initial commit / add all books

54 files changed, 1051 insertions, 0 deletions

diff --git a/1938/CH6/EX6.10/6_10.sce b/1938/CH6/EX6.10/6_10.sce
new file mode 100755
index 000000000..bea4e828a
--- /dev/null
+++ b/1938/CH6/EX6.10/6_10.sce
@@ -0,0 +1,33 @@
+clc,clear

+printf('Example 6.10\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+V_l=6000

+V_ph=V_l/sqrt(3)

+VA=2000*10^3

+I_FL=VA/(V_l*sqrt(3))

+X_s=complex(0,6) //synchronous reactance

+P=8

+f=50

+

+delta_mech=%pi/180 //phase displacemant in degree mechanical 

+//phase displacemant in degree electrical

+delta_elec=delta_mech*(P/2)  //P/2 is pole pairs(and not poles)

+

+phi=acosd(0.8)

+V=p2z(V_ph,phi)

+E=V+I_FL*X_s

+//E leads I by phasemag(E). V leads I by phasemag(V)

+

+delta=(%pi/180)* (phasemag(E)-phasemag(V) ) //power angle in radians

+P_SY=abs(E)*abs(V)*cos(delta)*sin(delta_elec)/abs(X_s) //synchronising power

+P_SY_total=3*P_SY //totla synchronising power 

+printf('Total synchronising power is %.3f kW',10^-3*P_SY_total)

+

+N_s=120*f/P //in rpm

+n_s=(N_s)/60 //in rps

+T_SY=P_SY_total/(2*%pi*n_s)

+printf('\nSynchronising torque is %.0f N-m',T_SY)

diff --git a/1938/CH6/EX6.11/6_11.sce b/1938/CH6/EX6.11/6_11.sce
new file mode 100755
index 000000000..343e2271c
--- /dev/null
+++ b/1938/CH6/EX6.11/6_11.sce
@@ -0,0 +1,38 @@
+clc,clear

+printf('Example 6.11\n\n')

+

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+V_l=3300

+V_ph=V_l/sqrt(3)

+VA=3*10^6

+I_FL=VA/(V_l*sqrt(3))

+IX_s=(25/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL) //synchronous reactance

+N_s=1000 //in rpm

+P=6

+f=50

+

+delta_dash_mech=%pi/180

+delta_dash_elec=delta_dash_mech*(P/2)  //P/2 is pole pairs(and not poles)

+

+I=I_FL

+phi=acosd(0.8)

+V=p2z(V_ph,phi)

+E=V+I*X_s

+//E leads I by phasemag(E). V leads I by phasemag(V)

+

+delta=(%pi/180)* (phasemag(E)-phasemag(V) ) //power angle in radians

+P_SY=abs(E)*abs(V)*cos(delta)*sin(delta_dash_elec)/abs(X_s) //Synchronising power per phase

+printf('Synchronising power is %.3f kW',10^-3*P_SY)

+P_SY_total=3*P_SY //Total synchronising power

+

+N_s=120*f/P //in rpm

+n_s=(N_s)/60 //in rps

+T_SY=P_SY_total/(2*%pi*n_s)

+printf('\nSynchronising torque is %.0f N-m',T_SY)

+

+printf('\n\nAnswer mismatches due to approximation')

diff --git a/1938/CH6/EX6.12/6_12.sce b/1938/CH6/EX6.12/6_12.sce
new file mode 100755
index 000000000..5c53e84d8
--- /dev/null
+++ b/1938/CH6/EX6.12/6_12.sce
@@ -0,0 +1,28 @@
+clc,clear

+printf('Example 6.12\n\n')

+

+V_l=3300

+V_ph=V_l/sqrt(3)

+VA=3*10^6

+I_FL=VA/(V_l*sqrt(3))

+IX_s=(20/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL) //synchronous reactance

+N_s=1000

+P=6

+f=50

+

+delta_dash_mech=%pi/180 //phase displacement in degree mechanical

+//phase displacement in degree electrical

+delta_dash_elec=delta_dash_mech*(P/2)  //P/2 is pole pairs(and not poles)

+

+E=V_ph

+Z_s=X_s //since R=0

+P_SY=abs(E)*abs(V_ph)*delta_dash_elec/abs(Z_s) //Synchronising power per phase

+printf('Synchronising power is %.3f kW',10^-3*P_SY)

+P_SY_total=3*P_SY //Total synchronising power

+printf('\n3 phase synchronising power is %.3f kW',10^-3*P_SY_total)

+

+N_s=120*f/P //in rpm

+n_s=(N_s)/60 //in rps

+T_SY=P_SY_total/(2*%pi*n_s)

+printf('\nSynchronising torque is %.0f N-m',T_SY)

diff --git a/1938/CH6/EX6.13/6_13.jpg b/1938/CH6/EX6.13/6_13.jpg
new file mode 100755
index 000000000..1713b0614
--- /dev/null
+++ b/1938/CH6/EX6.13/6_13.jpg
diff --git a/1938/CH6/EX6.13/6_13.sce b/1938/CH6/EX6.13/6_13.sce
new file mode 100755
index 000000000..f2c185b83
--- /dev/null
+++ b/1938/CH6/EX6.13/6_13.sce
@@ -0,0 +1,30 @@
+clc,clear

+printf('Example 6.13\n\n')

+

+V_L=11*10^3

+V_ph=V_L/sqrt(3)

+VA=700*10^3

+I_FL=VA/(sqrt(3)*V_L) //full load current

+IR_a=(1.5/100)*V_ph //product of I and R_a

+R_a=IR_a/I_FL

+IX_s=(14/100)*V_ph // product of I and X_s

+X_s=IX_s/I_FL //synchronous reactance

+

+//at full load and 0.8 pf

+I=I_FL

+phi=acos(0.8)

+V_ph=complex(V_ph*cos(phi),V_ph*sin(phi))  //just introduced the angle

+E_ph=sqrt(    (abs(V_ph)*cos(phi)+ IR_a)^2+   (abs(V_ph)*sin(phi)+ IX_s)^2     )

+

+Poles=4,f=50 //poles and frequency

+delta=asin( (abs(V_ph)*sin(phi)+IX_s)/E_ph)  -phi

+delta_dash_mech=(%pi/180) //displacement in degree mechanical

+//displacement in degree electrical

+delta_dash_elec=delta_dash_mech*(Poles/2)

+P_SY=abs(E_ph)*abs(V_ph)*cos(delta)*sin(delta_dash_elec)/X_s   //synchronising power per phase 

+P_SY_total=3*P_SY  //total synchronising power

+

+ns=120*f/(60*Poles)  //in r.p.s

+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 

+printf('Synchronising power is %.2fkW\n',P_SY_total/1000)

+printf('Synchronising torque is %.2f N-m',T_SY)

diff --git a/1938/CH6/EX6.14/6_14.sce b/1938/CH6/EX6.14/6_14.sce
new file mode 100755
index 000000000..4e28afaf0
--- /dev/null
+++ b/1938/CH6/EX6.14/6_14.sce
@@ -0,0 +1,24 @@
+clc,clear

+printf('Example 6.14\n\n')

+

+V_l=9*10^3

+V_ph=V_l/sqrt(3)

+VA=5.5*10^6

+I_FL=VA/(V_l*sqrt(3))

+IX_s=(25/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL) //synchronous reactance

+N_s=1500 //in rpm

+n_s=N_s/60 //in rps

+f=50,P=120*f/N_s //frequency and pole

+

+delta_dash_mech=%pi/180 //displacemnt in degree mechanical 

+//displacemnt in degree electrical

+delta_dash_elec=delta_dash_mech*(P/2)  //P/2 is pole pairs(and not poles)

