RE: Peak Primary Current

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Lau, Gary" <gary.lau@xxxxxx>

Re. the laushaus.com link to the primary resistance study - it works
better if you use forward slashes throughout ;-)
http://www.laushaus.com/tesla/primary_resistance.htm

The conclusion that I reached was that the choice of conductor geometry
will have a definitive impact on the primary AC resistance, and hence
losses.  But I am obliged to point out that I made no attempt to show
how significant these differences were in relation to the numerous other
losses in a coil system.

Regards, Gary Lau
MA, USA

> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi again Mark,
>
> At 02:48 PM 4/15/2005, you wrote:
>
> >All:
> >
> >I'm back from a 2 year hiatus from the list.  I could not handle the
> >"List" e-mail volume and had to quit and follow you guys in the
> >archives.
>
> I don't think the archiving is working right now...  Must tell
Chip......
>
> >I now have finally created a 2nd inbox for "List" e-mail and
> >can still get my work done and follow you guys as well.  I have
stored
> >up some subjects to discuss and this is the first which may be
obvious
> >to you, but not to me.
> >
> >I have used many different wire combinations for my primary wiring
> >thinking that the primary wiring was a major resistance in the
circuit.
> >Interestingly, no matter what I do with the primary wiring, I see no
> >change in the performance of my coil.  I have tried the following for
> >the primary wiring #18 ga, #14 ga, (2) #14 ga, #14 ga 20 KV, (2) #14
ga
> >20 KV, #12 ga, #8 ga, and 1/4" tubing(a real pain to set up).
>
> Interesting!!  See this:
>
> http://www.laushaus.com\tesla\primary_resistance.htm/
>
> http://www.laushaus.com/tesla/
>
> Looks link the link is broke... :-(, but Gary measured a bunch of
primary
> configurations for AC resistance.
>
>
> >I have run (2) coils with my primary and power suppy(Note I am using
DC
> >resonant charging so I have one extra degree of freedom than you AC
guys
> >and can pick my tank capacitor independent of the power supply).
> >
> >My small coil resonates and 383 kHz and runs great with an 18 nF
> >capacitor(18 to 24" streamers).
> >My medium size coil resonates at 100 kHz and runs with a 34 nF
> >capacitor(48 to 60" streamers).
> >
> >In both cases, I charge the capacitor to 20 kV.
> >
> >It takes 1/2 cycle to empty the capacitor - 1.3 uSec for the small
coil
> >and 5 uSec for the medium coil.
> >
> >Using I = Cdv/dt, I get 277 amps for the small coil and 136 amps for
the
> >large coil(Have I made a math error?).
>
> We need to know the primary inductance, and then finding the peak
current
> is easy.  but your calcs should be fine too.
>
>
> >These values seem absurd for my wire sizes.  How can I be moving this
> >level of current?
>
> You have 20,000 volts behind it!!!  20kV will pump 2000amps into a 10
ohm
> resistor!!
>
> >Also, note Peak current is dropping as the coil size
> >increases because the frequency dropped faster than the capacitor
> >increased in size.
> >
> >I think you're going to tell me that the spark gap creates such a
large
> >loss that the capacitor is significantly discharged during the first
> >cycle and does not recover until the next re-charge period.
>
> Spark gaps waist a lot of power, but not too bad at the beginning for
the
> firing cycle.
>
>
> >I tried to measure primary current with an isolated CT and got 88
amps.
> >This is obviously not accurate because resonance only occurs for
about
> >40 uSec(383kHz coil) until we reach the first notch and quench.  I'm
at
> >460 BPS so charging occurs for 2200 uSec.  During charging available
> >current is absolute max about 200 to 250 mA(documented by
> >studying/measuring power supply capability and typically only ~75
> >mA(~1.5kW).
>
> Sounds like a cool system!!  We can help getting the measurement stuff
> figured out so all should be in perfect agreement.  need to know more
> details like inductances and other general coil data to pin things
down.
>
> Cheers,
>
>          Terry
>
>
>
> >Straighten me out, please.
> >Thanks.
> >
> >Mark
> >
> >
> >
> >
> >
> >
> >
>