diff options
Diffstat (limited to '1938/CH2')
63 files changed, 769 insertions, 0 deletions
diff --git a/1938/CH2/EX2.1/2_1.sce b/1938/CH2/EX2.1/2_1.sce new file mode 100755 index 000000000..5a755ccce --- /dev/null +++ b/1938/CH2/EX2.1/2_1.sce @@ -0,0 +1,9 @@ +clc,clear
+printf('Example 2.1\n\n')
+
+V=220
+I_a=30 //armature currnet
+R_a=0.75 //Armature resistance
+
+E_b=V - I_a*R_a // Since V= E_b+ I_a*R_a
+printf('Induced EMF or back EMF in the motor is %.1f V',E_b)
diff --git a/1938/CH2/EX2.10/2_10.jpg b/1938/CH2/EX2.10/2_10.jpg Binary files differnew file mode 100755 index 000000000..5f6e71e32 --- /dev/null +++ b/1938/CH2/EX2.10/2_10.jpg diff --git a/1938/CH2/EX2.10/2_10.sce b/1938/CH2/EX2.10/2_10.sce new file mode 100755 index 000000000..f1135f623 --- /dev/null +++ b/1938/CH2/EX2.10/2_10.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.10\n\n')
+
+V=250
+R_a=0.15, R_se=0.1, R_x=0.1 //Resitance of armature , series field winding and extra resistance
+N_1 = 800 //initial speed before load torque is increased
+I_1= 30 , I_a1=I_1 , I_se1 = I_1 //initial currents
+
+T_2_by_T_1 = 1 + (50/100) //50 percent increase as mentioned in question
+I_se2_by_I_a2 = R_x/(R_x + R_se) //from the figure
+
+//T (prop.) phi*I_a (prop.) I_sh*I_a and T_1=T_2 and simplifying ,solving further
+I_a2=sqrt(I_a1*I_se1*T_2_by_T_1/I_se2_by_I_a2) //new armature current
+I_se2 = I_se2_by_I_a2 *I_a2 //new series field current
+
+E_b1 = V - I_a1*R_a - I_se1*R_se //indiced emf initially
+E_b2 = V - I_a2*R_a - I_se2*R_se //new induced emf
+N_2 = N_1 * (E_b2/E_b1) * (I_se1/I_se2) //required speed
+printf('The required running speed of motor is %.3f r.p.m',N_2)
diff --git a/1938/CH2/EX2.11/2_11.jpg b/1938/CH2/EX2.11/2_11.jpg Binary files differnew file mode 100755 index 000000000..2eda81906 --- /dev/null +++ b/1938/CH2/EX2.11/2_11.jpg diff --git a/1938/CH2/EX2.11/2_11.sce b/1938/CH2/EX2.11/2_11.sce new file mode 100755 index 000000000..a88a7620c --- /dev/null +++ b/1938/CH2/EX2.11/2_11.sce @@ -0,0 +1,15 @@ +clc,clear
+printf('Example 2.11\n\n')
+
+V=220
+I_1=50, I_a1=I_1 //Currents before adding extra resistance
+T_2_by_T_1 =0.5
+R_t=0.15 //R_e + R_se =0.15
+
+I_a2 =I_a1 * sqrt(T_2_by_T_1) //Because T (prop.) I_a^2
+E_b1=V-I_a1*(R_t) //induced emf before adding extra resistance
+N_1=500,N_2=300 //speeds before and adding extra resistance
+//N (prop.) E_b/phi (prop.) E_b/I_a
+E_b2=E_b1 *(I_a2/I_a1)*(N_2/N_1) //induced emf after adding resistance
+R_x= (V-E_b2)/I_a2 -R_t //because E_b2=V - I_a2*(R_a + R_se + R_x)
+printf('Desired extrea resistance= %.4f ohms ',R_x)
diff --git a/1938/CH2/EX2.12/2_12.sce b/1938/CH2/EX2.12/2_12.sce new file mode 100755 index 000000000..defe7c611 --- /dev/null +++ b/1938/CH2/EX2.12/2_12.sce @@ -0,0 +1,27 @@ +clc,clear
+printf('Example 2.12\n\n')
+
+R_a= 1, I_a=1.2 , V=50
+//part(i)
+E_b = V - I_a*R_a
+rot_loss_NL =E_b*I_a //no load rotational loss
+printf('(i)No load rotational losses = %.2f W',rot_loss_NL)
+
+//part(ii)
+omega_2000=2*%pi*2000/60 //angular velocity when speed of motor =2000 rpm
+K_m=E_b/omega_2000 //to determine K_m
+V=48
+omega_1800=2*%pi*1800/60 //angular velocity when speed of motor =1800 rpm
+E_b=K_m*omega_1800
+I_a = (V-E_b)/R_a //armature current
+P_dev = E_b*I_a//power developed
+motor_output = P_dev - rot_loss_NL
+printf('\n(ii)Motor output = %.2f W',motor_output)
+
+//part(iii)
+E_b=0 //when motor stalls
+V_stall=20 //voltage during stalling
+I_a=V_stall/R_a //armature current during stalling
+T_stall = K_m*I_a //stalling torque
+printf('\n(iii)Stalling torque = %.2f N-m',T_stall)
+printf('\n\npart(ii) answer is slightly different due to inaccurate calculation of Power developed')
diff --git a/1938/CH2/EX2.13/2_13.sce b/1938/CH2/EX2.13/2_13.sce new file mode 100755 index 000000000..2e948aec3 --- /dev/null +++ b/1938/CH2/EX2.13/2_13.sce @@ -0,0 +1,15 @@ +clc,clear
+printf('Example 2.13\n\n')
+
+V=120
+R_a=0.2 , R_sh=60 //armature and field resistance
+I_L1=40, N_1=1800
+I_sh= V/R_sh
+
+I_a1=I_L1 - I_sh
+E_b1 = V -I_a1*R_a //Induced emf at half load
+T2_by_T1 =1/2
+I_a2=I_a1*(T2_by_T1) //T (prop.)I_a
+E_b2=V- I_a2*R_a//induced emf at half load
+N_2 = N_1 *(E_b2/E_b1) //N (prop.) E_b as phi is constant
+printf('Speed on half load condition is %.2f r.p.m',N_2)
diff --git a/1938/CH2/EX2.14/2_14.jpg b/1938/CH2/EX2.14/2_14.jpg Binary files differnew file mode 100755 index 000000000..790833b91 --- /dev/null +++ b/1938/CH2/EX2.14/2_14.jpg diff --git a/1938/CH2/EX2.14/2_14.sce b/1938/CH2/EX2.14/2_14.sce new file mode 100755 index 000000000..cf610f216 --- /dev/null +++ b/1938/CH2/EX2.14/2_14.sce @@ -0,0 +1,24 @@ +clc,clear
