running a 32 amp supply for a 300 amp 230 v mig

[stumpy75]

ok so i rent a workshop/garage it is underneath a house the landlord also rents it has electric as part of the rent paid on it now i know nothing regards electrics [so assume your talking to a numpty]

so ive had a look at the electric supply today wooden board screwed into the wall large thick black cable coming through the old stone wall into the top of a small white box it has a single 100 amp 415v fuse/breaker there is meter next to the box with a spinning disc it has a cooker socket single off on switch to knock the electric off completely and thats about it what i need to know is can i run a 32 amp supply for the mig from whats there the only wires i can see are a black and a red going into the meter i will get pics fior you but i have only just found you tonight

 

[ericmark]

300 amp welder needs around 54 amp, voltage is approx 25 + 1 volt per 25 amp, so around 41 volt so assuming no losses needs 54 amp in real terms 32A 3 phase would normally used for a welder that size.

 

[JohnW2]

300 amp welder needs around 54 amp, voltage is approx 25 + 1 volt per 25 amp, so around 41 volt so assuming no losses needs 54 amp ...

For my future reference, could you perhaps explain that one to me?

Kind Regards, John

 

[ericmark]

When working for GEC large turbines I was very involved with welding sets, and I made measurements of many different makes, and found that to be the approximate output, which clearly relates to input. What I couldn't understand to start with was why two welders using 100A were using less power than one welder using 180A it did not seem to make sense, until one realised the rise in voltage.

So a welding inverter at 75 amp is running approx at 29 volt so 2175 VA and at 150 amp 32 volt so 4800 VA which is well over double.

 

[bernardgreen]

You or your land lord will need to contact the DNO ( details HERE ).

The contract to supply invariable requires that the DNO is informed of any disturbng loads that are to be connected to an existing supply

This is a typical application for supply form.

 

[JohnW2]

When working for GEC large turbines I was very involved with welding sets, and I made measurements of many different makes, and found that to be the approximate output, which clearly relates to input.

It was you aritmetic as much as anything else that I was a bit puzzled about.

So a welding inverter at 75 amp is running approx at 29 volt so 2175 VA and at 150 amp 32 volt so 4800 VA which is well over double.

Where does all this voltage (hence power dissipated) 'go'? - I find it a little difficult to believe that most of the p.d. would be 'across the weld'?

Kind Regards, John

 

[ericmark]

I did not study welding, I was only worried about repair of the welding machines, and I will admit some repairs were trial and error, the circuit boards had 4 741 opamps, what they did I don't know, but guessed these were likely to fail, so when a machine failed, I would replace opamp for a IC holder, then plug in new opamp, 80% of the time it worked, if not sent the board away for repair.

Board cost around £150 and opamps cost around £2 for 4 and took around 1/2 hour to fit, so it was a cost effective repair.

Some units 50 Hz AC, some kHz AC, and some DC. Some jobs needed to 25/75 heat split of DC, some needed the smooth weld with kHz supply and some 50 Hz was no problem. All I needed to know was there was a difference, I did not need to know what the difference felt like, in fact I got into trouble for testing welding sets, so any test with volt meter or ammeter that could point to fault was a bonus.

But from late 1990's did not repair welding sets, or set up cooper heat pre-heat or stress relief from then on, so now some 30 years ago, sorry can't remember all details.

 

[stumpy75]

i know nothing regards the above calculations but the welder is deffo a 300 amp 230v single phase if that makes a difference

 

[stumpy75]

here