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Re: PIRANHA SISG coil details...
Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
Hi Gerry,
At 01:12 AM 10/3/2006, you wrote:
Hi Terry,
Have you computed a Freau Factor for Piranha??
Gerry R.
No. Let me explain why...
The coil's BPS is rather chaotic and very sensitive to the exact
input voltage. It can jump around from 60BPS to 360 BPS rather
easily. The input power also can jump "very wildly" about depending
on just the "exact" variac setting. At low BPS, the Freau number is
"good" but the streamers are shorter at low input power. At high BPS
the input power nears 1kW and the streamers are longer but not by a
drastic amount so the Freau number is "bad".
It is sort of an odd thing this topology does... So my answer is the
Freau number can very easily cover a range from say 1.4 to 2.5. 1.4
may not sound good, but that is where the arcs are longest and at say
10 amps current draw. Is it sort of a don't care... But if you
don't mind shorter arcs, that Freau number can be pretty high. Just
imagine charging the cap from a very low impedance voltage source
where just "one" volt difference can change the BPS from 100 to
1000... With higher BPS, the spark length gets better but the power
is 10X!! I am not sure if there is a "world's Record" for Freau
factor, but this coils certainly would have "sweat spots" that get
real close. It would have "bad spots" too that would push for the
lowest record ;-))
So I sort of violate having a "fixed" "wallplug watts" the Freau
equation requires and I really can't control that with any
meaning... All I can say is with a single MOT at about 900W,
~~360BPS, it will do 45 inch arcs. At 120 BPS it might go down to 38
inches but the power is maybe 300W... Higher BPS also shows
significantly better leader growth which really throws everything
like that off further... I just assume the coil "knows what its
doing" ;-)) It "works fine!!" ;-)) Very little power that goes in
is "waisted" ;-)
BTW = The power factor I mentioned in the document is wrong. It is
hard to pin down, but I think this is fairly realistic. It is sort
of a "single point", but a typical one, so that's where I ran the
model (~215 BPS).
AC Line Voltage 106.1 Vac
AC Line Current 9.6 Arms
Real Input Power 890 W
Power Factor 0.92
I might try to figure out a way to add some randomness to MicroSim's
streamer load to be more realistic. The computer model is "too
perfect" really. Some random function might "smooth" the computer
model's data out so it would not be so sensitive to tiny parameter
variations...
Cheers,
Terry