User Manual

19
Capacitance
The impedance in a capacitor is negatively proportional. Therefore, the larger
capacitance means the lower impedance, the smaller capacitance reverts to
higher impedance. Figure 3.8 shows the equivalent circuit of capacitor. If the
capacitance is small, the parallel resistance (R
P
) becomes large and more
relevant than the series resistance (R
S
). If the capacitance is large, the series
resistance becomes dominant and the parallel resistance becomes
insignificant. Hence, it is proper to use the parallel model for low capacitance
measurement and series model for high capacitance measurement.
Figure 3.8 – Equivalent Capacitor Circuit
Inductance
The impedance of an inductor is positively proportional. Therefore, the larger
inductances equals to higher impedance and vice versa. Figure 3.9 shows the
equivalent circuit of an inductor. When the inductance is small, the series
resistance (R
S
) becomes more important than the parallel resistance (R
P
).
When the inductance is large, the parallel resistance should be taken into
consideration. Therefore, it is recommended to use the series model to
measure an inductor with low inductance and parallel model to measure an
inductor with high inductance.
Small Capacitor
(High Z)
R
P
Less relevant
C
Large Capacitor
(Low Z)
R
P
Relevant
C
R
S
Less relevant
R
S
Relevant