[TCML] Re:Pros and Cons

[uhvsystems@xxxxxxxx]

Steve,

Thanks for the explanation of DRSSTC tuning.I was wondering...
Good news is that we will not have to construct DRSSTC which fullfils our requirements.Yesterday,I talked to Mayer and ,in mere 10 min of a coffee break,we found the solution to the problem of tesla coil primary circuit :-)Looking back it is kind of funny that what I disliked the most now turns out to be the best option.
We are going to use 8 IGBT modules arranged in 2 paralleled stacks in series connected 4 IGBTs.Mayer knows pretty much everything of the safe driving of such configurations (with or wihout auxillary circuits).He designed 12 MVA AC/DC step-down transformerless converter for powering 3000 VDC railway network where HVIGBTs were connected in series stacks.
Thus,only 1.8 uF charged to about 14000 V will be enough to enable primary energy of about 180 J.Obtained benefits  are clear.Primary impedance and inductance increase,tesla coil efficiency increases,peak IGBT current drops below 1900 A,tuning by varying primary inductance becomes possible.The only downside we will need to get 4 more CM 600HB-90H modules (relatively acceptable).

I am not convinced I get your question about load and oil.Are you curious about E-field control techniques and electrostatic grading structures,or you are asking what we have in plan to test?
Regarding 800 kV and 25 feet discharges I must say I can hardly believe this. 25 feet is aproximately 8 meters.

And you're correct,we will need to retune to compensate.
 
Regards,

Fez Zaev



       


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Tuning DRSSTCs:
Most all tesla coils are 4th order systems.  This means that there are 2
esonant peaks due to the coupling of the 2 resonant circuits.  The DRSSTC
an excite the system at a lower or higher frequency than the natural
esonance, which means that 1 resonant peak (or "pole") is excited more than
he other.  This produces primary currents that never notch back down to 0A
ue to energy transfer to the secondary coil (there may be just a partial
otch in primary current).  In some instances of spark production, it can be
seful to detune the primary coil to a lower resonant frequency than the
econdary coil (i could explain why, but its getting off subject).
For your case, you are NOT trying to pump more energy into a spark, so you
ould not want to detune the system as mentioned.  You would exploit the
lassical and well-behaved ideal of tuning both primary and secondary LC's
o be the same Fo.  In this case, i see absolutely no reason why a "DRSSTC
s more sensitive".  Im not sure i understand that comment anyway, but
erhaps what was meant was that "DRSSTCs can work with different tunings".
Another question about your load... How will you suppress sparks from
orming?  Is the load completely under oil?  Or are all the radii something
uch larger than say 10"?  Last time i checked, 800kV is about the order of
ome very large tesla coils that hurl sparks in the 15-25 foot range (though
ot on a single-shot basis).  Also, given the extra capacitance of your
oad, im assuming you will need to re-tune to compensate?
Steve
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