In [1]:

```
#pg 363
#calculate the synchronous speed, speed and rotor current
# Given data
P = 4.;
f = 50.;# in Hz
s = 4.;
#calculations
Ns = (120*f)/P;# in rpm
# s = ((Ns-N)/Ns)*100;
N = Ns - ( (s*Ns)/100. );# in rpm
print "The speed of the motor in rpm is",N
N = 1000.;# in rpm
s = ((Ns-N)/Ns);
f_desh= s*f;# in Hz
#results
print "The synchronous speed in rpm is",Ns
print "The rotor current frequency in Hz is",round(f_desh,1)
```

In [2]:

```
#pg 363
#calculate the slip and speed
# Given data
f = 50.;# in Hz
P = 4.;
f_DASH = 2;# in Hz
#calculations
# f_DASH = s*f;
s = (f_DASH/f)*100;# in %
N_S = (120*f)/P;# in rpm
# s = (N_S-N)/N_S;
N = N_S - (s/100*N_S);# in rpm
#results
print "The slip in percentage is",s
print "The speed of the motor in rpm is",N
print 'The answer is a bit different due to rounding off error in textbook'
```

In [3]:

```
#pg 364
#calculate the speed, frequency
# Given data
P = 6.;
f = 50.;# in Hz
Snl = 1./100;
Sfl = 3./100;
#calculations
N_S = (120.*f)/P;# in rpm
print "The synchronous speed in rpm is",N_S
Nnl = N_S*(1-Snl);# in rpm
print "No load speed in rpm is",Nnl
Nfl = N_S*(1-Sfl);# in rpm.. correction
print "The full load speed in rpm is",Nfl
# frequency of rotor current
s = 1;
Sf = s*f;# in Hz
print "The frequency of rotor current in Hz is",Sf
# frequency of rotor current at full load
f_r = Sfl * f;# in Hz
print "The frequency of rotor current at full load in Hz is",f_r
print 'Note : The calculated value of Nnl is wrong and value of Nfl is correct but at last they printed wrong.'
```

In [4]:

```
#pg 364
#calculate the numbers and percentage slip
# Given data
Pa= 12.;
N= 1440.;# in rpm
Na= 500.;# in rpm
Nm= 1450.;# in rpm
#calculations
fa= Pa*Na/120;# in Hz
Pm= round(120*fa/Nm);
# Synchronous speed of motor
Ns= 120*fa/Pm;# in rpm
s= (Ns-N)/Ns*100;# in percentage
#results
print "The numbers of pole is : ",Pm
print "The percentage slip is : ",s
```

In [5]:

```
#pg 365
#calculate the frequency, induced emf
# Given data
from math import sqrt
K = 1./2;
P = 4.;
f = 50.;# in Hz
N = 1445.;# in rpm
E1line = 415.;# in V
N = 1455.;# in rpm
#calculations
Ns = (120*f)/P;# in rpm
s = (Ns-N)/Ns*100;# in %
f_r = s/100*f;# in Hz
print "The frequency of rotor in Hz is",f_r
E1ph = E1line/sqrt(3);# in V
# E2ph/E1ph = K;
E2ph = E1ph*K;# in V
print "The magnitude of induced emf in V is",round(E2ph,1)
E2r = s/100*E2ph;# in V
print "The magnitude of induced emf in the running condition in V is",round(E2r,3)
```

In [6]:

```
#pg 366
#calculate the rotor speed, frequency and Ns
# Given data
P = 4.;
S =4./100;
f = 50.;# in Hz
#calculations
Ns = (120*f/P);# in rpm
print "The value of Ns in rpm is",Ns
# The rotor speed when slip is 4 %
N = Ns*(1-S);# in rpm
print "The rotor speed when slip is 4 percent in rpm is",N
# The rotor speed when rotor runs at 600 rpm
N1 = 600;# in rpm
s1 = ((Ns-N1)/Ns)*100;# in %
f_r = (s1/100)*f;# in Hz
print "The rotor frequency when rotor runs at 600 rpm in Hz is",f_r
```

