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RE: Power factor correction



Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>

I've heard (though I may be wrong) that the PF of a
Jacob's ladder isn't that bad, since it's a short
circuit.  Isn't PF a bigger issue for large but
lightly-loaded transformers, motors, etc.?  Now I'm
gonna have to go do a bunch of reading...damn!! :-))

The biggest problem I've observed with large Jacob's
ladders is the voltage spikes created every time the
arc breaks and returns to the bottom.  You need a big
cap in *parallel* with the transformer, or you can
damage your home wiring and any plugged-in electronic
devices pretty easily.  These spikes are also hard on
the transformer's insulation, but I've never heard of
a pig dying this way.  At 15kVA, my pig was generating
600V (peak) spikes every time the arc broke!  When I
saw that on the scope, I stopped playing with large
Jacob's ladders :-(

At 15kVA, my pig-based ladder didn't go "bzzzz" at
all.  It made a very warm 60Hz tone that you could
"feel".  The output was a pure white, totally opaque
flame.  This was 14.7kV at nearly an amp.  I'm
guessing the sound has a lot more to do with current
than voltage, but I could be wrong about that.  I'm
thinking that an x-ray tranny will be more "bzzzz",
but a much longer initial arc (probably won't stretch
much, though, due to low current).  I've been told,
however, that x-ray trannies tend to ofen have high
open-circuit voltages (above their rating), and that
running them full-bore in a Jacob's ladder-type setup
can cause them to flash over internally and croak.
Anybody want to confirm or deny that?  I have the
opportunity to pick up an x-ray tranny, but they've
always sounded a bit fragile to me.

Regards,
Aaron, N7OE

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "Dave Halliday" <dh@xxxxxxxxxxxxxx>
>
> He is not talking "modest"
>
> Your Jacobs Ladder makes a nice bzzzzzzrt,
> bzzzzzzrt, bzzzzzzrt sound
> (at 3,000 Watts) while I bet that his sounds like a
> large wolverine in
> heat. I have one from a 15KV 60MA (9,000 Watts) neon
> transformer that
> sounds wonderful and I can only imagine what
> something running at 34KW
> would be like.
>
>
>
>  > -----Original Message-----
>  > From: Tesla list [mailto:tesla@xxxxxxxxxx]
>  > Sent: Tuesday, June 20, 2006 8:37 PM
>  > To: tesla@xxxxxxxxxx
>  > Subject: Re: Power factor correction
>  >
>  >
>  > Original poster: Skip Malley
> <skip@xxxxxxxxxxxxxxx>
>  >
>  > Am I missing something?
>  >
>  > An ideal transformer for a modest Jacob's ladder
> is an oil burner
>  > transformer of the 10KV / 30mA type.  To do a
> Jacob's ladder thing,
>  > that is the best XFMR to use.  For that, there
> also is no need for
>  > ballasting.  An oil burner transformer is
> designed to produce a
>  > continuous spark.
>  >
>  > Any Jacob's ladder that I have made draws about 3
> amps from the 120V
>  > AC line with NO ballasting using an oil burner
> transformer.
>  >
>  > An X-Ray transformer is the wrong transformer for
> your application.
>  >
>  > Skip
>  >
>  > At 07:26 PM 6/19/2006, you wrote:
>  > >Original poster: "Mike"
> <mike.marcum@xxxxxxxxxxxx>
>  > >
>  > >I was making a Jacob's ladder with a
> dialed-down/ballasted x-ray
>  > >transformer (83v 41A in atm, limited by the 30A
> breaker and dry atm
>  > >'till I build a tank and vacuum it, ebay special
> so was shipped ups
>  > >dry to save shipping). Close to 38kV and 90 mA
> out (making a
>  > >mean-looking 12" arc). I wanted to power factor
> correct this so I
>  > >can pull more current without popping the
> breaker (or frying my 20A
>  > >variac). What I don't know is what the starting
> pf is without
>  > >measuring it (good pf DMM's I've seen are
> $250+). Most nst's use .5
>  > >as a rule of thumb for correcting those. Could
> this setup be
>  > >considered as a big nst? If so I think I need
> 1526uF that won't
>  > >change as the current/voltage go up as long as
> the ballast stays the
>  > >same (unless I goofed on the math somewhere).
>  > >
>  > >PS - The ballast is 2 E cores from old C & H
> sales 4500v
>  > >transformers with about 5 lbs 10awg and 2"
> spacers (draws like 8A at
>  > >83V with no gap) between them if that makes a
> difference.
>  > >
>  > >Mike
>  >
>  >
>  >
>  >
>  >
>
>
>