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13.5.4
Correction procedure
Solid insulating materials
Table
513-55
Electrode and sample size combination of un-guarded electrode setup
Electrode and sample size combination
Sample diameter = Electrode diameter
Sample diameter ≠ Electrode diameter
High voltage electrode diameter = Measurement
electrode diameter
Sample diameter ≠ Electrode diameter
High voltage electrode diameter ≠ Measurement
electrode diameter
For electrodes without guarding, the electrodes shall
•
either extend to the edge of the sample or
•
be smaller than the sample.
In the latter case, it is acceptable for the upper and lower electrode to be equal or unequal in size.
If they are equal in size and smaller than the sample, the edge of the sample must extend the electrodes
by at least twice the sample thickness.
The choice between these electrode types will depend on convenience of application of the electrodes,
and on the type of measurement adopted.
When the electrodes extend to the edge of the sample, these edges must be sharp to guarantee a
precise measurement.
When equal-size electrodes smaller than the specimen are used, it is difficult to center them unless the
specimen is translucent, or an aligning fixture is mounted.
Cross section/Profile
Technical data
79
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