Re: SRSG break rate

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>" <vanyo-at-echoes-dot-net>

After reading Steve's original question, I'm still confused by the
answer.  I never gave it much thought before, but his question (or
rather the lack of an answer that I can grasp) has me puzzled.  Suppose
one break is at a positive peak.  Now, after that break, there is
positive voltage for a quarter cycle, then negative for a quarter cycle,
then the next break at the negative peak.  Won't the positive and
negative 1/4 cycles cancel each other out, as far as charge delivered to
the cap, before the next break?  It seems if you were to use 120bps (for
60hz), or one break per half cycle, you would want the breaks to be at
the 0 voltage points.  This way, between breaks, you have either all
positive or all negative voltage, getting as much charge to the cap as
possible.

Of course, I'm new at this, and either:
a) I don't know what the heck I'm talking about, or
b) Everybody already knew this.

I'm interested, because I'm thinking of going to rotary (synchronous,
with NST's), and I want to get it right.

BTW, is the voltage/current at the secondary of my NST's in phase with
the mains?  If not, is it always out of phase by the same degree?  I'm
just trying to get a handle on how to adjust the phase of a synchronous
rotary gap, without fancy equipment I don't have (like oscilloscopes). 
I don't want to fry my NST's.  If I use the fluorescent-light-as-strobe
technique, the light will flicker in phase to the mains - hopefully the
same as the phase of the NST's high voltage side.

	-  Bill Vanyo

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<FutureT-at-aol-dot-com>
> 
> In a message dated 6/21/01 10:00:27 AM Eastern Daylight Time,
> tesla-at-pupman-dot-com writes:
> 
> > Original poster: "Steve White by way of Terry Fritz <twftesla-at-qwest-dot-net>" <
> > slwhite-at-zeus.ia-dot-net>
> 
> Steve,
> 
> There are two peaks in a full sine wave.  One positive peak and one
> negative peak.  100 or 120 bps operation takes advantage of these
> peaks.  But the main benefit of 100 or 120 bps is not this, but
> rather the way that the sparks grow in the air over successive
> bangs.  For a given amount of energy in the caps over time, 120
> seems to be more efficient at producing long sparks from the work
> I've done.  I found about a 20% benefit from using 120 bps over 240 bps.
> 
>   http://hometown.aol-dot-com/futuret/page3.html        (click on theory)
> 
> Cheers,
> John
> 
> >
> >  I have been following the posts on SRSG break rates. Some people seem to
> > think
> >  100 BPS (50 HZ) or 120 BPS (60 HZ) is best. It seems to me that 200 BPS
> (50
> > HZ)
> >  or 240 BPS (60 HZ) would be optimum. Here is why I think this. If you
> > examine a
> >  single cycle of sine wave, there are 4 positions of maximum charging for a
> >  capacitor. During the first 1/4 cycle (starting at 0 degrees), the cap
> would
> >  reach its peak charge at about the 90 degree point of the sine wave. At
> this
> >  point the cap should be discharged. Continuing to charge the cap past 90
> >  degrees without discharge would not charge the cap any further because the
> >  voltage is now decreasing towards 0 at the 180 degree point. After
> > discharging
> >  at the 90 degree point, the charge cycle can begin again at the peak
> voltage
> >  and continue charging until the 180 degree point is reached. At this
> point,
> > the
> >  cap should again be discharged because after the 180 degree point, the
> > voltage
> >  will go negative and the cap will not reach any higher charge. 2 more
> > discharge
> >  points can be identified for the negative voltage at the 270 and 360
degree
> >  positions. This reasoning assumes that the transformer can supply
> sufficient
> >  current to fully charge the cap in 1/4 cycle. If not, then higher break
> > rates
> >  may be better.