+printf('Example 2.14\n\n')
+
+R_a=0.08, E_b1=242 , V=250
+//part(i)
+I_a1= (V-E_b1)/R_a
+printf('(i)Armature current = %.0f A',I_a1)
+
+//part(ii)
+N=0
+E_b=0 //because N=0
+I_a_start=V/R_a
+printf('\n(ii)Starting armature current = %.0f A',I_a_start)
+
+//part(iii)
+I_a2=120
+E_b2=V-I_a2*R_a
+printf('\n(iii)Back emf if armature current is changed to 120 A= %.1f V',E_b2)
+
+//part(iv)
+I_a=87,N_m=1500
+E_g=V + I_a*R_a //induced emf
+N_g=N_m*(E_g/E_b1)//as E (prop.) N
+printf('\n(iv)Generator speed to deliver 87 A at 250 V = %.1f rpm',N_g)
diff --git a/1938/CH2/EX2.15/2_15.jpg b/1938/CH2/EX2.15/2_15.jpg Binary files differnew file mode 100755 index 000000000..6da36eb26 --- /dev/null +++ b/1938/CH2/EX2.15/2_15.jpg diff --git a/1938/CH2/EX2.15/2_15.sce b/1938/CH2/EX2.15/2_15.sce new file mode 100755 index 000000000..18ec4e810 --- /dev/null +++ b/1938/CH2/EX2.15/2_15.sce @@ -0,0 +1,30 @@ +clc,clear
+printf('Example 2.15\n\n')
+
+shaft_output = 80*746 //coverted to watts
+eta= 80/100 //efficiency
+V=250
+N_1=1200
+R_a=0.04,R_sh = 250 //armature and shunt field resistance
+power_input = shaft_output/eta
+I_L= power_input /V
+I_sh= V / R_sh
+I_a = I_L - I_sh
+E_b1 = V - I_a*R_a
+
+gross_mechanical_power= E_b1*I_a //electrical equivalent of mechanical power developed
+stray_losses = gross_mechanical_power - shaft_output
+printf('Mechanical power developed on full load = %.3f kW\n',gross_mechanical_power/1000)
+
+//on no load shaft_output=0 and entire gross power is used to overcome stray losses
+Eb0_Ia0= stray_losses
+//E_b0 = V - I_a0*R_a ... solving for I_0
+p=[R_a -V Eb0_Ia0]
+roots(p)
+I_a0=ans(2) //first root is ignored since its too large
+I_L0 =I_sh+I_a0 //current drawn from supply
+E_b0 = V - I_a0*R_a
+
+//From speed equation N (prop.) E_b
+N_0 = N_1*(E_b0/E_b1)
+printf('No load speed and current are %.4f rpm and %.2f A respectively',N_0,I_L0)
diff --git a/1938/CH2/EX2.16/2_16.sce b/1938/CH2/EX2.16/2_16.sce new file mode 100755 index 000000000..04d0f6884 --- /dev/null +++ b/1938/CH2/EX2.16/2_16.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.16\n\n')
+
+V=250, P=4
+R_a=0.1 , R_sh =124 //armature and shunt field resistance
+I_L0=4,N_0=1200
+I_L_1=61
+I_sh=V/R_sh
+I_a0=I_L0-I_sh
+V_brush= 2 //voltage loss due to brush
+E_b0= V - I_a0*R_a- V_brush
+
+I_a1=I_L_1 - I_sh
+E_b1=V - I_a1*R_a -V_brush
+
+phi1_by_phi0=1-(5/100) //weakened by 5 %
+N_1 = N_0 *(E_b1/E_b0) /phi1_by_phi0
+
+printf('Full load speed is %.3f r.p.m',N_1)
diff --git a/1938/CH2/EX2.17/2_17.sce b/1938/CH2/EX2.17/2_17.sce new file mode 100755 index 000000000..2d4278875 --- /dev/null +++ b/1938/CH2/EX2.17/2_17.sce @@ -0,0 +1,37 @@ +clc,clear
+printf('Example 2.17\n\n')
+
+V=250
+R_a=0.15 , R_sh=167.67 //armature and shunt field resistance
+N_0=1280 //speed at no load
+
+//full load
+I_L1 = 67 //current drawn on full load
+I_sh = V / R_sh //as shunt motor
+I_a1= I_L1- I_sh
+E_b1= V - I_a1*R_a
+
+//on no load
+I_L0=6.5
+I_a0 = I_L0 - I_sh
+E_b0 = V - I_a0*R_a
+
+//part(i) USING SPEED EQUATION
+//N (prop.) E_b/phi (prop.)E_b //as phi is constant
+N_1 = N_0 * (E_b1 / E_b0)
+printf('(i)Full load speed = %.3f r.p.m\n',N_1)
+
+//part(ii)
+speed_regulation = 100* ((N_0-N_1)/N_1)
+//N_1 is full load speed and N_0=No load speed
+printf('(ii)Speed regulation = %.2f percent \n',speed_regulation )
+
+//part(iii)
+shaft_output_FL = E_b1*I_a1 - E_b0*I_a0 //full load power developed - stray losses
+hp_rating = shaft_output_FL /746
+printf('(iii)HP rating of machine = %.2f h.p\n',hp_rating)
+
+//part(iv)
+power_input= V*I_L1
+eta= 100*(shaft_output_FL/power_input) //full load efficiency
+printf('(iv)Full load efficiency = %.2f percent',eta)
diff --git a/1938/CH2/EX2.18/2_18.jpg b/1938/CH2/EX2.18/2_18.jpg Binary files differnew file mode 100755 index 000000000..06873afc5 --- /dev/null +++ b/1938/CH2/EX2.18/2_18.jpg diff --git a/1938/CH2/EX2.18/2_18.sce b/1938/CH2/EX2.18/2_18.sce new file mode 100755 index 000000000..4766737b5 --- /dev/null +++ b/1938/CH2/EX2.18/2_18.sce @@ -0,0 +1,16 @@ +clc,clear
+printf('Example 2.18\n\n')
+
+V=200
+R_a=0.5, R_se=0.2, R_x=0.2 //armature and series field resistance; extra resistance
+I_a1=20, I_1=I_a1 , I_se1=I_a1
+I_a2=20, I_2=I_a2
+I_se2= I_2 *(R_x/(R_se+R_x))
+
+E_b1 = V -I_a1*R_a - I_a1*R_se
+E_b2 = V -I_a2*R_a - I_se2*R_se
+
+phi2_by_phi1=70/100
+N_1=1000
+N_2=N_1*(E_b2/E_b1) /phi2_by_phi1 //N (prop.) E_b/phi
+printf('Required speed is %.2f r.p.m',N_2)
