3 phase convertors

[-ghost-]

So I bought a 350 amp mig welder on ebay but its 3 phase thinking I could pop down machine mart and get a 3 phase converter this doesn't seem to be the case I've found out.

All the welder says its input is 415v 3-Phase Input 12A 5KVA People keep telling me different things from 95% of welders only use 2 of the phases so just need a transformer to its not possible and it will break the welder. Then there is 3 types of converters with mixed reviews with working with welders?


So what can I use to power the beast?

[Si]

AFAIK you can't 'convert'. Most common solution with motor driven stuff is to get something that effectively kicks out an extra phase to spin up the motor, then runs it single phase, but it required a shitload of power and shortens the lifespan. That's irrelevant for a welder though.
You'll need 3 phase from the street, expect the network to ask a good few grand. Or get a massive, hugely expensive 3 phase genny.

[59bhp]

im considering using an inverter or generator to get my lathe working, both have their merits and flaws;

neither are particularly cheap but there isnt a way to do this that cheap :S

[-ghost-]

I hate electrics its so confusing.

After doing a bit of research 5 KVA is 4KW or 5.3HP meaning even the 3 phase converter from machine mart should technically power it but it seems to be the start up current(or what ever the word is) but a lot of the machines say that can take unto 3 times the power for unto 30 seconds.

My neighbour asked about installing 3 phase and the quote was something like 18,000 due to the way the cables would have to be run and you have to pay a day rate even if your not using any 3 phase.

I was thinking of going for a 7.5KW-10KW static converter as yeah they aren't cheap but once its brought it can be used to power welders, lathes , mills which all are a lot cheaper to buy if they are 3 phase.

But I can't get a 100% yes it will work?

[Si]

Again, I'm probably wrong, but I have always been lead to believe it's not possible to 'convert' single phase to 3 phase in an efficient manner. It will always be compromised.
You can effectively bodge it with motors, but the welder will need constant, stable power. In fact that Machine Mart link says it is to ' match the requirements of motors up to a max. of 3.5hp' implying that it won't be suitable.

I'm a bit out of my depth, but a bried Google suggests something like this: http://www.exfactory.com/DetailNew.a...00029&menu=new should be suitable. Assuming the normal thing of 'about the same in £', that's around 2k. Combine that with the electrical needs, and you're looking at a very expensive solution.
Can you not get an equivalent welder on single phase?

[Si]

Oh, and I don't know anything about MIG, but 350 seems a hell of a lot - WTF are you welding, RSJs?!?

[R3K1355]

Yea unless you're going to weld up a replica of the Titanic you won't need a 3-phase welder to work on cars at home.

[Dan@DB-Power]

Our welder here goes up to 300 amps 3 phase and too be fair if we put it on high power it just melts everything even thick steel

[wyn2k]

you can convert single phase to 3 phase with a stable output, theres no way its 350A as that would be more than a 3 phase supply. you can also wire it as single phase but you would need to make sure the supply cable feeding it is to suitable size, from a quick look at your specs it would seem its around the 30a mark which would mean you should use 10mm cable and run it on either a c or d type 40a mcb, if it were run on 3 phase you would get away with a 2.5mm cable and on 16a mcb as your effectively sharing the current with 3 cables (if that makes sense) its the same as running a radial socket circuit on a 2.5 and that would have to be put on a max 20a mcb or if you run it as a ring you could put it on 32a mcb as your sharing the load and get a greater csa. im shit at explaining hope this helps.

Sent from my GT-I9300 using Tapatalk 2

[-ghost-]

^^^^In english please^^^^^^ I'm a noob at wiring/electrics.


I'm about to go collect it now but its that what they told 350amp welds upto 15mm steel and has a load of adjustments that I don't understand (they are selling a 400 amp too)

So what your saying is it can be wired up just using the normal 2 phases? just needs the right breakers and cable?


This is all dans@dbpowers fault.

I'm not your normal diy garage welder si and r3k1355. See i look at it this way I could pay some guy £80 to weld my knuckles or I could throw a few more quid in and buy a upgrade welder that will last(hopefully) a fair few years so if I get other things(which I will) i can do them without having to get in outside help.

[R3K1355]

Can't you weld those knuckles with a nomal mig, like a Clarke 151 TE ??

[-ghost-]

I had a go with a 180amp slowed the wire feed right down but it just didn't have the power to melt 15mm even with the sides V'dand if it fails my rear calliper if coming off.

[green_rs13]

but what size was the mig wire?

what make is the mig? as some have 'jumpers' inside so you can convert between phases.

you cant run a welder off a converter you will just end up ruining it. they are for lathes/mills etc.. ive heard of people running 2 post ramps with the and finding the ramp struggles to lift heavy cars.

unless its mega cheap and you can sell it on I would pass on it as it wont be any use to you,

you can get single phase sets that go upto 400 amps but you would need a mega circuit breaker like 60 amp.

ive welded a few diffs for S bodies with my mates 130amp mig and .8 wire and they are still holding up.

personally id get a decent make 250 odd amp mig set that will be fine for welding caliper brackets etc..

[-ghost-]

Too late now just collected it man its a beast.

I've just been chatting to my neighbour he powers his ramp, mig+tig welder and few other things off a transwave converters 10hp they are made in birmingham his ran it for 2 years now and reckons his had no problems about £800.

Its made by R-tech

The wire was the normal 0.8 just wasn't happy with the penetration it looked like the weld was sitting on the top.