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Re: Re: T-24 Hours Until New (Really Bright 10KVA) Light...
I ran the pole pig just last night, not on my Tesla Coil, but just to
light it up in a Jacob's ladder. I was using only the 8-ohm element,
because I could not get ahold of my friend who had the arc welder. :) The
element got burning hot only after a second, and I wonder how long it would
last before meltdown. I didn't test it, but I suspect that there was quite
a voltage drop because the spark wasn't incredibly long, but it was many
times brighter and hotter than anything I had ever seen before. (500
milliamps) Hopefully tonight I'll have the welder. And oh yeah, I am
completely suffering with my capacitor. It is poorly constructed, ugly,
and underrated. It's made from MMC caps, but if anyone out has a ~.02µf -at-
20Kv or thereabout capacitor to sell, please let me know! :) And thanks
for all the information/help.
Ryan Ries
----------
> From: Tesla list <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: RE: Re: T-24 Hours Until New (Really Bright 10KVA) Light...
> Date: Friday, September 15, 2000 3:15 PM
>
> Original poster: "David Dean" <deano-at-corridor-dot-net>
>
> Hi Ryan,
>
> Actually it is not as simple as 240V/ 8 ohms = 30 amps. If you were only
> running resistive ballast, that would be true, insofar as if the output
of
> the pig were to be shorted, that is Vout = 0, taking the pig as an ideal
> transformer (which for all intents and purposes it is, or can be modeled
as,
> anyway) then Vin = 0 as well, so all the voltage drop would be across the
> resistor, and the maximum current would then be 30A at an angle of zero
> degrees. That is not to say that the 8 ohm resistance will absolutely
limit
> the current to 30 amps as a ballast for a TC power supply though.
Although
> it is very unlikely to happen, it is possible for there to be a
"kickback"
> which would put an aiding voltage across the input terminals of the
> transformer which would add to the supply voltage causing the current to
be
> higher. Of course if that were to happen, and it is very unlikely, it
would
> just be a spike which would at worst trip the circuit breaker. The
> probability of kickbacks is higher with inductive ballast than with
> resistive ballast, and more likely with a rotary spark gap than a static
> gap, and more likely with a non sync rotary than with a SRSG, and more
> likely with a coil that is out of tune than anything else, the other
factors
> are just incidental, in most cases. If you have safety gaps that are
> properly set, that will take care of the problem. But I digress...
>
> As I understand it, you are planning to power your existing coil, the
> veretus coil, right? And planning to use a blown static gap as well? I
don't
> recall what kind of capacitor you are using...The matched size stated on
> your website shows to be 26nf and the "needed to tune" size shows to be
> 19nf, so I assume something in that range. And you don't have a variac
large
> enough to handle 30A, do you? Putting all these assumptions together, I
> would suggest using the 8 ohm dryer element with a fan to cool it, and
leave
> the welder out to start with. I started with a furnace for a ballast, I
> pulled all the wires and could adjust the resistance from 50 ohms to
3.125
> by setting jumpers for series or parallel. (4 12.5 ohm elements) I found
the
> best results with 12.5 ohms using a 14.4 KV pig running off of 240VAC, an
> air blown static gap, and a 16nf rolled poly/aluminum flashing in oil
cap. I
> got 34" arcs to a grounded target with that setup. When I added the
welder,
> performance dropped considerably, I had to go down to 1.5 ohms, and the
> resister got hot. Amp draw was in the neighborhood of 22 amps, though
that
> was taken with an analog clamp on type ammeter, the needle jumps around a
> lot, so that is probably close to average. I found I could not run at all
> with the welder by itself, It wanted to thump and growl and the sparkgap
> fired erratically.
>
> After migrating to a SRSG, I found the 1.5 ohm resister was just barely
> getting warm, the amp draw dropped to 4.5 to 5 Amps, the needle on the
> ammeter was pretty steady, and spark length increased to 39". This of
course
> was using the welder, and I had changed to a MMC, still 16nf. I now don't
> use any resistance, just the welder, and sometimes some other inductors
in
> series to increase the inductance trying to get LTR operation. (I blew
out
> my 10nf lower voltage rating EMMC which was in parallel with the 16nf MMC
> when I got close to resonance in that configuration, but now I've got
some
> radar pulse caps, so all is well.)
>
> After experiencing the smooth, predictable, low power consuming, and
orders
> of magnitude quieter operation of a SRSG, I have given up on building an
> ASRSG, as I would not have anything else. Also, with the "variac to
adjust
> firing angle" trick now up my sleeve, operation of a SRSG is a cinch.
> Bottom line, I'm trying to sell you on a SRSG as your next project.
Should
> make that veretus coil go to 15' off of that dryer outlet, with a little
TLC
> and a reasonable size cap.
>
> Anyway, just my $0.02.
>
> later,
> deano
>
>
>
> > -----Original Message-----
> > From: Tesla list [mailto:tesla-at-pupman-dot-com]
> > Sent: Thursday, September 14, 2000 6:19 PM
> > To: tesla-at-pupman-dot-com
> > Subject: Re: Re: T-24 Hours Until New (Really Bright 10KVA) Light...
> >
> >
> > Original poster: "Ryan Ries" <spud-at-wf-dot-net>
> >
> > Why is 8 ohms too much? Is not as simple as 240v / 8ohms =
> > 30A? Or is it
> > just because of the extreme heat/power loss?
> >
> > Ryan Ries
> >
> > ----------
> > > From: Tesla list <tesla-at-pupman-dot-com>
> > > To: tesla-at-pupman-dot-com
> > > Subject: Re: T-24 Hours Until New (Really Bright 10KVA) Light...
> > > Date: Thursday, September 14, 2000 12:53 PM
> > >
> > > Original poster: Esondrmn-at-aol-dot-com
> > >
> > > In a message dated 9/12/00 9:47:02 PM Pacific Daylight Time,
> > tesla-at-pupman-dot-com
> > > writes:
> > >
> > > <<
> > > My 10KVA pig has been sitting very patiently in the garage
awaiting
> > its
> > > moment of glory. We have almost finished wiring up the big
extension
> > cord
> > > that is to be run from the big 240v dryer outlet. Very
> > convenient since
> > > that is only about 10 feet from where the transformer will be. We
have
> > a
> > > great arc welder to work with for ballasting, but I also went to the
> > local
> > > junkyard and ripped an element from a dryer. With my DMM, it
measures
> > > about 8 ohms. Does that sound right? I hope so, because I like the
> > idea
> > > of my coil running at a cool 30 amps. :-) Also, I imagine that that
> > > element is bound to get VERY hot. What do ya'll suggest to keep it
> > cool?
> > > >>
> > > Ryan,
> > >
> > > 8 ohms of resistance in series with the inductive ballast is a bit
too
> > much.
> > > You want somewhere in the range of .5 to 2.5 ohms. I used to use an
> > array of
> > > about 7 oven elements wired so I could switch in only one or all 7 of
> > them in
> > > parallel. I now use fixed resistors. I use a large fan blowing on
the
> > > resistors to help get rid of some of the heat - and yes, they
> > do get real
> > hot.
> > >
> > > Ed Sonderman
> > >
> > >
> > >
> >
> >
> >
>
>
>