diff --git a/1938/CH2/EX2.19/2_19.jpg b/1938/CH2/EX2.19/2_19.jpg Binary files differnew file mode 100755 index 000000000..38143c55b --- /dev/null +++ b/1938/CH2/EX2.19/2_19.jpg diff --git a/1938/CH2/EX2.19/2_19.sce b/1938/CH2/EX2.19/2_19.sce new file mode 100755 index 000000000..7b102705d --- /dev/null +++ b/1938/CH2/EX2.19/2_19.sce @@ -0,0 +1,27 @@ +clc,clear
+printf('Example 2.19\n\n')
+
+V=110
+P=4
+R_a = 0.1,R=0.01 //A resistance of 0.01 ohms
+R_se=R+R
+
+//case(i)
+I_1=50, I_a1=I_1
+N_1=700
+E_b1 = V -I_a1*(R_a + R_se)
+
+//T (prop.) phi*I_a from torque equation (1)
+
+//phi_1 (prop.) I_a1 (2)
+//case(ii) when I_a2 gets divided to half
+//phi_2 (prop.) I_a2/2 (3)
+
+//combining (1)(2)(3) and T1=T2
+I_a2 = sqrt(2*I_a1^2)
+R_se_eqvt=(R*R)/(R+R) //Equavalent of parallel combination
+E_b2 = V - I_a2*R_a - I_a2* R_se_eqvt
+
+//Using speed equation N (prop.) E_b / phi and using (2) and (3)
+N_2 = N_1 *( E_b2/E_b1) *(I_a1/(I_a2/2))
+printf('Speed after reconnection = %.3f r.p.m\n\n',N_2)
diff --git a/1938/CH2/EX2.2/2_2.sce b/1938/CH2/EX2.2/2_2.sce new file mode 100755 index 000000000..38d63897e --- /dev/null +++ b/1938/CH2/EX2.2/2_2.sce @@ -0,0 +1,13 @@ +clc,clear
+printf('Example 2.2\n\n')
+
+Pole=4
+A=Pole //for lap winding
+V=230
+Z=250 //number of armature conductors
+phi=30*10^-3 //flux per pole in weber
+I_a=40,R_a=0.6 //Armature resistance
+
+E_b=V - I_a*R_a // Since V= E_b+ I_a*R_a
+N=E_b * 60*A/(phi*Pole*Z) //because E_b = phi*P*N*Z/(60*A)
+printf('Back emf is %.0f V and running speed is %.0f rpm',E_b,N)
diff --git a/1938/CH2/EX2.20/2_20.jpg b/1938/CH2/EX2.20/2_20.jpg Binary files differnew file mode 100755 index 000000000..2b265953c --- /dev/null +++ b/1938/CH2/EX2.20/2_20.jpg diff --git a/1938/CH2/EX2.20/2_20.sce b/1938/CH2/EX2.20/2_20.sce new file mode 100755 index 000000000..03b9dfe61 --- /dev/null +++ b/1938/CH2/EX2.20/2_20.sce @@ -0,0 +1,28 @@ +clc,clear
+printf('Example 2.20\n\n')
+
+P=4, I_a1= 50, N_1=2000, V=230
+
+//phi_1 is proportioanl to total ampere-turns produced by field coils
+//phi_1 (prop.) I_a1*P*n (prop.) 200*n (1)
+
+//After reconnection, phi_2 proportional to ampere turns divided as follows
+//phi_2 (prop.) [I_a2/2*2*n + I_a2/2*2*n] (prop.) 2*n*I_a2 (2)
+
+// Dividing (1) and (2) , (phi_1/phi_2)=100 / I_a2 (3)
+
+//T (prop.) phi*I_a AND T (prop.) N^2 (4),(5)
+//therefore N^2 (prop.) phi*I_a (6)
+
+//N (prop.) E_b/phi (prop.) 1/phi ..
+//Because drops across windings can be neglected, E_b1=E_b2
+//therefore N (prop.) 1/phi (7)
+
+//Using (7) and (6) phi^3 (prop.) 1/I_a (8)
+
+//combining (3) and (8)
+I_a2 = (50*100^3)^(1/4) //new armature current
+printf('New armature current= %.3f A\n',I_a2)
+//combining (6) and (7) , N^3 (prop.) I_a1
+N_2=N_1 *(I_a2/I_a1)^(1/3)
+printf('New motor speed =%.3f r.p.m',N_2)
diff --git a/1938/CH2/EX2.21/2_21.sce b/1938/CH2/EX2.21/2_21.sce new file mode 100755 index 000000000..6b09b4821 --- /dev/null +++ b/1938/CH2/EX2.21/2_21.sce @@ -0,0 +1,12 @@ +clc,clear
+printf('Example 2.21\n\n')
+
+// K_1= E_b/N = (phi*P*Z)/(60*A)
+
+//P_m = T * omega
+//E_b*I_a = T *(2*%pi*N/60)
+//T= I_a (E_b*60 / 2*%pi*N )
+//Use E_b= phi*P*N*Z/(2*%pi*A)
+//T / I_a = phi*P*Z / (2*%pi*A) =K_dasah
+
+printf('The constant of proportionality in both the cases is K=K_dash = phi*P*Z /(2*3.142*A)')
diff --git a/1938/CH2/EX2.22/2_22.jpg b/1938/CH2/EX2.22/2_22.jpg Binary files differnew file mode 100755 index 000000000..a95265802 --- /dev/null +++ b/1938/CH2/EX2.22/2_22.jpg diff --git a/1938/CH2/EX2.22/2_22.sce b/1938/CH2/EX2.22/2_22.sce new file mode 100755 index 000000000..0f6daca14 --- /dev/null +++ b/1938/CH2/EX2.22/2_22.sce @@ -0,0 +1,16 @@ +clc,clear
+printf('Example 2.22\n\n')
+
+V=200,I_a1=30
+R_t=1.5 //R_a + R_se
+E_b1= V - I_a1*R_t
+N2_by_N1=(60/100)
+
+//T (prop.) I_a^2 and T (prop.) N_3....therefore I_a^2 (prop.) N^3
+I_a2 = I_a1*sqrt(N2_by_N1^3)
+
+//N (prop.) E_b/I_a
+N2_by_N1
+E_b2 = E_b1 *(I_a2/I_a1)*N2_by_N1
+R_x= (V- E_b2)/I_a2 - R_t //because E_b2= V - I_a2*(R_x+R_t)
+printf('Additional resistance to be added in series with motor circuit = %.3f ohms',R_x)
diff --git a/1938/CH2/EX2.23/2_23.jpg b/1938/CH2/EX2.23/2_23.jpg Binary files differnew file mode 100755 index 000000000..3860797a6 --- /dev/null +++ b/1938/CH2/EX2.23/2_23.jpg diff --git a/1938/CH2/EX2.23/2_23.sce b/1938/CH2/EX2.23/2_23.sce new file mode 100755 index 000000000..3efedab6b --- /dev/null +++ b/1938/CH2/EX2.23/2_23.sce @@ -0,0 +1,26 @@ +clc,clear
+printf('Example 2.23\n\n')
+
+V=250,
+R_a=0.4 , R_sh=100 //armature and shunt field resistance
+I_sh1=V / R_sh
+P_out_FL = 10 * 735.5
+eta=85/100 //efficiency
+P_in= P_out_FL/eta
+I_L1= P_in /V
+I_a1= I_L1 - I_sh1
+
+// T (prop.) phi*I_a (prop.) I_sh*I_a because phi (prop.) I_sh
+//Bu torque is constant..
