Hioki 3504-40 C HiTester, Инструкция по эксплуатации

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Appendix 3 Measurement of In-circuit Components
A4
Measurement Using Guarding Technique
Measure an in-circuit component after providing guarding.
When measuring the capacitance of
capacitor C
2
as shown in the diagram,
measure the parallel capacitance by add-
ing up the value of the current that flows
through capacitor C
2
and the values of
the current that flows through capacitors
C
3
and C
4
, after the probes are con-
nected to both sides of capacitor C2.
If you use a guard terminal as shown in
the diagram, however, the current does
not flow through capacitor C
4
and the
current that flows through capacitor C
3
is
absorbed by the guard terminal so that
you can measure the capacitance of
capacitor C
2
.
Appendix 3 Measurement of In-circuit
Components
C
4
C
3
C
2
C
1
H L
C C
2
C
3
C
4

C
3
C
4
+
------------------- +
=
C
4
C
3
C
2
C
1
H L
To guard terminal
• However, if, for example, the capacitance of C
2
is less than that of C
3
(C
2
<<
C
3
), this technique does not improve measurement precision.
• When two capacitors or a capacitor and a coil are connected in parallel as
shown in the diagram, you cannot measure each component separately.
Two capacitors connected
in parallel
A coil and a capacitor con-
nected in parallel