have used a 250A main breaker or even larger. Again, he said this was because codes allowed it and any losses due to heat generated would be borne by the power company and not me.

[MAC702]

...The electrician who installed the new breaker said, based on the wire gauge from the street, said I could have used a 250A main breaker or even larger. Again, he said this was because codes allowed it and any losses due to heat generated would be borne by the power company and not me.

Assuming the panel was designed for a breaker that large, yes. The expensive part of service upgrades is swapping out a panel and all the associated wiring labor.