Re: AC wire resistance with proximitry effects

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Gerry,

Hopefully the same one your using.

Rf = [2pi*N^2*a* effective_rho*(sinh(2theta)+sin(2theta)) ]  /
       [effective_sd*Lw*(cosh(2theta)-cos(2theta)) ]

I assume you ask because you are getting something different?

I didn't put theta in radians. The equation appears to be a classic 
cos(radians(x)), etc... but I got something off in nevernever land 
when I set it up. I then removed rads and Q popped up where expected. 
I left it that way. I have noted that eff_sD is quite a bit higher 
than other approximations make.

I'm in the middle of entering coils into the spreadsheet and 
currently going through Malcolms data concentrating mainly on the 
closewound coils. A day or so ago I entered Kurt Schraners' data as 
he made quite a few precise measurements of different h/d coils. I'll 
send my spreadsheet your way once I get some of Malcolms data logged. 
I could sure use a check on the implementation.

Take care,
Bart



Tesla list wrote:
> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Bart,
>
> What equation are you using for Qfraga???
>
> Gerry R.
>
> > Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>
> >
> > Hi all,
> >
> > I measured a few coils today, and a couple which are far outside the norm.
> >
> > ------------------------------------------
> >
> > 8.4375" x 39.75", 1789 turns, 24 awg, Loaded with 9" x 30" toroid.
> >
> > Freq = 73400 Hz.
> > Q meas = 183.5
> > Q Fraga = 218.09
> > Error = 15.86% (better than I thought it would be with a loaded coil)
> >
> > ------------------------------------------
> >
> > 4.5385" x 21.165", 900 turns, 24 awg. Bare coil with h/d of 4.4
> >
> > Freq = 406000 Hz
> > Q meas = 270
> > Q Fraga = 251.86
> > Error = 6.72%
> >
> > ------------------------------------------
> >
> > 1.6837" x 54.25" (Seibt coil), 2410 turns, 24 awg. Bare coil with 
> > h/d of 32.2
> >
> > Freq = 600000 Hz
> > Q meas = 100
> > Q Fraga = 138.27
> > Error = 27.68%
> > Q measurement accuracy difficult due to digital frequency readout 
> > is limited.
> >
> > ------------------------------------------
> >
> > 12.9" x 9.375", 215 turns, 18 awg. Bare coil with h/d of 0.7
> >
> > Freq = 388000 Hz
> > Q meas = 194
> > Q Fraga = 479.28
> > Error = 59.52%
> > Q measurement accuracy difficult due to digital frequency readout 
> > is limited.