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Re: New static gap and vacuum motor
Tesla List wrote:
>
> Original Poster: Esondrmn-at-aol-dot-com
>
> I posted the following message last week - and received no responses. I am
> thinking about going with 8 gaps of .050" each for a total of .400". I plan
> to mount the gap sections on 7" square pieces of bakelite, cutting about 1/8"
> slots between the gap sections. Then complete the box so It will be air
> tight and mount the vacuum motor on top of the box over a 4" hole. There
> will be 5 copper pipe sections on one side of the box and 5 more on the side
> opposite, all connected in series. I will probably need to use 1.25" dia
> copper pipe to make this fit. They will be about 5.0" long. Any comments
> from those who have made these type of gaps?
It is my experience, that "one" will not get enough cooling with only
the airflow possible btwn the emitting surface of the gap. Too much
airflow here will degrade gap performance. Better cooling can be
acheived by a design, that blows both trough the tubes lengthwise, _and_
draws _some_ air trough the arc channels.
But then I only ran my (was it) 30 section series gap for about a couple
of hours before giving up on the idea, and moving on to sync RSG
operation.
Which is a revelation.
>
> Steve Date was kind enough to send me a vacuum motor the other day. I had
> been planning to rebuild one of my RQ cylindrical gaps to use on my 6" coil
> powered by a 14.4 kv pole transformer running at about 7 kva. The
> modification was planned to seal off the bottom, cut slots in the sides
> between the gaps and install the vacuum motor on the top. Then I realized I
> only have 6 gaps each about .028" wide for a total gap width of about .170".
> I think this will severely limit the maximum voltage the caps (.05 ufd
> Condenser Products) can charge to and result in much less power in the
> primary than I have been running with my async rotary. My question for the
> group is - how wide of a gap do you think I can use and not overvoltage my
> C.P. caps rated at 20 kv (in Tesla coil operation). I found an old
> correspondence from C.P. where they state "the capacitor is designed for
> maximum of 34 kv peak, including safety". W.I. Mason, the President,
> suggested at the time that I use a maximum of 3/8" to limit the voltage to
> 31 kv max.
>
> I would like some suggestions on this. Should I go with his suggestion and
> design for 3/8" total gap? Like 6 gaps of .0625"?
The final breakdown voltage of the gap will be largely unpredictable,
since it depends on the geometry of the electrodes. You should set the
safety gaps (separately, out of the circuit) so that they fire at the
voltage you want to limit the system to. Then tap in progressively more
and more main gaps, untill the safety`s start to fire.
In my (medium power : ~5kW) static gap time, I had 30 gaps in series,
and got the best results with 16 thou in each gap, for a total of 480
thou. or 1/2 inch.
My 1 cent
cheers, Finn Hammer
(wondering why you don`t just sync-mod the motor, and take controll of
what is happening)
>
> Thanks, Ed Sonderman