RE: [TCML] Re: Spark gap Resistance

[drieben@xxxxxxxxxxx (David Rieben)]

Hi Terry,

I'm not sure myself but if we're talking about a real?
resistance, then the I2R loss formula would have to ap-
ply. I was assuming that this would have to represent a 
loss? Maybe you're correct since we are talking about,
in Greg's words, "the effective impedance". Impedance
does refer to the apparent or perceived resistance, ac-
cording to Ohm's law. I guess that's how you can actually
come up with a negative resistance in certain situations.

David Rieben

-------------- Original message -------------- 
From: "Terry Oxandale" <Toxandale@xxxxxxx> 

> Is that a loss, or power passing through the coil circuit? 
> 
> -----Original Message----- 
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On 
> Behalf Of David Rieben 
> Sent: Wednesday, December 05, 2007 12:42 PM 
> To: Tesla Coil Mailing List 
> Subject: Re: [TCML] Re: Spark gap Resistance 
> 
> Hi Greg, all, 
> 
> Maybe I'm missing something here. 4200 amps (peak) across 
> 0.65 ohms translates to 11.466 MEGAwatts peak power loss! 
> I know the SG is the culprit for the biggest waste of power in 
> the primary circuit (the heat associated with the SG electrodes 
> and their associated mounting hardware verifies a significant 
> power loss) but this seems like a rather large sum of 
> lost power, even for peak levels.? Even with the really low 
> 0.005 ohms for the silicon switch there would still be over 100kW 
> peak power loss at 4500 amps peak. I'm not that great on the higher 
> math but this seems to suggest that with an assumed 80% effeciency, 
> the primary circuit's peak power must be on the order of >50 
> MW? I suppose with the size of coils that Greg builds, 50 
> MW isn't that unthinkable for peak power levels, though. 
> 
> David Rieben 
> 
> -------------- Original message -------------- 
> From: Greg Leyh 
> 
> > Hi Dave, 
> > 
> > Measuring across the rotary gap using a compensated divider and a CT, 
> I 
> > found the effective impedance of the gap to be about 0.65ohm at 
> > 4200A[pk.] This was on the 120L50K coil, before I reconfigured the 
> > primary circuit for a higher Zchar. The voltage drop waveform showed 
> > some non-linearity, as one might expect. 
> > 
> > Here's a desc of the 120L coil: 
> > http://www.lod.org/Projects/120L50K/120L50K.html 
> > 
> > By comparison, the 4500V silicon switches in the 90L10K prototype 
> coils 
> > exhibit an effective impedance of about 0.005ohm, at 4350A[pk.] GL 
> > 
> > 
> > 
> > > David N. Van Doren wrote: 
> > > 
> > > Does anyone have any data on spark gap resistance? 
> > > and for that matter Streamer impedance? 
> > > I've been doing some simulations, and for the lack of any better 
> number I've 
> > been using 4 ohms for spark gap R's and have tried using 
> 220kohm+1.5pf'/ft for 
> > streamers, but doesn't always seem to look right in the sims. Trying 
> to 
> > characterize plasma is always difficult at best. 
> > > 
> > > Thanks 
> > > 
> > > Dave 
> > > 
> > 
> > 
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