Measurement Principles - Promax MZ-805 Manual De Instrucciones

MZ-805 L/C/R meter

6 MEASUREMENT PRINCIPLES

Circuit models
Resistors, capacitors and inductors can all be represented at a given
frequency by a simple series or parallel equivalent circuit. It must be stressed
that this is a simple equivalent circuit and as such will only be representative
over a limited frequency range. The effects of a wide frequency range are
discussed later.
The Models used by the MZ-805 are as follows:
=
Zs Rs
j
=
Zp
Rp
Rp
=
Q
ω
Lp
2
Q
=
Ls Lp Rs
1 + 2
Q
Resistors
All resistors have parasitic impedances, both inductance and capacitance
and distributed effects of both. Fortunately, however, in normal use these
parasitic effects are usually very small compared with the resistance.
August 2002
ω
+
j Ls
ω
LpRp
ω
+
j Lp
ω
Ls
=
Rs
ω
L
ω
= =
s Rp Q Lp
Q
where ω = 2 π f
1
= −
Zs Rs j
ω
Cs
Rp
=
Zp
ω
+
1 j RpCp
1
ω
= =
D RsCs
ω
RpCp
(D is also knom as tan δ )
= + =
2
Cs 1 ( D ) Cp Rs
1
=
D
Q
2
D
Rp
1 +
2
D
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