Re: Ok, what is an LTR cap.

["Ed Phillips" <evp-at-pacbell-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Tesla list wrote:
> 
> Original poster: Terry Fritz <twftesla-at-uswest-dot-net>
> 
> Hi Deano,
> 
>         The real key here is that in an NST the primary to secondary
coupling is a
> little loose so the secondary is sort of free to ring up.
> 
>         In a pig, with very tight coupling, this degree of freedom would
have to
> be the ballast.  So if you rang the secondary up into ultra high voltages,
> the primary would follow via the turns ratio.

	Sort of lost the thread here, but the leakage reactance of the
transformer (referred to the secondary terminals, of course) can be
found by dividing the open-circuit voltage by the short-circuit
current.  As an example, take a 16 kV, 60 ma transformer.

	Xl = 15000/0.06 = 250,000 ohms  (leakage inductance = 663 h)

	Resonant capacitance = 0.0106 ufd

This calculation assumes that the permeability of the core doesn't
change with applied voltage, which is wrong, but the general numbers are
about OK.

>         It all sounds sort of nasty.  Personally "i" would try in on a
computer
> first ;-))
> 
>         Off hand, I would think you would divide the ballast inductance
by the
> turns ratio squared to get the transformed impedance value of the ballast
> as it looks on the secondary side.  Then choose your capacitor to resonate
> at 60Hz with that value.
> 
> At 220VAC and 10kW at 60 Hz, we could choose a ballast of Xl = 4.84 ohms or
> 12.84mH.  With a 14400 pig that transforms to 3uH

	0.01234 x (14400/220)^2 = 53.1 h
	Resonant capacitance = 0.1325 ufd

.  To resonate at 60 Hz
> the cap value is 2.34F.  An impossibly high cap value...
> 
> So it would appear that there is no chance of getting resonant or LTR
> charging from a pig.  However, if I should have multiplied the square of
> the turns ratio instead of dividing, I would get 127.5nF...  If I have made
> that error (which the book on my lap says I didn't...) then the resonate
> case would be easy...  Perhaps others could please double check my
> reasoning and math here...
> 
> I would think such a resonant system would make one darn good bang!!
> 
> Cheers,
> 
>         Terry

Ed