My 25 kVA 14.4 kV 120/240 pig was liberated with a chainsaw and ropes. The only thing it cost me was an upgrade chip from a dude that had a truck, and an old 486.
________________________________
From: David Rieben <drieben@xxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sunday, August 31, 2014 4:02 PM
Subject: Re: [TCML] NIST High Voltage Laboratory Testing / Safety Reference
Hi,
Not trying to still Adam's thunder here at all, as I'm sure that he will want to address these questions since it was directed to his previous post. I was going to comment on your question #1, though, about "the cost of such a transformer" from my personal experience. Just a few months ago, I happened to locate such a 25 kVA, 14.4 kV rated "pole pig" transformer on ebay that was listed for $0.99, with no reserve. After actually calling the seller (he had listed his personal phone number on the ebay listing for any further inquiries) and asking him how soon he would require a personal pick up from the winning bidder, I just through a $50 bid on it not really expecting to win the auction, as I didn't really need another pole pig. However, only one other bidder placed two "low-ball" bids of $15 and then $25, so at the auction's end, I was the proud owner of a like new 25 kVA polemount transformer for $26! It was a pretty long round trip of around 16 hours
to pick it up in my p/u truck but well worth it, considering that even with my gas-guzzling heavy duty rated V-8 truck, I still have <$250 invested into this beast. At 400 lbs, that's just 62.5 cents / pound ;^)
The bottom line is that it will probably take some persistence and patience to find one at a deal like this and it be within a day's drive, but it can happen. There are transformers like this all the time on ebay, but typically they have opening bids or "buy-it-nows" of $750 and up, not including freight S&H. It may take you a bit of time searching but if you are patient, you can probably get one much cheaper. You could also try your local electrical utility company or maybe a local scrap metal recycler, or simply a request to this list for someone willing to sell one of theirs.
David
On Sunday, August 31, 2014 12:50 PM, "rd_parker@xxxxxxxx" <rd_parker@xxxxxxxx> wrote:
A couple of questions if I may: 1 - what would be the cost of a
transformer such as you are displaying, and 2) what is the expected
voltage generated and the voltage input? I am new to this 'hobby'.
Thanks,
Bob in Bellflower.
On Fri, 22 Aug 2014 18:42:41 -0700 Yurtle Turtle via Tesla
<tesla@xxxxxxxxxx> writes:
>
http://s1050.photobucket.com/user/yurtleturtle/media/Untitled.png.html?so
rt=3&o=0
>
> This is my work in progress. I haven't updated it in quite some
> time. I think the only thing that's missing is the dedicated 100 amp
> breaker, and the line filters. It's probably not what I would have
> done from scratch, as it has evolved. Anyway, suggestions/comments
>
are welcome.
>
>
>
> ________________________________
> From: David Sharpe <sparktron01@xxxxxxxxx>
> To: Tesla Coil Mail List <tesla@xxxxxxxxxx>
> Sent: Wednesday, August 20, 2014 7:09 AM
> Subject: [TCML] NIST High Voltage Laboratory Testing / Safety
> Reference
>
>
> Truly excellent reference for use when designing
> medium or high voltage equipment or performing HV lab work,
> from NIST. This document was referenced in a recent
> EDN e-blog. The great thing about this document is it
> is succinct, brief (9 pages), specific, and to the point.
>
> http://www.nist.gov/el/isd/mmc/upload/high_voltage_rules_revised.pdf
>
> One recommendation is the requirement of having "2"
> separate operations to turn on high voltage; this requires
> at a minimum a Main Disconnect (Lockable Safety Switch)
> and a start-stop push-button station with seal in contactor.
> This requirement supports my contention you should never
> "instant on" high voltage equipment. YMMV, but I've seen
> catastrophic, spectacular failures doing this.
>
> The additional requirements of a RTZ (Return to Zero) interlock,
> on all HV equipment is very interesting, and I'd bet less then
> 5% of the amateur Tesla Coil HV equipment built worldwide
> has that feature. But RTZ could save your life, and possibly
> infrastructure too. I am designing a solid state power controller
> with integral ballasting and
current limit regulation (240V/100A)
> utilizing AC Chopper technology that I have decided to incorporate
> this feature into the design. An additional requirement is a
> flashing red beacon with the presence of High Voltage (if it
> doesn't interfere with testing). If the SG is not firing, you have
> no outward indication that there is high voltage present, which
> could
> have very dangerous consequences.
>
> I hope this document is useful to the Tesla Community
>
> Best Regards
>
>
> --
> Dave Sharpe, TCBOR/HEAS
> Chesterfield, VA USA
>
> Sharpe's Axiom of Murphy's Law
> "Physics trumps opinion!"
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>
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