Model 6517B Electrometer Reference Manual
Section 4: Basic measurements
6517B-901-01 Rev. C / August 2015
4-25
Where:
V
= Volume resistivity.
K
V
= The effective area of the guarded electrode for the particular electrode arrangement
employed.
= Average thickness of the sample (mm).
R = Measured resistance in ohms (V/I).
For circular electrodes:
D
1
= Outside diameter of guarded electrode.
g = Distance between the guarded electrode and the ring electrode.
B = Effective area coefficient.
Volume resistivity is measured by applying a voltage potential across opposite sides of the insulator
sample and measuring the resultant current through the sample as seen in the following diagram.
Figure 47: Volume resistivity measurement technique
Refer to the "Circular electrode dimensions" in
Surface resistivity
(on page 4-23) to determine
dimensions D
1
and g. An effective area of coefficient (B) of 0 is typically used for volume resistivity.
General measurement procedure
The following steps summarize the basic steps to measure resistivity. To ensure proper operation,
always enable zero check ("ZeroCheck" displayed) before changing functions (V, I, R, or Q). The Z-
CHK key controls zero check.
Hazardous voltages may be present on the output and guard terminals. To prevent
electrical shock that could cause injury or death, NEVER make or break connections to the
Model 6517B while the output is on. Power off the equipment from the front panel or
disconnect the main power cord from the rear of the Model 6517B before handling cables
connected to the outputs. Putting the equipment in standby mode does not guarantee that
the outputs are not powered if a hardware or software fault occurs.
