Monroe Electronics Electrostatic Fieldmeter - Static Monitor - model 177A - Manual (Page 8)

7
Effect of Probe Type on Fieldmeter Readings
For measurement of insulating web surfaces, it is best to maintain the same distance from the
fieldmeter to the web as when the fieldmeter was calibrated. Since most fieldmeters are calibrated at
one inch, their apertures should be positioned one inch from the web. The Model 1036E probe will
give accurate readings (as-is) at a measurement distance of one inch because its large grounded
face helps to create a uniform electric field near the aperture of the probe. The Model 1036F probe is
significantly smaller than the Model 1036E probe. Unless a grounded shroud is used to enlarge the
smaller ground plane of the 1036F probe, the fieldmeter readings will be about 12% high because
the electric field will converge on the small probe.
Figure 5: Field Lines Straight to 1036E Probe
Figure 6: Field Lines Converging to 1036F Probe
Convergent field lines
1036F Probe
Charged
Surface
1”
Straight field lines
1036E Probe
Charged
Surface
1”
Aperture