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Re: Avalon
Chris, list,
<snip>
> > 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.
<snip>
As someone with a bit of experience with mechanical design, I'd like to
throw a few comments out there regarding the ARSG (I don't think there's any
argument about the type...). I'd also like to appologize if my inexperience
with TCs causes an obviously incorrect assumption ;-)
I've noticed several things about the big TC's spark gaps (mainly the 13M
and Electrum). First, 13M uses a sync, and Electrum uses Async. Second,
the 13M uses a pressurized (~30psi of Sulfur Hexaflouride) two-break system
with electrodes on a 24" Diameter circle. Electrum uses a series 8 break
system running at STP in the open air with a 28" diameter electrode circle.
The 13M uses a 10HP 3phase motor. Electrum uses a 15HP 3 phase motor with a
variable frequency speed adjustment (a standard approach to vary the speed
of an AC motor).
Question: why use so many breaks? The spark gap is supposed to be one of
the main sources of loss in the primary system.
Ok, on to Avalon. I don't think that mounting the tungsten electrodes
axially on a disk (similar to Electrum) is a good idea: if a set screw
isn't tight enough, or loosens over time, you have a catostrophic failure.
If memory serves correct, a 5 kg electrode would have about 750kJ of energy
at 3600RPM on a 24" diameter disk! I think that electrodes should be
mounted through the disk near the periphery. I have a little experience
with large DC motors (1000+HP!!), and they are HUGE compared to an AC motor
with the same torque and HP ratings.
Use fewer disks: only one or two. Use Aluminum or titanium (MUCH stronger,
and expensive, but won't "creep" like aluminum will) disks if a design like
Electrum's is to be used. Otherwise, a G-10, or something similar.
Use a high torque 3phase AC motor, with a variable frequency controller to
adjust speed, torque, and HP. I have a little experience with large DC
motors, and they are HUGE compared to an AC motor with the same torque and
HP ratings.
In my mind, use a system like Electrum's. However, use only two G10 disks,
each with 4 tungsten carbide electrodes mounted through the disk on a 24"
center-to-center diameter with a total of 4 series breaks. Design it to run
at some unGodly high speed (~7200RPM) using a 25HP, ultra-high torque 3Phase
motor. Standard high-speed bearings could be used (American Roller Bearing
or Timken). Mounting horizontally or vertically is something to be
investigated.
I know that's pretty fast, but a well designed, well balanced rotor system
will be able to handle the speed.
Please comment....
Mark