In [1]:

```
from __future__ import division
import math
#given data :
s=22;# shaft of the motor in hp
Tsh=210;# torue in hp
#calculations:
N=(s*60*746)/(2*math.pi*Tsh);
#Results
print "speed,N(rpm) = ",N
```

In [2]:

```
from __future__ import division
import math
#given data :
N=955;# in r.p.m
V=230;# voltage in volts
I=72;# current in A
s=968;# stray losses
Rsh=115;# shunt field resistance in ohm
Ra=0.5# armature resistance in ohm
#calculations:
W=V*I;
Ish=V/Rsh# shunt field resistance
Ia=I-Ish;
Eb=V-(Ia*Ra)# back emf in volts
Dpd=Eb*Ia# driving power developed
Mpo=Dpd-s;
bhp=Mpo/746;
c_losses=W-Dpd;
Ta=(9.55*Eb*Ia)/N;
Tsh=(bhp*60*746)/(2*math.pi*N);
Tl=Ta-Tsh;
eta=(Mpo/W)*100;
#Results
print "(a)bhp = ",bhp
print "(b)copper losses(W) = ",c_losses
print "(c)torque armature,Ta(N-m) = ",Ta
print "(d)shaft torque,Tsh(N-m) = ",round(Tsh,2)
print "(e)lost torque,Tl(N-m) = ",round(Tl,2)
print "(f)commercial efficioency,eta(%) = ",round(eta,2)
```

In [3]:

```
from __future__ import division
import math
#given data:
V=230# in volts
I=5 # in amperes
rpm=914#turns
ra=0.5#resistance of armature in ihms
rsh=115#shunt field in ohms
Il=30# in amperes
ar=10# in percent
#calculations:
Ish=V/rsh# in amperes
anl=I-Ish#armature current in amperes at no load
al=Il-Ish#armature currentin amperes at load
Eb1=(V-anl*ra)#back emf at no load
Eb2=(V-al*ra)#back emf at load
ph1=100#
ph2=90#
Ns=(rpm*Eb2*ph1)/(Eb1*ph2)#speed when loaded in rpm
#Results
print "speed when loaded in rpm is ",Ns
```

In [4]:

```
from __future__ import division
import math
#given data:
Il=83# WHEN LOADED IN AMPERES
V=110# in volts
I=5 # in amperes without load
ra=0.5#armature resistance in ohms
rsh=110#shunt field in ohms
#calculations:
Ish=V/rsh# in ampere
anl=I-Ish#armature current in amperes at no load
al=Il-Ish#armature currentin amperes at load
Eb1=(V-anl*ra)#back emf at no load
Eb2=(V-al*ra)#back emf at load
Dp=Eb1*anl#driving power at no load in watt
Dpl=Eb2*al#driving power at load in watt
mo=Dpl-Dp#out of motor in watt
bhp=mo/746#horse power
mi=V*Il#input power in watt
n=(mo/mi)*100#efficiency in percentage
#Results
print "(a)stray losses in watt is",Dp
print "(b)horse power in ampere is",round(bhp,1)
print "(c)efficiency of motor when it is work on full ,load in percentage is",round(n,2)
#answer(c) is wrong in the textbook
```

In [5]:

```
from __future__ import division
import math
#given data:
V=230# in volts
I=60# in amperes
rpm=955#turns
ra=0.2#resistance of armature in ihms
rsh=0.15#shunt field in ohms
sl=604#stray losses in watts
#calculations:
Rm=ra+rsh# in ohms
Eb=(V-I*Rm)# back emf in volts
Dp=Eb*I#driving power in watts
mi=V*I#input power in watts
Cl=mi-Dp# copper losses in watts
mo=Dp-sl#output of motor
bhp=mo/746# horse power in bhp
Ta=(9.55*Eb*I)/rpm#total torque in N-m
Ts=(bhp*60*746)/(2*math.pi*rpm)#shaft torque in N-m
Tl=Ta-Ts#lost torque in N-m
nc=(mo/mi)*100#commercial efficiency in percentge
#Results
print "(a)back emf in volts is",Eb
print "(b)copper losses in watts is ",Cl
print "(c)horse power is", bhp
print "(d)total torque in N-m is",Ta
print "(e)shaft torque in N-m is",round(Ts,1)
print "(f)lost torque in N-m is",round(Tl,1)
print "(g)commercial efficiency in percentge is",round(nc,2)
```

In [6]:

```
from __future__ import division
import math
#given data:
V=220# in volts
I=60# in amperes
rpm=728#turns
Ts=150#shaft torque in N-m
nc=80#commercial efficiency in percentge
#calculations:
I=((Ts*2*math.pi*rpm*746)/(60*746*(nc/100)*V))# CURRENT TAKEN IN AMPERES
#Results
print "current taken in amperes is",round(I,1)
```

In [7]:

```
from __future__ import division
import math
#given data:
V=220# in volts
rpm=2100#turns
ra=0.5#resistance of armature in ihms
rsh=220#shunt field in ohms
Il=21# in amperes
R1=220# in ohms
ph1=50#
ph2=100#
#calculations:
Ish=V/rsh# in amperes
Ifs=V/(rsh+R1)#shunt field current in second case in ampere
n2=(rpm*ph2)/ph1#speed in rpm
#Results
print "speed in rpm is",n2
```