Re: secondary frequency problem (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sat, 22 Sep 2007 12:22:29 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: secondary frequency problem (fwd)

Hi Ed,

Agreed. Not important for spark generation. It does give a sense of 
secondary losses at fr if you are accustomed to looking at it. If not, 
the value is meaningless. Because I run the program on so many coil 
geometry's, it is a quick check for me. Something like this: "wow, Q is 
oddly low. Ahh, look how high Rac is". That's about all I do with it.

Javatc calc's Q as Q = sqrt(Les/Ces)/Rac. The method used for Rac is 
from a paper written by Fraga, Padros, and Chen "Practical Method and 
Calculation of AC Resistance of Long Solenoids", IEEE Transactions on 
Magnetics, Vol. 34, No. 1, January, 1998, pp. 205-212.

It's for long solenoids. So I grabbed over 140 actual Q measurements for 
an empirical evaluation against Fraga's method and with a bit of work 
figured out a factor to accommodate the huge discrepancies as h/d was 
reduced. The factor used is 1+(spacing ratio/(h/d)). What I have 
accounted for in that expression is turn to turn proximity and h/d. The 
factor really helped bring the prediction close to real world 
measurements. Although accuracy still reduces as h/d is decreased, the 
factor improved the accuracy greatly.

But still, Q is mostly just an academic number for spark generating 
Tesla Coils. But if you do see oddly low Q values, it is a little window 
that maybe the designer might want to take a look at the secondary 
losses. Granted secondary losses are negligible to other losses in the 
system, but if were going to design coils, we might as well reduce as 
many losses as we can identify.

Take care,
Bart





Tesla list wrote:

>---------- Forwarded message ----------
>Date: Fri, 21 Sep 2007 17:04:39 -0700
>From: Ed Phillips <evp@xxxxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: secondary frequency problem (fwd)
>
>As I mentioned, using DCR for Q is not accurate. But, sometimes 
>measurement is needed to prove it."
>
>	Also Q isn't that important since it is very low with streamer loading.  Good for bragging purposes - I've done that but still not very important.
>
>Ed
>
>
>
>
>
>
>
>  
>