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tesla coil operation illustration (fwd)



---------- Forwarded message ----------
Date: Fri, 24 Aug 2007 21:26:10 -0400
From: Jared Dwarshuis <jdwarshuis@xxxxxxxxx>
To: Pupman <tesla@xxxxxxxxxx>
Subject: tesla coil operation illustration

Subject: Re: tesla coil operation illustration (fwd)

Hi Scott B., Dr. R, Matt D., Jeff P., ...


Tesla list wrote:
> ---------- Forwarded message ----------
> Date: Thu, 23 Aug 2007 18:04:06 -0700
> From: Teslacoil Workshop <workshop@xxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: tesla coil operation illustration (fwd)
>
> Dr. Res beat me to it... I'm a fan of Richie's work too...
>
> Jeff Parisse
> kVA Effects
>
> ----- Original Message -----
>> Richie Burnett's website is the best to understand coils.
>> Dr. Resonance

...I confess to be a total fan of Richie Burnett's work fan as well!
Specifically the detail-link:

http://www.richieburnett.co.uk/operation.html#operation

should be digested by every coiler, IMHO. I'd also recommend to realize the
simple coupled double pendulum, mentioned in step 8 of the above site,
...and contemplating about it. It's a great analogy. And when I try to
explain TC's to laymen, I'm starting with it. And it can make one starting
to think about resonance in disruptive TC's. And if resonance effects really
exceeding transformation ratio, as mentioned in some of your mails. Let's
make an example, which is not taking extreme conditions: my B&W coil.

secondary n2=813 turns
primary   n1=5.2 turns (at tap)
--> transformation ratio N=n2/n1 = 156
charging voltage of cap = 22kV (16kVrms, without resonant rise; estimated)
--> sec. voltage by N: 22kV*156 = 3.43 MV (!!!)

Well, that's just nonsense, 'cause I'm shure not to exceed ~700kV
sec-voltage. Why? An energy balance is more appropriate and easy (as is the
case in many thermodynamic's problems!):

(1/2)C1*V1^2 = (1/2)C2*V2^2 if 100% efficient transfer of the primary energy
to the secondary.

With C1=165nF; L1=27.5uH --- C2=84pF; L2=53.7mH this leads to around 1MV max
(using my TCplan), while in practice the 70% efficiency ~680kV value is more
probable; even optimistic.

So what about resonance in disruptive coils? - In contrast to i.e. DRSSTC's
or CW coils, we will _not_ observe real resonant voltage rise, higher than
i.e. the transfomation ratio. But resonance in the loosly coupled
dual-resonant, well tuned, system, anyway is needed, in order to transfer
the (almost)whole primary energy to the secondary, in a limited number of
cycles. The investigation, of how close to 100% the energy transfer can be,
leads also to the so called "magical values" of the coupling coefficient.
I'm shure, some of my friends on the list are able to elaborate more and
better on the missing resonant rise in disruptive TC's ;-)

Cheers,  Kurt

..........................................................................................................................

Turn ratio transformers assume that all of the magnetic flux is shared. This
is not the case with a large air cored primary enveloping a smaller  air
cored secondary. The math does exist for describing the voltage in
this situation. Look up mutual inductance in textbooks. They like to use
concentric air cored solenoids as examples.

Jared Dwarshuis