Fluke 87 III - Manual (Page 26)

80 Series III
Users Manual
18
Using Conductance for High Resistance or
Leakage Tests
Conductance, the inverse of resistance, is the ability of a
circuit to pass current. High values of conductance
correspond to low values of resistance.
The unit of conductance is the Siemen (S). The meter’s
40 nS range measures conductance in nanosiemens
(1 nS = 0.000000001 Siemens). Because such small
amounts of conductance correspond to extremely high
resistance, the nS range lets you determine the
resistance of components up to 100,000 M
Ω
, or
100,000,000,000
Ω
(1/1 nS = 1,000 M
Ω
).
To measure conductance, set up the meter as shown for
measuring resistance (Figure 4); then press
K
until
the nS indicator appears on the display.
The following are some tips for measuring conductance:
•
High-resistance readings are susceptible to electrical
noise. To smooth out most noisy readings, enter the
MIN MAX recording mode; then scroll to the average
(AVG) reading.
•
There is normally a residual conductance reading
with the test leads open. To ensure accurate
readings, use the relative (REL) mode to subtract the
residual value.
Measuring Capacitance
Caution
To avoid possible damage to the meter or to
the equipment under test, disconnect circuit
power and discharge all high-voltage
capacitors before measuring capacitance.
Use the dc voltage function to confirm that
the capacitor is discharged.
Capacitance is the ability of a component to store an
electrical charge. The unit of capacitance is the farad (F).
Most capacitors are in the nanofarad to microfarad range.