Dr Resonance,
I have a 8" coil with a retired NST farm and air blown gap. I plan to run
async with a 14400v 5kva GE instrument transformer. I assuming at those
break rates the Cap value must be keep small enough to reach a reasonable
charge level. This is no 25KVA transformer like you use! Please explain how
your gaps are connected. I have seen it but don't remember.
This same async gap will be used on my DC powered 12" coil at 28kv. I don't
know the KVA yet though it will be running on three phase. I have 12 1.5" x
.5" pure tungsten electrodes for the rotor which is 5/8 18" G10. The motor
is a variable speed Permanent Magnet type DC using PWM control though I have
several other motors if the velocity electronics fail.
Thanks,
Jim Mora
-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Saturday, March 03, 2007 9:23 PM
To: tesla@xxxxxxxxxx
Subject: Re: non sync rotary.....
Original poster: "resonance" <resonance@xxxxxxxxxxxx>
If you are running a pole xmfr, a design I use a lot is:
3450 rpm 3/4 hp 10 electrodes on 18 inch dia. G-10 phenolic, 17
inch electrode to electrode spacing, 4 main spark gaps (two each side
of the wheel). This gives 575 pulses/sec which "grows" very long
sparks. Electrodes are 1/2 inch dia screw in tungsten/molydenum
alloy, axial feedthru is 1/2 x 1 1/2 inch dia solid brass rod.
500-600 pps works very well with asynch rsg and pole xmfr.
Dave --- Contact me off-list and I can email you photos.
Dr. Resonance
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Saturday, March 03, 2007 2:42 PM
Subject: Re: non sync rotary.....
>Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>
>
>Hi David, all,
>
>I have experienced this situation with an async RSG, where
>the output would get erratic to the point that the "kickbacks"
>would damage and/or destroy nearby electrical equipment.
>Let me explain. In the async RSGs that I have built, if I tried
>to run it with 4 stationary electrodes (2 pair of 2 w/ each pair
>set 180 degrees apart from the other), it would run extrem-
>ly erratically, to the point that the output was not at all "useful".
>It would also damage or destroy electrical equipment in the
>vacinity. I smoked the 1kV, 50 amp rated FWB that I was
>using to rectify the 120 VAC to DC for my DC rotary gap
>motor in this manner! Once I bypassed the second pair of sta-
>tionary electrodes and operated with just one set, this problem
>completely disappeared. And before you say it, it did not matter
>how close I set the gap presentations in the 2 stationary elec-
>trode pair setup and once I bypassed the secondary set of
>stationary electrodes, I could operate with the single stationary
>electrode pair with over 3/8" total gap spacing with no misfires.
>At the power levels that I run, I need some "extra" gaps to help
>in heat dissipation, so I finally built a seriesed segmented, air-
>cooled, 3-gap "RQ" style of stationary gap out of (4) 1" x 5"
>copper tubes, each with 2 appropriately sized copper splicer
>tubes soldered over them, to increase the wall thickness and
>thermal mass. I simply run this in series with my main RSG to
>assist in heat dissipation and quenching and don't have the
>erratic misfiring, as long as I keep the sum total gap width to
>reasonable levels. I have posted this issue to the considerable
>pooled knowledge of this list before but no one could seem to
>satisfactorily explain my dilemma. Also, I once had a SYNC
>rotary gap assembly that did have the 2 pairs of stationary
>electrodes set at 180 degrees apart from the disc and it worked
>fine w/out a hitch, assuming proper gap spacing. It's just the
>async rotary gaps that I have never been able to get to run right
>with 2 pairs of stationary electrodes.? Anyone like to try to tackle
>this one again?
>
>David Rieben
>
>PS: The power supply was a 14,400 volt pig, either 10 or 15 kVA
>in all of the above situations.
>
>----- Original Message -----
>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: <tesla@xxxxxxxxxx>
>Sent: Friday, March 02, 2007 9:59 PM
>Subject: non sync rotary.....
>
>
> > Original poster: "david baehr" <dfb25@xxxxxxxxxxx>
> >
> > Have ya ever had a coil that just wouldnt run right with a rotary,
> > but runs great with a static gap ?
> > I built an eight point Async rotary for my Lil' 4"
> > coil, ive messed with gap spacings , speed, and ballast
> > adjustments,...the result is erratic operation and low spark otput...
> >
> > years ago, I built a gap for my 8" coil,.....it worked great,
> > and, I could switch between static and rotary with no coil adjustment
> >
> > not sure whats going on,...hey, static gaps are cool, right ? :-)
> >
> >
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>
>