How to run a 400V 3-phase welder on 1-phase supply

[Echidna]

The title says it all. I have found a good bargain on a 3-phase 400V TIG AC/DC 315A machine but i have the traditional European 220V 1-phase supply.
How can i convert my supply to be able to work with this machine?

 

[madkayaker]

difficult to say with out some more info on the machine. A transformer would work but would be power hungry. Is the machine three phase or 400V (380) single phase?

 

[Wozzaaah]

This has been asked before and I think the general consencus is that it can't be done. Some of the bigger so-called 3 phase machines are in fact single phase but if it specifically says 400V 3 phase then you're out of luck I'm afraid .
Keep looking .

Blimey MK, your sparky spider senses must have been tingling while Echidna was writing his post!

 

[simon718]

would help if you could post a link mate, is it in greece? shouldn't be any worry of anyone sniping it out from under you if it is

 

[Echidna]

difficult to say with out some more info on the machine. A transformer would work but would be power hungry. Is the machine three phase or 400V (380) single phase?

It is 400V 3-phase.

 

[Echidna]

would help if you could post a link mate, is it in greece? shouldn't be any worry of anyone sniping it out from under you if it is

That's it!
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=270325773740

 

[madkayaker]

are you shore how many cores has the supply cable got

 

[Wozzaaah]

You could possibly run it off a large rotary phase converter but they're incredibly expensive so really not worth it for a cheap welder.

Edit: Thought it was going to be a transformer machine but it's an inverter so wouldn't need such a big RPC.

 

[Echidna]

are you shore how many cores has the supply cable got

No, i don't!

 

[Echidna]

Edit: Thought it was going to be a transformer machine but it's an inverter so wouldn't need such a big RPC.

Still not worth it?

 

[madkayaker]

inverter might not like running of rotary phase converter the output can have lots of spikes and bad harmonics

 

[Wozzaaah]

You'd need to work out what size of converter you need, price that in with the welder and it's no longer a bargain .
Also, I'm not sure how happy inverters are running off RPCs, they may not be suitable.
Do you really need a tig that powerful? You can get 200A single phase ones very cheaply.

 

[madkayaker]

i keep beating you to it Wozz

 

[Wozzaaah]

That's cos when I hit submit it makes me wait ages before it goes and I don't know why! Grrrrrr
It's only this site that it happens on too .

Anyhoo, back to the welder before we go o/t, echidna, if you want a powerful tig consider an old miller or murex if you can find one, they're often single phase but people advertise them as 3 phase because they don't realise.

 

[Echidna]

In reality i don't need anything bigger than 200A, but the price was very good for such a powerful machine, that's why i considered it as a bargain. Thanks anyway guys!

 

[madkayaker]

check with the seller if it uses all three phases a photo of the data plate would tell us all we needed to answer the questions or how many cores has the cable got!

 

[irondarren]

Anyhoo, back to the welder before we go o/t, echidna, if you want a powerful tig consider an old miller or murex if you can find one, they're often single phase but people advertise them as 3 phase because they don't realise.

Some transformer types just need a wire or two changing inside the machines, rather like some of the old oxfords. funny though many welders say 3 phase but only actually use 2 phases, which technically isnt that clever as i always was told it was best to balance the power draw acrossed the phases.

 

[madkayaker]

it uses the two to get the 400V in protecntial differ ace between th two. always best to balance to reduce current in N

 

[eddie49]

On the downside, the machine appears to be Chinese, with the potential reliability and maintenance issues that brings, so maybe it wasn't such a huge bargain.
Regarding alternative power inputs: on an inverter, the input is rectified right away. I'm guessing here, but probably the input 3-phase 380VAC goes straight to 6 fat diodes and a big capacitor. The resultant 600-ish VDC then feeds the inverter, with MOSFET or IGBT devices switching at 20 to 100 KHz to do the rest of the job. So it would be fairly tolerant of rough 3-phase input from a rotary phase converter.
Theoretically, you could also step up single-phase 220VAC with a transformer, and feed that to just one leg of the 3-phase bridge rectifier in the welder, but, as was previously stated by madkayaker, the power ( i.e. current ) to support 315 Amp welding would be very high for a single-phase circuit.