Re: 5MV, 312kW

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

Original poster: Jim Lux <jimlux-at-earthlink-dot-net> 

At 07:55 AM 1/6/2004 -0700, you wrote:
>Original poster: Greg Leyh <lod-at-pacbell-dot-net>
>5MV along 250" of coil length equals 2o,oooV per inch *average* 
>gradient.  I'd venture to say that such a gradient is unrealistic by about 
>a factor of 3 for a pampered indoor coil, and a factor of 5 for an 
>outdoor-rated coil structure [where a coil of such dimensions would 
>probably end up].

The usual guideline is to make the creepage distance (i.e. along the 
coilform) 3-5x the free air spark distance for the voltage. Using 70kV/inch 
for uniform breakdown, and 50kV/inch for a sort of working number, you'd 
really want about an inch for every 10kV, or 500 inches for 5MV (call it 
12-13 meters).


>For the ALF, I'm designing for 4.8MV, supported by an 1152" 
>coilform.  This might seem a bit conservative, but failures of the tower 
>structure could be quite costly.


Indeed, with large, expensive structures, one would certainly want a 
substantial design margin, especially since it probably wouldn't change the 
cost very much, when all is said and done.

I think the 5MV Marx at Les Renardiers was in the 15 meter tall range... 
(indoors, in a HV lab)

Anybody have any estimates on how big the big generator is in the Bazelyan 
and Raizer book picture?  If the spark is 100+m long, the structure is 
probably in the 25-30 meter tall range.