+

+E=V_ph

+P_SY=abs(E)*abs(V_ph)*delta_dash_elec/abs(X_s) //Synchronising power per phase

+P_SY_total=3*P_SY //Total synchronising power

+

+T_SY=P_SY_total/(2*%pi*n_s)

+printf('\nSynchronising torque is %.2f N-m',T_SY)

+printf('\nAnswer mismatches due to approximation')

diff --git a/1938/CH6/EX6.15/6_15.jpg b/1938/CH6/EX6.15/6_15.jpg
new file mode 100755
index 000000000..7a78b1b80
--- /dev/null
+++ b/1938/CH6/EX6.15/6_15.jpg
diff --git a/1938/CH6/EX6.15/6_15.sce b/1938/CH6/EX6.15/6_15.sce
new file mode 100755
index 000000000..26c99672a
--- /dev/null
+++ b/1938/CH6/EX6.15/6_15.sce
@@ -0,0 +1,35 @@
+clc,clear

+printf('Example 6.15\n\n')

+

+V_L=6*10^3

+V_ph=V_L/sqrt(3)

+VA=2000*10^3

+I_FL=VA/(sqrt(3)*V_L)  ,I=I_FL

+

+X_s=1.2,R_a=0.01 //both per unit

+IR_a=(1/100)*V_ph //product of I and R_a

+R_a=IR_a/I_FL

+IX_s=(120/100)*V_ph //product of I and X_s

+//IX_s=(12/100)*V_ph   // this is the mistake made in the textbook

+X_s=IX_s/I_FL

+

+//at full load and 0.8 pf

+phi=acos(0.8)

+//V_ph=complex(V_ph*cos(phi),V_ph*sin(phi))  //just introduced the angle

+E_ph=sqrt(    (abs(V_ph)*cos(phi)+ IR_a)^2+   (abs(V_ph)*sin(phi)+ IX_s)^2     )

+Poles=8,f=50

+

+delta=asin( (abs(V_ph)*sin(phi)+IX_s)/E_ph)  -phi

+delta_dash_mech=(%pi/180) //displacemnt in degree mechanical 

+//displacemnt in degree electrical

+delta_dash_elec=delta_dash_mech*(Poles/2)

+P_SY=abs(E_ph)*abs(V_ph)*cos(delta)*sin(delta_dash_elec)/X_s   //synchronising power per phase

+P_SY_total=3*P_SY  //total synchronising power

+

+ns=120*f/(60*Poles)  //in r.p.s

+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 

+

+printf('Synchronising power is %.2f kW\n',P_SY_total/1000)

+printf('Synchronising torque is %.2f N-m',T_SY)

+

+printf('\n\nNote that answer obtained doesnt match with textbook due to the following reasons: \n(i)IX_s is considered wrong in textbook.\nIt should have been 4156.92(instead of 415.692)  \nTo verify this use commented statement of IX_s (line 13)and notice that it matches with textbook ans then' )

diff --git a/1938/CH6/EX6.16/6_16.sce b/1938/CH6/EX6.16/6_16.sce
new file mode 100755
index 000000000..784300d04
--- /dev/null
+++ b/1938/CH6/EX6.16/6_16.sce
@@ -0,0 +1,16 @@
+clc,clear

+printf('Example 6.16\n\n')

+

+E=11*10^3/sqrt(3)

+I_sc=1000,Pole=2,f=50

+delta_dash_mech=1*%pi/180 //displacemnt in degree mechanical 

+//displacemnt in degree electrical 

+delta_dash_elec=delta_dash_mech*(Pole/2)

+P_SY=E*I_sc*delta_dash_mech //synchronising power per phase

+P_SY_total=P_SY*3 //total synchronising power

+

+ns=120*f/(60*Pole)  //in r.p.s

+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 

+

+printf('Synchronising power is %.2f kW\n',P_SY_total/1000)

+printf('Synchronising torque is %.2f N-m',T_SY)

diff --git a/1938/CH6/EX6.17/6_17.jpg b/1938/CH6/EX6.17/6_17.jpg
new file mode 100755
index 000000000..dcdadc934
--- /dev/null
+++ b/1938/CH6/EX6.17/6_17.jpg
diff --git a/1938/CH6/EX6.17/6_17.sce b/1938/CH6/EX6.17/6_17.sce
new file mode 100755
index 000000000..c862100b3
--- /dev/null
+++ b/1938/CH6/EX6.17/6_17.sce
@@ -0,0 +1,20 @@
+clc,clear

+printf('Example 6.17\n\n')

+//Line PQ for Altermnator 1, and PR for alternaator 2.AB is at frequency x from P where total load is 30 MW

+QT=25,PT=2,//PC=x

+SR=25,PS=1.5

+

+//using similarity of triangles PAC and PQT

+AC_by_PC=(QT/PT)// because (AC/QT)=(PC/PT)

+//using similarity of triangles PCB and PSR

+CB_by_PC=(SR/PS)

+

+AC_by_x=AC_by_PC   //which implies AC=12.5*x

+CB_by_x=CB_by_PC  //which implies CB=16.67*x

+

+AC_plus_CB=30  //total load at the frequency at P is 30 MW

+x= AC_plus_CB/(AC_by_x + CB_by_x)

+AC=12.5*x

+CB=16.67*x  

+frequency=50-x

+printf('Loads shared by alternator 1 and 2 are %.2f MW and %.2f MW respectively',AC,CB)

diff --git a/1938/CH6/EX6.18/6_18.jpg b/1938/CH6/EX6.18/6_18.jpg
new file mode 100755
index 000000000..8ff024583
--- /dev/null
+++ b/1938/CH6/EX6.18/6_18.jpg
diff --git a/1938/CH6/EX6.18/6_18.sce b/1938/CH6/EX6.18/6_18.sce
new file mode 100755
index 000000000..ca1a30f4f
--- /dev/null
+++ b/1938/CH6/EX6.18/6_18.sce
@@ -0,0 +1,23 @@
+clc,clear

+printf('Example 6.18\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+load_total=1600*10^3

+pf=1/sqrt(2)  //lag

+V_L=6600

+I_L=p2z(load_total/(sqrt(3)*V_L*pf),-1*acosd(pf)) 

+I_1=p2z(90,-1*acosd(0.8))

+I_2=I_L-I_1

+phi=abs(phasemag(I_2))

+I_a=abs(I_2)

+R_a=1.05,X_s=5 //resistance and synchronous reactance per phase

+V_ph=V_L/sqrt(3)

+E_ph=sqrt(  (V_ph*cos(phi)+I_a*R_a )^2 + ( V_ph*sin(phi)+I_a*X_s )^2        )

+E_line=sqrt(3)*E_ph

+

+printf('Excitation of second alternator is %.2f V ',E_line)

+printf('\n The corresponding field current from the graph is about 310 A\n\n')

+printf('Note: The answer obtained will differ from textbook answer because of higher degree \nof accuracy while storing I_2 and the improper rounding off of I_2 in the textbook')

diff --git a/1938/CH6/EX6.19/6_19.sce b/1938/CH6/EX6.19/6_19.sce
new file mode 100755
index 000000000..b55154582
--- /dev/null
+++ b/1938/CH6/EX6.19/6_19.sce
@@ -0,0 +1,18 @@
+clc,clear

+printf('Example 6.19\n\n')

+

+V_L=10*10^3

+V_ph=V_L/sqrt(3)

+VA=5*10^6

+I_FL=VA/(sqrt(3)*V_L) //full-load current

+IX_s=(20/100)*V_ph //product of I and X_s

+X_s=IX_s/I_FL //synchronous reactance

+P=4

+delta_dash_mech=1*(%pi/180) //displacement in degree mechanical 

+//displacement in degree electrical

+delta_dash_elec=delta_dash_mech*(P/2)

+E=V_ph  //at no load

+P_SY= delta_dash_elec*E^2/X_s  //synchronising power per phase

+P_SY_total=P_SY*3  //Total synchronising power

+

+printf('Synchronising power per phase is %.2fkW\nTotal synchronising power is %.2fkW ',P_SY/1000,P_SY_total/1000)

diff --git a/1938/CH6/EX6.2/6_2.sce b/1938/CH6/EX6.2/6_2.sce
new file mode 100755
index 000000000..4fd405e4d
--- /dev/null
+++ b/1938/CH6/EX6.2/6_2.sce
@@ -0,0 +1,16 @@
+clc,clear

+printf('Example 6.2\n\n')

+

+X_d=0.7 , X_q=0.4  //direct and quadrature axis synchronous reactance p.u.

