Re: DC H-Bridge Measurements

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

Original poster: "S & J Young by way of Terry Fritz <twftesla-at-qwest-dot-net>" <youngs-at-konnections-dot-net>

Bart,

I provided the DC power supply volts in my last posting, and of course it
does drop down (from 8.6 KV at 200 BPS to 6.4 KV at 700 BPS).  Nevertheless,
if you do the calculations,  (0.5 * 27 nF * (6.4KV * 2)^2 * 700 BPS) you get
1548 watts, but the measured power (6.4 KV * 170 ma) is only 1088 watts.  So
there must be some residual voltage in the caps when they get
reverse-charged, plus what gets wasted heating the gaps.

I agree - it would be nice if more people would publish some real data to
study.
--Steve
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, May 29, 2002 7:52 AM
Subject: Re: DC H-Bridge Measurements


> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
>
> Hi Steve,
>
> Neat data. Love it when data pops up! Regarding the doubling at 300 bps
and
> up. You mentioned the
> effective voltage was not doubled which seems to based on your measured to
> calc'd watts in a doubled
> circuit. Is this just a case of charge time affecting the result? In
> otherwords, as the bps climbes, I
> would expect a drop in the VA measurements because the cap voltage should
> fall off (doubled or not) as
> bps increases. I would guess the doubling is working just fine the voltage
> is what is dropping. I'm
> just curious if you have looked at that in any detail.
>
> Take care,
> Bart
>
> Tesla list wrote:
>
> > Original poster: "S & J Young by way of Terry Fritz
<twftesla-at-qwest-dot-net>"
> <youngs-at-konnections-dot-net>
> >
> > I fired up my reworked DPDT 16 rotating electrode RSG today in an
H-Bridge
> > configuration and took some quick measurements that I am posting here.
> > Measurements are at the onset of a 48 inch streamer between breakout
> points on
> > a twin TC.  This is quite subjective as the transition from heavy corona
> to an
> > actual streamer is not very pronounced at the lower break rates.  The
> streamer
> > at 700 BPS is awesome - almost like a heat arc!
> >
> > The H-bridge alternately reverses HVDC (from a low esr 6 mF pulse cap)
to the
> > primary tank circuit, which theoretically doubles the effective voltage
> to the
> > cap (27 nF).   *** is the calculated power in the primary =
.5*C*(V*2)^2*BPS.
> > I will switch to fixed font:
> >
> > BPS    DCKV    DCMa    DC Watts   ***
> > 200     8.6     98      843       769
> > 300     8.0    118      944      1036
> > 400     7.2    132      950      1148
> > 500     6.9    148     1021      1286
> > 600     6.6    160     1056      1411
> > 700     6.4    170     1086      1548
> >
> > As BPS goes up, the streamer gets brighter and and thicker, and makes a
more
> > pleasing musical sound than the usual AC powered TC.   The lower BPS is
more
> > efficient (as John Freau has said many times), but high BPS is more
> > interesting.
> >
> > The *** column is interesting for the 300 BPS and up cases.  Obviously,
the
> > effective voltage across the tank cap is not doubled.  At 700 BPS, ***
> > calculates to 1086 watts with 2V = 10.7 KV. This is about 2 KV less than
the
> > 12.8 KV for true voltage doubling.   That is 500 volts across each of
the
> four
> > active RSG gaps.
> >
> > I am more and more convinced that nothing takes the place of starting
with a
> > relatively high DC voltage in the first place.  H-Bridges, resonant
charging
> > schemes, Marx-gap schemes and the like to effectively increase the tank
cap
> > voltage all have their drawbacks in lower efficiency and complexity.  My
> > H-Bridge RSG has eight stationary electrodes, for example!  Back to the
> drawing
> > board . . .
> >
> > --Steve Young
>
>
>