Re: HV Arc Resistance

In a message dated 99-07-13 05:28:37 EDT, you write:

> Original Poster: "Lau, Gary" <Gary.Lau-at-compaq-dot-com> 
> Perhaps I'm missing something.  If a rotary gap fires 1/4 inch before
> electrode alignment, of what value is close electrode spacing?  It seems to
> me that arcing distance is determined by electrode radius of curvature and
> Vcap, and that aligned-electrode-spacing wouldn't matter, since quench would
> probably have been achieved before alignment.
> Regards, Gary Lau
> Waltham, MA USA >>

Gary, all,

One advantage is that the gap is becoming (slightly) narrower as it
fires, thereby lowering the gap resistance.  I suspect too that the 
whipping air tends to disrupt corona streamers around the electrodes,
and delay the firing perhaps?  I agree that it's best to prevent
early firing as much as possible.  To prevent early firing, I like to
round off the tip of the electrodes to create a hemisphere shape, which
hopefully increases the hold off voltage and permits the gap to fire only
when they are closer.  I think the hemisphere should be somewhat flat
in the middle to give a large surface area for cooling however.  I 
remember you did work with the pipe electrodes, and other schemes
which give a similar result. 

John Freau