Re: HV Meter

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

Original poster: "Bert Pool by way of Terry Fritz <twftesla-at-qwest-dot-net>" <txsharpie-at-prodigy-dot-net>

At 07:46 PM 11/9/02 -0700, you wrote:
>Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><jimlux-at-earthlink-dot-net>
>
>A question about electrostatic meters, having never seen the innards of
>one...  Don't they rely on effectively averaging the coulomb force between
>two plates, which is linearly proportional to voltage.  True, they measure
>AC and DC, basically being an absolute value device, but I would think that
>they measure average AC voltage, not RMS.  Where's the squaring function
>necessary for RMS measurements coming from, otherwise?
[BIG SNIP]

Jim,

 From one of the best HV books around, "High Power Electronics" by W. James 
Sargent and R.E. Dollinger:

         Page 303 & 304.  . . . ."Because of the v^2 dependance of the 
forces (between the disks) the output is nonlinear.  Linearizing mechanisms 
are possible, but not usual.  One consequence of the v^2 dependance is lack 
of polarity sensitivity.  Also, ac waveforms will work, and a true RMS 
reading results."

I stand behind my original statement that electrostatic meters measure ac 
in true RMS.

Bert Pool