Re: Converting to "Pig Power"

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Bart Anderson <classi6-at-classictesla-dot-com> 

Randy, Ed,

Tesla list wrote:

>Original poster: "Randy & Lori" <rburney6-at-comcast-dot-net>
>Ed, and list
>
>The reason given by Dr. Resonance for grounding one of the HV terminals 
>(and I liked the idea) was to put the bottom of the secondary and the 
>center of the primary at the same potential. Also this configuration would 
>leave me with only one HV line to run.

Exactly. That's how I run these days. I have a 2-bushing pig and simply tie 
1 bushing to RF and run the other to the coil. The inside of the primary is 
at the same potential as the bottom of the secondary (RF ground). Without 
that, there is "some" potential difference between the two coils. I'm not 
sure there is a great deal of difference that might force pri to sec 
arcing, but I liked the idea of knowing the beginning of the inner primary 
is at RF ground. David Rieben is the one that turned me on to this about 2 
years ago. I also like less mess with cables.

>My coil is currently tuned, and unless someone had a reason to not just 
>shoot the power to it; then that was the plan.

Agree with Ed here. It is certainly better to control the both voltage and 
current then to just throw a switch. Hopefully, you can find a suitable 
variac for the purpose.

>120 instead of 240 first certainly. Don't get me wrong, I would very much 
>like to ramp it up slow, but I'm not sure that my Variac is quite large 
>enough to deal with 30+ amps.

I don't remember if you described your ballasting scheme (please forgive if 
you already posted it), but with an adjustable inductance, you can limit 
the current down to well below 30+ amps.

>If anyone can tell me how to figure out the current ratting of my variac, 
>I would appreciate it(it came without an ID plate). I like the idea of 
>bringing it back down slow as well, rather than just opening the contacts 
>on the relay.

Maybe you can post some winding dimensions, wire size, core dimensions, 
etc.. and we can probably tell you the current rating. BTW, I'm also one of 
those that cut the core in a perfectly good Powerstat 28A variac which I 
use for a ballast. Why? Simply because I only had this variac available at 
the time and knew I would be running well over from time to time. If this 
variac would have been in the 40 or 50 A range, I would not have cut it. I 
also use an identical variac for the voltage control (this one of course is 
not cut - just a normal variac in normal voltage adjusting application).

Take care,
Bart



>So far I have:
>2 get more caps
>2 put a variac on it
>1 filter ok
>1 get a bigger filter
>
>Anybody else have any suggestions? Like I said, it would be kind of stupid 
>of me not to ask.
>
>Randy
>-----Original Message-----
>From: Tesla list [mailto:tesla-at-pupman-dot-com]
>Sent: Wednesday, March 10, 2004 7:07 PM
>To: tesla-at-pupman-dot-com
>Subject: Re: Converting to "Pig Power"
>
>Original poster: Esondrmn-at-aol-dot-com
>
>In a message dated 3/9/04 11:55:40 AM Pacific Standard Time,
>tesla-at-pupman-dot-com writes:
>
>
> >Original poster: "Randy & Lori" <rburney6-at-comcast-dot-net>
> >
> >The pig is due in this week(14.4 10 KVA), and being as intelligent as I am,
> >I thought I would run my setup past the list. The secondary is 6.25� X
> >24.5� with 26 gauge. The Tank cap is 2 strings of 10 942Cs for a 
> total of
> >.03 uF. I am currently tapped on the primary at about 12 turns (out of
> >23). I�m not sure just what the modified 15/30 is putting out (half the
>e
> >shunts removed). The gap is currently a sucker gap (vacuum through ¾�
> >copper pipe).
> >
> >I plan to ground one HV terminal of the pig to the case, center of the
> >primary, bottom of the secondary and of course earth ground, as recommended
> >by Dr. Resonance. I have a 30 Amp line filter, the 500� roll of Home
>e
> >Depot special for some current limiting.
> >
> >My concerns: If the 500� roll is to hold me to about 30 Amps, is the line
>e
> >filter too small?
> >Will the sucker gap give any kind of acceptable performance (or will it
> >just �Power Arc�)?
>)?
> >Do I need more capacitors (to spread the wealth)?
> >I read (one place only) that a pig doesn�t need any PFC???
>?
> >
> >I�m not asking for someone to do all of my math for me; just give some
>e
> >suggestions from your personal experience. I just feel that throwing power
> >to a pig for the fist time without running my setup past the list would be
> >a little stupid and arrogant on my part.
> >
> >Randy
>
>
>Randy,
>
>I have a two bushing 5 kva pole transformer and just leave both bushings
>and the primary floating - i.e. not connected to ground. Why do you want
>to ground one HV output and the primary?
>
>Are you really going to just throw full power to the coil? Or do you have
>a variac to ramp the voltage up nice and slow? If you don't have a variac,
>I would at least only apply one half power to the pig. Like using 120
>volts in instead of 220. You want to make sure it is all going to work
>before just slamming full power to it. You could also add some resistive
>ballast in series with the pig primary, like oven heating elements,
>electric heaters, etc.
>
>Will two strings of mmc caps in parallel be enough to handle the high tank
>currents? My opinion is no. I think you need four strings in
>parallel. Someone more knowledgeable than I should provide input on this.
>
>I am also not real familiar with the sucker gap. I could not get a copper
>segment pipe gap to quench and had to go to a rotary.
>
>I use a 30 amp line filter and regularly run 30 to 35 amps through it.
>
>Ed Sonderman
>
>
>