From: Bert Hickman
Date: Fri, 18 Oct 2002 07:20:31 -0500
Subject: Re: [TSSP] Top Voltage
Paul, You're correct. In the sphere-sphere case, V should be defined as the differential voltage between the spheres. This is also the case in the sphere-plane case as well, but the plane is often set to ground potential. So, Figure 7.4 is inconsistent with the corresponding gradient equation - the battery voltages should indeed be +/- V/2 instead of +/-V. Best regards, -- Bert -- -- Bert Hickman Stoneridge Engineering "Electromagically" (TM) Shrunken Coins! http://www.teslamania.com Paul wrote: > Hi All, > > Further to last message, I'm definately an idiot, but > unfortunately the model is correct after all. There was > a typo in my test setup involving the North report formula. > > Having fixed that, the model agrees with North again. > The error on max surface field is circa 0.5% for a sphere well > above the groundplane, and deteriorates as the sphere becomes > lower, reaching 5% error when the sphere-plane gap equals the > sphere radius. > > Oh well. > > I think there's something wrong with fig 7-4 on p59. > The formulas for sphere-sphere peak gradient only make > sense if the spheres in fig 7-4 are at +/-V/2 rather > than +/-V. In other words, the formulas seem to be > correct if V is taken as the differential voltage between > the spheres, rather than the voltage between either sphere > and a zero of potential at infinity. Can someone check this > conclusion? > > -- > Paul Nicholson, > -- >
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.