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Rotaries and Neons new question (fwd)
----------
From: Mad Coiler [SMTP:tesla_coiler-at-hotmail-dot-com]
Sent: Monday, August 10, 1998 7:56 PM
To: tesla-at-pupman-dot-com
Subject: Re: Rotaries and Neons new question (fwd)
>---------- Forwarded message ----------
>Date: Fri, 7 Aug 98 11:36:51 EDT
>From: Gary Lau 07-Aug-1998 1059 <lau-at-hdecad.ENET.dec-dot-com>
>To: tesla-at-pupman-dot-com
>Subject: Re: Rotaries and Neons new question
>
>>From: Mad Coiler <tesla_coiler-at-hotmail-dot-com>
>>I really have no intention of using an asynch rotary on a NST but I
>>would like to learn as much as possible regardless. If you were using
a
>>rotary with an NST, and also kept the break rate at 240BPS minimum,
then
>>wouldnt that work? With atleast 240BPS you cant miss a gap firing on
>>each half cycle, right?
>
>Hi Tristan:
>
>You've fallen into the same trap as I once did.
>
>The problem is that while an RSG offers the opportunity to make 240
>connections per second, it will only make those connections if the cap
is
>sufficiently charged to break down the air gaps involved. The correct
>terminology is that it offers 240 gap PRESENTATIONS per second. It
does
>not guarantee that the cap will be discharged 240 times per second.
>
>Consider this contrived example. Maximum charging voltage of the xfmr
is
>10KV, 60 Hz. Ignore resonance. RSG is running 240 presentations per
>second (exactly two per half cycle), and gap breakdown voltage at each
>presentation is 7.1KV. If the phasing of the rotor is such that the
>presentations occur at 45, 135, 225, and 315 degrees of each cycle (90
>and 270 being the peaks), the gaps will never fire, since Vcap is
>10KV*sin(45)= 7.07KV at each presentation.
Yes, I did forget that it was really presentations per second and not
fully ensured of firing. But, I have found (atleast with my coils) that
the closer the contacts of the gaps the better performance. So, in my
case the firing voltage would be a few thousand volts at the most. Would
this not ensure that no matter what the voltage level of the capacitor,
it would be discharged regardless?
You could also choose a value of capcitance that would be able to be
charged in the shorter time. Howerver, I dont think that this would be
that beneficial, since you lose the extra energy of the larger
capacitor. But even though it may not be any better does it not go to
show that you could get higher break rates more safely with a NST?
Tristan Stewart
>This is obviously a contrived and worst-case example, but it
illustrates
>the fact that missed presentations will occur if they do not coincide
>with mains peaks.
>
>>And if you cap wasnt close to being resonant at
>>50/60Hz than it wouldnt charge to 'dangerously high' voltage levels?
You
>>could use half the matched capacitance and twice as high break rate
and
>>get the same average energy delivered into the primary?
>
>If you deliberately avoid mains resonance, you'll be OK as far as the
>dangerous voltage levels, but you'll only get a fraction of your NST's
>potential resonant-charging power.
>
>>Like I said I havent tried any of this - just wondering what the
flaws are
>>with my thinking.
>>
>>Tristan Stewart
>
>Regards,
>Gary Lau
>Waltham, MA USA
>
>
>
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