In [7]:

```
#pg 366
#calculate the poles, full load slip, induced voltage and frequency
# Given data
V_L = 230.;# in V
f = 50.;# in Hz
N = 950.;# in rpm
E2 = 100.;# in V
Ns =1000.;# in rpm
#calculations
# Ns = 120*f/P;
P = (120*f)/Ns;
print "The Number of poles is",P
s = ((Ns-N)/Ns)*100;# %s in %
print "The percentage of full load slip in percent is",s
# The rotor induced voltage at full load
E2r = (s/100)*E2;# in V
print "The rotor induced voltage in V is",E2r
# The rotor frequency at full load
f_r = (s/100)*f;# in Hz
print "The frequency at full load in Hz is",f_r
```

In [8]:

```
#pg 367
#calculate the poles, speed, emf and frequency
# Given data
V = 440.;# in V
f = 50.;# in Hz
N = 1450.;# in rpm
Ns = 1450.;# in rpm
Nr = 1450.;# in rpm
#calculations
P = round((120*f)/Ns);
print "The number of poles in the machine is",P
P = 4;
Ns = (120*f)/P;# in rpm
print "Speed of rotation air gap field in rpm is",Ns
k = 0.8/1;
# Pemf = k*E1 = k*V;
Pemf = k*V;# produced emf in rotor in V
print "Produced emf in rotor in V is",Pemf
s = ((Ns-Nr)/Ns)*100;# in %
Ivoltage = k*(s/100)*V;# rotor induces voltage in V
f_r = (s/100)*f;# in Hz
print "The frequency of rotor current in Hz is ",round(f_r,2)
```

In [9]:

```
#pg 367
#calculate the full load slip, speed
# Given data
P = 8.;
f = 50.;# in Hz
f_r = 2.;# in Hz
#calculations
# f_r = s*f;
s = (f_r/f)*100;# in %
# s = Ns-N/Ns;
Ns = (120*f)/P;# in rpm
N = Ns*(1-(s/100));# in rpm
#results
print "The full load slip in percent is",s
print "The corresponding speed in rpm is",N
```

In [10]:

```
#pg 368
#calculate the speed
# Given data
R2 = 0.024;# in per phase
X2 = 0.6;# in ohm per phase
#calculations
s = R2/X2;
f = 50;# in Hz
P = 4;
Ns = (120*f)/P;# in rpm
# Speed corresponding to maximum torque
N = Ns*(1-s);# in rpm
#results
print "The speed at which maximum torque is developed in rpm is",N
```

In [11]:

```
#pg 368
#calculate the speed, frequency
# Given data
P = 4.;
f =60.;# in Hz
s = 0.03;
#calculations
Ns = (120*f)/P;# in rpm
N = Ns*(1-s);# in rpm
print "The synchronous speed in rpm is : ",Ns
print "The rotor speed in rpm is",N
f_r = s*f;# in Hz
print "The rotor current frequency in Hz is",f_r
# Rotor magnetic field rorats at speed
Rm = (120*f_r)/P;# in rpm
print "The rotor magnetic field rotates at speed in rpm is",Rm
```

In [12]:

```
#pg 369
#calculate the frequency, poles and speed
# Given data
N = 960.;# in rpm
f = 50.;# in Hz
Ns = 1000.;# in rpm
#calculations
s = ((Ns-N)/Ns)*100;# %s in %
print "The slip in percent is",s
f_r = (s/100)*f;# in Hz
print "The frequency of rotor induced emf in Hz is",f_r
# Ns = (120*f)/P;
P = (120*f)/Ns;
print "The number of poles is",P
# Speed of rotor field with respect to rotor structure
s1 = (120*f_r)/P;# in rpm
print "Speed of rotor field with respect to rotor structure in rpm is",s1
```

In [13]:

```
#pg 369
#calculate the full load speed
# Given data
P = 4.;
f = 50.;# in Hz
Sfl = 4./100;
#calculations
Ns = (120*f)/P;# in rpm
# The full load speed, Sfl = (Ns-Nfl)/Ns;
Nfl = Ns - (Sfl*Ns);# in rpm
#results
print "The full load speed in rpm is",Nfl
```