Re: Chaotic Resonance(Solid State Coilers)

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

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Chuck,

Computer programs like MicroSim, and all, can actually model resonant rise
very well.  In fact the models I use for LTR coils depend on gap timing to
fire the gap at just the instant the resonant voltages on the cap are
maximized while using the stored current in the NST secondary to "kick"
that voltage even higher.

Two areas that the computer does have problems with is the nasty Saturating
LTR coil case where the shunts in the core go into saturation and in the
simple resonant case accounting for the core saturation which ultimately
determines the maximum voltage.  The computer models actually do have this
ability but it is messy and they need data which is not available (requires
blowing some trannies...).  Fortunately, in normal Tesla coil operation,
saturation is not a factor and the models do fine.  You may want to check
the paper on this at:

http://hot-streamer-dot-com/TeslaCoils/MyPapers/modact/modact.html

One may also wonder at resonance, will the computer's numbers drift as the
model rings since the numbers are all digital and time sliced?  I have
found that as long at the resolution is not terribly choppy, the programs
do a fine job of keeping the total system energy constant despite all the
digital stuff going on.  A true mark of good calculation engines!

It seems to me that the computer models can do just about anything they can
be feed accurate data for.  If you want to see them fall apart fast, try
using them to guess data that is not confirmed by actual testing!  The
models are very powerful and can predict all sorts of odd, wonderful, and
very wrong things with ease without actual data keeping them pinned down to
reality. 

Cheers,

	Terry


At 09:06 AM 1/7/2001 +0000, you wrote:
>Hello all,
>
>There has been a lot of traffic on "Chaotic" so here's my contribution:
>
>I recently did a series of measurements and calculations on a Boiler
>Ignition Transformer  (8.3kV/20mA)  to determine, amongst other things,
>what value capacitor will resonate with the secondary winding. Because 240V
>mains and 8.3kV are not friendly, I fed 18V to the primary winding instead
>and measured 630V output, a predictable result. I then applied various loads
>to the transformer and measured and recorded primary and secondary voltages
>and currents.
>
>Under these conditions, the transformer secondary took a fancy to a
> 0.0047uF (4.7nF) capacitor. That's where it resonated at 50Hz. The output
>voltage sky rocketed to 4000V. Now here is where some software may get its
>knickers in a twist:
>
>a. formula for transformer voltage and turns ratio not applicable to
>reactive loads
>b. VA in secondary =23.6, VA in primary = 1.98  at resonance
>
>Where do all those Volt Amperes in the secondary come from? Do we have a
>free lunch here?  No! definitely not. The computer tends to look at a steady
>state conditions and make calculations accordingly. Some software may even
>tell you that there is a Power Gain in a linear non-active circuit. Most
>software I think can recognize true power, apparent power, and reactive
>power differences, but resonance poses some problems.
>
>What is actually happening is the secondary circuit under resonance is
>ringing. Energy is moving back and forth between the capacitor and
>transformer inductance. much like a pendulum or child on a swing is moving
>up and down from one side to the other. The small amount of energy being
>consumed by I square losses R in the transformer is all that is needed to
>keep it going, like that small nudge on the swing to keep it going. How did
>the swing get started? The struggle to lift the swing from rest to a release
>point. The transformer's initial energy was supplied as a transient when
>first connected. (the large surge of current at switch on). The product of
>this and 18 Volts integrated over the short time of occurrence represents
>this initial energy.  Mystery of the great joule robbery solved.
>
>Chuck    .
>