Prostat CVM-780 - Performance Characteristics & Considerations

14
Rev. D / January 2015
CVM-780 Contact Voltmeter
5. Once the probe is zeroed touch the p to the conducve ob-
ject being measured
a. Hold the probe steady with slight pressure on the p.
Avoid p damage, 

b. The voltage measurement will be seen on the front panel
LED display
c. Indicated voltage will stabilize quickly, usually within 2 to 5 seconds
d. Should changes in displayed voltage occur during measurement they are typically due to:
i. Natural ionizaon of the electrostac charge to air
ii. The eect of nearby ionizaon
iii. Capacive coupling with moving objects and personnel nearby
iv. Charging or Discharge of the conducve object being measured by means other than
the CVM-780 measurement
6. Ground probe p to the front panel ground plate
between measurements
7. Turn the CVM-780 power switch to OFF when instru-
ment is not in use, and replace probe p cover
8. If Low Ba LED on front panel illuminates, recharge
the unit’s baeries.  The CVM-780 may be
used for measurements during charging. However,
as baery voltage will be changing during the charge
be sure to ground and re-zero the probe p between
measurements.
VII. 
While CVM-780 measurements are easily performed, one should develop and pracce a consistent tech-
nique to make accurate measurements with the CVM-780. Grounding the instrument is important for
accurate results because “ground” is the instrument’s zero reference for its measurement circuit.
The CVM-780 probe is “acve”. Its internal components assess p voltage as it approaches a charged
conductor. It communicates with the instrument package to increase, and provide similar p voltage upon
contact with the conductor being measured. The front panel LED displays p voltage measurements upon
contact with an object or material.
Once the measurement is obtained, separaon from the conductor being measured does not reset the
probe to zero. In eect it remains at a similar voltage as the last measurement, or may “oat”. Grounding
the p between measurements resets the system to zero as can be seen of the front panel LED display.