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
> >
> >
> >
> >
> >
>
>
>