+Ia2_Ish2= I_a1*I_sh1
+E_b1= V - I_a1*R_a
+
+//N (prop.) E_b/I_sh
+//put E_b2= V - I_a2*R_a and solving further for I_sh2 we get, I_sh2^2 - 1.8824 I_sh2 +0.2417=0
+p=[1 -1.8824 0.2417]
+roots(p)
+I_sh2=ans(1)
+//root 1 was considered because its always easier to attain root(1) because less resistacne is needeed
+//R_x in series with field
+R_x = (V/I_sh2) -R_sh //because I_sh2 = V/(R_sh + R_x)
+printf('Extra Resistance to be added = %.2f ohms',R_x)
diff --git a/1938/CH2/EX2.24/2_24.sce b/1938/CH2/EX2.24/2_24.sce new file mode 100755 index 000000000..9f3b5ebd8 --- /dev/null +++ b/1938/CH2/EX2.24/2_24.sce @@ -0,0 +1,16 @@ +clc,clear
+printf('Example 2.24\n\n')
+
+R_t=1 //R_t = R_se + R_a
+V_1= 230
+N_1=300,N_2=375
+I_1=15, I_a1=I_1
+
+//T (prop.) I_a^2 and T (prop.) N_2....therefore I_a^2 (prop.) N^2
+I_a2=I_a1 *(N_2/N_1)
+E_b1 = V_1 - I_a1*(R_t)
+
+//N (prop.) E_b/I_a
+E_b2= E_b1*(I_a2/I_a1)*(N_2/N_1)
+V_2=E_b2 + I_a2* (R_t) //because E_b2 = V_2 - I_a2*(R_a+R_se)
+printf('Voltage supply needed = %.4f V',V_2)
diff --git a/1938/CH2/EX2.25/2_25.jpg b/1938/CH2/EX2.25/2_25.jpg Binary files differnew file mode 100755 index 000000000..df5158794 --- /dev/null +++ b/1938/CH2/EX2.25/2_25.jpg diff --git a/1938/CH2/EX2.25/2_25.sce b/1938/CH2/EX2.25/2_25.sce new file mode 100755 index 000000000..c29186395 --- /dev/null +++ b/1938/CH2/EX2.25/2_25.sce @@ -0,0 +1,17 @@ +clc,clear
+printf('Example 2.25\n\n')
+
+I_L1=30,V=230
+R_sh=230,R_a=1
+I_sh= V / R_sh
+I_a1= I_L1 - I_sh
+E_b1 = V - I_a1*R_a
+
+//T (prop.) phi*I_a (prop.) I_a as phi is constant
+//and torque is constant
+I_a2 = I_a1
+N2_by_N1= 1/2
+//N (prop.) E_b/phi (prop.) E_b
+E_b2= E_b1 *(N2_by_N1)
+R_x= (V- E_b2)/I_a2 - R_a //Because E_b2 = V - I_a2*(R_a + R_x)
+printf('Resistance to be inserted in series = %.4f ohms ',R_x)
diff --git a/1938/CH2/EX2.26/2_26.sce b/1938/CH2/EX2.26/2_26.sce new file mode 100755 index 000000000..7f31d8efe --- /dev/null +++ b/1938/CH2/EX2.26/2_26.sce @@ -0,0 +1,15 @@ +clc,clear
+printf('Example 2.26\n\n')
+
+T_1=40 //initial torque
+//phi_1 is initial flux
+//phi_2 is new flux
+//T_2 is new torque
+//I_a1 is initial current
+//I_a2 is new current
+phi2_by_phi1 = 1- (30/100) //decrease by 30 percent
+Ia2_by_Ia1=1+(15/100) //increase by 15 percent
+
+//T (prop.)phi*I_a
+T_2=T_1*(phi2_by_phi1)*(Ia2_by_Ia1)
+printf('New torque is %.1f N-m',T_2)
diff --git a/1938/CH2/EX2.27/2_27.jpg b/1938/CH2/EX2.27/2_27.jpg Binary files differnew file mode 100755 index 000000000..f5fdaa5a0 --- /dev/null +++ b/1938/CH2/EX2.27/2_27.jpg diff --git a/1938/CH2/EX2.27/2_27.sce b/1938/CH2/EX2.27/2_27.sce new file mode 100755 index 000000000..d64752e41 --- /dev/null +++ b/1938/CH2/EX2.27/2_27.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.27\n\n')
+
+V=230
+N_1=1000,N_2=950
+R_a=0.5, R_sh=230 //armature and shunt field resistance
+I_L1=10
+
+I_sh = V/R_sh
+I_a1 = I_L1 - I_sh
+
+//T (prop.) phi*I_a (prop.) I_a with phi constant and T is constant due to full-load
+I_a2=I_a1
+
+E_b1 = V - I_a1*R_a
+E_b2=E_b1*(N_2/N_1) //N (prop.) E_b /phi (prop.) E_b as phi is constant
+
+R_x = (V-E_b2)/I_a2 -R_a
+printf('Resistance to be inserted in series with armature = %.4f ohms',R_x)
diff --git a/1938/CH2/EX2.28/2_28.sce b/1938/CH2/EX2.28/2_28.sce new file mode 100755 index 000000000..5fbf05e07 --- /dev/null +++ b/1938/CH2/EX2.28/2_28.sce @@ -0,0 +1,16 @@ +clc,clear
+printf('Example 2.28\n\n')
+
+V=250,N_0=1000,I_0=5
+R_a=0.2,R_sh=250 //armature and shunt field resistance
+I_L=50 //on no load
+I_sh=V / R_sh
+I_a0 = I_0 - I_sh
+I_a = I_L - I_sh
+E_b0 = V- I_a0*R_a
+E_b1 = V- I_a *R_a
+
+phi1_by_phi0 =1-(3/100) //weakens by 3 percent
+//N (prop.) E_b/phi
+N_1 = N_0 *(E_b1/E_b0) /phi1_by_phi0
+printf('Speed when loaded and drawing 50A current is %.3f r.p.m',N_1)
