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RE: an interesting mechanical engineering problem

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Hi DC,

Wow, is this to be driven by a semi sized generator?

Just a thought, since 4" tubing has a surface area of ~12", could you use 6"
wide flat copper stock and bolt it together? I'm not sure what the surface
depth is but use a thickness that suits.

The joints could be shaved on the end of each length to keep the windings
symmetrical. It seems to me such an assembly wouldn't be too hard to put up
and tear down, and the curvature could be cut to serve the transport needs.
Just a thought. Let the brain storming begin :-))

I sure want to see this marvel!

Jim Mora

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Sunday, January 07, 2007 8:44 PM
To: tesla@xxxxxxxxxx
Subject: an interesting mechanical engineering problem

Original poster: "D.C. Cox" <resonance@xxxxxxxxxxxx>

I'm presently in the process of designing the "world's largest
portable Tesla transformer".  It will be a 60 ft tall unit x 7 ft.
dia sec coil, running as a DRSSTC,  160 kW continuous input, crowned
with a 8 ft dia. toroid and above that, a 20 ft dia toroid.  Our
present design target, using 24 pcs of PowerEx 2400 Amp, 1700 Volt
IGBTs, all carefully linked together in a low inductance
configuration, with 3 inch wide x 1/4 inch thick copper plate
(H-bridge with 6 of these massive IGBTs on each corner).
Planned buss voltage is 800 VDC.  Solid state control of the 440
Volt, 3 phase, 400 Amp inputs with very large SCRs --- similar to the
smaller control system we are developing for our dual MOT coil with 7
- 7.5 ft long sparks running off a 120 VAC circuit.

Pri cap, with res. freq of 10 kHz, works out to 6 uF, 10 kV Maxwell
pulse cap, with a 3.1 turn pri (thanks again to Bart's great JAVATC

The base will be 26 ft in dia. and can be disassembled for
transport.  The sec coil is going to have the winding, 31,000 ft of #
6 AWG wire, glassed inside after winding.  This unit is 7 ft in dia
and 44 ft long, but still transportable on a lowboy truck.

The primary is 3.1 turns, tapped, with a total of 3.5 turns.  Our
original design was to use 4 inch copper tubing to form the pri, but
this is where the problem is coming into play.  If we build a 26 ft
dia coil, 3 turns, of 4 inch dia copper tubing, how do we disassemble
the beast for transport.?

So far, a few ideas we are tossing around:

1) Use 1/4 turn sections of the copper tubing and link each 1/4 turn
section together with massive copper blocks, 5 x 5 inches square x 6
inches long.  Butt the primary 1/4 turn sections together and use a
lot of brass setscrews to firmly capture the 1/4 turn sections in the
brass blocks.  I'm worried the resistance might become an issue with
nearly 12 "copper connectors" joining the pieces together.  I would
like to use he large 4 inch copper tubing but it seems joining them
together might be a problem, and trying to haul it assembled just
will not work as the height would be too much for interstate bridges
and city streets with cross-wires, etc.

2) It's not possible to use 2-3 inch dia. copper cable as the weight
would be too high for assembly handling.

3) Perhaps use 1 inch dia copper cable and then wind 4 of these 1
inch dia. lengths in parallel to form the 3.5 turn primary.  Handling
1 inch dia. copper cable should not be too much of a problem for a
crew working with a small crane (which we will have onsite to erect
the sec coil and attach the large toroids). With this idea, I
probably would join the 4 cables together every 1/4 turn with some
solid machined copper clamps to insure even current distribution in
the primary.

I know there are some great thinkers on this list and a few good
machinists, so ideas please!!   We are open to consider every idea
and try to adopt the one we think will work best.

Best regards,

Dr. Resonance
Resonance Research Corp.