3.
Very low capacitances should be measured by using extremely short
leads in order to avoid introducing any stray capacitances
..
4.
When using the optional test leads, remember that the leads introduce
a measurable capacitance.
5.
Capacitors, especially electrolytics, often have wide tolerances. The
measured value may be greater than the value marked on the
capacitor. However, values are seldom drastically below the rated
value.
6.
The existence of a leaky capacitor may be detected if the value
changes significantly as the ranges are changed.
large Unknown Capacitance Test Method
To. test a large unknown capacitance of more than 20,000 I'F, use the
following procedure:
1. Select a capacitor with a known value (over 10,000 I'F and as close to
20,000 I'F as possible), this value becomes Ck.
2. Place the unknown capacitor (Cx) in series with the known value
capacitor (see Figure 1).
3.
Measure the capacitance of this series combination. The measured
value becomes Cs.
4.
The unknown capacitor's value can now be calculated by using the
following formula:
Cx
=
Ck x Cs
Ck - Cs
Cx
Ck
Cs
+
Figure 1
Useful Conversions
p
F
nF
I'F
mF
1,000
1.0
0.001
10,000
10.0
0.01
100,000
100.0
0.1
1,000,000
1000.0
1.0
10,000
10.0
100,000
100.0
1,000,000
1000.0
10,000
10
-4-
Farad
0.001
0.01
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