Re: 10kva pole pig needed with 29kv primary

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Gerry,

>From what I gathered, Scot is running his pigs in a "piggy-back"
configuration - the second pig's input is riding on the 14.4 kV
output of the first one, leaving the "zero-volt" side of the second
pig "floating" at 14.4 kV, just as I suggested in my first posting
on this thread. That would definitely account for the corona
'hissing" coming from inside the pig. BTW, Scot also mentioned
that he took the guts of (2) 14.4 kV pigs and placed them both
in one pig tank. That would make for one really stuffed and heavy
piggie ;^) and would also explain the tight internal clearances for
the ~30 kV. If wired as you're suggesting, then each pig would
indeed only see its rated 14.4 kV in relation to ground and there
would be little if any internal "hissing" ;^)

BTW, Scot, if you're following this, you stated in your previous
post that your double 10 kV pig was good for 30 kV at 10 kVA.
Wouldn't the (2) 10 kVA pigs now be good for 20 kVA? They
would put out twice the voltage as one pig with the same amper-
age if in series.

David Rieben

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Friday, October 20, 2006 2:17 PM
Subject: Re: 10kva pole pig needed with 29kv primary


> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Scot,
>
> I seems like one could ground one of the bushings for each of the two
> PIGs and connect the two chassis to ground.  If one phased the LV of
> the two PIGs correctly, you would have +14400V output from one PIG
> and -14400V from the other PIG and then connect them in series so you
> have 28800V across the two bushings but any one PIG would only see
> 14400V.  Is this the case where you experienced corona sizzling
> inside the case.  I thought that grounding one of the bushings of a
> two bushing PIG was an OK thing to do so I'm not clear on the need to
> "triple the insulation between the trannies and the case.
>
> Gerry R.
>
>
> >Original poster: BunnyKiller <bunnikillr@xxxxxxx>
> >
> >looks like Bellsouth doesnt like alot of  traffic....   thats why I
> >dropped them and went to Cox Cable...  but anyway..
> >
> >yes I seriesed  2 14.4KV piggies for 28.8 KV and when driven by the
> >variacs can obtain a little over 30KV  but at 10KVA ( both piggies
> >are rated for 10KVA)
> >
> >when seriesed transformers are applied ( considering both are
> >equally made) you get additive voltage but the amperage remains
> >equal.  If paralleled, you get the opposite...  same voltage but
> >additive amperage.
> >
> >If one plans on placing two piggies in series, you NEED to triple
> >insulate the trannies from the case very well...  seems that the
> >clearances from the case walls and the trannies is minimal for the
> >original voltage set. Dont throw away any of the "paper" insulative
> >material found in the case and consider procuring even more, you
> >will need as much as you can use. Pay attention to the way the
> >trannies are originally set up when you open the case... draw a
> >schematic of how it was connected. Also another thing to watch for
> >is the "polarity" of the transformers output, its the same as in NST
> >or MOT applications when going series.
> >
> >as far as connections, I paralled the "primary" ( input) side of the
> >coil and seriesed the "secondary" ( output) side.
> >
> >Even tho I have a bundle of insulation in my piggie, at the higher
> >input voltages ( when the output is getting into the 29KV plus) you
> >can hear "corona sizzle" in the case. I also ground the case to a
> >dedicated ground rod just in case something breaks down....
> >
> >Scot D
> >
> >
> >
> >
> >Tesla list wrote:
> >
> >>Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
> >>
> >>Hi Jim,
> >>
> >>Yes, you could do exactly that ;^) Or, if you have at least
> >>one of the pig trannies with 2 HV bushings, or "horns", you
> >>could "float" one at 14,400 volts and "piggy-back" it on the
> >>other one's output for additive voltage. Of course, you'd
> >>at least want the pig that's floating at 14.4 kV to be a 2 HV
> >>bushinged unit, as the outer tank of a pig floating at 14.4 kV,
> >>relative to ground, would be an electrocution waiting to hap-
> >>pen ;^0 The pigs' BIL rating should allow for piggy-backing
> >>of the HV output of one pig on another, though. I think Scot
> >>"Bunnykiller" Dingman uses 2 seriesed 14.4 kV pigs for up
> >>to ~30 kV input for his big coil's primary circuit. He discusses
> >>this on his website. http://bellsouthpwp.net/B/u/BunnyKiller/bigpig.html
> >>
> >>David Rieben
> >
> >
> >
> >
>
>
>
>