diff --git a/1938/CH2/EX2.29/2_29.jpg b/1938/CH2/EX2.29/2_29.jpg Binary files differnew file mode 100755 index 000000000..5f7cf0402 --- /dev/null +++ b/1938/CH2/EX2.29/2_29.jpg diff --git a/1938/CH2/EX2.29/2_29.sce b/1938/CH2/EX2.29/2_29.sce new file mode 100755 index 000000000..44e0c0466 --- /dev/null +++ b/1938/CH2/EX2.29/2_29.sce @@ -0,0 +1,17 @@ +clc,clear
+printf('Example 2.29\n\n')
+
+V=230,I_a0=3.3
+R_a=0.3,R_sh=160 //armature and shunt field resistance
+I_L1=40,N_0=1000
+E_b0 = V - I_a0*R_a
+I_sh=V/ R_sh
+I_a1 = I_L1 - I_sh
+E_b1 = V - I_a1*R_a
+phi1_by_phi0= 1- (4/100) //weakening by 4 percent
+
+N_1 = N_0 *(E_b1/E_b0)/(phi1_by_phi0) //because N (prop.) E_b/phi
+printf('Full load speed is %.4f rpm\n',N_1)
+T_0 = E_b0*I_a0/(2*%pi*N_0/60)
+T_1 = T_0*(I_a1/I_a0)*phi1_by_phi0 // because T (prop.) phi*I_a
+printf('Full load developed torque is %.4f N-m',T_1)
diff --git a/1938/CH2/EX2.3/2_3.sce b/1938/CH2/EX2.3/2_3.sce new file mode 100755 index 000000000..9979f739a --- /dev/null +++ b/1938/CH2/EX2.3/2_3.sce @@ -0,0 +1,10 @@ +clc,clear
+printf('Example 2.3\n\n')
+
+Pole=4
+A=Pole //for lap winding
+Z=480//number of armature conductors
+phi=20*10^-3 //flux per pole in weber
+I_a=50 //Armature current
+T_a = 0.159*phi*I_a*Pole*Z/A //Gross torque developed by armature
+printf('Gross torque developed by armature is %.3f N-m',T_a)
diff --git a/1938/CH2/EX2.30/2_30.jpg b/1938/CH2/EX2.30/2_30.jpg Binary files differnew file mode 100755 index 000000000..61ea168f8 --- /dev/null +++ b/1938/CH2/EX2.30/2_30.jpg diff --git a/1938/CH2/EX2.30/2_30.sce b/1938/CH2/EX2.30/2_30.sce new file mode 100755 index 000000000..9ae243ed3 --- /dev/null +++ b/1938/CH2/EX2.30/2_30.sce @@ -0,0 +1,28 @@ +clc,clear
+printf('Example 2.30\n\n')
+
+V=220
+I_L=52
+N_1=750, N_2=600
+R_a=0.2, R_sh = 110 //armature and shunt field resistance
+
+I_sh=V/ R_sh
+I_a1= I_L - I_sh
+I_a2=I_a1//T (prop.) I_a and T is constant
+E_b1 = V - I_a1*R_a
+
+//N (prop.) E_b/phi (prop.) E_b
+E_b2 = E_b1*(N_2/N_1)
+R_x = (V- E_b2)/I_a2 -R_a //Because E_b2 = V - I_a2*(R_a+R_x)
+printf('Resistance to be connected in series = %.2f ohms\n',R_x)
+
+//After R_x gets connected in series with armature and 110 ohms in series with field winding
+N_1=600
+I_sh2=V /(R_sh+110)
+I_a1=50,I_sh1=2,I_sh2=1
+//T (prop.) I_a*I_sh and T doesn't vary
+I_a2 = I_a1*(I_sh1/I_sh2)
+E_b1 = V - I_a1*(R_a+R_x)
+E_b2 = V - I_a2*(R_a+R_x)
+N_2 = N_1*(E_b2/E_b1)*(I_sh1/I_sh2) //Because N (prop.) E_b/I_sh
+printf('New speed= %.3f rpm',N_2)
diff --git a/1938/CH2/EX2.31/2_31.jpg b/1938/CH2/EX2.31/2_31.jpg Binary files differnew file mode 100755 index 000000000..5556b4e67 --- /dev/null +++ b/1938/CH2/EX2.31/2_31.jpg diff --git a/1938/CH2/EX2.31/2_31.sce b/1938/CH2/EX2.31/2_31.sce new file mode 100755 index 000000000..0dd04a94f --- /dev/null +++ b/1938/CH2/EX2.31/2_31.sce @@ -0,0 +1,15 @@ +clc,clear
+printf('Example 2.31\n\n')
+
+V=230
+R_a=0.15,R_sh=250 //armature and shunt field resistance
+I_a1=50, I_a2= 80
+N_1=800, N_2=1000
+I_sh1= V / R_sh
+
+E_b1 = V - I_a1*R_a
+E_b2 = V - I_a2*R_a
+
+I_sh2=I_sh1*(E_b2/E_b1)*(N_1/N_2) //Because N (prop.) E_b/ I_sh
+R_x= (V/I_sh2 ) - R_sh //because I_sh2 = V /(R_x+ R_sh)
+printf('Resistance to be added is \n\nR_x=%.0f ohms',R_x)
diff --git a/1938/CH2/EX2.32/2_32.jpg b/1938/CH2/EX2.32/2_32.jpg Binary files differnew file mode 100755 index 000000000..0bd5c1702 --- /dev/null +++ b/1938/CH2/EX2.32/2_32.jpg diff --git a/1938/CH2/EX2.32/2_32.sce b/1938/CH2/EX2.32/2_32.sce new file mode 100755 index 000000000..88cd9ee60 --- /dev/null +++ b/1938/CH2/EX2.32/2_32.sce @@ -0,0 +1,13 @@ +clc,clear
+printf('Example 2.32\n\n')
+
+V=230,R_a=0.5
+N_1=800,N_2=600
+I_a2 =20 , I_a1=I_a2
+E_b1 = V - I_a1*R_a
+
+//N (prop.) E_b/phi (prop.) E_b as phi is constant
+E_b2=E_b1 *(N_2/N_1)
+//additional resistance required
+R_x = (V -E_b2)/I_a2 - R_a //because E_b2 = V - I_a2*(R_a+R_x)
+printf('Additional resistance required = %.2f ohms ',R_x)
