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Re: [TCML] Effects of SRSG Dwell Time on Coil Performance



Hi Gary,
of course I meant a cog belt ;) But if you only have access to 1500rpm motors, this would be a good possibility to achive 3000rpm.

Stefan

----- Original Message ----- From: "Gary Lau" <glau1024@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, September 27, 2010 2:09 PM
Subject: Re: [TCML] Effects of SRSG Dwell Time on Coil Performance


I have only ever used a 3600RPM motor in both a propeller and small
disk-based SRSG, but I haven't had any balance issues. Granted the disk was
relatively small (6" x .09" thk).

If the gap is to be synchronous, then using a belt drive is a bad idea,
unless it is a cog belt that won't slip, but that's just adding an
additional layer of complexity and offers no advantage as far as balance,
economy, or simplicity.

Regards, Gary Lau
MA, USA

On Mon, Sep 27, 2010 at 7:28 AM, Teslalabor <teslalabor@xxxxxxxxxxx> wrote:

Hi John,
thank you for that explanation. I think I will have to try this. Just
replace the 3000rpm motor by 1500rpm, adding another 2 rotating electrodes
and see what happens. If there is no re-firing, the main advantage of
1500rpm I can see is, that the mechanical balancing of the rotating disk or
the propeller in propellerdesign-gaps, is much easier done. BTW, another
idea is to use a 1500rpm motor in combination with a gearmeachanism or
simply a belt drive with a gear ratio 1:2 to achive 3000rpm. Think this
might work well.

Stefan

----- Original Message ----- From: "Futuret" <futuret@xxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, September 26, 2010 5:46 PM
Subject: Re: [TCML] Effects of SRSG Dwell Time on Coil Performance


Stefan,

That's a good question.  A faster mechanical dwell time is generally
better.
There's an old myth that fast dwell time gives faster gap quenching.  In
reality
the quench-time depends more on output spark streamer loading. But if the
mechanical dwell time is too long, a condition called "re-firing" of the
spark gap can occur, which results in very inefficient operation.  This
re-firing occurs when the capacitor is able to recharge to a sufficient
voltage to permit the cap to fire again while the electrodes are still
aligned
from the previous firing.  Many factors determine whether a gap will
re-fire such as; low rotary rpm, small rotary disc diameter, small
capacitor size,
wide electrode diameter, narrow electrode gap spacing, etc.  Usually
re-firing is
not a problem until the factors mentioned reach an extreme, or combine
to the extreme.

Generally speaking, the faster 3000 rpm is preferable to the 1500 rpm.
That said, you'll usually see no difference in performance either way.
The 300 rpm might give a little more of a swirling air effect, and slightly
help the quenching that way.  Fast quenching is preferable, if it can
be achieved without increasing gap resistive losses.

Cheers,
John





-----Original Message-----
From: Teslalabor <teslalabor@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Sun, Sep 26, 2010 9:50 am
Subject: [TCML] Effects of SRSG Dwell Time on Coil Performance


Hi List,
I allready have built some nice SRSG's with very good results. All of my
SRSG's run with 200BPS. They use 2 rotating and 4 stationary electrodes.
They run with 3000rpm Motors (50Hz here in Germany).
I also own many 1500rpm sync.motors. So the question is:

Let's say, there is some TC system with given parameters. It runs with
200BPS.
Can somebody tell me, which effects in performance result in the different
dwell times, when using a 3000rpm Motor with 2 rotating and 4 stationary
electrodes OR use a 1500rpm Motor with 4 rotating and 4 stationary
electrodes?
In both cases there are 200BPS but the dwell time is different!

Greets
Stefan



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