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RE: The Pain-Performance Barrier, was Secondary

Original poster: "Loudner, Godfrey by way of Terry Fritz <twftesla-at-uswest-dot-net>" <gloudner-at-SINTE.EDU>

Hello Christopher and All

The only kind of three phase x-ray power supply I know about consist of
three separate and identical single phase transformers with their high
voltage sides in a wye-connection. The output of the high side of each
transformer would be 150,000 volt divided by the square root of 3 = 86,603
volt. The current output of the high side of each transformer would be 1500
MA. This outfit is easier to construct than designing one transformer for
150,000 volt. The transformer you saw probably consisted of three
transformers, thereby making it funny looking. The voltage to the low side
of each transformer would be 480 volt or 277 volt (square root of 3 again)
respectively if their low sides are connected in a delta or a wye. There is
a point I must make. Suppose that the x-ray tube draws a 1500 MA load at a
potential of 150,000 volt. If one drove this system of transformers with no
load (open circuited), then the actual voltage output may be much in excess
of 150,000 volt. This aspect will depend upon the quality of the
transformer. When I was about 15 years of age, I had a 1000 lb single phase
transformer that was capable of 150,000 volt and 1000 MA. It was used to
burn a conductive path through a cement mixture, after which the cement was
cooked by high currents from a big bank of yard transformers. After seeing
me draw a nine foot power arc, my folks had a junkyard come and take it
away. I'll never see the likes of such a transformer again---once in a life
time find.

Godfrey Loudner

> -----Original Message-----
> From:	Tesla list [SMTP:tesla-at-pupman-dot-com]
> Sent:	Friday, May 11, 2001 5:35 PM
> To:	tesla-at-pupman-dot-com
> Subject:	The Pain-Performance Barrier, was Secondary
> Original poster: "Christopher Boden by way of Terry Fritz
> <twftesla-at-uswest-dot-net>" <chrisboden-at-hotmail-dot-com>
> >Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" 
> ><A123X-at-aol-dot-com>
> >
> >Do you put buy "something" from the geek group in every post?
> Whenever I can, yeah. The Group is growing up fast, we're expanding out 
> facility, our abilities, our membership, and out budget. We're also 
> expanding our bills.
> Because of our unique position in the Tesla Community I'm driven to do 
> everything I can to help as much as I can. Especially with one of the 
> hardest aspects to building a coil, equipment scrounging. Remember, the 
> mission of the Group is to make the subjects of science and technology 
> accessable to those with a sincere desire to learn. I spend a LOT of time 
> working on getting gear donated, or scrounged. Frequently we get things
> that 
> we can sell or donte to other Groups because either we have 400 of them
> and 
> only needed 8 (this happens regularly, I only triend to get 2 X-ray 
> transformers, I have 7 and counting) or we get something we can't use or 
> whatever.
> In the past year the Group has contributed signifigantly to the Coiling 
> community, and it's my hopes that we will increase this aspect of our 
> operations greatly, with the eventuall opening of the High Voltage Labs at
> Sigma-6 where members can come and work together to study hands on large 
> coils, and other HV, HE projects. I hope to make it possible to remove a
> LOT 
> of the myth and mystery of Tesla Coils, and some of Tesla's other work.
> I gotta build one of those Mark Twain tables :)
> At this moment the Group is the largest supplier of MMC caps out there, 
> we're selling as many as you need at great prices, in 2 sizes. We've also 
> got the Shirts, some HV gear (I'm the definitive packrat and won't sell 
> anything I think we'll EVER use), Custom street luges (summer's here!),
> and 
> some other goodies.
> What price
> >would like a 2KVA potential tranny cost?
> >
> Well, the shipping is gonna kill ya. Make me an offer (Off list), but 
> really, it's only a 1.5kVA PT, and that's kind of a pain. For a 1.5kVA
> power 
> supply, you can gang a few NST's and have a supply that
> s alreay current limited and not have to dink around with all that
> headache. 
> I think that for anyting under 10kVA it's not worth the trouble to use a
> PT 
> or a Pig. I was wondering what others thought on this. What is the point
> at 
> which an unballested transformer is too small to be worth the trouble? I
> say 
> 10kVA is the Pain-Performance Barrier.
> As an aside,
> The XRay place has a M A S S I V E Transformer. I don't know weather it's 
> continuous or X-Ray duty but I heard from the owner that it's 1500mA -at- 
> 150kV, and from the size of this thing I believe it could actually be 
> continuous. It's fed with 3Ph 480VAC. I know the math gets weird with 3Ph,
> what is the imput amerage for this beast? kVA?
> He says he already has a home for it (either that or he's afraid I'll kill
> the town with neutron emmisions), but he said I can have the next one he
> has 
> coming in in a few months, it's a duplicate to this one.
> I'll have to rent a truck to move it though, it's WELL over a ton.
> It's rather funny looking, I'll get some pics soon and hopefully get close
> enough to examine the makerplate.
> Have fun!
> Duck
> Christopher A. Boden Geek#1
> President / C.E.O. / Alpha Geek
> The Geek Group
> www.thegeekgroup-dot-org
> Because the Geek shall inherit the Earth!
> _________________________________________________________________
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