diff --git a/1938/CH2/EX2.33/2_33.jpg b/1938/CH2/EX2.33/2_33.jpg Binary files differnew file mode 100755 index 000000000..8082a81e9 --- /dev/null +++ b/1938/CH2/EX2.33/2_33.jpg diff --git a/1938/CH2/EX2.33/2_33.sce b/1938/CH2/EX2.33/2_33.sce new file mode 100755 index 000000000..720308561 --- /dev/null +++ b/1938/CH2/EX2.33/2_33.sce @@ -0,0 +1,13 @@ +clc,clear
+printf('Example 2.33\n\n')
+
+V=220
+R_a=0.5,R_x=5 //armature resistacne and extra resistance
+I_1=15, I_se1=I_1, I_se2=I_se1 , I_2=I_se2
+N_1=800
+
+E_b1 = V - I_1*R_a
+E_b2 = V - I_2*(R_a+R_x)
+
+N_2= N_1*(E_b2/E_b1)*(I_se1/I_se2) //because N (prop.) E_b/I_se
+printf('New speed of rotor = %.3f r.p.m',N_2)
diff --git a/1938/CH2/EX2.34/2_34.jpg b/1938/CH2/EX2.34/2_34.jpg Binary files differnew file mode 100755 index 000000000..59828e5f5 --- /dev/null +++ b/1938/CH2/EX2.34/2_34.jpg diff --git a/1938/CH2/EX2.34/2_34.sce b/1938/CH2/EX2.34/2_34.sce new file mode 100755 index 000000000..1486be271 --- /dev/null +++ b/1938/CH2/EX2.34/2_34.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.34\n\n')
+
+V=250, I_a1=20, R_a=0.5
+N_1=1000, N_2=500
+
+//T (prop.) I_a and T_1=T_2
+I_a2=I_a1
+E_b1 = V - I_a1*R_a
+
+//N (prop.) E_b
+E_b2= E_b1 *(N_2/N_1)
+R_x= (V-E_b2)/I_a2 - R_a //because E_b2 = V - I_a2*(R_a+R_x)
+printf('Additional resistance = %.0f ohms',R_x)
+T3_by_T2=0.5 //torque is halved
+I_a3= I_a2 *(T3_by_T2) //new armature current
+E_b3 = V - I_a3*(R_x + R_a)
+N_3=E_b3*N_2 / E_b2 //N (prop.) E_b
+printf('\nNew speed = %.3f rpm',N_3)
diff --git a/1938/CH2/EX2.35/2_35.sce b/1938/CH2/EX2.35/2_35.sce new file mode 100755 index 000000000..c0629bf4a --- /dev/null +++ b/1938/CH2/EX2.35/2_35.sce @@ -0,0 +1,23 @@ +clc,clear
+printf('Example 2.35\n\n')
+
+P_out= 100*735.5
+V=500
+P=4
+A=2// due to wave winding
+Z=492 //no of conductors
+phi=50*10^-3 //flux per pole
+eta=92/100 //efficiency
+P_in= P_out/eta
+R_a=0.1 , R_sh=250 //amature and shunt field resistance
+
+I_L=P_in/V
+I_sh = V/ R_sh
+I_a = I_L - I_sh
+E_b = V - I_a*R_a
+N=E_b*60*A/(phi*P*Z) //because E_b= phi*P*N*Z/(60*A)
+
+T_sh= P_out/(2*%pi*N/60) //Useful torque
+printf('(i)Speed at full load = %.4f rpm',N)
+printf('\n(ii)Useful torque = %.2f N-m',T_sh)
+printf('\n\nAnswer mismatches due to improper approximation')
diff --git a/1938/CH2/EX2.36/2_36.sce b/1938/CH2/EX2.36/2_36.sce new file mode 100755 index 000000000..022ccaa72 --- /dev/null +++ b/1938/CH2/EX2.36/2_36.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.36\n\n')
+
+N_1=1000
+I_1=50,I_a1=I_1
+V=250
+R_x=4.4, R_t=0.6 //R_t = R_a+R_se
+E_b1=V - I_a1*(R_t)
+
+//T (prop.)I_a^2 , T (prop.) N^2 .... hence N (prop.) I_a
+//N (prop.) E_b /I_a
+//combining both , E_b (prop.) I_a^2
+//using E_b2 = V - I_a2*(R_a + R_se + R_x) and solving for I_a2 , we get 0.088 I_a2^2 +5 I_a2 -250=0
+p=[0.088 5 -250]
+roots(p)
+I_a2=ans(2) //root(1) is ignored as it is -ve
+E_b2 = V - I_a2*(R_t + R_x)
+N_2=N_1*(E_b2/E_b1)*(I_a1/I_a2)
+printf('Motor speed = %.2f r.p.m',N_2)
diff --git a/1938/CH2/EX2.37/2_37.jpg b/1938/CH2/EX2.37/2_37.jpg Binary files differnew file mode 100755 index 000000000..34f8dec85 --- /dev/null +++ b/1938/CH2/EX2.37/2_37.jpg diff --git a/1938/CH2/EX2.37/2_37.sce b/1938/CH2/EX2.37/2_37.sce new file mode 100755 index 000000000..465637af9 --- /dev/null +++ b/1938/CH2/EX2.37/2_37.sce @@ -0,0 +1,21 @@ +clc,clear
+printf('Example 2.37\n\n')
+
+V=250, I_a1=20
+R_sh= 250,R_a=0.5 //shunt field and armature resistance
+I_sh1= V / R_sh
+E_b1 = V - I_a1*R_a
+
+//T (prop.) phi*I_a (prop.) I_sh*I_a
+//since T_1 = T_2, I_sh2_I_a2 = I_sh1*I_a1
+I_sh2_I_a2 = I_sh1*I_a1 //=20
+
+//N (prop.) E_b/I_sh
+//E_b1 = V - I_a1*R_a
+//Solving further for I_a2, we get I_a2^2 -500 I_a2 + 12800
+p=[1 -500 12800]
+roots(p)
+I_a2=ans(2) //higher root is neglected
+I_sh2= I_sh2_I_a2 / I_a2
+R_x= (V / I_sh2) - R_sh //resistance to be inserted in shunt field
+printf('Resistance to be inserted = %.4f ohms ',R_x)
diff --git a/1938/CH2/EX2.38/2_38.sce b/1938/CH2/EX2.38/2_38.sce new file mode 100755 index 000000000..571e98e71 --- /dev/null +++ b/1938/CH2/EX2.38/2_38.sce @@ -0,0 +1,25 @@ +clc,clear
