Hioki Super megohm SM7110 - Measurement Using an Electrode for a Flat Sample; Volume Resistance Measurement and Surface Resistivity Measurement (the Functional Role of the Guard Electrode)

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Measuring Flat Sample
Measurement using an electrode for a at sample
The “volume resistance” and “surface resistance” must be measured separately because their
properties are di󰀨erent from each other.
To compare di󰀨erent insulating materials in terms of insulation resistance, the insulating material-
specic resistance values that are not a󰀨ected by the shape of the terminal are required. They are
considered to be the volume resistivity or surface resistivity. Use an electrode (such as optional
Model SME-8310 or SME-8311) to determine the volume resistance value or the surface resistance
value. Then, multiply the values by each of the electrode constants to calculate the volume
resistance value or the surface resistivity. The instrument can automatically calculate the volume
resistivity or the surface resistivity.
Setting the instrument
Settings for calculating the resistivity are required.
See “4.13 Setting Resistivity Calculation (Resistivity Measurement Function)” (p. 73).
Press the MODE key to switch the measurement mode to volume resistivity measurement mode,
and then perform measurement. (p. 39)
Volume resistance measurement and surface resistivity measurement
(the functional role of the guard electrode)
A guard is required for measuring volume resistance and surface resistivity.
Hioki provides Model SME-8310 Plate Sample Electrode and Model SME-8311 Electrode for Flat
Sample as options.
Both the devices consists of 3 electrodes: “main electrode,” “counter electrode,” and “guard
electrode.”
Because measurement using Model SME-8301 Surface Resistance Measurement Electrode is equivalent
to the measurement described in “Surface resistance measurement (1) Measurement without the guard
electrode (p. 84),” it cannot provide accurate surface resistance measurement.
Volume resistance measurement
(1) Measurement without the guard electrode
Because the current owing along the surface of the measured object is also measured
unnecessarily, the current owing across the object in the thickness direction cannot be separately
measured.
A
(+)
(−)
Internal ammeter of the Super Megohm Meter
Current to be measured
owing across the object in the
thickness direction
Current owing along the surface of
the measured object
Measured object
Main electrode
Counter electrode
Internal power
supply of the Super
Megohm Meter
5
Measurement Methods Suitable for Various Objects to Be Measured