Re: More on oil-cooled welders and 4 mm rods

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Re: More on oil-cooled welders and 4 mm rods Tim Leech 10-11-2006
Posted by Tim Leech on October 11, 2006, 5:11 am
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 On 11 Oct 2006 01:52:50 -0700, "david.sanderson@bem.fki-et.com"


>>From a quick poke at
>http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
>assuming your welder is 50V and 180A -> 9Kw power (might not be
>correct, but reasonable guess?) then for 40M run you should be using
>10mm sq cable, and that would give a 3% voltage drop. With 2.5mm you
>can probably only pull about 3Kw?
>
>
>

It won't be 50V and 180A at the same time, the 50V is open-circuit,
the 180A is pretty much short-circuit. It might be as much as 6KW.

>
>Try an old/cheap cooker hood, (possibly with charcoal filters). Not as
>effective aas a real welding extractor, but certainly an improvement. I
>use one for OA welding extraction (not as much smoke, but lots of
>soot...)
>
Sounds like a good idea.

Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

Posted by david.sanderson@bem.fki-et.com on October 11, 2006, 7:34 am
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Tim Leech wrote:
> On 11 Oct 2006 01:52:50 -0700, "david.sanderson@bem.fki-et.com"
>
>
> >>From a quick poke at
> >http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
> >assuming your welder is 50V and 180A -> 9Kw power (might not be
> >correct, but reasonable guess?) then for 40M run you should be using
> >10mm sq cable, and that would give a 3% voltage drop. With 2.5mm you
> >can probably only pull about 3Kw?
> >
> >
> >
>
> It won't be 50V and 180A at the same time, the 50V is open-circuit,
> the 180A is pretty much short-circuit. It might be as much as 6KW.
>

Hmm, yes of course... back to school for me
Dave


Posted by Andrew Mawson on October 11, 2006, 11:48 am
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> On 11 Oct 2006 01:52:50 -0700, "david.sanderson@bem.fki-et.com"
>
>
> >>From a quick poke at
> >http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
> >assuming your welder is 50V and 180A -> 9Kw power (might not be
> >correct, but reasonable guess?) then for 40M run you should be
using
> >10mm sq cable, and that would give a 3% voltage drop. With 2.5mm
you
> >can probably only pull about 3Kw?
> >
> >
> >
>
> It won't be 50V and 180A at the same time, the 50V is open-circuit,
> the 180A is pretty much short-circuit. It might be as much as 6KW.
>
> >
> >Try an old/cheap cooker hood, (possibly with charcoal filters). Not
as
> >effective aas a real welding extractor, but certainly an
improvement. I
> >use one for OA welding extraction (not as much smoke, but lots of
> >soot...)
> >
> Sounds like a good idea.
>
> Tim
>
> Dutton Dry-Dock
> Traditional & Modern canal craft repairs
> Vintage diesel engine service

Arc voltages when welding are remarkably constant at about 20-25 v

AWEM



Posted by Mark Rand on October 11, 2006, 12:19 pm
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On Wed, 11 Oct 2006 16:48:01 +0100, "Andrew Mawson"

>
>> On 11 Oct 2006 01:52:50 -0700, "david.sanderson@bem.fki-et.com"
>>
>>
>> >>From a quick poke at
>> >http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
>> >assuming your welder is 50V and 180A -> 9Kw power (might not be
>> >correct, but reasonable guess?) then for 40M run you should be
>using
>> >10mm sq cable, and that would give a 3% voltage drop. With 2.5mm
>you
>> >can probably only pull about 3Kw?
>> >
>> >
>> >
>>
>> It won't be 50V and 180A at the same time, the 50V is open-circuit,
>> the 180A is pretty much short-circuit. It might be as much as 6KW.
>>
>> >
>> >Try an old/cheap cooker hood, (possibly with charcoal filters). Not
>as
>> >effective aas a real welding extractor, but certainly an
>improvement. I
>> >use one for OA welding extraction (not as much smoke, but lots of
>> >soot...)
>> >
>> Sounds like a good idea.
>>
>> Tim
>>
>> Dutton Dry-Dock
>> Traditional & Modern canal craft repairs
>> Vintage diesel engine service
>
>Arc voltages when welding are remarkably constant at about 20-25 v
>
>AWEM
>


A significant point is that the voltage drop between the 50V or 80V open
circuit voltage and the 20-25V arc voltage occurs in the separate choke or
built in leakage reactance of the welder. so although it might only be pulling
3kW, it could well be pulling 9kVA. transformer Welders have _nasty_ power
factors.

Mark Rand
RTFM

Posted by Tim Leech on October 12, 2006, 2:28 am
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On Wed, 11 Oct 2006 17:19:17 +0100, Mark Rand


>
>A significant point is that the voltage drop between the 50V or 80V open
>circuit voltage and the 20-25V arc voltage occurs in the separate choke or
>built in leakage reactance of the welder. so although it might only be pulling
>3kW, it could well be pulling 9kVA. transformer Welders have _nasty_ power
>factors.
>
Power factor correction capacitors used to be available as an option
for Oxford style sets, maybe they still are, but I've only ever seen
one with them fitted.
Presumably inverter type welding sets can have a better power factor,
and so in theory would do better on the end of a long cable than a
straight transformer type?

Cheers
Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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