# Re: [TCML] Spark gap loss

```That is a peak power loss which only lasts for a few microseconds each time the spark gap fires. I don't know his operating voltage but if we assume it is 20,000 volts peak, then his peak power output would be 84 megawatts per firing. This would yield a spark gap loss of 11M/84M = 0.13 or 13% which is not unreasonable. Looking at only peak power can be very misleading unless you also look at the time duration.

----- Original Message -----
From: "David Rieben" <drieben@xxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Wednesday, November 15, 2017 5:33:54 AM
Subject: Re: [TCML] Spark gap loss

----- Original Message -----
From: "Bert Hickman" <bert@xxxxxxxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, November 14, 2017 8:00 PM
Subject: Re: [TCML] Spark gap loss

> Hi Steve,
>
> Sounds very interesting. What is the title and author for the thesis?
>
> If the TRIGGER energy was 1 kJ(!), the energy of the main pulse must have
> been really huge. > The calculated gap resistances for Gary's gaps were
> between 430-520 milliohms.
>
> There are other interesting comments in this thread that you may also find
> useful.
>
> In 2007 Greg Leyh measured the spark gap resistance of a rotary gap in his
> model 120L50K Tesla coil. At 4200 peak amps, he measured a total gap
> resistance of 650 milliohms. Although not stated, I am guessing that the
> For comparison, a 4500 volt silicon switch measured only 5 milliohms at
> 4350 peak amps (since Vsat is much lower than the hundreds of volts
> typically seen per spark gap.

Hi Bert,

Wow! Applying the I2R law of resistive losses, 4200 pk amps across 0.65 ohms
of gap resistance would translate to over 11 megawatts of pk power loss! I
assume Greg's 120L50K coil was of gargantuan proportions.

David Rieben

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