Three Phase Power and Welding

[BrokenTrack]

Does anyone really know what the difference is in welding with Three Phase Power versus that of Single Phase Power?

I have been told that with 3 phase power the arc is more stable, but since most welders convert to DC I cannot see where that would make a huge difference. Perhaps on some tasks like welding Cast iron or Aluminum where the welder is running AC power instead, or in pulse welding if the background current is AC, but what would it matter to a welder in most welding DC configurations?

I say this because, if a welder has enough amps and volts to make an arc, what would it matter if that current is being drawn from one source or three sources?

I always assumed we just ran 3 phase power on welders because it was less costly, and because i was already in the building in high voltages anyway (480 volt) for motors and such?

 

[ptsg]

It's much more noticeable on the older AC rectifier welders, which is what I only use.

Over here, we have 3 phase pretty much on all houses, unless the owner doesn't really want that.

It's night and day difference between using the welder at 3 phase @400V or single phase @ 220V. With 3 phase, it's much more stable and you can weld at higher currents than at 220v single phase.

On the other hand, I have a newer inverter welder that runs single phase @ 220V and will weld as good as my older rectifier welder in 3 phase. That's what I use when I need to weld on places that it's hard to get 3 phase.

 

[Motorboatin]

Newer machines don’t know the difference. Your wallet will

 

[drysalty]

I’ll second what ptsg said. If you are working with an transformer style welder the three phase is a noticeable improvement. The arc with be smoother and it will just weld nicer. The inverter machines weld pretty much the same on single phase as they do on three phase. Inverters use less power for a given welding amp setting which is a big consideration if you are choosing a machine for home use. Running an inverter type welder on three phase gives an improvement in duty cycle but I have never come close to hitting the duty cycle of any of my inverter machines. Transformer machines are very durable but they don’t offer the features that the inverters offer in terms of pulse, square wave, frequency etc.

 

[3Ts]

Part of the consideration is how much power you need. In the USA you can only draw 26KW from a single phase electrical connection. That's 108 amps and most residential connections are a lot less than that. If you need more power, it will have to be 3 phase. I have (2) electric meters rated for 200 amps tied into a 60 amp transformer. Even though I have several 50 amp machines, it all seems to work ok.

 

[Sodo]

Three phase electric motors operate more efficiently than 2-phase. (save some $).
A factory running 3-phase eqpt continuously can realize savings.
But there's no $ savings if you have to pay extra to install the 3-phase.

Modern welders are inverter type. Input and output are completely separated.
The inverter takes any power it can get, even dirty generator power and changes it to what its designed to output.

There's almost no reason to "want" 3-phase power (for welding) other than to make use of old 3-phase equipment you got for cheap 'cuz nobody else can use it.
Provided you're p[lugging into 3-phase power that's already installed.
The fan motors of a welder have to be 3-phase.

I have a hard time believing it's worth putting any effort towards, I think it will actually be a rather significant cost that will never pay back.

 

[aczlan]

Part of the consideration is how much power you need. In the USA you can only draw 26KW from a single phase electrical connection. That's 108 amps and most residential connections are a lot less than that. If you need more power, it will have to be 3 phase. I have (2) electric meters rated for 200 amps tied into a 60 amp transformer. Even though I have several 50 amp machines, it all seems to work ok.

How do you figure that?
A 200 amp service loaded to 80% is 38,400 watts.
320 amp and 400 amp services are not uncommon on larger homes (generally a 320 or 400 amp meter with a pair of 200 amp panels running off of it). A 320 meter at 80% capacity is good for 61,440 watts at 80% load and a 400 amp meter is good for 76,800 watts at 80% load.

Aaron Z

 

[3Ts]

How do you figure that?
A 200 amp service loaded to 80% is 38,400 watts.
320 amp and 400 amp services are not uncommon on larger homes (generally a 320 or 400 amp meter with a pair of 200 amp panels running off of it). A 320 meter at 80% capacity is good for 61,440 watts at 80% load and a 400 amp meter is good for 76,800 watts at 80% load.

Aaron Z

Hmmm, you're correct, but I'm sure the coop told me 26 kw. I'm wondering now if that was a coop imposed limit? They also told me $48k to string wire down the road for 3 phase several years ago.

 

[yomax4]

You can also pick up a phase converter for under $100 if you are diligent. I picked one up for $90. Weighs about 90#. Never used it. It is an option though. I can weld 1/2" plate all day long on single phase so I'm good.

 

[caver]

If it's a pole mount xfrmr it usually has the KVA rating on the side in big letters that cab be seen from the ground. Some are on a sticker. 25= 25KVA