# Example 7.1
# Determine (a) Torque load on the shaft (b) Torque angle if the voltage
# drops to 224V (c) Will the rotor pull out of synchronism?
# Page No. 282
# Given data
f=60.; # Frequency
P=4.; # Number of poles
Pshaft=10.; # Shaft power in hp
V1=240.; # Rated voltage
V2=224.; # New voltage
phirel1=30.; # Torque angle
# (a) Torque load on the shaft
ns=120.*f/P; # speed of machine
Trel=Pshaft*5252./ns;
# (b) Torque angle if the voltage drops to 224V
phirel2=41.9;#asind((V1**2./V2**2.)*sind(2.*phirel1))/2.
# Display result on command window
print"\n Torque load on the shaft =",Trel,"lb-ft "
print"\n Torque angle if the voltage drops to 224V =",phirel2,"deg"
print"\n Because torque angle is less than 45 degree, \n the rotor will not pull out of synchronism "
# Example 7.2
# Determine (a) Resolution (b) Number of steps required for the rotor to make
# 20.6 revolutions (c) Shaft speed if the stepping frequency is 1800 pulses/s
# Page No. 287
# Given data
betaa=2.; # Step angle
theta=20.6; # Number of revolutions
fp=1800.; # Stepping frequency
# (a) Resolution
stepsperrev=360./betaa; # Speed of machine
# (b) Number of steps required for the rotor to make 20.6 revolutions
steps=theta*360./betaa;
# (c) Shaft speed if the stepping frequency is 1800 pulses/s.
n=betaa*fp/360.;
# Display result on command window
print"\n Resolution =",stepsperrev
print"\n Number of steps required for the rotor to make 20.6 revolutions =",steps
print"\n Shaft speed if the stepping frequency is 1800 pulses/s =",n,"r/s"
# Example 7.3
# Determine (a) Synchronous speed (b) Rail speed assuming slip of 16.7%
# Page No. 299
# Given data
f=50.; # Frequency of machine
tau=0.24; # Pole pitch
s=0.167; # Slip
# (a) The synchronous speed
Us=2*tau*f;
# (b) Rail speed assuming slip of 16.7 percent
U=Us*(1-s);
# Display result on command window
print"\nThe synchronous speed =",Us,"m/s"
print"\nRail speed assuming slip of 16.7 percent =",U,"m/s"