# 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)

#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("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