New Oxford welder

[L P]

I've a fair bit of heavy fabrication to do, so taken delivery of a 330 Oxford multi arc. It's 3 phase but only came on a 3 wire supply. Having wired it up it blows the mcb as soon as you turn the switch. Admittedly the mcb is type B and 10a rated, surprised it does it on initial start up though rather than under load. Before I put a 20a type d in has anyone had the same issue? I don't want to exacerbate the pop by winding more amps and a slower fuse, seems very odd to me to wire up 3 phase on two live wires.

 

[TheTallGuy]

I've a fair bit of heavy fabrication to do, so taken delivery of a 330 Oxford multi arc. It's 3 phase but only came on a 3 wire supply. Having wired it up it blows the mcb as soon as you turn the switch. Admittedly the mcb is type B and 10a rated, surprised it does it on initial start up though rather than under load. Before I put a 20a type d in has anyone had the same issue? I don't want to exacerbate the pop by winding more amps and a slower fuse, seems very odd to me to wire up 3 phase on two live wires.

Inrush on the transformer will easily pop a 10A B MCB.

 

[Longpod]

Im sure the old Oxford welders running on 3 phase also only used 2 phases.

E to Earth
0 to L1
415 to L3

But might be wrong........

 

[L P]

Inrush on the transformer will easily pop a 10A B MCB.

Thank you. Still find it odd that a 3ph welder is wired as 2ph.

 

[Badshot]

My single phase Oxford 330 amp mig needs a 30 amp trip, even then the wrong type tripped easily, can't remember which it was off the top 9f my head. Type b rings a bell.

 

[L P]

Im sure the old Oxford welders running on 3 phase also only used 2 phases.

E to Earth
0 to L1
415 to L3

But might be wrong........

Shouldn't matter l1,2,3 are all live, just earth is critical

 

[L P]

My single phase Oxford 330 amp mig needs a 30 amp trip, even then the wrong type tripped easily, can't remember which it was off the top 9f my head. Type b rings a bell.

I'll get another mcb tomorrow and try it with that. 3 sparkys here can't give an answer to the claimed 3ph bit, can't be 3ph with only 2 lives. It's clearly stated in the book how to wire it for 3ph with just two of them but it's a bit baffling. Wye and delta don't come into this oxford dictionary

 

[TheTallGuy]

I'll get another mcb tomorrow and try it with that. 3 sparkys here can't give an answer to the claimed 3ph bit, can't be 3ph with only 2 lives. It's clearly stated in the book how to wire it for 3ph with just two of them but it's a bit baffling. Wye and delta don't come into this oxford dictionary

Strictly speaking it's 400V single phase, but since we don't generally have that in the UK we use two phases out of a 3 phase circuit which we do have & that's why it's referred to as 3 phase.

 

[goldeneagle]

I recently took delivery of a 3 phase 470 Oxford and just wired as the instruction and haven’t had any issue. It is on a 16amp supply until new part of shed is finished then will go onto 32a.

May be a faulty component in welder these things do happen???

Haven’t got on to heavy stuff yet but has been welding 4mm wall box fine.

 

[Welderloon]

Assuming you have confirmed it is a 3 phase machine & not actually single phase then it should't really matter which of the other 2 wires go where if the earth is in the correct place.
Sounds like either an issue with the machine or a supply issue...............try it somewhere else with 3ph to aid the process of elimination.

I purchased a machine that was 3 phase, it arrived in a 3 phase marked box, with a 3 phase plug already attached with a manual stating how to wire it up...............& was single phase. it had been assembled & boxed up incorrectly..........trust no-one.

 

[bravheart]

Could his Lordship not just contact the supplier or manufacturer to get it sorted out to the point its not the machine as supplied that's at fault.

 

[L P]

Could his Lordship not just contact the supplier or manufacturer to get it sorted out to the point its not the machine as supplied that's at fault.

His Lordship spoke to supplier, went and got an MCB and it works just fine now, must take a lot of poke to fire up initially. 2 phase rather than 3 further reduces the break point as you're losing 10 amps from 1 phase.

 

[L P]

So, my 3 phase 2 phase welder is working well with the right mcb. Got going with it today for the house frame. I cut my teeth with mma and have done very little with mig, well, nothing in 20 years. It's a pleasure to use and very quick. I'm conscious I've done no mig welding in years and never self taught myself well even then. It cleans off with a wire brush, but the brown flecks I guess are red oxide residue? Flap wheeled it off prior to welding. But would appreciate a mig welders opinion.

 

[Welderloon]

Stevie Wonder would love to see that

Always try to make sure the surfaces are shiny clean & contaminant free...............it really is all in the preparation with mig, if you can weld mma then mig will be no drama.
Push don't pull, as high a current as is possible, keep the arc length (gap) constant & your wire speed & travel speed in sync..................that's it really

 

[Exfarmer]

So, my 3 phase 2 phase welder is working well with the right mcb. Got going with it today for the house frame. I cut my teeth with mma and have done very little with mig, well, nothing in 20 years. It's a pleasure to use and very quick. I'm conscious I've done no mig welding in years and never self taught myself well even then. It cleans off with a wire brush, but the brown flecks I guess are red oxide residue? Flap wheeled it off prior to welding. But would appreciate a mig welders opinion.

I velieve all 3 phase welders only actually use 2 phases as it makes the wiring of the transformer very much simpler. 3 phases supplies are about 380 volts across the phases no matter which phases you use since actually only 2 phases are ever live at any one time ( momentarily of course).
To complicate the issue many welders require a neutral to run the wire feed and controls which are single phase

 

[Welderloon]

Buy yourself some Anti-spatter, either spray or tip dip, & spray inside the shroud................will help the consumables last a bit longer, trust me on this, some folk go mad spraying it on the work surfaces also - it's up to you.

 

[L P]

Stevie Wonder would love to see that

Always try to make sure the surfaces are shiny clean & contaminant free...............it really is all in the preparation with mig, if you can weld mma then mig will be no drama.
Push don't pull, as high a current as is possible, keep the arc length (gap) constant & your wire speed & travel speed in sync..................that's it really

Push not pull will take memory! It seems very odd welding backwards, cumbersome with that umbilical chord too... I'm told the "slag" is actually silica in the photo?

 

[L P]

Buy yourself some Anti-spatter, either spray or tip dip, & spray inside the shroud................will help the consumables last a bit longer, trust me on this, some folk go mad spraying it on the work surfaces also - it's up to you.

Thank you, I'll amazon that, all up for the handy hints!

 

[Welderloon]

Push not pull will take memory! It seems very odd welding backwards, cumbersome with that umbilical chord too... I'm told the "slag" is actually silica in the photo?

yes, more a glaze than a slag.
Wire size & Gas mix makes a huge difference to how you weld also, most farmers are burning 1.0 mm wire when they could really get away with 0.8mm for most jobs, they'd probably find they get a better finish.

 

[fiatf130]

Any pics of your welder? Are you pleased with its performance?