+R_a=0

+phi=acos(0.8)  //Lag

+

+V_t=1 //assumed rated terminal Voltage 

+I_a=1 //Full-load armature current

+

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+delta=psi-phi

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+printf('Total e.m.f induced on open circuit is %.4f p.u.',E_f)

diff --git a/1938/CH6/EX6.20/6_20.jpg b/1938/CH6/EX6.20/6_20.jpg
new file mode 100755
index 000000000..6df2542e6
--- /dev/null
+++ b/1938/CH6/EX6.20/6_20.jpg
diff --git a/1938/CH6/EX6.20/6_20.sce b/1938/CH6/EX6.20/6_20.sce
new file mode 100755
index 000000000..ebf997886
--- /dev/null
+++ b/1938/CH6/EX6.20/6_20.sce
@@ -0,0 +1,23 @@
+clc,clear

+printf('Example 6.20\n\n')

+

+Power_total=1.414 //per unit

+V_L=1 //per unit

+phi_t=acos(0.707)

+I_L_T=Power_total/(sqrt(3)*V_L*cos(phi_t))  //Total current

+//Current supplied by each alternator

+I_1=I_L_T/2

+I_2=I_1

+V_ph=V_L/sqrt(3)

+

+phi=acos(0.707)

+R_a=0,X_s=0.6 //resistacne and synchronous reactance

+E_ph=sqrt(  (V_ph*cos(phi)+ I_1*R_a)^2 + (V_ph*sin(phi)+I_1*X_s)^2          )

+delta= atan((I_1*X_s+V_ph*sin(phi)) / (V_ph*cos(phi))) - phi    //power angle

+

+printf('EMF is %.4f p.u. and power angle is %.2f degrees ',E_ph,delta*(180/%pi))

+printf('\n\nFollowing assumptions were made :\n')

+printf('1.Terminal or bus bar voltage at ppoint of connection is constant\n')

+printf('2.The alternators are identical and are initially equally excited\n')

+printf('3.The power supplied by prime movers is adjusted so that each machine carries half the load represented by external impedance Z=R+ j 2pifL , where R and L are constant\n')

+printf('4.The stator resistance is negligible')

diff --git a/1938/CH6/EX6.21/6_21.sce b/1938/CH6/EX6.21/6_21.sce
new file mode 100755
index 000000000..a394d2a07
--- /dev/null
+++ b/1938/CH6/EX6.21/6_21.sce
@@ -0,0 +1,18 @@
+clc,clear

+printf('Example 6.21\n\n')

+

+V_l=480

+X_d=0.1,X_q=0.075,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+I_l=1200

+I_ph=I_l/sqrt(3)

+V_ph=V_l

+V_t=V_l,I_a=I_ph

+phi=acos(0.8)

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+delta=psi-phi 

+

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+

+printf('Excitation e.m.f is %.2f V ',E_f)

diff --git a/1938/CH6/EX6.22/6_22.sce b/1938/CH6/EX6.22/6_22.sce
new file mode 100755
index 000000000..518782824
--- /dev/null
+++ b/1938/CH6/EX6.22/6_22.sce
@@ -0,0 +1,22 @@
+clc,clear

+printf('Example 6.22\n\n')

+

+VA=3.5*10^6

+P=32        //Poles

+Power=2.5*10^6 //In watts

+V_l=6.6*10^3

+phi=acos(0.8)

+I_l=Power/(V_l*cos(phi)*sqrt(3))

+X_d=9.6,X_q=6,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+

+V_t=V_l/sqrt(3)

+psi=atan(  (V_t*sin(phi)+I_l*X_q)/(V_t*cos(phi)+I_l*R_a)            )

+delta=psi-phi

+I_s=I_l

+I_d=I_s*sin(psi)

+I_q=I_s*cos(psi)

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+

+regulation=100*(E_f-V_t)/V_t

+printf('percentage regulation is %.2f percent',regulation)

+printf('\nExcitation emf= %.0f V',E_f)

diff --git a/1938/CH6/EX6.23/6_23.sce b/1938/CH6/EX6.23/6_23.sce
new file mode 100755
index 000000000..c164e4907
--- /dev/null
+++ b/1938/CH6/EX6.23/6_23.sce
@@ -0,0 +1,20 @@
+clc,clear

+printf('Example 6.23\n\n')

+

+X_d=7.6,X_q=4.5,R_a=0.15 //armature resistance and synchronous reactance of direct,quadrature axisV_l=13.8*10^3

+V_l=13.8*10^3

+V_t=V_l/sqrt(3)

+phi=acos(0.8)

+VA=25*10^6

+I_a=VA/(sqrt(3)*V_l)

+psi=atan(  (V_t*cos(phi)+I_a*X_q)/(V_t*sin(phi)+I_a*R_a)            )

+

+delta=psi-phi

+I_s=I_a

+I_d=I_s*sin(psi)

+I_q=I_s*cos(psi)

+

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+regulation=100*(E_f-V_t)/V_t

+

+printf('percentage regulation is %.2f percent',regulation)

diff --git a/1938/CH6/EX6.24/6_24.sce b/1938/CH6/EX6.24/6_24.sce
new file mode 100755
index 000000000..ff0df37b0
--- /dev/null
+++ b/1938/CH6/EX6.24/6_24.sce
@@ -0,0 +1,17 @@
+clc,clear

+printf('Example 6.24\n\n')

+

+X_d=1,X_q=0.6,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+phi=acos(0.8) //lag

+V_t=1

+I_a=1 //full load

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+

+delta=psi-phi

+I_s=I_a

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+regulation=100*(E_f-V_t)/V_t

+printf('percentage regulation is %.2f percent',regulation)

diff --git a/1938/CH6/EX6.25/6_25.sce b/1938/CH6/EX6.25/6_25.sce
new file mode 100755
index 000000000..c9f779bf3
--- /dev/null
+++ b/1938/CH6/EX6.25/6_25.sce
@@ -0,0 +1,15 @@
+clc,clear

+printf('Example 6.25\n\n')

+

+I_a=10

+phi=20 //lag and degrees

+V_t=400

+X_d=10,X_q=6.5,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+

+psi=atand(  (V_t*sind(phi)+I_a*X_q)/(V_t*cosd(phi)+I_a*R_a)            )

+delta=psi-phi

+I_d=I_a*sind(psi)

+I_q=I_a*cosd(psi)

+

+printf('Load angle is %.2f degrees \n',delta)

+printf('I_d and I_q are %.4f A and %.4f A respectively ',I_d,I_q  )

diff --git a/1938/CH6/EX6.26/6_26.sce b/1938/CH6/EX6.26/6_26.sce
new file mode 100755
index 000000000..622f3e19e
--- /dev/null
+++ b/1938/CH6/EX6.26/6_26.sce
@@ -0,0 +1,30 @@
+clc,clear

+printf('Example 6.26\n\n')

+

+X_d=0.8,X_q=0.5,R_a=0.02 //armature resistance and synchronous reactance of direct,quadrature axis

+

+//case(i)  lag

+phi=acos(0.8)

