13 files changed, 263 insertions, 0 deletions
diff --git a/2252/CH19/EX19.1/Ex19_1.sce b/2252/CH19/EX19.1/Ex19_1.sce
new file mode 100755
index 000000000..3604fb04d
--- /dev/null
+++ b/2252/CH19/EX19.1/Ex19_1.sce
@@ -0,0 +1,19 @@
+
+//calculating torque deveoped
+P=6//no. of poles 
+A=6//no. of parallel circuits
+Ia=300//armature current
+n=500//no. of armature turns
+Z=2*500//total no. of conductors
+phi=75D-3//flux per pole
+Ta=.159*P*phi*Ia*Z/A
+mprintf("Torque developed=%f N-m\n",Ta)
+//calculating shaft torque
+T=2.5*Ta/100//torque lost in windage, friction and iron losses
+Tsh=Ta-T
+mprintf("Shaft torque=%f N-m\n",Tsh)
+//calculating shaft power
+N=400//speed in rpm
+Psh=2*%pi*N*Tsh/60
+mprintf("Shaft power=%f kW",Psh/1000)
+//answer vary from the textbook due to round off error
diff --git a/2252/CH19/EX19.10/Ex19_10.sce b/2252/CH19/EX19.10/Ex19_10.sce
new file mode 100755
index 000000000..363416c44
--- /dev/null
+++ b/2252/CH19/EX19.10/Ex19_10.sce
@@ -0,0 +1,11 @@
+
+V=500//applied voltage
+N1=700//initial speed of motor
+Ia1=50//armature current
+Ra=.4//effective armature resistance
+Eb1=V-Ia1*Ra
+N2=600//reduced speeed of motor
+Ia2=Ia1//as torque and flux remains same
+//back emf is directly proportional to speed
+R=((V-Ia2*Ra)*N1-Eb1*N2)/(Ia2*N1)
+mprintf("Additional resistance in the armature circuit is %f ohm",R)
diff --git a/2252/CH19/EX19.11/Ex19_11.sce b/2252/CH19/EX19.11/Ex19_11.sce
new file mode 100755
index 000000000..5575480c9
--- /dev/null
+++ b/2252/CH19/EX19.11/Ex19_11.sce
@@ -0,0 +1,20 @@
+
+R=.25+.05//total resistance of the armature circuit
+N1=500//normal speed
+V=250//applied voltage
+Ia1=100//armature current at normal speed
+Eb1=V-Ia1*R
+//solving part (i)
+R1=R+1//total resisitance in the armature circuit
+Ia2=50//armature current
+Eb2=V-Ia2*R1
+//back emf is directly proportional to speed
+N2=Eb2/Eb1*N1
+mprintf("For(i)\nSpeed=%d rpm\n",round(N2))
+//solving part (ii)
+Ia3=50//armature current
+Eb3=V-Ia3*R
+//Ish3=.6*Ish1-->phi3/phi1=.6
+//back emf is directly proportional to flux and speed
+N3=(Eb3/Eb1)*N1/.6
+mprintf("For(ii)\nSpeed=%d rpm", N3)
diff --git a/2252/CH19/EX19.12/Ex19_12.sce b/2252/CH19/EX19.12/Ex19_12.sce
new file mode 100755
index 000000000..9829f1222
--- /dev/null
+++ b/2252/CH19/EX19.12/Ex19_12.sce
@@ -0,0 +1,23 @@
+
+//solving (i)
+Il=70//current drawn by the motor
+V=200//applied voltage
+Rsh=100//shunt field resistance
+Ish=V/Rsh//shunt field current
+Ia1=Il-Ish
+N1=500//initial speed
+Ra1=.2//armature resistance
+Eb1=200-Ia1*Ra1
+N2=350//reduced speed of motor
+Ia2=Ia1//armature current remains same
+//Eb2=200-68*(R+.2)
+//back emf is proportional to speed
+R=((V-Ia2*Ra1)*N1-Eb1*N2)/(Ia2*N1)
+mprintf("Additional resistance in the armature circuit=%f ohm\n",R)
+//solving (ii)
+Ra2=R+Ra1//armature resistance
+Ia3=35//armature current
+Eb3=V-Ia3*Ra2
+N3=N1*Eb3/Eb1
+mprintf("Speed=%d rpm",N3)
+//answer vary from the textbook due to round off error
diff --git a/2252/CH19/EX19.13/Ex19_13.sce b/2252/CH19/EX19.13/Ex19_13.sce
new file mode 100755
index 000000000..e8416ea15
--- /dev/null
+++ b/2252/CH19/EX19.13/Ex19_13.sce
@@ -0,0 +1,14 @@
+
+V=250//voltage applied to the motor
+Eb1=V//Ra is negligible
+N1=500//speed in rpm
+Ia1=40//armature current
+R=25//additional resistance
+//as flux remains same, back emf is directly proportional to speed; and torque is directly proportional to armature current
