Re: OLTC update - Poor seconadry Q

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 9/2/02 10:15:50 AM Eastern Daylight Time, tesla-at-pupman-dot-com
writes:


>
> Original poster: "Greg Leyh by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <lod-at-pacbell-dot-net>
>
> Hi John,
>
> That's an interesting equation... I'd like to
> see it with the non-whole number roots.



Hi Greg,

I don't think I have the non-whole number root
equation handy.  I think it's locked up in a defunct
computer.  Maybe the person who sent it to me will
see this if they're still on the list.  I can't remember
who it was.

>
> Did you arrive at this equation empirically
> by matching it to data points?



Yes, it's just empirical, just a guide.


>
> The 120" secondary out at Jim Heagy's place
> in the shipyard beats the equation by about
> 15%, 

and Electrum falls short of the equation,

>
> also by about 15%.  



Oh, of the new equation.  Still, I thought Electrum was
quite efficient at the lower breakrates.  I must have
misunderstood some of your old e-mails.  I'd appreciate
it if you could post a small table of breakrate vs. spark length
for the Electrum. 

This could be explained by

>
> the different engineering approaches of the two
> coils.  Electrum is conservatively designed, and
> has a few 'artistic compromises' in the engineering
> solution as well.  The shipyard coil enjoys a more
> optimal top load capacitance and primary Q, and is
> run 'balls out', in terms of design conservatism.



Understood.


>
> Are there many data points that fall in a nice
> distribution around this curve?  It would be
> interesting to find how far out this curve
> could be reasonably extrapolated.



The data points I've seen fall nicely on the new curve, but may
be leaving the curve at higher powers. 
I've ignored inefficient coil which may be power-arcing,
or have other obvious design flaws.  I have no idea
how far the curve can be reasonably extrapolated.
I assumed the limit is the limit you have spoken about
in the past.


>
> Inserting 240BPS and 3.6MW into the equation
> yields 402ft... which is more than twice the
> spark length performance required per tower.
> On the other hand it's probably good to have
> some reserve capacity, especially when it's
> not practical to field rework many of the
> critical coil parameters.



Sounds good.  The new equation is somewhat
too optimistic at the higher breakrates I think,
and may be too optimistic as the power rises.
It needs the non-whole number roots to be more
accurate.  

John