+V_t=1

+I_a=1//full-load

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+delta=psi-phi

+

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+regulation=100*(E_f-V_t)/V_t

+printf('percentage regulation at 0.8 pf lag is %.2f percent',regulation)

+

+//case(ii)  lead

+phi2=-1*acos(0.8) //minus sign because of leading pf

+psi2=atan(  (V_t*sin(phi2)+I_a*X_q)/(V_t*cos(phi2)+I_a*R_a)            )

+delta2=psi2-phi2

+

+I_d2=I_a*sin(psi2)

+I_q2=I_a*cos(psi2)

+

+E_f2=V_t*cos(delta2)+I_d2*X_d+I_q2*R_a

+regulation2=100*(E_f2-V_t)/V_t

+printf('\npercentage regulation at 0.8 pf lead is %.2f percent',regulation2)

diff --git a/1938/CH6/EX6.27/6_27.sce b/1938/CH6/EX6.27/6_27.sce
new file mode 100755
index 000000000..c3d873593
--- /dev/null
+++ b/1938/CH6/EX6.27/6_27.sce
@@ -0,0 +1,23 @@
+clc,clear

+printf('Example 6.27\n\n')

+

+kW=[800,500,1000,600]

+cosphi=[1,0.9,0.8,0.9]

+tanphi=tan(acos(cosphi))

+kVAR=kW.*tanphi

+

+kW_total=kW(1)+kW(2)+kW(3)+kW(4)

+kVAR_total=kVAR(1)+kVAR(2)+kVAR(3)+-1*kVAR(4) //4th case is leading 

+

+phi_c=atan(kVAR_total/kW_total)  //total power factor angle

+phi_1=acos(0.95)//pf of machine 1

+kW_1=1000 //active component of machine 1

+kVAR_1=kW_1*tan(phi_1) //reactive component of machine 1

+kW_2=kW_total - kW_1 //active component of machine 1

+kVAR_2=kVAR_total-kVAR_1 //reactive component of machine 2

+

+phi_2=atan(kVAR_2/kW_2) 

+pf_2=cos(phi_2) //power factor of machine 2

+

+printf('Output of second alternator= %.0f kW',kW_2)

+printf('\npower factor of machine 2 = %.2f and lagging',pf_2)

diff --git a/1938/CH6/EX6.28/6_28.sce b/1938/CH6/EX6.28/6_28.sce
new file mode 100755
index 000000000..3046729ec
--- /dev/null
+++ b/1938/CH6/EX6.28/6_28.sce
@@ -0,0 +1,21 @@
+clc,clear

+printf('Example 6.28\n\n')

+

+kW=[250,300,150]

+cosphi=[0.9,0.75,0.8] //all lagging

+tanphi=tan(acos(cosphi))

+kVAR=kW.*tanphi

+

+kW_total=kW(1)+kW(2)+kW(3)

+kVAR_total=kVAR(1)+kVAR(2)+kVAR(3) 

+

+phi_1=acos(0.8)//pf of machine 1

+kW_1=100 //active component of machine 1

+kVAR_1=kW_1*tan(phi_1) //reactive component of machine 1

+kW_2=kW_total - kW_1 //active component of machine 1

+kVAR_2=kVAR_total-kVAR_1 //reactive component of machine 2

+phi_2=atan(kVAR_2/kW_2) 

+pf_2=cos(phi_2) //power factor of machine 2

+

+printf('Output of second alternator= %.0f kW',kW_2)

+printf('\npower factor of machine 2 = %.4f and lagging',pf_2)

diff --git a/1938/CH6/EX6.29/6_29.sce b/1938/CH6/EX6.29/6_29.sce
new file mode 100755
index 000000000..3a8d4283b
--- /dev/null
+++ b/1938/CH6/EX6.29/6_29.sce
@@ -0,0 +1,24 @@
+clc,clear

+printf('Example 6.29\n\n')

+

+V_L=6.6*10^3

+V_ph=V_L/sqrt(3)

+V_t=V_ph

+X_d=9.6,X_q=6,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+VA=3.5*10^6

+I_L=VA/(sqrt(3)*V_L)

+

+P=2.5*10^6,phi=acos(0.8)

+I_a=P/(sqrt(3)*V_L*cos(phi))

+psi=atan(  (V_t*sin(phi)+ I_a*X_q)/(V_t*cos(phi)+ I_a*R_a)     )

+

+delta=psi-phi

+I_d=I_a*sin(psi)

+I_q=I_a*cos(phi)

+

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+regulation=100*(E_f-V_t)/V_t

+P_max=(V_ph^2/2)*((X_d-X_q)/(X_d*X_q))*(sin(2*delta))

+

+printf('percentage voltage regulation is %.2f percent',regulation)

+printf('\nPower under open circuit is %.1f kW per phase',P_max/1000)

diff --git a/1938/CH6/EX6.3/6_3.sce b/1938/CH6/EX6.3/6_3.sce
new file mode 100755
index 000000000..ab19695f2
--- /dev/null
+++ b/1938/CH6/EX6.3/6_3.sce
@@ -0,0 +1,28 @@
+clc,clear

+printf('Example 6.3\n\n')

+

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+Z1=complex(0,3) //impedance of alternator 1

+Z2=complex(0,4) //impedance of alternator 2

+Z=6 //load

+E1=p2z(220,0) //induced emf vector on no load

+E2=p2z(220,10)//induced emf vector on no load

+

+I1=((E1-E2)*Z+E1*Z2)/(Z*(Z1+Z2)+Z1*Z2)

+I2=((E2-E1)*Z+E2*Z1)/(Z*(Z1+Z2)+Z1*Z2)

+

+phi1=phasemag(I1)  //Phasemag returns the angle of complex number in degrees

+phi2=phasemag(I2)  //Phasemag returns the angle of complex number in degrees

+

+I=I1+I2

+V=I*Z //Terminal voltage

+printf('(i) Terminal voltage is %.1f volts at %.2f degrees\n',abs(V),phasemag(V))

+printf('(ii) Currents are %.2f A at %.2f degrees and %.2f A at %.2f degrees\n     Total current is %.2f A at %.2f degrees  ',abs(I1),phasemag(I1),abs(I2),phasemag(I2),abs(I),phasemag(I))

+

+P1=abs(V)*abs(I1)*cosd(phi1)

+P2=abs(V)*abs(I2)*cosd(phi2)

+printf('\n(iii)Power delivered is %.2f watts and %.2f watts',P1,P2)

diff --git a/1938/CH6/EX6.30/6_30.sce b/1938/CH6/EX6.30/6_30.sce
new file mode 100755
index 000000000..0e93ef101
--- /dev/null
+++ b/1938/CH6/EX6.30/6_30.sce
@@ -0,0 +1,29 @@
+clc,clear

+printf('Example 6.30\n\n')

+

+V_L=3.3*10^3

+V_ph=V_L/sqrt(3)

+VA=3*10^6

+I_FL=VA/(sqrt(3)*V_L)

+IX_s=(25/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL)

+N_s=1000 //in r.p.m

+

+Poles=6,f=50

+delta_dash_mech=(%pi/180) //displacement in degree mechanical

+//displacement in degree electrical

+delta_dash_elec=delta_dash_mech*(Poles/2)

+

+I=I_FL,phi=acos(0.8)

+V=complex(V_ph*cos(phi),V_ph*sin(phi))

+E= V+ I*X_s

+

+delta=(%pi/180)*phasemag(E)-phi   //E leads I by (%pi/180)*phasemag(E) and V leads I by phi radians 

+P_SY=abs(E)*abs(V_ph)*cos(delta)*sin(delta_dash_elec)/abs(X_s)   //synchronising power per phase 

