OT. Sparks

One of my sons called in, have you still got your arc welder only my mig is
no good for a job I need to do. So we went into my barn and moved a lot of
tat it was buried under, unplugged and un-used for at least 15 years I
pulled on the welding leads the the electrode holder fell onto the earth
clamp and a big spark arc'ed across it, I certainly made me jump. The
Welder is a 200 amp dry transformer arc welder the model name of is "Twicky"
I purchased it new about 1961.

Bill Burgoyne


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On Fri, 30 Mar 2012 11:45:53 +0100, "Bill Burgoyne"
wrote:

One of my sons called in, have you still got your arc welder only my mig is
no good for a job I need to do. So we went into my barn and moved a lot of
tat it was buried under, unplugged and un-used for at least 15 years I
pulled on the welding leads the the electrode holder fell onto the earth
clamp and a big spark arc'ed across it, I certainly made me jump. The
Welder is a 200 amp dry transformer arc welder the model name of is "Twicky"
I purchased it new about 1961.

I'd think that's a good sign. If unused for 15 years and it still
sparked, I'd think the winding insulation is in good condition,
especially if stored in the dry.
Given the guts of a simple arc welder are nothing more than a
transformer, I suppose some charge was held in the coil, but it's not
something I've noticed on any other arc welder.

In article ,
wrote:
Given the guts of a simple arc welder are nothing more than a
transformer, I suppose some charge was held in the coil, but it's not
something I've noticed on any other arc welder.

Sounds like exactly what's needed for electric cars - a 'battery' which
holds its charge for 15 years.

--
*The more I learn about women, the more I love my car

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

In article ,
wrote:
On Fri, 30 Mar 2012 11:45:53 +0100, "Bill Burgoyne"
wrote:

One of my sons called in, have you still got your arc welder only my
mig is no good for a job I need to do. So we went into my barn and
moved a lot of tat it was buried under, unplugged and un-used for at
least 15 years I pulled on the welding leads the the electrode holder
fell onto the earth clamp and a big spark arc'ed across it, I
certainly made me jump. The Welder is a 200 amp dry transformer arc
welder the model name of is "Twicky" I purchased it new about 1961.

I'd think that's a good sign. If unused for 15 years and it still
sparked, I'd think the winding insulation is in good condition,
especially if stored in the dry. Given the guts of a simple arc welder
are nothing more than a transformer, I suppose some charge was held in
the coil, but it's not something I've noticed on any other arc welder.


Afraid I don't know anything about arc welders. But a 'coil' doesn't hold a
'charge'.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Jim Lesurf wrote:
In article ,
wrote:
On Fri, 30 Mar 2012 11:45:53 +0100, "Bill Burgoyne"
wrote:

One of my sons called in, have you still got your arc welder only my
mig is no good for a job I need to do. So we went into my barn and
moved a lot of tat it was buried under, unplugged and un-used for at
least 15 years I pulled on the welding leads the the electrode holder
fell onto the earth clamp and a big spark arc'ed across it, I
certainly made me jump. The Welder is a 200 amp dry transformer arc
welder the model name of is "Twicky" I purchased it new about 1961.

I'd think that's a good sign. If unused for 15 years and it still
sparked, I'd think the winding insulation is in good condition,
especially if stored in the dry. Given the guts of a simple arc welder
are nothing more than a transformer, I suppose some charge was held in
the coil, but it's not something I've noticed on any other arc welder.


Afraid I don't know anything about arc welders. But a 'coil' doesn't hold a
'charge'.

Slainte,

Jim


That's what I was going to say but wasn't sure enough on my electronics to
be certain. ;-)

Tim

On Fri, 30 Mar 2012 17:13:07 +0100, Jim Lesurf
wrote:

Afraid I don't know anything about arc welders. But a 'coil' doesn't hold a
'charge'.

So a coil has no capacitance whatsoever?

On Sat, 31 Mar 2012 00:14:24 +0100,
wrote:

Afraid I don't know anything about arc welders. But a 'coil' doesn't hold a
'charge'.

So a coil has no capacitance whatsoever?

No, it has inductance.

In message , Paul Ratcliffe
writes
On Sat, 31 Mar 2012 00:14:24 +0100,
wrote:

Afraid I don't know anything about arc welders. But a 'coil' doesn't hold a
'charge'.

So a coil has no capacitance whatsoever?

No, it has inductance.

The coil - like any coil - will have capacitance - 'self capacitance'.
However, self-capacitance cannot hold a charge as any charge is acquires
will be almost immediately shorted out by the DC connectivity of the
winding. In this situation, any reference to it is absolutely and
totally irrelevant.
--
Ian

In article , Ian Jackson
wrote:
In message , Paul Ratcliffe
writes
On Sat, 31 Mar 2012 00:14:24 +0100,
wrote:

Afraid I don't know anything about arc welders. But a 'coil' doesn't
hold a 'charge'.

So a coil has no capacitance whatsoever?

No, it has inductance.

The coil - like any coil - will have capacitance - 'self capacitance'.
However, self-capacitance cannot hold a charge as any charge is acquires
will be almost immediately shorted out by the DC connectivity of the
winding. In this situation, any reference to it is absolutely and
totally irrelevant.

Yes.

There may also be some inter-winding capacitance between primary and
secondary. But again, that would be tiny, and it seems pretty unlikely to
be a way to store a high charge for any length of time. Particularly as it
would raise the question of how the charge got there in the first place.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Frankly this is a massive mystery. An arc welder is just a transformer
- there is nothing that can store a charge. The probe and the earth
clamp are connected together internally by the coil secondary.

To get a flash from the electrodes implies it must have been plugged
in. are you *sure* it wasn't?

The only explanation that tentatively comes to mind is if it's a DC
welder (as used for cast iron). I assume they have some kind of
rectification. If there were a capacitor across the DC output, then I
guess it could store a charge, although fifteen years is impressive.

Bill, we need you to take the case off and investigate. :-)

--
SteveT