Re: SRSG break rate

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

Original poster: "Charles Hobson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <charles.a.hobson-at-btinternet-dot-com>

Hey you guys,

I've been following this through and am getting more confused with each
read.

My thoughts:

There is more than one condition to start with:

1. The transformer and primary capacitor are resonant to the line freq.
50/60Hz.
As such the circuit is resistive with voltages and currents in phase.
Current is limited by circuit resistance. The voltage across the capacitor
will be exceedingly high equal to  Xc(N x Vp)/Rs where N is transformer
turns ratio, Vp is primary (mains) voltage, Rs is transformer secondary
circuit including secondary winding resistance, and Xc is primary circuit
capacitive reactance. Such a situation is typical for NST set ups and result
in smoke and fire and permanent damage when not protected by proper safety
and static spark gap settings.

2. Pole pigs without inductive ballast: The secondary circuit behaves
capacitively before spark gap firings. Without spark gap firing, the
secondary voltage across the capacitor does not exceed the rated transformer
voltage, i. e. a 10kV rms 5A transformer supplies 10kV to the primary
capacitor, no more, no less. However, with a spark gap fitted to this
arrangement, stand back as all hell breaks loose when the gap fires. The
secondary current will try for about 10kV/(Rs+SG res.), several hundreds of
amps while the primary winding will be reaching for some few thousand amps.
Of course breakers open up, fuses blow, etc. and perhaps some smoke will be
generated. Resistive ballasts are used by some to limit these currents, one
can get multiple spark gap firings each half of the AC cycle but still not
exceeding the peak voltage of the transformer specified rms voltage.
(usually less due to voltage drop across the ballast resistor). NST will out
perform pole pigs with resistive ballasts all other things being equal when
the primary capacitor is matched reasonaby well to the NST.

3. Pole pigs with inductive ballasts: The inductive ballast performs at
least two functions, luimits the transformer primary current during spark
gap firings, and reflects inductive reactance to the transformer secondary
at other times and thus resonates with the primary capactor. As such, the
spark gaps can be set to voltages larger than the pole pig specification and
multiple firings during each half of the AC cycle can occur. Appropriately
designed  rotary spark gaps are then used. I suppose with synchronous rotary
gaps the multiple firings will be 2Nf  where N is a whole number and f =
line frequency. With asynchronous Rotary Spark Gaps, the firing rate will be
2kNf where the gaps will go in and out of alignment. k some number less than
one.

These explanations are how I think these things work. What really throws the
spanner in the works are the voltage and current transients necessary for
Tesla Coil operation, the non-linear behaviour of power transformers, and
complicated and varying impedances reflected from a streamer emitting
terminal to the primary circuit. I am sure other items can be added here.

SRSG break rate is the subject I believe. My personal view is that with NST
this shold be twice the line frequency only.
With pole pigs, this can go up in multiples of twice the line frequency
100/120, 200/240, 300/360 --- to an optimum rate depending on system
components.

ASRSG I don't thik it's a good idea for NST. The gaps go in and out of
alignment which result proper firings in alignment and safety gap firings
out of alignment.