+P_SY_total=3*P_SY  //total synchronising power

+

+ns=120*f/(60*Poles)  //in r.p.m

+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 

+printf('Synchronising power per phase is %.3f kW\n',P_SY/1000)

+printf('Synchronising torque is %.0f N-m',T_SY)

+printf('\n\nAnswer mismatches due to improper approximation')

diff --git a/1938/CH6/EX6.31/6_31.sce b/1938/CH6/EX6.31/6_31.sce
new file mode 100755
index 000000000..a8e0513ba
--- /dev/null
+++ b/1938/CH6/EX6.31/6_31.sce
@@ -0,0 +1,25 @@
+clc,clear

+printf('Example 6.31\n\n')

+

+V_L=3.3*10^3

+V_ph=V_L/sqrt(3)

+VA=3*10^6

+I_FL=VA/(sqrt(3)*V_L)

+IX_s=(20/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL)

+N_s=1000 //in r.p.m

+Poles=6,f=50

+

+delta_dash_mech=(%pi/180) //displacement in degree mechanical

+//displacement in degree electrical 

+delta_dash_elec=delta_dash_mech*(Poles/2)

+

+//E=V as the alternator is on no-load and X_s=Z_s

+P_SY=abs(V_ph)^2*(delta_dash_elec)/abs(X_s)   //synchronising power per phase

+P_SY_total=3*P_SY  //total synchronising power

+

+ns=120*f/(60*Poles)  //in r.p.s

+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 

+printf('Synchronising power per phase is %.3f kW\n',P_SY/1000)

+printf('Total Synchronising power is %.3f kW',P_SY_total/1000)

+printf('\nSynchronising torque is %.0f N-m',T_SY)

diff --git a/1938/CH6/EX6.32/6_32.jpg b/1938/CH6/EX6.32/6_32.jpg
new file mode 100755
index 000000000..6c38a11a7
--- /dev/null
+++ b/1938/CH6/EX6.32/6_32.jpg
diff --git a/1938/CH6/EX6.32/6_32.sce b/1938/CH6/EX6.32/6_32.sce
new file mode 100755
index 000000000..fdbca2b8d
--- /dev/null
+++ b/1938/CH6/EX6.32/6_32.sce
@@ -0,0 +1,32 @@
+clc,clear
+printf('Example 6.32\n\n')
+
+V_L=11*10^3
+V_ph=V_L/sqrt(3)
+VA=700*10^3
+I_FL=VA/(sqrt(3)*V_L)
+IX_s=(14/100)*V_ph //product of I and X_s
+X_s=IX_s/I_FL
+//X_s=complex(0,IX_s/I_FL)
+IR_a=(1.5/100)*V_ph //product of I and R_a
+R_a=IR_a/I_FL
+
+I=I_FL,phi=acos(0.8)
+V=complex(V_ph*cos(phi),V_ph*sin(phi))
+E_ph=sqrt(  (V_ph*cos(phi)+IR_a)^2 +(V_ph*sin(phi)+IX_s)^2    )
+
+delta=asin((V_ph*sin(phi)+IX_s)/E_ph)   -phi
+
+Poles=4,f=50
+delta_dash_mech=(%pi/180) //phase displacemnt in degree mechanical
+delta_dash_elec=delta_dash_mech*(Poles/2)//phase displacemnt in degree electrical
+
+P_SY=abs(V_ph)*abs(E_ph)*cos(delta)*sin(delta_dash_elec)/abs(X_s)   //synchronising power per phase
+P_SY_total=3*P_SY  //total synchronising power
+
+ns=120*f/(60*Poles)  //in r.p.s
+T_SY=P_SY_total/(2*%pi*ns)   //Synchronising torque 
+printf('Synchronising power per phase is %.3f kW\n',P_SY/1000)
+printf('Synchronising power is %.3f kW ; ',P_SY/1000)
+printf('Total Synchronising power is %.3f kW',P_SY_total/1000)
+printf('\nSynchronising torque is %.2f N-m',T_SY)
diff --git a/1938/CH6/EX6.33/6_33.sce b/1938/CH6/EX6.33/6_33.sce
new file mode 100755
index 000000000..b6e6c0403
--- /dev/null
+++ b/1938/CH6/EX6.33/6_33.sce
@@ -0,0 +1,27 @@
+clc,clear

+printf('Example 6.33\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+Z1=complex(0,2)

+Z2=complex(0,3)

+Z=6

+E1=p2z(230,0)

+E2=p2z(230,10)

+

+I1=((E1-E2)*Z+E1*Z2)/(Z*(Z1+Z2)+Z1*Z2)

+I2=((E2-E1)*Z+E2*Z1)/(Z*(Z1+Z2)+Z1*Z2)

+

+phi1=phasemag(I1)  //Phasemag returns the angle of complex number in degrees

+phi2=phasemag(I2)  //Phasemag returns the angle of complex number in degrees

+

+I=I1+I2

+V=I*Z //Terminal voltage

+printf('(i) Terminal voltage is %.2f volts at %.1f degrees\n',abs(V),phasemag(V))

+printf('(ii) Currents are %.2f A at %.0f degrees and %.2f A at %.2f degrees\n     Total current is %.2f A at %.1f degrees  ',abs(I1),phasemag(I1),abs(I2),phasemag(I2),abs(I),phasemag(I))

+

+P1=abs(V)*abs(I1)*cosd(phi1)

+P2=abs(V)*abs(I2)*cosd(phi2)

+printf('\n(iii)Power delivered %.2f watts and  %.2f watts',P1,P2)

diff --git a/1938/CH6/EX6.34/6_34.sce b/1938/CH6/EX6.34/6_34.sce
new file mode 100755
index 000000000..3e31f18ee
--- /dev/null
+++ b/1938/CH6/EX6.34/6_34.sce
@@ -0,0 +1,16 @@
+clc,clear

+printf('Example 6.34\n\n')

+

+X_d=0.8,X_q=0.5  //both per unit

+R_a=0 //assumed

+phi=acos(0.8)

+V_t=1//pu

+I_a=1 //full-load

+

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+delta=psi-phi

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+

+printf('Open circuit voltage is %.3f p.u.',E_f)

diff --git a/1938/CH6/EX6.35/6_35.sce b/1938/CH6/EX6.35/6_35.sce
new file mode 100755
index 000000000..d112e4257
--- /dev/null
+++ b/1938/CH6/EX6.35/6_35.sce
@@ -0,0 +1,25 @@
+clc,clear

+printf('Example 6.35\n\n')

+

+V_L=6600,I_L=110,phi_1=acos(0.9) //lagging

+kW=[400,1000,400,300]*10^3

+cosphi=[1,0.71,0.8,0.9]

+tanphi=tan(acos(cosphi))

+kVAR=kW.*tanphi

+

+kW_total=kW(1)+kW(2)+kW(3)+kW(4)

+kVAR_total=kVAR(1)+kVAR(2)+kVAR(3)+kVAR(4)

+

+phi_c=atan(kVAR_total/kW_total)  //total power factor angle

+load_1=sqrt(3)*V_L*I_L*cos(phi_1)

+

+kW_1=load_1 //active component of machine 1

+kVAR_1=kW_1*tan(phi_1) //reactive component of machine 1

+kW_2=kW_total - kW_1 //active component of machine 1

+kVAR_2=kVAR_total-kVAR_1 //reactive component of machine 2

+

+phi_2=atan(kVAR_2/kW_2) 

+pf_2=cos(phi_2) //power factor of machine 2

+

+printf('Output of second alternator= %.2f kW',kW_2/1000)

