Measuring Capacitance - Fluke 187 User Manual

Model 187 & 189
Users Manual

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 (nF) to microfarad
( F) range.
The meter measures capacitance by charging the
capacitor with a known current for a known period of time,
measuring the resulting voltage, then calculating the
capacitance. Capacitors larger than 100 F take several
seconds to charge. The capacitor charge can be up to
3 V.
The meter's capacitance ranges are 1 nF, 10 nF, 100 nF,
1 F, 10 F, 100 F, 1 mF, 10 mF, and 50 mF.
3-12
To measure capacitance, set up the meter as shown in
Figure 3-8. The blue key toggles the selection between
capacitance and diode test.
While measuring capacitance, the following pushbutton
functions are not available:
Frequency ( )
FAST MN MX (
The following are some tips for measuring capacitance:
To speed up measurements of similar values, press
to manually select the proper range.
To improve the measurement accuracy of small value
capacitors, press
subtract the residual capacitance of the meter and
leads.
)
with the test leads open to