+//Eb2=250-Ia2*25, N2=500-50*Ia2
+//also, torque varies as cube of speed
+//from these conditions, we get, Ia2^3-30*Ia2^2+325*Ia2-1000=0
+//solving this equation, we get
+Ia2=5
+N2=(Ia2/Ia1)^(1/3)*N1
+mprintf("Speed of the motor with 25 ohm resistor in the armature circuit=%d rpm",N2)
diff --git a/2252/CH19/EX19.2/Ex19_2.sce b/2252/CH19/EX19.2/Ex19_2.sce
new file mode 100755
index 000000000..029497bb6
--- /dev/null
+++ b/2252/CH19/EX19.2/Ex19_2.sce
@@ -0,0 +1,28 @@
+
+//calculating torque developed by armature
+V=200//voltage applied across the motor
+Rsh=40//resistance of shunt field winding
+Ish=V/Rsh
+I=100//total current drawn by motor
+Ia=I-Ish
+Ra=.1//armature resistance
+Eb=V-Ia*Ra
+P=Eb*Ia//mechanical power developed
+N=750//speed in rpm
+Ta=60*P/(2*%pi*N)
+mprintf("Torque developed by armature=%f N-m\n",Ta)
+//calculating copper losses
+Wcu1=V*Ia-Eb*Ia//armature copper losses
+Wcu2=Ish^2*Rsh//field copper losses
+mprintf("Total copper losses=%f W\n",Wcu1+Wcu2)
+//calculating shaft power
+Wc=1500//friction and iron losses
+Pi=200*100//input to motor
+Psh=Pi-(Wc+Wcu1+Wcu2)
+mprintf("Shaft power=%f kW\n",Psh/1000)
+//calculating shaft torque
+Tsh=60*Psh/(2*%pi*N)
+mprintf("Shaft torque=%f N-m\n",Tsh)
+//calculating efficiency
+e=Psh/Pi*100
+mprintf("Efficiency=%f percent",e)
diff --git a/2252/CH19/EX19.3/Ex19_3.sce b/2252/CH19/EX19.3/Ex19_3.sce
new file mode 100755
index 000000000..bf4c06282
--- /dev/null
+++ b/2252/CH19/EX19.3/Ex19_3.sce
@@ -0,0 +1,25 @@
+
+Po=60D+3//full load output of the motor 
+e=0.905//efficiency of the motor
+Pin=Po/e
+V=400//applied voltage
+I=Pin/V//line current drawn by the motor
+Rsh=200//resistance of the shunt field winding
+Ish=V/Rsh
+Ia=I-Ish
+Ra=0.1//armature resistance
+Eb=V-Ia*Ra
+A=2//no. of parallel paths in armature winding
+P=4//no. of poles
+phi=45D-3//flux per pole
+Z=450//total number of conductors
+N=round(60*Eb*A/(P*phi*Z))
+mprintf("Full load speed=%d rpm\n",N)
+//calculating armature torque
+Ta=0.159*P*phi*Ia*Z/A
+mprintf("Torque developed by the armature of the DC motor=%f N-m\n",Ta)
+//calculating useful torque
+Psh=60D+3//shaft power
+Tsh=60*Psh/(2*%pi*N)
+mprintf("Useful torque=%f N-m",Tsh)
+//error in the textbook answer for useful torque
diff --git a/2252/CH19/EX19.4/Ex19_4.sce b/2252/CH19/EX19.4/Ex19_4.sce
new file mode 100755
index 000000000..12d1aa463
--- /dev/null
+++ b/2252/CH19/EX19.4/Ex19_4.sce
@@ -0,0 +1,17 @@
+
+V=220//voltage applied to motor
+Rsh=157//shunt field resistance
+Ra=0.3//armature resistance
+Ish=V/Rsh
+I0=4.5//current drawn by the motor at no load
+Ia0=I0-Ish
+Eb0=V-Ia0*Ra
+//under loaded conditions,
+I=30//current drawn by motor
+Ia=I-Ish
+Eb=V-Ia*Ra
+//phi=.97*phi0
+//back emf is directly proportional to flux and speed
+N0=1000//speed at no load
+N=Eb*N0/(Eb0*.97)
+mprintf("Speed under loaded condition=%d rpm", round(N))
diff --git a/2252/CH19/EX19.5/Ex19_5.sce b/2252/CH19/EX19.5/Ex19_5.sce
new file mode 100755
index 000000000..c49bfb308
--- /dev/null
+++ b/2252/CH19/EX19.5/Ex19_5.sce
@@ -0,0 +1,19 @@
+
+//calculating shaft power
+V=100//voltage applied to series motor
+Ra=.22//armature resistance
+Rse=.13//series field resistance
+Rm=Ra+Rse//total resistance
+Ia=45//current in armature circuit
+Eb=V-Ia*Rm
+Pm=Eb*Ia//mechanical power developed
+Wc=750//iron and friction losses
+Psh=Pm-Wc
+mprintf("Shaft power=%f kW\n",Psh/1000)
+//calculating torque developed
