Re: Need help with mystery

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

Original poster: "Rick W by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rickwilliams404-at-earthlink-dot-net>

Hey Steve,
A thought. The short charge time can't be good asa far as pulse current is
concerned. Your tank cap charges awful fast with 67 ohms. A 1 millisecond
charge time would still be quick enough for the BPS desired. 10K ohms * 19nF
= .19ms then times 5 time constants = close to 1 ms. I don't know the size
of the RSG disk or the rpm but 1ms is about 1/2" of travel on the outside of
a disk rotating at 1800rpm.

What I'm getting at is try a higher resistance, a few K anyway. You
shouldn't be hurt by increased charge time and it would help keep sudden
pulse current down.

Rick Williams
Salt Lake City

----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Sunday, July 22, 2001 8:17 PM
Subject: Re: Need help with mystery


> Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>
>
> Tesla list wrote:
> >
> > Original poster: "S & J Young by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <youngs-at-konnections-dot-net>
>
> > Here is the puzzle.  My most recent power resistor is 6 400 ohm 10 watt
> > power resistors in parallel for 67 ohms at 60 watts.  Current going the
> > resistors is high amperage pulses, but the average current is only 50
> > milliamps.  Current is measured with an ordinary moving coil ma meter.
> >
> > Power dissapation for this series resistor is I-squared R = .05 x .05 x
67
> > which is about 0.17 watt.  So the resistors will stay cold, right?
Wrong!!
> > When the TC runs for a minute, the resistors get literally smoking hot!
I
> > am guessing the power dissapated is well over 100 watts!!  This means
the
> > resistor impedance is at least 40K??
> >
> > Another clue is that the voltage pulse across this power resistor is on
the
> > order of 5 KV as it will jump across a 1/4 inch gap.  If the power
resistor
> > is a pure resistor, this would indicate current pulses of about 75 amps
> > flowing into the 19 nF tank cap.
>
> The problem is that you are mixing RMS and average values. You are
> really
> charging the capacitor with pulses of 75 amperes, that make the RMS
> current
> on the resistors far larger than the average 50 mA that you measure.
>
> Antonio Carlos M. de Queiroz
>
>
>
>