RE: [TCML] Pig Ballasting...

["Phil Tuck" <phil@xxxxxxxxxxx>]

Wind your own as Dave advises, - if you can find suitably sized cores. 
It's all right saying "a certain sized coil of wire of 'x' number of turns
works ok, bit it always gets hot/warm", but that heat is wasted power that
could be in the coil. For every volt dropped before the pig primary, it will
mean 45 or more volts less in the secondary HV output.
Here is a link to winding one http://www.hvtesla.com/pig.html with a video
(section is half way down the page,"A Replacement Ballast") I find this gets
no noticanly warmer after a 30 amp run.

Phil


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf
Of Travis Tabbal
Sent: 28 October 2012 19:44
To: Tesla Coil Mailing List
Subject: Re: [TCML] Pig Ballasting...

Good thoughts, but how does one locate scrapped transformers? Seems like a
rather speciality type item.
On Oct 27, 2012 6:28 PM, "drieben" <drieben@xxxxxxx> wrote:

> Travis,
>
> If you could get your hands on an scrapped out decent sized
> transformer, say like 10 kVA, and wind your own windings
> on it, this would tend to minimize the eddy current heating,
> as transformer cores are specifically designed to minimize
> this.
>
> I ended up getting the core from a scrapped out x-ray
> transformer to build mine. This core was is two "C's"
> and I had to install some no-ferrous spacers between the
> two "C" halves to get the desired current control. With
> no spacing, there was not enough current flow, even into
> dead short. With too much spacing, the current would
> go too high, so I placed an AC clamp-on ammeter on
> it and kept adjusting the spacing until I got the desired
> current flow into a dead short. Seems like I ended up
> with about 3/8" spacing to get the current flow that I
> wanted (around 100 amps for me ;^).  I wound each
> "leg" of one of the "C's" with about 110 turns of #6
> THNN copper cable and ran them in parallel. IIRC,
> the core cross section is about 11 square inches and
> this makes for a very robust ballast that's never gotten
> even noticably warmer than ambient temperature through
> all of my abuse ;^)
>
> Maybe this will give you some ideas,
> David
>
> ----- Original Message ----- From: "Travis Tabbal" <travis@xxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Sent: Saturday, October 27, 2012 9:50 AM
> Subject: Re: [TCML] Pig Ballasting...
>
>
>  Thanks for the info Joe. I was wondering what you got for current when
>> running as an air core.? I saw one post last night where someone just
used
>> the spool of wire as it came from Home Depot and it didn't get too hot. I
>> seem to recall the current being about 20 amps. I'm tempted to try it
just
>> to see what it does.
>> On Oct 27, 2012 7:53 AM, "Joe Mastroianni" <joe@xxxxxxxxxxxxxx> wrote:
>>
>>
>>> I did what you are suggesting, only I used 500' of 10GA.   I made a
spool
>>> out of 2" PVC with some flat polycarbonate scraps glued on the ends (but
>>> not blocking the interior hole of the PVC) to hold on the wire.   The
>>> spool
>>> is about 18" long. Took quite a bit of muscle to wind.
>>>
>>> I experimented with different configurations for the core.  I had a
>>> couple
>>> 8' rods of aluminum and steel that I cut up into 2" sections.  Generally
>>> speaking the forces want to pull the rods into the core, not visa versa.
>>>  If you do the math you see it doesn't matter which way the current is
>>> flowing in the solenoid, so it doesn't matter that it's AC, then,
either.
>>>
>>> The real issue you face is heating of the core materials.  My pig is
only
>>> rated at 5KVA so I rarely pushed it above 10.  And in any case at 6kVA I
>>> was getting ground strikes so I didn't feel the need for much more.  I
>>> was
>>> measuring the input V and I to the variac, as well as the output, and
>>> shoving things into and out of the ballast core to get reasonable
levels.
>>> But those interior rods got really hot, probably because I just threw
>>> them
>>> in there, but also probably because the eddies in some of the materials
>>> were severe.
>>>
>>> And the core would stay hot for a long time.  I never melted through the
>>> PVC, but I was close.   I'm not sure the best way to cool it down as I
>>> switched to DR coils and didn't experiment much more with that.
>>>
>>> Cheers,
>>> Joe
>>>
>>>
>>> On Oct 26, 2012, at 10:27 AM, Travis Tabbal wrote:
>>>
>>> > I've seen a number of options in the archive. I was just wanting to
get
>>> > input on what I wanted to try to make sure I'm not off the deep end
>>> > somewhere before I mess with it. Piggy is 14.4kV 10kVA.
>>> >
>>> > I was thinking of getting a 500' spool of AWG12 THHN wire from Home >
>>> Depot
>>> > or similar and winding it around a 2" PVC or similar tube, about 1.5ft
>>> > winding length. Then getting some ferrous wire from there as well,
>>> perhaps
>>> > something like the little yard flags or something from the fencing
>>> > department for the core. I'd pot the core material inside a smaller >
>>> tube,
>>> > even just as a mandrel, with epoxy or similar (Bondo?). With a
threaded
>>> rod
>>> > at the top of the potting for adjustment. Then just build a frame to >
>>> hold
>>> > it together while in operation, seems like the cycling of the magnetic
>>> > field from the 60Hz AC might want to push the core out otherwise?
>>>
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