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

In article ,
Phil wrote:
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.

It's some welder if it takes 125 amps at 240 volts.

--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.

Most of the modern welders do draw a fair amount of current at full
capacity, my unit is an older Miller machine and it draws 105 amp. at 240 v
.. , a Miller Syncrowave draws approx. 135 amp. at 240 v., takes a lot of
power to weld tin foil.Thanks , Phil
"Dave Plowman (News)" wrote in message
...
In article ,
Phil wrote:
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.

It's some welder if it takes 125 amps at 240 volts.

--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.

and my dog can lick your dog...

David

"Dave Plowman (News)" wrote...




--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Phil wrote:
Most of the modern welders do draw a fair amount of current at full
capacity, my unit is an older Miller machine and it draws 105 amp. at
240 v . , a Miller Syncrowave draws approx. 135 amp. at 240 v., takes a
lot of power to weld tin foil

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.

--
*The e-mail of the species is more deadly than the mail *

Dave Plowman London SW
To e-mail, change noise into sound.

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
...
and my dog can lick your dog...

David

"Dave Plowman (News)" wrote...




--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.

"Dave Plowman (News)" wrote in message
...
In article ,
Phil wrote:
Most of the modern welders do draw a fair amount of current at full
capacity, my unit is an older Miller machine and it draws 105 amp. at
240 v . , a Miller Syncrowave draws approx. 135 amp. at 240 v., takes a
lot of power to weld tin foil

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.


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.

"Phil" wrote in message
...
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
...
and my dog can lick your dog...

David

"Dave Plowman (News)" wrote...




--
*My dog can lick anyone

Dave Plowman London SW
To e-mail, change noise into sound.




Just curious :-)
If you're pulling 100amps on the primary at 240v, what are the secondary
currents you are welding at ??

--
Regards ......... Rheilly Phoull

"Phil" wrote in message
...
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

Phil.. Are you confusing input voltage and secondary output amps??

Did look up the specs. for welder, INPUT, 230v.@ 96 amps. , OUTPUT ,40v. @
470amp. , read out of the Miller bible, and yes it will POP a 100amp.
breaker under full load , Phil
"Warren Weber" hiview68NO wrote in message
...

"Phil" wrote in message
...
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

Phil.. Are you confusing input voltage and secondary output amps??

Did look up the specs. for welder, INPUT, 230v.@ 96 amps. , OUTPUT ,40v. @
470amp. , read out of the Miller bible, and yes it will POP a 100amp.
breaker under full load , Phil
"Warren Weber" hiview68NO wrote in message
...

"Phil" wrote in message
...
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

Phil.. Are you confusing input voltage and secondary output amps??

In article ,
Phil wrote:
Did look up the specs. for welder, INPUT, 230v.@ 96 amps. , OUTPUT ,40v.
@ 470amp. , read out of the Miller bible, and yes it will POP a 100amp.
breaker under full load , Phil

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.

--
*Husbands should come with instructions

Dave Plowman London SW
To e-mail, change noise into sound.

"Phil" bravely wrote to "All" (24 Sep 05 20:44:12)
--- on the heady topic of " 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.

A*s*i*m*o*v

.... Of course it's grounded! ...watch, ...YEEEEEAAAAAAAAHHHHHHHH!!!!