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Re: Avalon



Hi Chris,

My "meat" is interspersed.

> Original Poster: "Christopher Boden" <chrisboden-at-hotmail-dot-com>

> 1. Should the system be AC or DC? Why?

For a coil THIS size, I would go for DC. Why? Two reasons:
You can run three phase power, which means less current
draw per phase (smaller wiring, more practical, "easier" to
fuse AND switch properly). Secondly, you can run an ASRSG,
by which means you can control the power, which you feed
the coil, by varying the breakrate. Power control =>> easy
=>> ;o)). Finding diodes that will handle your power might be
a problem, I donīt know. Of course, you will need to design
a charging reactor to limit the inrush current (cap and diode
death).

> 3. Primary type? (I am thinking interior helical like Electrum, but is
>here a better way?) I would like to be able to change tuneing
>without too much hassle.

For this kind of power, I donīt think you NEED a helical coil.
A flat one would be more than adequate. Donīt know why
Greg went for the helical coil. I would do tuning off axis. I.e.:
a big tuning coil (easy to build) during building. After you have
the final setup, make a "fitting" primary with small adjustment
possibilities. I wouldnīt worry about "ease" too much. Once
you are set, you wonīt be changing it much anyway.

> 5. Power source? I am thinking 200 - 250 kVA from a large
>pig, or pig array,  powered from 240 or 480 at high amperages.

A single phase pig with 250kVA running on 240v would be (I
think) a hard-to-find item and it would be crazy. At 250kVA and
240V you would need at LEAST 1300 amps supply. This is for
a cos phi of 0.8, which I doubt transformers in that class can
achieve. Go for 3 phase 660V setup. Much lower amperage
per phase and much easier to handle. You can run your ASRSG
on 3 phase, too. A 3 phase power frequency converter could
be used to change the rotating speed (induction motor) of the
gap. Plan on using a 25-30 hp motor for that gap and DESIGN
it well. The G-forces on a the big (necessary) disk are almost
unimaginably high. Take material growth (due to heat) into
account.

> 6. Control system?

Very little bells and whistles. Multiple safety circuits, including
temperature monitoring, etc. Amps, volts, speed control,
interlock relays, DUAL (!!) SAFETY KEY. Best bet would be
to use dual operator control, i.e.: make it IMPOSSIBLE to fire
the coil alone. Remember you WANT (actually your life WILL
depend on it) total control, NOT good looks. The ahhs and oohs
should come from a working coil, NOT a cool-looking control
cabinet that takes a half an hour to find the off switch.

> 8 Gap type? I like the Electrum gap best as far as design,
> I am thnking of  something similar. 10 Gap series rotary?

ASRSG, number of gaps would depend on processing power.

> I would like to have the maximum amount of flexibility in operation of
>the coil. Variable tuning, single shot modes, variable spark gap
>speed...etc. I would like to have an ASync spark gap that we can
>lock on with a tach or computer control to be sync. This isn;t just
>for pretty, I would like it to be a research tool to better the state
>of the art in Tesla Coil design.

Most of this can be included in the control cabinet. I would build
the control unit, so that you can fire in a "sure mode". Make a
secondary cabinet, with add-ons, which can be plugged into the
primary control circuit to add these variables. Do NOT build all
of it into one cabinet. The main control cabinet MUST be neat and
anyone should be able to find the important controls in the worst
case FAST. Make your control cabinet, so that you MUST switch
off lights manually, but they automatically come back on, once
power is cut OR a failure occurs.

> 9. Cap type and size? Or should I call the Corona Bottleing
>company....lol > :) just kidding.

Theoretically, you could build an MMC. I would go for the MMC
technique, but use Maxwell, etc caps instead of MCs. The name
for this would be MBPCA ;o)) (Multiple Big Pulse Cap Array). If
you plan on building beer bottle caps, you had better BUY a
brewery AND a company that recycles old glass (parts) ;o)))
Sorry, but I just couldnīt resist that one. Maxwell could custom
design a cap (array) for you. Aerovox is another company,
which I have found to be VERY helpfull and informative.

More thoughts: run your lights from a two DIFFERENT supply
sources. (not counting the TC power input). There is nothing worse
than HV and darkness ;o((((. Plan an emergency exit and post it so
that ALL can see and find their way out. Make an automated fire
extinguisher system around all power parts (xformer, rsg, cap,
etc). Install some turbo fans that can exhaust fumes, etc.  fast, if it
should ever be necessary. There is nothing worse than bad
publicity. Make a HEAVY (twice the necessary size) duty grounding
system. This will require a lot of earth work.  Be prepared to see
around 1.5-2kA (!!!) peak current in your grounding path. You DONīT
want that to go astray. Place the xformer, the caps and the RSG
in shatter proof "containers". If any of these blow, you want to
contain the hazard to one area and not have it spread around.

BTW: Thanks for putting me in the league with the big dawgs. I donīt
think I deserve that ;o)) I DO have some knowledge on coils. Some
of which has been "calculated and tested", the rest is based on not
so scientific methods (like trial and error ;o)). However, I have NO
experience with coils anywhere as large as you are planning. Most
likely, I wont be able to make it, due to lack of money and the fact
that I am training into a new job field (very limited time; even for my
own hobbies). However, I can provide assistance per e-mail or
phone, if that is of any help. I would try to make it over on the *BIG*
day, of course ;o)) My phone number is 049 for Germany, 6425 (area
code) and 8210075 (actual number).

If any of the coilers on this list ever come over to Germany, they
are (of course!!)  more than welcome to come over and stay a
few days (weeks, etc ;o)). It would be most enjoyable ;o))

Coiler greets from Germany,
Reinhard