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Technical data
13.3.4 Correction procedure
Solid insulating materials
Electrode systems with guarding and suitable connections ensure a precise measurement by shunting
edge currents from spurious external voltages away from the measuring circuit. This reduces the
probability of a measurement error significantly. In theory the edge capacitances c
e
are zero.
Figure 13-2 Measurement circuit, guarded electrode
Nevertheless, stray capacitances of the test cell or between the leads and to ground are not shunted.
The of such capacitance could still influence the measurement accuracy for example of thin samples (µm
range). We recommend to
•
Perform a standardized air reference measurement using the
SPECTANO Analyzer Suite
•
Activate the correction to display the corrected capacitance and relative p
ermittivity ε
r
values.
For more information about the air reference correction and its equations read chapter “10.4
Perform reference measurements”.
In addition, we recommend using a material sample diameter equal to the measurement electrode
to ensure an optimal measurement accuracy. At least the material
should cover the Guard ring half as seen in the image below (has to contact the Guard ring 50%).
Figure 13-3 Sample dimension recommendations for high accuracy measurements
using a guarded electrode
