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Re: Greg's Ballast problem.



Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bigfoo39-at-telocity-dot-com>

Tesla list wrote:

>Original poster: "Gregory Peters by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <s371034-at-student.uq.edu.au>
>
>Hello all,
>
>I believe that with the welder leads open circuit, practically NO 
>urrent should flow. I did some tests, described in the email below. I 
>have read agreeable results in the archives. I feel that Greg 
>Hunter's welder may have a minor internal fault. The previous owner 
>said he could never weld well with it. I think maybe his welder has a 
>minor short somewhere or something, which is decreasing the primary 
>impedance, allowing unusually large current flow with the leads open 
>circuit. Here is the email:
>
snipperzz...

using any type of iron cored transformer without the secondary side 
"loaded" will have some current draw depending on its size and the 
primary.  The current draw results from the magnitization of the core ( 
making it as an inductor). When 2 " inductors" ( transformers) are 
seriesed ( as in the welder/ pig configuration) the curcuit will see 2 
cores to magnitize ...thus a bit more current will be drawn ...

Once the pig has a reflected load ( its hi volt side shorted) there is 
even more of a current load ...  but basically limited by the missing 
reflected load from the welder ( which at this point is acting as just 
an inductor which can in some cases reduce current flow to almost 
nothing OR allow a few amps to energize the piggie)   the absolute 
minimum my welder would produce was 8 A when used with my pigggie.

Add the load to the welder ( short its secondary side)  and the 
inductance changes dramatically ... thus allowing much larger currents 
to reach the piggie.  ( mine would go to 50 A (( untill it melted the 
primary on the welder)).

Sooo...   depending on the size and make of the welder, current flow is 
possible with the welder secondary open ...


Scot D