Chapter 03 : Capacitance of Transmission Lines

Example 3.1, Page No 49

In [1]:
import math
#initialisation of variables
Dm=2.015 		# mutual GMD of conductors(m)
r=0.4 			# radius of conductor(cm)

#Calculations
C=10**-9*1000.0/(18*math.log(201.5/.4)) 
Ic=132*1000.0*8.928*314*(10**-9)/math.sqrt(3.0)

#Results
print("capacitance =%.13f F/km" %C)  #Answers don't match due to different representation
print("charging current=%.4f amp/km" %Ic) 

capacitance =0.0000000089288 F/km
charging current=0.2136 amp/km

Example 3.2, Page No 52

In [2]:
import math
#initialisation of variables
GMDm=6.61 		#mutual GMD(m)

#Calculations
Ds1=math.sqrt(1.25*(10**-2)*10.965) 
Ds3=Ds1 
Ds2=math.sqrt(1.25*(10**-2)*9) 
Ds=((Ds1*Ds2*Ds3)**.333333) 
C=1/(18*math.log(GMDm/Ds)) 
Ic=220*1000*314*.01905*(10**-6)/math.sqrt(3) 

#Results
print("capacitance =%.6f micro-Farad/km" %C) 
print("charging current =%.2f amp/km" %Ic)

capacitance =0.019057 micro-Farad/km
charging current =0.76 amp/km

Example 3.3, Page No 53

In [3]:
import math
#initialisation of variables
GMD=8.19 

#Calculations
Ds=math.sqrt(2.25*(10**-2)*.4) 
C=1/(18*math.log(GMD/Ds)) 
Ic=220*1000*314*C*(10**-6)/math.sqrt(3) 

#Results
print("capacitance per km =%.5f micro-Farad" %C) 
print("charging current =%.3f amp" %Ic) 

capacitance per km =0.01246 micro-Farad
charging current =0.497 amp