Re: Capacitor in series with transformer or S.G ? What is right?

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

Hi,

My comments are interspersed with yours below:

> The thing that I always had problem fathoming, is
> that
> when the arc gap fires, it then appears as a short
> to
> the power supply, yet at the same time this does not
> cause a great jump in (transformer primary)amperage
> input. The explanation given for the use of the

Yes, the spark gap does short out the power supply
each time it fires. If we are using a shunted or
ballasted power supply, it simply limits itself to the
short-circuit amperage. If we are not using a shunted
or ballasted power supply, the arc will remain lit
until the circuit breaker trips (in roughly one
eyeblink!)

> rotary
> arc gap seems to make this comprehensible, because
> then the electrodes only come together for arcing
> when
> the source AC cycle goes to its zero point in the
> cycle, because the rotation of the arc gap
> electrodes
> is timed to the source frequency. If the gap fires
> at
> its AC zero crossing point, then a short at zero
> amperage input is of no consequence.

(???) You are talking about a synchronous RSG, and
they are not synched to the zero crossing point. Most
coilers synch them to achieve best spark production,
which is probably closer to the AC peak on the tank
cap, rather than the zero crossing point. Likewise,
you have dismissed the very popular asynchronous RSG,
wherein electrode alignment has no relationship with
the 50/60Hz AC line frequency. These align & fire at
random points around the AC cycle, but still give very
satisfactory results.

> 
> Thus the gap operated in static case must be
> modeling
> the same behavior? In one half cycle of source
> frequency, the cap must be fully charged,(if the 
> supply can meet the demand of current made by the
> capacitive reactance being used) The resistance of
> the
> arc gap is such then that when the cap is fully
> charged at the source frequency, it then discharges
> across that gap to produce the hf oscillation on the
> tank itself. But since the time for cap charging
> must
> occur during the half cycle of the input, by the
> time
> the discharge at gap occurs the source frequency
> must
> be coming close to its zero crossing point. Thus the
> arc gap already models what the rotary scheme
> manipulates,No?

No. The static gap is triggered by voltage, so it
tends to fire at the voltage peaks on the tank cap,
not at zero. Also, spark gaps are very fast switches,
so no delay is possible. For all practical purposes,
when the potential on the tank cap equals the
breakdown potential of the static gap, it fires
instantly. It does not wait for the 50/60Hz AC
waveform to move on.

> 
> Here is where another question comes up. Suppose we
> have a TC driven from a NST 15,000 volt 30 ma
> supply.
> By calculating the reactance of around 50 nf, we
> also
> find that is the ~value of capacity that would would
> allow that 30 ma conduction to occur. Doesnt this
> imply then that if we drive a TC with cap values
> above
> that 50  nf in its tank circuit,from this
> transformer
> NST , the source would not be meeting the demand?
> HDN

50nF is a too much of a load for a 15kv/30ma NST--it
would act much like a short. 5nF is closer to the
mark. Many coilers use an oversize tank cap, up to
2.5X resonant size, the so-called 'LTR' cap. However,
a 10X above resonance cap would feel like a
short-circuit to the neon, and firing would sporadic,
if at all.

> 
> =====
> Tesla Research Group; Pioneering the Applications of
> Interphasal Resonances
> http://groups.yahoo-dot-com/group/teslafy/
> 

Best Regards,

Greg
http://hot-streamer-dot-com/greg


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