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[TCML] Re: Spark gap Resistance

Hi Bart,
I think that 0.65ohm accurately reflected the gap losses, or very nearly so, since the voltage and current waveforms were in phase, except that the voltage waveform was somewhat distorted relative to the sinusoidal current waveform. Still, by eye I would estimate this distortion was at no more than 10%. At 4200A the peak gap voltage drop was about 2700V.
Given that the operating Zpri was 5.3ohm, one might imagine that this system would nominally work, as it did, although with considerable gap losses. The design improvements made in 1998 [increasing Zpri to 14ohm, larger toroid] actually increased the arc performance while reducing the maximum wall-plug draw down to about 25kW. The rotary gap can now operate steady-state without significant heating, as the peak currents are now only about 2500A. GL 




From: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
Subject: Re: [TCML] Re: Spark gap Resistance
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Message-ID: <47576D54.1050304@xxxxxxxxxxxxxxxx>
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0.65 ohms is significant! I have to assume that 0.65 was an averaged value? It is still relatively small and I don't think reflects the gap losses associated with spark gaps. I wonder if those gap losses included the primary losses as part of the mix? 

Take care,
Bart

Lau, Gary wrote:

> Actually, since power is I-squared * R, peak power in the gap is 1316 MegaWatts, or 1.3GW.  But that's a peak value, for a very brief interval - good for bragging rights, but little else.  The RMS current value for the duration of the gap on-time is a small fraction of the 4200A (sorry, no estimate, but <<4200A).  And when you average that over a duty cycle (picking numbers out of the air) of ~ 10usec/8msec or 0.125% that the gap is actually on, you'd arrive at a more realistic figure for the amount of energy that's actually dissipated in the gap.
>
> Regards, Gary Lau
> MA, USA
>



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