Chapter7 - Measurement of Capacitance & Inductance

Exa 7.1 page 174

In [1]:
#The coil has resistance of R ohm and inductance L2
#ZKL=25+j(2*pi*f)*0.05 
ZLM=100 
#ZKN=(R+2)+j(2*pi*f)*L2 
ZNM=100 
#Now (ZKL/ZLM)=(ZKN/ZNM)
#((25+j(2*pi*f)*0.05)/100)=((R+2)+j(2*pi*f)*L2/100)
#Equating Real and imaginary parts
#we have 25=R+2
#2*pi*f)*0.05=2*pi*f)*L2
R=23 
L2=50 
print "Resistance=%.0f ohm"%(R)
print "Inductance=%.0f mH"%(L2)

Resistance=23 ohm
Inductance=50 mH

Exa 7.2 page 175

In [2]:
from __future__ import division
from math import atan, degrees, pi
C1=50*10**-12 
r2=1500/pi 
r3=120 
Cs=C1*r2/r3*10**12 
print "Cable capacitance=%.1f pF"%(Cs)
C2=0.95*10**-6 
rs=C2*r3/(C1*10**6) 
print "Parallel loss resistance=%.2f Mega-ohm"%(rs)
w=314 
Loss_angle=degrees(atan(rs*w*Cs) )
print "Loss angle=%.1f degree"%(Loss_angle)

Cable capacitance=198.9 pF
Parallel loss resistance=2.28 Mega-ohm
Loss angle=90.0 degree

Exa 7.3 page 176

In [3]:
C3=106*10**-12 
C1=0.35*10**-6 
R1=318 
R2=130 
C2=C3*R1/R2 
Rx=R2*C1/C3 
print "Series Resistance = %.2f ohm"%(Rx)
wr=314 
pf=wr*Rx*C2 
print "Power factor = %.2f"%(pf)

Series Resistance = 429245.28 ohm
Power factor = 0.03

Exa 7.4 page 176

In [4]:
Q=10 
Cs=0.2 
P=2 
Cx=Q*Cs/P 
print "Capacitance = %.1f uF"%(Cx)
S=5 
rx=P*S/Q 
print "Resistance = %.0f Kohm"%(rx)

Capacitance = 1.0 uF
Resistance = 1 Kohm

Exa 7.5 page 177

In [5]:
S=900 
P=1.5*10**3 
Q=2*10**3 
Cs=0.2*10**-6 
rx=S*P/Q 
print "Resistance=%.0f ohm"%(rx)
Lx=P*Cs*S 
print "Inductance=%.2f H"%(Lx)

Resistance=675 ohm
Inductance=0.27 H

Exa 7.6 page 178

In [6]:
R1=2 
R2=1 
R4=500 
L4=0.1
R3=R1*R4/R2 
print "Resistance=%.0f ohm"%(R3)
L3=R1*L4/R2 
print "Inductance=%.2f H"%(L3)

Resistance=1000 ohm
Inductance=0.20 H

Exa 7.7 page 178

In [7]:
S=0.875 
P=1.35*10**3 
Q=1*10**3 
Cs=0.1*10**-6 
rx=S*P/Q 
print "Resistance = %.2f ohm"%(rx)
Lx=P*Cs*S*10**3 
print "Inductance = %.3f mH"%(Lx)

Resistance = 1.18 ohm
Inductance = 0.118 mH

Exa 7.8 page 179

In [8]:
r1=250 
r4=1200 
r2=10**6 
C4=4*10**-5 
r3=r1*r4/r2 
print "Resistance=%.2f ohm"%(r3)
C3=r2*C4/r1 
print "Capacitance=%.2f uF"%(C3)

Resistance=0.30 ohm
Capacitance=0.16 uF

Exa 7.9 page 180

In [9]:
R2=1000 
R4=833 
f=50 
w=2*pi*f 
C=0.38*10**-6 
R3=16800 
R1=(R2*R3*R4*w**2*C**2)/(1+w**2*R4**2*C**2) 
print "Resistance = %.2f ohm"%(R1)
L=R2*R3*C/(1+w**2*R4**2*C**2) 
print "Inductance = %.2f H"%(L)

Resistance = 197.49 ohm
Inductance = 6.32 H