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Re: Can anyone help ?
Tesla List wrote:
>
> Original Poster: Cabbott Sanders <cabbott-at-cyberis-dot-net>
>
> Bert said once:
>
> "The bottom line:
> A system using resonant charging will see "optimum" performance at
> between 3-4 "bangs" per half cycle of the AC mains with a properly
> chosen static or synchronous RSG (360 - 480 BPS at 60 Hz). Just make
> sure that you always break down either the main gap or a safety gap
> before smoking your NST or tank cap. By adjusting the gap spacing
> closer, higher breakrates can also be achieved, but with poorer overall
> performance due to the reduced bang size (as you surmised above).
>
> Safe coilin' to you!
>
> -- Bert --"
>
> Bert, you say that optimum resonant charging of the tank cap is 360-480
> bps....
> that would mean you need a NST or PIG that is capable of charging a cap
> that fast,
> right? What break rate do programs such as wintesla assume your using??
If i
> match 15 kva to a .161 ufd cap, what is my optimum break rate? 120 bps?
Cabbott,
AC resonant charging will only occur at the mains frequency. By
adjusting the gap breakdown voltage (by controlling the spacing and
number of the series static gaps) you can adjust them to fire 3-4 times
(or more) every half cycle. This is because the tank cap is being
recharged more quickly than would be predicted by the faceplate rating
of the NST. This technique is quite popular, since it permits you to
obtain better performance from a given NST than would otherwise be
possible. You're literally "sucking" more current out of them than their
rated current.
Although AC resonant charging can also be used on a ballasted pig, this
really isn't necessary, nor is it even desirable under most
circumstances, since you can actually end up overvolting and smoking
your tank cap! It's also not necessary, since a pig can deliver as much
tank cap recharge current as the (adjustable) ballast inductance and the
power mains fusing will allow.
Tesla design programs don't really cover sparkgaps and breakrates at
all... and probably won't for the foreseeable future! Empirical results
by a number of coilers on this list have shown that breakrates in the
300-700 per second seem to provide best performance. Higher break rates
can lead to overstressing (internal overheating?) and premature cap
failures, with marginal performance improvement.
Assuming that you've ballasted the pig such that it WILL deliver over 15
KVA, you should be able to hit 400+ BPS with a 0.16 uF tank cap. It's
not essential that you use the maximum tank cap size. At 20-25
Joules/bang with a 0.16 uF cap, the rest of the system will need to be
quite robust to safely make use of this energy. If this is your first
coil, you might want to consider reducing the tank cap size a bit.
-- Bert --