RE: Pig inrush limiting

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Cameron B. Prince" <cplists@xxxxxxxxxxxxxxxxx>

Hi Tom,

In my experience, resistive ballasting is a good thing when used in
combination with inductive ballast as it makes my coil run smoother. But
normally about 0.8 - 2.0 ohms is the best range with 5 - 10 mH of
inductance. If you've got a spool of 6 or 8 AWG wire, that might work or you
could use a transformer from a welder.

7 ohms of purely resistive ballast is probably going to result in more
energy being wasted in heat than will be used to drive the transformer.

Good luck,
Cameron

> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: Thursday, October 19, 2006 10:19 PM
> To: tesla@xxxxxxxxxx
> Subject: Re: Pig inrush limiting
>
> Original poster: "Thomas Coyle" <zxcasd@xxxxxxxxx>
>
> Thanks, Jim - all great questions. I'll get all the answers tomorrow
> when I finish unearthing everything.
>
> Oh - and I am using the 1/2" copper for the ladder - this also came
> in the package when I bought this whole suite of toys from a retiring
> coiler, so I know it was working for him at one point! The only shame
> is that I can't get the 9-foot-tall VDG that I also bought from him
> hooked up - it's too tall for my garage when fully assembled and the
> discharge terminal alone weighs 200 pounds (he homemade it from
> fiberglass and aluminum tape) so I can't just put it on and take it
> off easily to run it outside - it's been amazingly dry lately, so I'm
> sure I could have had some fun with that. Oh well.
>
> On 10/19/06, Tesla list <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> wrote:
> Original poster: "Jim Mora" <<mailto:jmora@xxxxxxxxxxx>jmora@xxxxxxxxxxx>
>
> Thomas,
>
> Ramping up the voltage is a good thing as you could bring it to the max
> before the breaker trips. Otherwise you're inviting inrush. I ran my Pig
> (much smaller) at 50amps. That's when the flames gets knurly to use CA
> speak. Be sure to use posts that won't melt, I had 3/8 steel. I think
> others
> use hard type 1/2" copper tubing.
>
> Someone else may want to discuss ballasting a 25KVA... out of my present
> league. Too bad someone just bought my 20KVA saturable reactor. You say
> "one
> of" your big variacs. If its heavy enough, run the other one in series on
> the down hill side of you voltage variac so you can control current and
> voltage. Just be sure to Mains ground the variac cases. What are the
> variacs
> rated at? Also what Size wire is in you dryer jack?
>
> Hmm I was asking this not long ago...
>
> Big Flames,
> Jim Mora
>
> -----Original Message-----
> From: Tesla list [mailto: tesla@xxxxxxxxxx]
> Sent: Thursday, October 19, 2006 6:18 PM
> To: <mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx
> Subject: Pig inrush limiting
>
> Original poster: "Thomas Coyle" <<mailto:zxcasd@xxxxxxxxx>
> zxcasd@xxxxxxxxx>
>
> Well, I got some of my stuff out of storage including my 25kVA pig, a
> resistive ballast (pair of large heating elements that measure out to
> about 7 ohms), and various other odds and ends. I saw this pig in
> operation before I bought it a year or so ago, and then immediately
> stuck it into storage. Now I want to fire it up with just a jacob's
> ladder to see if it still works (and because I've never done a JL on
> anything except an NST), but I'm concerned about the inrush draw on
> such a monster.
>
> If my math is right, that resistive limiter should keep the pig to
> under 20 amps, and I'm planning to plug it into my 30 amp dryer
> outlet in the garage. So, presumably no problem. But - can I get away
> with just plugging it in with the circuit breaker off, and then
> turning on the breaker? Or should I stick one of my big variacs in
> between and ramp up the voltage slowly?
>
> In short, what can I do to get pretty sparks without blowing
> breakers, melting my pig, or killing myself?
>
> I'm getting the rest of my Big Coil parts out of storage tomorrow, so
> if this thing works I'm going to try to throw it back together this
> weekend.
>
> Thanks!
>
> Tom
>
>