+printf('Example 2.38\n\n')
+
+V=250, N_1=1000
+I_L1=25
+R_a=0.2, R_sh=250 //armature and shunt field resistance
+V_brush= 1 //voltage drop due to brushes
+
+I_sh1 = V/R_sh
+I_a1= I_L1 - I_sh1
+E_b1= V- I_a1*R_a - 2 *V_brush
+
+//when loaded
+I_L2=50
+I_sh2=I_sh1 //as flux weakensby armature reaction,shunt field current remains same
+I_a2= I_L2 - I_sh2
+E_b2= V- I_a2*R_a - 2 *V_brush
+
+phi2_by_phi1= 1- (3/100) //weakens by 3 percent
+N_2= N_1*(E_b2/E_b1)/ phi2_by_phi1 //N (prop.) E_b/phi
+printf('New speed = %.3f rpm',N_2)
+T_1= E_b1*I_a1/(2*%pi*N_1/60)
+T_2= E_b2*I_a2/(2*%pi*N_2/60)
+printf('\nTorque before field weakening = %.4f N-m',T_1)
+printf('\nTorque after field weakening = %.4f N-m',T_2)
diff --git a/1938/CH2/EX2.39/2_39.sce b/1938/CH2/EX2.39/2_39.sce new file mode 100755 index 000000000..5be15c138 --- /dev/null +++ b/1938/CH2/EX2.39/2_39.sce @@ -0,0 +1,30 @@ +clc,clear
+printf('Example 2.39\n\n')
+
+V=220
+R_a=0.5, R_x=1 //armature resistance and extra resistance
+N_FL=500 //full load speed in r.p.m
+I_a_FL=30
+
+//part(i) Full load
+E_b_FL= V- I_a_FL * R_a
+//T (prop.) I_a... T is constant
+I_a_dash_FL = I_a_FL
+E_b_dash_FL = V- I_a_dash_FL * (R_a+R_x)
+//N (prop.) E_b/phi (prop.) E_b
+N_dash_FL = N_FL*(E_b_dash_FL/E_b_FL)
+printf('(i)Speed at full load torque =%.4f r.p.m\n',N_dash_FL)
+
+//part(ii)
+T2_by_T1 = 2
+I_a_dash_FL = I_a_FL *(T2_by_T1)
+E_b_dash_FL = V- I_a_dash_FL * (R_a+R_x)
+N_dash_FL = N_FL*(E_b_dash_FL/E_b_FL)
+printf('(ii)Speed at double full load torque =%.3f r.p.m\n',N_dash_FL)
+
+//part(iii) ...stalling
+E_b=0 //as speed is zero in case of stalling torque
+I_a_stall=(V-E_b)/(R_a+R_x)
+T_FL = E_b_FL * I_a_FL/(2*%pi*N_FL/60)
+T_stall = T_FL *(I_a_stall/ I_a_FL)
+printf('(iii)Stalling torque = %.3f Nm',T_stall)
diff --git a/1938/CH2/EX2.4/2_4.sce b/1938/CH2/EX2.4/2_4.sce new file mode 100755 index 000000000..687a3f0a7 --- /dev/null +++ b/1938/CH2/EX2.4/2_4.sce @@ -0,0 +1,22 @@ +clc,clear
+printf('Example 2.4\n\n')
+
+Pole=4
+A=Pole //for lap winding
+V=230,R_a=0.8 //Armature resistance
+N_0=1000 //no load speed in rpm
+Z=540 //number of armature conductors
+phi=25*10^-3 //flux per pole in weber
+E_b0 = phi*Pole*N_0*Z/(60*A) //induced emf
+
+//part(i)
+printf('(i)Induced e.m.f = %.0f V\n',E_b0)
+//part(ii)
+I_a0 = (V- E_b0)/R_a //because V= E_b0+ I_a0*R_a
+printf('(ii)Armature current = %.2f A\n',I_a0)
+//part(iii)
+stray_losses = E_b0*I_a0 //on no load ,power developed is fully power required to overcome strya losses
+printf('(iii)Stray loss = %.2f W\n',stray_losses)
+//part(iv)
+T_f = E_b0*I_a0/(2*%pi*N_0/60) //lost torque
+printf('(iv)Lost torque = %.3f N-m\n',T_f)
diff --git a/1938/CH2/EX2.40/2_40.sce b/1938/CH2/EX2.40/2_40.sce new file mode 100755 index 000000000..8cc809d33 --- /dev/null +++ b/1938/CH2/EX2.40/2_40.sce @@ -0,0 +1,20 @@ +clc,clear
+printf('Example 2.40\n\n')
+
+V=230, I_a1=30
+R_a=0.4,R_x=1.1//armature resistance and extra resistance
+N_1=500
+
+//part(i)
+E_b1= V - I_a1*R_a
+I_a2 = I_a1 //I_a is constant as T, phi are constant
+E_b2= V - I_a2*(R_a+R_x)
+N_2 = N_1 *(E_b2/E_b1) //Because N (prop.) E_b/phi (prop.) E_b
+printf('(i)Speed at full load torque = %.3f r.p.m\n',N_2)
+
+//part(ii)
+T2_by_T1=1.5
+I_a2= I_a1 * T2_by_T1
+E_b2= V - I_a2*(R_a+R_x)
+N_2 = N_1 *(E_b2/E_b1) //Because N (prop.) E_b/phi (prop.) E_b
+printf('(ii)Speed at 1.5 times full load torque = %.3f r.p.m\n',N_2)
diff --git a/1938/CH2/EX2.5/2_5.jpg b/1938/CH2/EX2.5/2_5.jpg Binary files differnew file mode 100755 index 000000000..0f992cecf --- /dev/null +++ b/1938/CH2/EX2.5/2_5.jpg diff --git a/1938/CH2/EX2.5/2_5.sce b/1938/CH2/EX2.5/2_5.sce new file mode 100755 index 000000000..d553cd209 --- /dev/null +++ b/1938/CH2/EX2.5/2_5.sce @@ -0,0 +1,13 @@ +clc,clear
+printf('Example 2.5\n\n')
+
+Pole=4
+Z=200 //No of armature conductors
+A=2 //wave connected armature
