Re: Measurements using field probe (fwd)

---------- Forwarded message ----------
Date: Thu, 9 Jul 1998 11:22:16 -0600
From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Measurements using field probe (fwd)

to: John

The probe is the meter itselff which alternately covers and uncovers a
capacitor vane, ie, it shields and unshields a flat metal plate.  It does,
as you suggested, work on the field principle.  It is, in effect, a
capacitive pickup probe that is actually the entire instrument itself.  A
synchronous motor operates 4 vanes the run at 1800 RPM to give a close
model of a 60 Hertz input wave to the o-scope.  The standard distance
equation is employed, ie, v1/v2 = d1/d2 when v1 and d1 are calibrated
distances with known potentials, d2 is measured with the unknown potential,
and then v2 is solved with cross multiplication.  Our machine is rather
large with total vane diameter at 18 inches and a reasonably large
"butterfly" design cross section on the vane.  We found the design in an
old book on electrostatics.


> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Measurements using field probe (fwd)
> Date: Wednesday, July 08, 1998 9:55 PM
> ---------- Forwarded message ----------
> Date: Wed, 8 Jul 1998 06:44:49 +0000
> From: "John H. Couture" <couturejh-at-worldnet.att-dot-net>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: Measurements using field probe (fwd)
>   The AC peak should equal the DC peak? This would be true when the AC is
> rectified and stored. However, that would depend on the probe and the
> instrumentation. I have not been able to find in my literature where a
> mill measures the potential. 
>   What are you using for a probe? What is the equation used?
>   John Couture
> -----------------------------------------------------
> At 04:30 PM 7/7/98 -0600, you wrote:
> >
> >
> >---------- Forwarded message ----------
> >Date: Tue, 7 Jul 1998 08:24:08 -0600
> >From: "D.C. Cox" <DR.RESONANCE-at-next-wave-dot-net>
> >To: Tesla List <tesla-at-pupman-dot-com>
> >Subject: Re: Measurements using field probe (fwd)
> >
> >Hi John:
> >
> >The field mill meter actually measures the potential difference and is
> >usually used with a calibration voltage.  We use 150 kV DC to calibrate
> >units, and then the potential is directly proportional to the distance
> >the measured terminal.  Wouldn't the AC peak be equal to 1.4 x Erms? 
> >would mean the ACpeak should be equal to the DCpeak.  Example, if you
use a
> >common 1N4007 to rectify the AC line which is 120 VAC Erms, then the DC
> >reading is around 170 volts.  This is the same as measuring the AC line
> >with a meter than is not a true RMS meter and gives only the peak AC
> >reading --- again around 170 volts.
> >
> >DR.RESONANCE-at-next-wave-dot-net