+N=750//speed in rpm
+Ta=60*Pm/(2*%pi*N)
+mprintf("Total torque=%f N-m\n",Ta)
+//calculating shaft torque
+Tsh=60*Psh/(2*%pi*N)
+mprintf("Shaft torque=%f N-m",Tsh)
diff --git a/2252/CH19/EX19.6/Ex19_6.sce b/2252/CH19/EX19.6/Ex19_6.sce
new file mode 100755
index 000000000..e509de1c4
--- /dev/null
+++ b/2252/CH19/EX19.6/Ex19_6.sce
@@ -0,0 +1,29 @@
+
+//calculating speed
+P=4//no. of poles
+V=220//applied voltage
+Ia=46//current in armature circuit
+Ra=.25//field resistance
+Rse=.15//series field resistance
+Rm=Ra+Rse
+Eb=V-Ia*Rm
+A=2//no. of parallel circuits
+phi=20D-3//flux per pole
+Z=1200//total conductors on armature
+N=round(60*Eb*A/(P*phi*Z))
+mprintf("Speed, N=%d rpm\n", N)
+//calculating total torque
+Ta=.159*P*phi*Ia*Z/A
+mprintf("Total torque=%f N-m\n",Ta)
+//calculating shaft power
+Pm=Eb*Ia//mechanical power developed
+Wc=900//iron and friction losses
+Po=Pm-Wc
+mprintf("Shaft power=%f kW\n",Po/1000)
+//calculating shaft torque
+Tsh=60*Po/(2*%pi*N)
+mprintf("Shaft torque Tsh=%f N-m\n", Tsh)
+//calculating efficiency
+Pin=V*Ia//input to motor
+e=Po/Pin*100
+mprintf("Efficiency=%f percent",e)
diff --git a/2252/CH19/EX19.7/Ex19_7.sce b/2252/CH19/EX19.7/Ex19_7.sce
new file mode 100755
index 000000000..3ab09f805
--- /dev/null
+++ b/2252/CH19/EX19.7/Ex19_7.sce
@@ -0,0 +1,27 @@
+
+//working as motor
+V1=110//applied voltage to motor
+Rsh=45//shunt field resistance
+Ish1=V1/Rsh//shunt field current
+Il=230
+Ia1=Il-Ish1
+Ra=.03//armature resistance
+Eb1=V1-Ia1*Ra
+N1=450//speed in rpm
+V2=210//changed value of applied voltage
+Ish2=V2/Rsh
+Il=85//current drawn by the motor from the main
+Ia2=Il-Ish2
+Eb2=V2-Ia2*Ra
+//back emf is directly proportional to shunt field current and speed
+N2=(Eb2/Eb1)*(Ish1/Ish2)*N1
+mprintf("Speed of the motor=%d rpm\n",N2)
+//working as generator
+V=200//terminal voltage across the load
+Ish3=V/Rsh
+Il=140//load current on the generator
+Ia3=Il+Ish3
+Eg=V+Ia3*Ra
+N3=(Eg/Eb1)*(Ish1/Ish3)*N1
+mprintf("Speed at which generator would have to run=%d rpm",N3)
+//answers vary from the textbook due to round off error
diff --git a/2252/CH19/EX19.8/Ex19_8.sce b/2252/CH19/EX19.8/Ex19_8.sce
new file mode 100755
index 000000000..142ba9a9e
--- /dev/null
+++ b/2252/CH19/EX19.8/Ex19_8.sce
@@ -0,0 +1,12 @@
+
+V=230//voltage applied to motor
+N1=1000//initial speed
+Ia=35//armature current
+Ra=.3//resistance of armature circuit
+Eb1=V-Ia*Ra
+N1=1000//speed in rpm
+Ia=25//armature current in new situation
+N2=750//changed speed in rpm
+//back emf is directly proportional to speed
+R=((V-Ia*Ra)*N1-N2*Eb1)/(Ia*N1)
+mprintf("Additional resistance in armature circuit=%f ohm",R)
diff --git a/2252/CH19/EX19.9/Ex19_9.sce b/2252/CH19/EX19.9/Ex19_9.sce
new file mode 100755
index 000000000..266cd5a22
--- /dev/null
+++ b/2252/CH19/EX19.9/Ex19_9.sce
@@ -0,0 +1,19 @@
+
+N1=600//initial speed of the motor in rpm
+Ia1=20//armature current
+V=200//applied voltage
+Ra=.4//armature resistance
+Eb1=V-Ia1*Ra
+Rf1=200//field resistance
+If1=200/200//field current
+N2=900//increased speed in rpm
+//If2=200/Rf
+//phi1/phi2=If1/If2=Rf/200
+//Ia2=Ia1*phi1/phi2=.1*Rf
+//Eb2=200-.04*Rf 
+//back emf is directly proportional to flux and speed
+//we get a quadratic equation in Rf as .04*Rf^2-200*Rf+57600=0
+//solving for Rf
+Rf2=(200-sqrt(200^2-4*.04*57600))/(2*.04)
+mprintf("Additional resistance in the shunt field circuit=%f ohm",Rf2-Rf1)
+