Appendix B

Example 2(b) : Page B1

from __future__ import division
#power absorbed
from numpy import sqrt, pi, cos, sin
vsrms=230 #volts
vm=(sqrt(2)*vsrms)/2 #volts
alpha1=45 #degree
alpha2=90 #degree
x1=45*(pi/180)
x2=90*(pi/180)
vldc1=(vm/pi)*(1+cos(alpha1*pi/180)) 
vldc2=(vm/pi)*(1+cos(alpha2*pi/180)) 
vlms1=vm*((1/pi)*(pi-x1+(sin(2*x1))/2))**(1/2) 
vlms2=vm*((1/pi)*(pi-x2+(sin(2*x2))/2))**(1/2) 
r1=100 #OHM
pl1=((vlms1)**2)/r1 #W
pl2=((vlms2)**2)/r1 #W
print "power absorbed = %0.2f W" %pl1
print "power absorbed = %0.2f W" %pl2

power absorbed = 240.47 W
power absorbed = 132.25 W

Example 5(b) Page B3

#power absorbed
v=400 #V
po=15 #kW
nfx=1440 #rpm
f=50 #Hz
z2=0.4+1J*1.6 #ohm
p=4
x=120 #Hz
ns=((x*f)/p) #rpm
s=((ns-nfx)/ns) #slip
ns1=(x*x)/p #rpm
nfl1=(1-s)*ns1 #rpm
print "full load speed = %0.2f rpm"%nfl1
sm=(z2.real)/(z2.imag) #slip
print "slip is = ",sm
tfy=((po*10**3)/(2*pi*(nfl1/60))) #N-m
a=sm
tm=((a**2+s**2)/(2*a*s))*tfy #N-m
print "maximum torque = %0.2f N-m"%tm

full load speed = 3456.00 rpm
slip is =  0.25
maximum torque = 132.84 N-m