+printf('\nPower factor of machine 2 = %.4f and lagging',pf_2)

diff --git a/1938/CH6/EX6.36/6_36.jpg b/1938/CH6/EX6.36/6_36.jpg
new file mode 100755
index 000000000..324ec1efb
--- /dev/null
+++ b/1938/CH6/EX6.36/6_36.jpg
diff --git a/1938/CH6/EX6.36/6_36.sce b/1938/CH6/EX6.36/6_36.sce
new file mode 100755
index 000000000..619b67c74
--- /dev/null
+++ b/1938/CH6/EX6.36/6_36.sce
@@ -0,0 +1,26 @@
+clc,clear

+printf('Example 6.36\n\n')

+

+V_L=11000

+V_ph=V_L/sqrt(3)

+VA=2*10^6,phi=acos(0.8)

+I_FL=VA/(sqrt(3)*V_L)

+phi_1=acos(0.8)

+IX_s=(20/100)*V_ph //product of I and X_s

+X_s=IX_s/I_FL

+I_1=I_FL

+BC=I_1*cos(phi_1)*X_s

+AB=I_1*sin(phi_1)*X_s    , OA=V_ph

+OC=sqrt( (OA+AB)^2+(BC)^2 ) ,E_1=OC

+E_2=1.25*E_1,OE=E_2

+DE=BC

+AD=sqrt(OE^2-DE^2) -OA           //because OE=sqrt( (OA+AD)^2 + (DE)^2  )

+

+I_2sinphi2=AD/X_s

+I_2cosphi2=I_1*cos(phi)

+I_2=sqrt( (I_2cosphi2)^2 + (I_2sinphi2)^2  )

+phi2=atan( I_2sinphi2/ I_2cosphi2 )

+new_pf=cos(phi2)

+

+printf('Machine current is %.2f A \n',I_2)

+printf('Power factor is  %.4f lagging',new_pf)

diff --git a/1938/CH6/EX6.37/6_37.sce b/1938/CH6/EX6.37/6_37.sce
new file mode 100755
index 000000000..2d5adba0b
--- /dev/null
+++ b/1938/CH6/EX6.37/6_37.sce
@@ -0,0 +1,34 @@
+clc,clear

+printf('Example 6.37\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+P_out=3000*10^3

+V_L=6.6*10^3,V_ph=V_L/sqrt(3)

+phi=acos(0.8)

+I_L=p2z(P_out/(sqrt(3)*V_L*cos(phi)),-1*(180/%pi)*phi)

+

+P_out1=P_out/2

+I_L1=150  //given

+phi_L1=acos(    P_out1/(sqrt(3)*V_L*I_L1)  )

+I_L1=p2z(I_L1,-1*(180/%pi)*phi_L1)

+

+I_L2=I_L-I_L1

+pf_2=cosd(phasemag(I_L2))

+Z_1=complex(0.5,10)

+I_1=I_L1

+E_1=V_ph + I_1*Z_1

+delta_1=(%pi/180)*phasemag(E_1)    //load angle of alternator 1

+E_1L=sqrt(3)*E_1

+

+Z_2=complex(0.4,12)

+I_2=I_L2

+E_2=V_ph + I_2*Z_2

+delta_2=(%pi/180)*phasemag(E_2)    //load angle of alternator 2

+

+printf('Part(i)\nCurrents are %.0f A at %.1f degrees and %.1f A at %.1f degrees\nTotal current is %.0f at %.2f\n',abs(I_L1),phasemag(I_L1),abs(I_L2),phasemag(I_L2),abs(I_L),phasemag(I_L))

+printf('Part(ii)\nPower factor is %.4f and lagging\n',cos(phi_L1))

+printf('Part(iii)\nemf are %.2f V at %.2f degrees and %.4f V at %.0f degrees\n',abs(E_1),phasemag(E_1),abs(E_2),phasemag(E_2))

+printf('Part(iv)\nPower angles are %.2f degrees and %.0f degrees \n',(180/%pi)*delta_1,(180/%pi)*delta_2)

diff --git a/1938/CH6/EX6.38/6_38.jpg b/1938/CH6/EX6.38/6_38.jpg
new file mode 100755
index 000000000..07e7a0bbb
--- /dev/null
+++ b/1938/CH6/EX6.38/6_38.jpg
diff --git a/1938/CH6/EX6.38/6_38.sce b/1938/CH6/EX6.38/6_38.sce
new file mode 100755
index 000000000..7fa95646a
--- /dev/null
+++ b/1938/CH6/EX6.38/6_38.sce
@@ -0,0 +1,22 @@
+clc,clear

+printf('Example 6.38\n\n')

+

+Z1=complex(0.2,2)

+Z2=Z1

+ZL=complex(3,4)

+Z=ZL

+E1=complex(2000,0)

+E2=complex(2200,100)

+

+I1=((E1-E2)*Z+E1*Z2)/(Z*(Z1+Z2)+Z1*Z2)

+I2=((E2-E1)*Z+E2*Z1)/(Z*(Z1+Z2)+Z1*Z2)

+

+IL=I1+I2

+V=IL*Z //Terminal voltage

+

+phi1=phasemag(V)-phasemag(I1)  //Phasemag returns the angle of complex number in degrees

+phi2=phasemag(V)-phasemag(I2)  //Phasemag returns the angle of complex number in degrees

+

+Pout1=sqrt(3)*sqrt(3)*abs(V)*abs(I1)*cosd(phi1)

+Pout2=sqrt(3)*sqrt(3)*abs(V)*abs(I2)*cosd(phi2)

+printf('\nPower delivered is %.2f kW and %.2f kW at power-factors %.4f lag and %.4f lag respectively',Pout1/1000,Pout2/1000,cosd(phi1),cosd(phi2))

diff --git a/1938/CH6/EX6.39/6_39.sce b/1938/CH6/EX6.39/6_39.sce
new file mode 100755
index 000000000..c2f86e764
--- /dev/null
+++ b/1938/CH6/EX6.39/6_39.sce
@@ -0,0 +1,25 @@
+clc,clear

+printf('Example 6.39\n\n')

+

+f=50

+P=12

+V_L=6600

+V_ph=V_L/sqrt(3)

+VA=2000*10^3

+I_FL=VA/(sqrt(3)*V_L)

+

+IX_s=(25/100)*V_ph //product of I and X_s

+X_s=complex(0,IX_s/I_FL)

+N_s=12*f/P //in rpm

+delta_dash_mech=(%pi/180) //phase displacemnt in degree mechanical

+delta_dash_elec=delta_dash_mech*(P/2) //phase displacemnt in degree electrical

+

+phi=acos(0.8) //lag

+I=complex(I_FL*cos(-1*phi),I_FL*sin(-1*phi))

+V=V_ph

+E=V + I*X_s

+delta=phasemag(E)*(%pi/180)

+P_SY=abs(E)*abs(V)*cos(delta)*sin(delta_dash_elec)/abs(X_s)

+P_SY_total=3*P_SY

+printf('\nSynchronising power is %.2f kW',P_SY/1000)

+printf('\nTotal synchronising power is %.2f kW',P_SY_total/1000)

diff --git a/1938/CH6/EX6.4/6_4.sce b/1938/CH6/EX6.4/6_4.sce
new file mode 100755
index 000000000..6ec656633
--- /dev/null
+++ b/1938/CH6/EX6.4/6_4.sce
@@ -0,0 +1,21 @@
+clc,clear

+printf('Example 6.4\n\n')

+

+V_l=10000

+V_ph=V_l/sqrt(3)

+VA=10*10^6

+I_FL=VA/(V_l*sqrt(3)) //Current at full laod

+IX_s=(20/100)*V_ph //product of I and X_s

+

+X_s=IX_s/I_FL

+N_s=1500

+f=50

+P=120*f/N_s //poles

+

+delta_dash_mech=%pi/180 //phase displacement in degree mechanical

+delta_dash_elec=delta_dash_mech*(P/2)  //P/2 is pole pairs(and not poles)

