Re: Minimum distance

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "David Rieben" <drieben@xxxxxxxxxxxxxxx>

Hi Ben, all,

A 10 kV/inch rule of thumb should prevent almost any
flashover danger, at least at 60 Hz or DC, as you say.
However, there are a number variables when determining
the breakdown distance vs voltage, such as atmospheric
conditions (temperature, humidity, barometric pressure)
and the physical size and geometry of the electrodes.
This makes an "ironclad" voltage/spark length graph all
but impossible. I think the theoretical maximum voltage standoff that 
1" of air can withstand is 76 kV, but of course that's with smooth 
spherical electrodes of at least the dia-
meter of the spark gap distance itself. Any deviation from this 
"controled" laboratory spark gap setup will result in a much lower 
kV/inch rating. I've heard that with needle
point electrodes, the kV/inch is somewhere between 15
kV and 25 kV(DC). And of course, with high frequency AC, all bets are 
off as the voltage/spark length ratio goes
down significantly with a subsequent increase in frequency. Also, 
remember that a 60 Hz AC rms voltage  reading must be multiplied by 
1.4 to determine the true sine wave peak
voltage.

David Rieben

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, August 23, 2006 7:52 AM
Subject: RE: Minimum distance


> Original poster: "Bill Miller" <screengrid@xxxxxxxxxxx>
> Hello,
>     When dealing with high voltages, I always use the rule of 
> 10,000 volts per inch. Thats at 60 cycles or DC, not sure if it 
> works at other frequencies.
> Thank You,
> Tony
>
> > From: "Tesla list" <tesla@xxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: Minimum distance
> > Date: Tue, 22 Aug 2006 19:46:05 -0600
> >
> > Original poster: "CajunCoiler" <cajuncoiler@xxxxxxxxxxx>
> >
> >
> > The almost-recent talk about transformers below the
> > primary/secondary coil assembly causing interference
> > has me pondering...
> >
> > ...is there a formula for calculating a
> > minimum non-interfering clearance?  Perhaps even a
> > "rule of thumb" method?
> >
> > I'd like to be able to get placement right the first
> > time, as financial restraints forbid making changes
> > to the supporting framework under the supply components
> > this time around.
> >
> > Project parameter data at...
> > http://www.msbdatasystems.com/cajuncoiler/kongjr.txt
> > --
> > C.L. Mayeux
> > cajuncoiler@xxxxxxxxxxxxxxxxxx