Hello Would like to replace a mechanical contactor on welder with an electronic switch, have access to high voltage high current SCR's, guess a TRIAC would be the simple way to go, not really practical for 240 v. , 125 amp.A.C., If someone has been down this road before , I would appreciate hearing from you. Thanks Phil
It's some welder if it takes 125 amps at 240 volts.
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Dave Plowman dave@davenoise.co.uk London SW
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"Dave Plowman (News)" wrote...
I'd love to know what you're welding. You can do near everything with one which runs off a standard 13 amp 230v supply. Commercial ones might use a
16 amp one. Of course if you're welding ships together you'll need something bigger.Most domestic UK installations are restricted to 100 amps. Many less.
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Dave Plowman dave@davenoise.co.uk London SW
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Have been welding for about 30 years, have joined metal from .010 " to 2" thick , worked as certified Aircraft welder for several years, mostly TIG or GTAW and Electron Beam, typical aircraft tubular assembly would be either .035 or .049 wall thickness, electron beam of Titanium would be on the order of .25" thick, welding light gauge 4130 or 308 Stainless would require very little D.C.to join, if one were to join two pieces of .75" ,6061-T6 Alum., you would need A.C. with the square wave skewed to nearly 70% negative with
75% Helium 25% Argon gas and approx. 400 amp. at the torch , this load will pop a 100 amp. breaker in a heartbeat, and no I have never done any ship building, thanks for your interest. Dr. Phil "quietguy" wrote in message news: snipped-for-privacy@REMOVE-TO-REPLYconfidential-counselling.com...
He's probably not in the UK, here in the US 200A 240V is the standard domestic service, at least in areas built in the last 30 years or so, but
400 or even 600A is not unheard of in larger houses.Still welders can indeed draw a huge amount of current, a friend of mine has a large arc welder that requires a dedicated 30A circuit, and the inrush current is much higher. Another friend has a machine shop and they have a couple even larger welders that run off 480V 3 phase, I'm not sure what amperage the circuit is but the wiring is heavy and the welder is capable of supplying 250A.
Just curious :-) If you're pulling 100amps on the primary at 240v, what are the secondary currents you are welding at ??
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Phil.. Are you confusing input voltage and secondary output amps??
Did look up the specs. for welder, INPUT, 230v.@ 96 amps. , OUTPUT ,40v. @
Did look up the specs. for welder, INPUT, 230v.@ 96 amps. , OUTPUT ,40v. @
Sounds like since you're obviously doing industrial welding it would be better to buy a modern machine suited to your needs rather than trying a DIY bodge.
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Dave Plowman dave@davenoise.co.uk London SW
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"Phil" bravely wrote to "All" (24 Sep 05 20:44:12) --- on the heady topic of "Re: AC Switch or contactor"
Ph> From: "Phil" Ph> Xref: core-easynews sci.electronics.repair:343036
Ph> Have been welding for about 30 years, have joined metal from .010 " to Ph> 2" thick , worked as certified Aircraft welder for several years, Ph> mostly TIG or GTAW and Electron Beam, typical aircraft tubular Ph> assembly would be either .035 or .049 wall thickness, electron beam of Ph> Titanium would be on the order of .25" thick, welding light gauge 4130 Ph> or 308 Stainless would require very little D.C.to join, if one were to Ph> join two pieces of .75" ,6061-T6 Alum., you would need A.C. with the Ph> square wave skewed to nearly 70% negative with 75% Helium 25% Argon Ph> gas and approx. 400 amp. at the torch , this load will pop a 100 amp. Ph> breaker in a heartbeat, and no I have never done any ship building, Ph> thanks for your interest. Dr. Phil "quietguy"
Assuming the arc voltage is around 50 to 80 volts then 400 amps at the electrodes could indeed have surges exceeding 100 amps from the 240 volt supply.
What immediately comes to mind is to use a bank of triacs in parallel or a single BIG f***er. I know they make 400 amp and even 1,000 amp triacs though these are industrial types not available at the corner diode convenience store.
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