Page 486 - Instrumentation Reference Book 3E

The measurement of resistance, capacitance, and inductance 469

Ideal Equivalent circuit of Simplified
componen,! physical realization equivalent circuit

Resistance
R Rd = - R L
1
-cz=i-- wC, D
C
Rd& d.c. resistance
Re: eddy-current loss and skin effect changes
Rd: dielectric loss in C, and Cd
1: inductance
C,: lumped capacitance
cd: distributed capacitance
,.

RI
C
Capacitance Rd R R L L C
+it-
R R
C,: electrostatic capacitance
C,: increase in C, caused by interfacial polarization with time
constant R,C,
1: series inductance
R,: series resistance
R,: leakage resistance
Rd: dielectric loss

R L
Inductance
L
m-
C
Lo: inductance
R,: winding resistance
Re: eddy-current loss
Rh: hysteresis loss (iron-cored inductors)
C: capacitance
Rd: dielectric loss

Figure 20.57 Equivalent circuit for physical realizations of resistance, capacitance, and inductance.

effect. Figure 20.61(a) shows these capacitances. source and detector. The stray admittances across
and Figure 20.61(b) shows the equivalent circuit the source and detector do not affect the balance
with the stray capacitances transformed to admit- condition. The balance condition of the bridge in
tances across the branches of the bridge and the terms of the admittances of the branches and