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RE: Peak Primary Current
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- Subject: RE: Peak Primary Current
- From: "Tesla list" <tesla@xxxxxxxxxx>
- Date: Sat, 16 Apr 2005 11:02:37 -0600
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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 ;-)
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
> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> Hi again Mark,
> At 02:48 PM 4/15/2005, you wrote:
> >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
> I don't think the archiving is working right now... Must tell
> >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
> >up some subjects to discuss and this is the first which may be
> >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
> >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
> >20 KV, #12 ga, #8 ga, and 1/4" tubing(a real pain to set up).
> Interesting!! See this:
> Looks link the link is broke... :-(, but Gary measured a bunch of
> configurations for AC resistance.
> >I have run (2) coils with my primary and power suppy(Note I am using
> >resonant charging so I have one extra degree of freedom than you AC
> >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
> >and 5 uSec for the medium coil.
> >Using I = Cdv/dt, I get 277 amps for the small coil and 136 amps for
> >large coil(Have I made a math error?).
> We need to know the primary inductance, and then finding the peak
> 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
> >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
> >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
> firing cycle.
> >I tried to measure primary current with an isolated CT and got 88
> >This is obviously not accurate because resonance only occurs for
> >40 uSec(383kHz coil) until we reach the first notch and quench. I'm
> >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
> 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
> >Straighten me out, please.