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Re: Ragowski(sp?) coils



Original poster: "Bert Hickman by way of Terry Fritz <twftesla-at-uswest-dot-net>" <bert.hickman-at-aquila-dot-net>

Hi Dave,

Thanks for providing some more detail - I remember Richard discussing
this a while back, but this provides more missing info. Did he build his
own integrator with a high slew rate integrator? Calibration for very
high currents was done via comparison with calculated peak currents for
high-current discharge with known L and C and attenuators on output? I
was looking at buying a high current one (100 kA), but the cost was
almost $1k for the coil and battery powered integrator module, so I
opted to use a Current Viewing Resistor (CVR) instead...

Happy New Year to you!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "David Sharpe by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <sccr4us-at-erols-dot-com>
> 
> Hi Bert, Terry, All
> 
> Richard wound a home brew Rogowski Coil (RC) on 3/8 PE tubing
("polyflow") like
> a typical close wound resonator, then bent back on itself and epoxied into a
> solid 1/4" to close coil.  From what I've read, to de-Q a RC, you have to
> tap the
> coil and place non inductive swamping resistors in parallel across the coil
> segments.
> The advantage of this is the Rload is automatically built around the coil.
> Total resistance of series RL parallel segments can be anything you want,
> but IMO
> I'd shoot for 50 ohms, since that is a standard input impedance for just
about
> all instrumentation.
> 
> To calibrate, you need a low impedance power signal generator driving into a
> resistive load, sine wave AC power up to perhaps 500kHz.  A multiplier and
> offset
> term can be developed (2 point calibration).  While used in conjunction of
> water arc
> explosion work, typical accuracy's was better then 10%, and much better is
> possible with good calibration/measurement techniques and equipment.
Currents
> up to 14 kA peak at 16-18kVDC was measured successfully, and when back
> calculated to Zsurge and charge voltage, calculated peak currents agreed with
> calibrated measured values from RC within 5-10%.
> 
> In closing, the advantages of an RC are:
> 1.  Diameter can be made size commensurate with hold off voltage requirements
>      Diameter of unit mentioned above was about 8-10" if my memory is
correct.
> 2.  Capable if measuring extremely high currents (mega-amperes)
> 3.  Wide bandwidth (depending on construction 100 MHz or more)
> 4.  Relatively inexpensive to make
> 5.  Only real difficulty is fabrication and calibration, this is the cost
> factor in commercial
>      units..
> 
> Happy New Year All!
> 
> Regards
> Dave Sharpe, TCBOR
> Chesterfield, VA. USA
> 
> Tesla list wrote:
> 
> SNIP----------------->