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I obtained a pole pig

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Shaun

Thu May 15 2008, 01:46AM

Registered Member #690 Joined: Tue May 08 2007, 03:47AM
Location: New Jersey, USA
Posts: 616

Those transformers you linked to make a pole pig look like a 2n3055-driven flyback...
Seriously good luck with it teslacoolguy, hoping to see a bigass SGTC come of it.

J. Aaron Holmes

Thu May 15 2008, 03:30AM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Quantum Singularity wrote ...

Only downside is it is single pole.

Downside? Nahh... Not to get too OT, but many pig coilers, myself included, prefer the single-bushing types. Or if they get a two-bushing type, they'll tie one HV lead to the can, thereby making it (effectively) a single-bushing pig. Just remove the neutral-to-can connection (if it exists), then wire the pig can to the inner turn of the primary, the base of the secondary, and on to your RF ground. Yup, you tie all that stuff together. Simplifies wiring and puts the primary and secondary coils at the same potential where they're the closest, thereby reducing the chances of primary-to-secondary flashovers. D.C. Cox and many other well-known coilers have recommended this arrangement for years. See TCML for abundant discussion on the matter.

Some very HV two-bushing pigs are not meant to have one HV lead tied to the can, but most ordinary 7.2- and 14.4kV units are, since they're designed to work either Y- or delta-connected. If you live in an area served by Y three-phase distribution lines, you'll see two-bushing pigs up there all the time with one HV lead just tied to the can. They're just a little more expensive because of the second bushing, so single-bushing types are preferred where possible.

Ok, probably drilled a little too far into that!!

Cheers,
Aaron, N7OE

teslacoolguy

Thu May 15 2008, 04:17AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

Im kinda glad that i was able to get a 2 bushing pig now that you said this and i do not connect the one hv lead to the can.

flannelhead

Thu May 15 2008, 12:47PM

Registered Member #952 Joined: Mon Aug 13 2007, 11:07AM
Location: Finland
Posts: 388

One thing that confuses me with pole pigs is that even when they're run with multiple kilowatts of power, the arcs seem very thin (compared to a resonant MOT stack, for example), but I assume they are very high current because they can be stretched so far. Do you have any better explanation on why pole pigs have so thin arcs?

J. Aaron Holmes

Thu May 15 2008, 01:31PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

teslacoolguy wrote ...

Im kinda glad that i was able to get a 2 bushing pig now that you said this and i do not connect the one hv lead to the can.

There's definitely nothing wrong with the two-bushing type. I just bought one myself. My point was that the single-bushing types are not "bad" like people once thought. In fact, single-bushing (or grounded bushing) arrangements make Tesla coiling easier. The false impression that single-bushing pigs were "bad" prevailed 3+ years ago, and caused many people to avoid getting the single-bushing kind.

Dr. 2N3055 wrote ...

One thing that confuses me with pole pigs is that even when they're run with multiple kilowatts of power, the arcs seem very thin (compared to a resonant MOT stack, for example), but I assume they are very high current because they can be stretched so far. Do you have any better explanation on why pole pigs have so thin arcs?

It's the amps. Takes a lot more power to get amps at 14+kV than at 2kV, obviously

Check out some pictures of large (25kVA+) pig-powered Jacob's ladders and you'll see that pig arcs can be the same opaque white flames as MOT arcs given enough juice.

Cheers,
Aaron, N7OE

lpfthings

Thu May 15 2008, 09:38PM

Registered Member #1361 Joined: Thu Feb 28 2008, 10:57AM
Location: Cairns, Australia
Posts: 305

lol at school they have one of those pad-mounted substations out front. Sometimes i walk around it abit, it emits a nice 50hz hummm, though seeing vids on youtube of these things blowing up isn't to comforting. I dont think my parents would let me get more power than a NST, having a pig in the house would be fun though.In Australia, since we dont have all those tornado's and huge hail and icestorms, the transformers arent replaced often, as there is no need, so you wont find em laying around here. The substations are self contained things, i doubt there is anyone in there, i have seen a few pigs in those, but no way im going in there

Quantum Singularity

Fri May 16 2008, 01:18AM

Registered Member #158 Joined: Sun Feb 12 2006, 09:53PM
Location: Central Ohio
Posts: 282

Depends on how much power your letting them take... when I had my pig setup for max power on a big jacobs ladder at max current draw I was pegging a 100A clamp on meter (on the 240VAC side) so output was probably around 20KVA or more? The arc was pretty serious and bigger around than my forearm. Not thin at all. Never used a MOT myself yet, so dont know much about them, but probably just a lot easier for folks to get higher current out of the outputs.

J.A. Holmes... yeah it might not be a big deal, back when I got it (late 90's) folks were kinda worried about the case floating or whatever, arcing over, etc. It is a 20kV unit, 10kVA, single pole with 240V low side. Here it is when I got it

teslacoolguy

Mon May 19 2008, 03:56PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

I had my pig ballasted with 1 mot pulling around 13 amps and the are was almost the size of my thumb so i dont think that is considered small at all. Then again im sure the air temprature and humidity might have something to do with it also.

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