+E=V_ph //since alternator is on no-load

+P_SY=delta_dash_elec*E^2/X_s  //Synchronous Power

+P_SY_3ph=P_SY*3 //For 3 phases

+

+printf('Synchronising Power of armature is %.3f kW.\nSynchronising Power for 3 phase is %.3f kW',P_SY*10^-3,P_SY_3ph*10^-3)

diff --git a/1938/CH6/EX6.40/6_40.jpg b/1938/CH6/EX6.40/6_40.jpg
new file mode 100755
index 000000000..10cfbf523
--- /dev/null
+++ b/1938/CH6/EX6.40/6_40.jpg
diff --git a/1938/CH6/EX6.40/6_40.sce b/1938/CH6/EX6.40/6_40.sce
new file mode 100755
index 000000000..89324be78
--- /dev/null
+++ b/1938/CH6/EX6.40/6_40.sce
@@ -0,0 +1,24 @@
+clc,clear

+printf('Example 6.40\n\n')

+

+V_L=22000

+V_ph=V_L/sqrt(3)

+power=230*10^6

+phi=acos(1)

+I_FL=power/(sqrt(3)*V_L*cos(phi))

+I_1=I_FL

+X_s=1.2

+

+E_1=sqrt( V_ph^2 + (I_1*X_s)^2 )

+E_2=1.3*E_1

+AC=  sqrt( E_2^2-(I_1*X_s)^2  )   -V_ph     // because E^2=(V_ph+AC)^2+(I_1*X_s)^2

+I2X_S=AC

+

+I_2cosphi2=I_1  //because phi_2=acos(I_1/I_2) //from ACD

+I_2sinphi2=AC/X_s

+I_2=sqrt( (I_2cosphi2)^2 + (I_2sinphi2)^2  )

+phi2=atan( I_2sinphi2/ I_2cosphi2 )

+new_pf=cos(phi2)

+

+printf('Machine current is %.2f A \n',I_2)

+printf('Power factor is  %.4f and lagging',new_pf)

diff --git a/1938/CH6/EX6.41/6_41.sce b/1938/CH6/EX6.41/6_41.sce
new file mode 100755
index 000000000..3bf957da2
--- /dev/null
+++ b/1938/CH6/EX6.41/6_41.sce
@@ -0,0 +1,33 @@
+clc,clear

+printf('Example 6.41\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+P_out=1500*10^3

+V_L=3.3*10^3

+phi=acos(0.8)

+I_L=p2z(P_out/(sqrt(3)*V_L*cos(phi)),-1*acosd(0.8))

+

+I_L1_magnitude=150  //given

+P_out1=(3*10^6)/2 //because load is EQUALLY shared between 2 alternators

+pf_L1=P_out1/(sqrt(3)*2*V_L*I_L1_magnitude)  //operating pf of alternator 1

+phi1=acosd(pf_L1)

+I_L1=p2z(I_L1_magnitude,-1*phi1)

+I_L2=I_L-I_L1   //because I_L=I_L1 + I_L2

+pf_L2=cosd(phasemag(I_L2))

+

+V_ph=6.6*10^3/sqrt(3)

+Z_1=complex(0.5,10)

+I_1=I_L1

+E_1= V_ph + I_1*Z_1

+delta_1=phasemag(E_1)  //load angle of alternator 1

+I_2=I_L2

+

+Z_2=complex(0.4,12)

+E_2= V_ph + I_2*Z_2

+delta_2=phasemag(E_2)  //load angle of alternator 1

+

+printf('for machine 1\ncurrent is %.0f A at %.2f degrees\nPower factor of %.4f lag\ninduced emf of %.2f V\nload angle of %.2f degrees',abs(I_L1),phasemag(I_L1),pf_L1,abs(E_1),delta_1)

+printf('\n\nfor machine 2\ncurrent is %.1f A at %.1f degrees\nPower factor of %.4f lag\ninduced emf of %.2f V\nload angle of %.0f degrees',abs(I_L2),phasemag(I_L2),pf_L2,abs(E_2),delta_2)

diff --git a/1938/CH6/EX6.42/6_42.sce b/1938/CH6/EX6.42/6_42.sce
new file mode 100755
index 000000000..a6a33dd39
--- /dev/null
+++ b/1938/CH6/EX6.42/6_42.sce
@@ -0,0 +1,19 @@
+clc,clear

+printf('Example 6.42\n\n')

+

+V_l=230

+VA=5*10^3

+X_d=12,X_q=7,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+phi=acos(1)

+

+I_l=VA/(V_l*sqrt(3))

+V_ph=V_l/sqrt(3)

+V_t=V_ph,I_a=I_l

+

+psi=atan(  (V_t*sin(phi)+I_a*X_q)/(V_t*cos(phi)+I_a*R_a)            )

+delta=psi-phi

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+E_f=V_t*cos(delta)+I_d*X_d+I_q*R_a

+

+printf('Excitation voltage is %.3f V ',E_f)

diff --git a/1938/CH6/EX6.43/6_43.sce b/1938/CH6/EX6.43/6_43.sce
new file mode 100755
index 000000000..095fdd865
--- /dev/null
+++ b/1938/CH6/EX6.43/6_43.sce
@@ -0,0 +1,25 @@
+clc,clear

+printf('Example 6.43\n\n')

+

+V_l=6.6*10^3

+V_t=V_l/sqrt(3)

+X_d=23.2,X_q=14.5,R_a=0 //armature resistance and synchronous reactance of direct,quadrature axis

+VA=1800*10^3

+phi=acos(0.8) //lag

+

+I_a=VA/(V_l*sqrt(3))

+

+psi=atan(  (V_t*sin(phi)-I_a*X_q)/(V_t*cos(phi)-I_a*R_a)  ) //minus sign in numerator and denomenator for motors

+delta=psi+phi

+I_d=I_a*sin(psi)

+I_q=I_a*cos(psi)

+E_f=V_t*cos(delta)-I_d*X_d-I_q*R_a

+printf('Excitation emf = %.4f V\n',E_f)

+//P_m= ( V_t*E_f*sin(delta)/X_d  ) + ((1/X_q)-(1/X_d))*0.5*sin(2*delta)*V_t^2

+//P_m=0.4996*cos(delta)+0.1877*sin(2*delta)

+//for maximum power output, differenciate and equate to zero

+

+delta_max=63.4 //degree

+

+P_m_max=((1/X_q)-(1/X_d))*0.5*sind(2*delta_max)*V_t^2   //Maximuum load supplied with E_f=0

+printf('Maximum load the motor can supply is %.4f MW per phase ',P_m_max*10^-6      )

diff --git a/1938/CH6/EX6.5/6_5.sce b/1938/CH6/EX6.5/6_5.sce
new file mode 100755
index 000000000..b6e457b7e
--- /dev/null
+++ b/1938/CH6/EX6.5/6_5.sce
@@ -0,0 +1,46 @@
+clc,clear

+printf('Example 6.5\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+V_L=6.6*10^3

+V_ph=V_L/sqrt(3)

+VA=3*10^6

+I_FL=VA/(V_L*sqrt(3)) //full load current 

+P=8,f=50 //poles and frequency

+

+X_s=complex(0,2.9)//X_s=2.9

+delta_dash_mech=%pi/180

+delta_dash_elec=delta_dash_mech*(P/2)  //P/2 is pole pairs(and not poles)

+

+//part(i)

+E=V_ph

+P_SY=delta_dash_elec*E^2/abs(X_s)  //Synchronous Power per phase

+P_SY_3ph=P_SY*3 //For 3 phases

+printf('(i)   Synchronising power at no load is %.3f kW',P_SY*10^-3)

+printf('\n   Total synchronising power at no load is %.2f kW\n',P_SY_3ph*10^-3)

+

+N_s=120*f/P //in rpm

+n_s=(N_s)/60 //in rps

+T_SY=P_SY_3ph/(2*%pi*n_s)