+V=250
+phi=25*10^-3 //flux per pole in weber
+I_a =60, I_L =I_a //armature current
+R_a=0.15, R_se=0.2 //resistances of armature and series field winding
+E_b= V - I_a*(R_a+R_se) //induced emf
+N=E_b * 60*A/(phi*Pole*Z) //because E_b = phi*P*N*Z/(60*A)
+printf('Required speed is %.0f r.p.m',N)
diff --git a/1938/CH2/EX2.6/2_6.jpg b/1938/CH2/EX2.6/2_6.jpg Binary files differnew file mode 100755 index 000000000..7ebed949c --- /dev/null +++ b/1938/CH2/EX2.6/2_6.jpg diff --git a/1938/CH2/EX2.6/2_6.sce b/1938/CH2/EX2.6/2_6.sce new file mode 100755 index 000000000..d6aa75283 --- /dev/null +++ b/1938/CH2/EX2.6/2_6.sce @@ -0,0 +1,11 @@ +clc,clear
+printf('Example 2.6\n\n')
+
+V=250
+I_L =20 //load current
+R_a=0.3, R_sh=200 //Armature and shunt field winding
+I_sh=V/R_sh //shunt current
+I_a=I_L-I_sh //armature current
+E_b= V - I_a*R_a //emf generated
+printf('Armature current is %.2f A\n',I_a)
+printf('Back e.m.f is %.3f V',E_b)
diff --git a/1938/CH2/EX2.7/2_7.jpg b/1938/CH2/EX2.7/2_7.jpg Binary files differnew file mode 100755 index 000000000..d88100b47 --- /dev/null +++ b/1938/CH2/EX2.7/2_7.jpg diff --git a/1938/CH2/EX2.7/2_7.sce b/1938/CH2/EX2.7/2_7.sce new file mode 100755 index 000000000..ccf6fbd2a --- /dev/null +++ b/1938/CH2/EX2.7/2_7.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.7\n\n')
+
+V=220,R_a=0.3,R_sh=110 //resistance of armature and shunt field winding
+//no load
+N_0=1000 //no load speed in r.p.m
+I_L0 =6 //line current on no load
+I_sh= V/R_sh //no load shnt current
+I_a0 = I_L0 - I_sh //no load armature current
+E_b0= V - I_a0*R_a //no load induced emf
+
+//full load
+I_sh_FL= V/R_sh
+I_L_FL=50 //line current at full load
+I_a_FL= I_L_FL - I_sh_FL//full load armature current
+E_b_FL= V - I_a_FL * R_a //full load induced emf
+//using speed equation, as treating phi as constant
+N_FL=N_0 * (E_b_FL/E_b0)
+printf('Speed on full load is %.2f r.p.m',N_FL)
diff --git a/1938/CH2/EX2.8/2_8.jpg b/1938/CH2/EX2.8/2_8.jpg Binary files differnew file mode 100755 index 000000000..6cf199a23 --- /dev/null +++ b/1938/CH2/EX2.8/2_8.jpg diff --git a/1938/CH2/EX2.8/2_8.sce b/1938/CH2/EX2.8/2_8.sce new file mode 100755 index 000000000..ad9725647 --- /dev/null +++ b/1938/CH2/EX2.8/2_8.sce @@ -0,0 +1,16 @@ +clc,clear
+printf('Example 2.8\n\n')
+
+R_a=0.2, R_se =0.3 //Resistance of armature and series field winding
+//following variables correspond to load 1
+V=250
+N_1=800
+I_1=20, I_a1=I_1,I_se1= I_a1
+E_b1= V - I_a1*(R_a+R_se)
+//following variables correspond to load 2
+I_2=50, I_a2=I_2
+E_b2= V - I_a2*(R_a+R_se)
+
+//from speed equation it can be derived that,
+N_2 = N_1 * (E_b2/E_b1) * (I_a1/I_a2)
+printf('Speed on motor on no load is %.0f r.p.m',N_2)
diff --git a/1938/CH2/EX2.9/2_9.jpg b/1938/CH2/EX2.9/2_9.jpg Binary files differnew file mode 100755 index 000000000..7c06ee7f5 --- /dev/null +++ b/1938/CH2/EX2.9/2_9.jpg diff --git a/1938/CH2/EX2.9/2_9.sce b/1938/CH2/EX2.9/2_9.sce new file mode 100755 index 000000000..3b1fee062 --- /dev/null +++ b/1938/CH2/EX2.9/2_9.sce @@ -0,0 +1,19 @@ +clc,clear
+printf('Example 2.9\n\n')
+
+V=250
+R_a=0.3,R_sh=200 //resistance of armature and shunt field winding
+R_x=150 //additional resistance added in series to field winding
+I_L1=22
+I_sh1=V/R_sh //initial shunt current before adding 150 ohms resistance
+I_a1 = I_L1 - I_sh1 //initial armature current before adding 150 ohms resistance
+N_1=1500 //initial speed before adding 150 ohms resistance
+//T (prop.) phi*I_a (prop.) I_sh*I_a and T_1=T_2 and simplifying further
+I_sh2=V/(R_sh + R_x) //new shunt current
+I_a2= I_sh1*I_a1/I_sh2 //New armature current
+
+E_b1=V - I_a1*R_a //induced emf before adding 150 ohms resistance
+E_b2=V - I_a2*R_a //new emf
+
+N_2 = N_1 * (E_b2/E_b1) * (I_sh1/I_sh2) //new speed
+printf('New armature current and speed are %.4f A and %.2f r.p.m respectively',I_a2,N_2)
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