OLTC Update - Primary circuit resistance.

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

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

Hi All,
>
>Here is the primary voltage and drive signal at about 50 volts input (all I 
>can reasonably do right now):
>
>	http://hot-streamer-dot-com/temp/OLTC08-18-07.gif
>
>I will have to figure out the loss and divide it by ten for the 500 volt 
>case where the coil will actually run.  The losses of IGBTs or more or less 
>proportional to current, but the power is proportional to current squared.  
>So as you increase the current (drive voltage), efficiency of the coil 
>increases.  So right now, the all important primary loss looks fine.
>

I calculated and measured and estimated the full power (550V) resistance of
the primary circuit.  It came out to a stunning 0.0006 ohms!!  600uOhms.
That is well over 10X what the coil needed ;-))  With such tiny primary
circuit resistances and associated very low losses, many other low voltage
Tesla coil schemes are possible too!

However, the current is "high"!  In my 50 volt testing tonight, I must have
been hitting 500 amps peak!  It may turn into a 120VAC coil instead of a
240VAC coil...  Or, get rid of that charging reactor...  Definitely must be
very careful of running without a secondary or a miss-tuned secondary.
MicroSim says I could hit 5000 amps in a nice slow ringdown.  That would
destroy the IGBTs...

Even in the full coil MicroSim warns of 6000! Amps now....

This changes things a bit, but it is wonderful in the long run :-)))  As
odd as it sounds, I may have to run my coil off 120 VAC without resonant
charging (but at higher break rates?)...  An even simpler coil.  Or add
primary loss.  In the first stage, I may have to run it on a variac just to
"reduce" the voltage!  I may be able to pump up the break rate, but hat
means more currents that I was not expecting...  Many complexities are
added here, but they are good ones ;-))

I seem to have far more power than I expected :o))

The whole idea was to pump 2000 amps at about 30kHz through a primary coil
coupled to the secondary.  I may have vastly overdone it ;-)))  With only
0.0006 ohms of primary resistance, I could use a 1.5 volt battery :o)))

Cheers,

	Terry