+printf('\nSynchronous torque per mechanical degree of phase displacement is %.2f * 10^3 N-m',T_SY*10^-3)

+

+//part(ii)

+phi=acosd(0.85)

+I=p2z(I_FL,0)

+V=p2z(V_ph,phi)

+

+E=V+I*X_s

+//E leads I by phasemag(E). V leads I by phasemag(V)

+

+delta=(%pi/180)* (phasemag(E)-phasemag(V) ) //power angle in radians

+P_SY2=abs(E)*abs(V)*cos(delta)*sin(delta_dash_elec)/abs(X_s)

+

+P_SY_total_2=3*P_SY2

+//n_s=T_SY/(P_SY/(2*%pi) )       //because T_SY=P_SY/(2*%pi*n_s)

+printf('\n\n(ii)Total synchronising power is %.0f kW',P_SY_total_2*10^-3)

+

+T_SY2=P_SY_total_2/(2*%pi*n_s)

+printf('\nSynchronising torque is %.2f * 10^3 N-m',T_SY2/1000)

diff --git a/1938/CH6/EX6.6/6_6.sce b/1938/CH6/EX6.6/6_6.sce
new file mode 100755
index 000000000..627bebe6d
--- /dev/null
+++ b/1938/CH6/EX6.6/6_6.sce
@@ -0,0 +1,29 @@
+clc,clear

+printf('Example 6.6\n\n')

+//note that a new function p2z has been defined below for direct representation of complex numbers in polar form

+function [FUN] = p2z(RRRR,Theeeta)

+ FUN = RRRR.*exp(%i*%pi*Theeeta/180.);

+endfunction

+

+V_l=10*10^3

+V_ph=V_l/sqrt(3)

+R_a=0.4

+Z=complex(R_a,6)

+I_a=p2z(300,-acosd(0.8))

+E=V_ph+I_a*Z

+

+phi=acos(0.8)

+alternator_op_ph=V_ph*abs(I_a)*cos(phi) //Power delivered to infinite bus per phase

+

+//Power deliered to the altrernator = Power delivewred to bus bar +  I^2*R losses in armature

+alternator_power= alternator_op_ph+ abs(I_a)^2*R_a

+

+//this power developed remains constant.change pf to 1 and calculate corresponding armature current

+//alternator_power=V_ph*I_a1*cos(phi1)+I_a1^2*0.4

+//solve the quadratic equation  0.4 I_a1^2+5773.50 I_a1- 1421640 =0

+I_a1=(-1*V_ph+sqrt(V_ph^2-4*R_a*-1*alternator_power))/(2*R_a)

+

+//also as follows 

+E1=V_ph+I_a1*Z

+decrease=100*(abs(E)-abs(E1))/abs(E)

+printf('Percentage decrease in induced e.m.f is %.1f percent',decrease)

diff --git a/1938/CH6/EX6.7/6_7.jpg b/1938/CH6/EX6.7/6_7.jpg
new file mode 100755
index 000000000..d77d5707b
--- /dev/null
+++ b/1938/CH6/EX6.7/6_7.jpg
diff --git a/1938/CH6/EX6.7/6_7.sce b/1938/CH6/EX6.7/6_7.sce
new file mode 100755
index 000000000..be43842c6
--- /dev/null
+++ b/1938/CH6/EX6.7/6_7.sce
@@ -0,0 +1,28 @@
+clc,clear

+printf('Example 6.7\n\n')

+

+//Line PQ for Altermnator 1, and PR for alternaator 2.AB is at frequency x from P where total load is 3000 kW

+QC=2000,PS=2.5,//PC=x

+TR=2000,PT=2

+

+//using similarity of triangles PAC and PQS

+AC_by_PC=(QC/PS)// because (AC/QC)=(PC/PS)

+//using similarity of triangles PCB and PTR

+CB_by_PC=(TR/PT) // because (CB/TR)=(PC/PT)

+

+AC_by_x=AC_by_PC   //which implies AC=12.5*x

+CB_by_x=CB_by_PC  //which implies CB=16.67*x

+

+AC_plus_CB=3000  //total load at the frequency at P is 30 kW

+x= AC_plus_CB/(AC_by_x + CB_by_x)

+AC=AC_by_x * x

+CB=CB_by_x * x  

+frequency=50-x

+printf('Loads shared by alternator 1 and 2 are %.2f kW and %.2f kW respectively',AC,CB)

+

+//construction for max load: RT is extended to cut PQ at X.

+QS=2000,RT=2000 //see figure

+XT=QS*(PT/PS)

+RX=RT+XT  //maximum load

+

+printf('\nMaximum load is %.0f kW',RX)

diff --git a/1938/CH6/EX6.8/6_8.jpg b/1938/CH6/EX6.8/6_8.jpg
new file mode 100755
index 000000000..43e333f6c
--- /dev/null
+++ b/1938/CH6/EX6.8/6_8.jpg
diff --git a/1938/CH6/EX6.8/6_8.sce b/1938/CH6/EX6.8/6_8.sce
new file mode 100755
index 000000000..ef4b798c3
--- /dev/null
+++ b/1938/CH6/EX6.8/6_8.sce
@@ -0,0 +1,22 @@
+clc,clear

+printf('Example 6.8\n\n')

+

+P_out=1500*10^3

+V_L=11000

+phi=acos(0.8)

+I_L=P_out/(sqrt(3)*V_L*cos(phi))

+

+I_L_actv=I_L*cos(phi)   //wattful or active component of current

+I_L_reactive=I_L*sin(phi) //wattless or reactive component of current

+

+I_each=I_L/2  //in identical conditions

+I_arm1=45 //given

+I_1_reactive=sqrt(I_arm1^2-39.364^2 )  //from the power triangle 

+I_2_reactive=59.046-21.80

+I_a_2=sqrt( 39.364^2 + I_2_reactive^2 )  //required armature current of 2nd alternator

+printf('Required armature current of second alternator is %.4f A\n',I_a_2)

+//power factors of 2 machines

+cos_phi1=39.364/45 

+cos_phi2=39.364/54.1921

+

+printf('Power factors are %.4f lagging and %.4f lagging',cos_phi1,cos_phi2)

diff --git a/1938/CH6/EX6.9/6_9.jpg b/1938/CH6/EX6.9/6_9.jpg
new file mode 100755
index 000000000..298e464cf
--- /dev/null
+++ b/1938/CH6/EX6.9/6_9.jpg
diff --git a/1938/CH6/EX6.9/6_9.sce b/1938/CH6/EX6.9/6_9.sce
new file mode 100755
index 000000000..b197cdd00
--- /dev/null
+++ b/1938/CH6/EX6.9/6_9.sce
@@ -0,0 +1,21 @@
+clc,clear

+printf('Example 6.9\n\n')

+

+//Line AB for Altermnator 1, and AC for alternator 2.AF is at frequency x measured from A where total load is 3000 kW

+BO=2000,AO=5//AF=x

+DC=2000,AD=3,//AF=x

+

+//using similarity of triangles AEF and ABO

+EF_by_AF=(BO/AO)// because (EF/BO)=(AF/AO)

+//using similarity of triangles AFG and ADC

+FG_by_AF=(DC/AD) //because (FG/DC)=(AF/AD)

+

+EF_by_x=EF_by_AF   //which implies EF=400*x

+FG_by_x=FG_by_AF   //which implies FG=666.67*x

+

+EF_plus_FG=3000  //total load at the frequency at P is 3000 kW

+x= EF_plus_FG/(EF_by_x + FG_by_x)

+EF=(BO/AO)*x

+FG=(DC/AD)*x  

+

+printf('Loads shared by machine 1 and 2 are %.0f kW and %.0f kW respectively',EF,FG)