Re: Power in a TC System

To: tesla-at-pupman-dot-com
Subject: Re: Power in a TC System
From: "Gavin Dingley" <gavin.dingley-at-astra.ukf-dot-net> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Wed, 17 May 2000 18:08:30 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi John,
I have a copy of the Tesla Coil Design Manual and so know that you take a
practical engineering approach to coil design.
My goal in this question is to find a mathematical, but practical rule for
calculating the primary capacitor value for a given NST knowing it's max power
rating and rms voltage output. I want to get the maximum power out of the NST
without it being destroyed/ magnetically saturated etc. One formula states that
the reactance of the capacitor should be equal to X = V/I, where V is the NST's
output voltage and I is the maximum current that can be drawn from it. It goes
on to say that the capacitor value that comes out of this relation can be
doubled due to the low duty cycle of the resulting impulsing current.

I had a look at the graph in the above mentioned book (fig 14) and found the
graph to be linearish (big emphasis on the "ish"). From it I deduced a very
rough formula:

C = POWER (VA) / 45,000      uF

This in not perfect and personally I have got away with more capacitance
than is
lifted from the graph (12nF for a 5kV/125VA NST). Of course, the graph probably
represents NST voltages in the range of 10kV and so would not give a good
indication for my 5kV set-up.

I can see what you mean regarding energy and power, the streamers from the
secondary isotropic are more to do with energy, mainly due to the very low
currents flowing in them. Put at the primary circuit, we must be talking power.
At the end of the day average energy over time equals power and this is
fore the
whole process from NST to streamer. But it is get the most from your tank cap
that matters to me at this time, the rest has too many variables as you have
pointed out.

So, how do you calculate the highest value of primary tank cap given NST specs,
while taking into account the irregular current wave form drawn from the NST?

Thanks for your help and look forward to your reply,

Regards,

Gavin, U.K.

Tesla List wrote:

> Original Poster: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
>
> Gavin, All -
>
> Good question. The answer is neither method is correct without more
> information. This question has been discussed many times in the past on the
> List and with much confusion. The problem is that coilers confuse power and
> energy. These are two completely different parameters. Are you interested in
> the output power, output energy, or both for your NST?
>
> John H. Couture
>
> ----------------------------
>