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1.2.2. Measuring impedance
Impedance can be measured in series or in parallel. In parallel
mode, impedance can be represented as reciprocal of admittance
(
Y
). The admittance can be defined as
Y
=
G
+ j
B
, where:
G
= Conductance
B
= Susceptance
Series impedance Parallel admittance
To understand the ratio of resistance and reactance, it is
important to consider two factors: quality factor (
Q
) and
dissipation factor (
D
). Usually
Q
is used when measuring
inductance and
D
is used when measuring capacitance.
D
is
defined as the reciprocal of
Q
.
Q
= 1/
D
= tan
Θ
Q
=
Xs
/
Rs
= 2πf
Ls
/
Rs
= ½πf
CsRs
Q
=
B
/
G
=
Rp
/|
Xp
| =
Rp
/2πf
Lp
= 2πf
CpRp
Rs = Series resistance
Xs = Series reactance
Cs = Series capacitance
Ls = Series Inductance
Rp = Parallel resistance
Xp = Parallel reactance
Cp = Parallel capacitance
Lp = Parallel inductance
Y = 1/Z = 1/Rp + 1/jXp = G+jB
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