Subject: Does a carbon arc damage an electric welder ?

From: C++ Freak <[email-masked]>
Date: 26 Jun 1996 07:43:57 GMT

A friend of mine told that making carbon arcs may damage an electric welder.
It's a 150 Amps one with 48 Volts AC secondary with a thermal circuitbreaker
(when the windings get too hot it will shut down).
I don't agree with him, but am not sure.
When I weld with it I make an arc using iron electrodes (the work and the
welding rod) and when I make an arc the "work" is the graphite crucible
attached
to the work clamp and the "welding rod" is the carbon stick attached via a 
6 sq mm copper wire to the handpiece with which you normally weld. 
He told me that the longer arc in the latter case makes the difference. 
Any opinion or advice on this ?

Thanks.

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From: [email-masked] (Don Clarke)
Date: Thu, 27 Jun 96 23:06:04 GMT

In article <[email-masked]>,
   C++ Freak <[email-masked]> wrote:
>A friend of mine told that making carbon arcs may damage an 
>electric welder. It's a 150 Amps one with 48 Volts AC 
>secondary with a thermal circuitbreaker

>Any opinion or advice on this ?

Your friend has been reading Grim's fables.

An arc is an arc. If it's the arc you expect between the + 
and the - terminals, it won't do any damage to the machine. 
After all, the machine is made to make arcs... and as long 
as the machine is protected by the thermal overload switch 
there is no problem.

When I arc-air, I use 400 amp machines. 550V three phase 
power. If carbon arcs damaged machines, I'd have a long 
trail of $5,000.00 machines behind me, eh?

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From: [email-masked] (Robert Galloway)
Date: 28 Jun 1996 09:33:39 -0600

An arc is an arc.  Where you can get into trouble is on the duty cycle.  
In stick welding, setup and rod changes will usually keep you within the 
duty cycle without paying any direct attention to it.  With a twin carbon 
arc it's pretty easy to go way beyond the duty cycle on a light duty 
welder.  You should pay attention to how long you let the arc run and 
then let the welder rest.

rhg

A $5,000 machine would be likely to have a 100% duty cycle.

---

From: [email-masked] (Andy Dingley)
Date: Fri, 28 Jun 1996 14:16:04 GMT

>A friend of mine told that making carbon arcs may damage an electric welder.

This has been a problem in the past, but it's not a biggie.

Many smaller arc welders are only rated for intermittent use. If
you're stick welding, you'll naturally tend to work in a rather
intermittent style. If you're using a carbon arc torch for brazing or
metal-bashing work, you might have the arc struck for a longer
continuous period and thus exceed the limits of the welder.

It used to be a problem with the first "domestic" arc welders in the
'70s, particularly that little round one on the UK market (whose brand
name I've forgotten). Nowadays they're better made and generally well
protected with thermal cutouts.

I'd not use a welder without some fan cooling. Surplus computer fans
are cheap & easily available - bolt a couple on the side and get some
cold air moving.