Chapter 9 : Silicon Controlled Rectifier

Example 9.1, Page No. 238

In [2]:
# average voltage

import math
#Variable declaration
Vm=200.0           #in V
theta=30.0         #firing angle in degree

#Calculations
vdc=((Vm/math.pi)*(1+math.cos(theta*math.pi/180)))

#Result
print("average value of voltage is ,(V)= %.f"%(round(vdc)))

average value of voltage is ,(V)= 119

Example 9.2, Page No. 238

In [7]:
# dc load current rms load current amd power dissipiated

import math
#Variable declaration
Va=300.0                 # in V
Vm=300.0*math.sqrt(2)    # in V
Rl=50.0                  #in ohm
theta1=90.0              #firing angle in degree

#Calculations
idc=((Vm/(2*math.pi*Rl))*(1+math.cos(theta1*math.pi/180)))
irms=Va/(2*Rl)
P=irms**2*Rl

#Result
print("(i)   The dc load current is ,(A)             = %.2f"%idc)
print("(ii)  The rms load current is ,(A)            = %.f"%(round(irms)))
print("(iii) The power dissipated by the load is ,(W)= %.f"%(round(P)))

(i)   The dc load current is ,(A)             = 1.35
(ii)  The rms load current is ,(A)            = 3
(iii) The power dissipated by the load is ,(W)= 450

Example 9.3, Page No. 239

In [10]:
# firing angle conducting angle and average current

import math
#Variable declaration
Ih=0.0                        #in A
Vi=100.0                      #in V
Vm=200.0                      #in V
Rl=100.0                      #in ohm

#Calculations
theta1=(180/math.pi)*math.asin(Vi/Vm) #firing angle in degree
ca=180-theta1                         #conducting angle in dehree
av=((Vm/(2*math.pi))*(1+math.cos(theta1*math.pi/180)))
ac=av/Rl               

#Result 
print("(i)   firing angle is ,(degree)     = %.f°"%(theta1))
print("(ii)  conducting angle is ,(degree) = %.f°"%ca)
print("(iii) average current is ,(A)       = %.4f"%ac)
#average current is wrong in the textbook

(i)   firing angle is ,(degree)     = 30°
(ii)  conducting angle is ,(degree) = 150°
(iii) average current is ,(A)       = 0.5940