Chapter4 - Measurement of Resistance

Exa 4.1 page 121

In [2]:
from __future__ import division
from math import log10
t=20 
C=8*10**-10 
E=200 
e=150 
a=log10(E/e)
R=(0.4343*t)/(C*a)*10**-6 
print "Insulation resistance = %.2f mega-ohm"%(R)

Insulation resistance = 86902.59 mega-ohm

Exa 4.2 page 121

In [10]:
t=600 
C=2.5*10**-12 
E=500 
e=300 
a=log10(E/e)
R=(0.4343*t)/(C*a) 
print "Insulation resistance=%.2f mega-ohm"%(R/1e6)

Insulation resistance=469833614.93 mega-ohm

Exa 4.3 page 122

In [4]:
from math import log
#V=Eexp(-t/tc)   where tc= RC=Time constant
t=30 
V=125 
E=200 
tc=-30/log(V/E) 
R=(7/15)*tc-7 
print "Insulation resistance=%.2f mega-ohm"%(R)

Insulation resistance=22.79 mega-ohm

Exa 4.4 page 122

In [5]:
Q=3000 
S=0.1 
M=2000 
X=Q*S/M 
print "The value of X=%.2f ohm"%(X)

The value of X=0.15 ohm

Exa 4.5 page 122

In [6]:
lx=55 
ly=100-lx 
Y=100 
X=Y*(lx/ly) 
print "Resistance of the field coil=%.2f ohm"%(X)

Resistance of the field coil=122.22 ohm

Exa 4.6 page 122

In [7]:
p=200.7 
q=400 
S=200.05*10**-6 
P=200.5 
Q=400 
r=1400*10**-6 
X=((P*S/Q)+((q*r)/(p+q))*((P/Q)-(p/q)))*10**6 
print "Unknown resistance=%.2f micro-ohm"%(X)

Unknown resistance=99.81 micro-ohm

Exa 4.7 page 123

In [8]:
E=230 
V1=60 
V2=40 
Rv=50000 
R1=((E-(V1+V2))/V2)*Rv*10**-3 
print "Resistance between positive and earth=%.2f Kohm"%(R1)
R2=((E-(V1+V2))/V1)*Rv*10**-3 
print "\nResistance between -ve and earth=%.2f Kohm"%(R2)

Resistance between positive and earth=162.50 Kohm

Resistance between -ve and earth=108.33 Kohm

Exa 4.8 page 124

In [9]:
Q=100.5 
M=300 
q=100.6 
m=300.25 
r=0.1 
S=0.0045 
X=((M*S/Q)+((r)/(r+m*q))*((M*q/Q)-(m)))*10**6 
print "Unknown resistance=%.2f micro-ohm"%(X)

Unknown resistance=13433.00 micro-ohm