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diff --git a/1820/CH4/EX4.1/Example4_1.sce b/1820/CH4/EX4.1/Example4_1.sce
new file mode 100755
index 000000000..fc905cafb
--- /dev/null
+++ b/1820/CH4/EX4.1/Example4_1.sce
@@ -0,0 +1,114 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.1 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+V_RL_L = 23*10^3 ; // line to line voltage in volts
+z_t = 2.48+%i*6.57 ; // Total impedance in ohm/phase
+p = 9*10^6 ; // load in watts
+pf = 0.85 ; // lagging power factor
+
+// CALCULATIONS
+// METHOD I : USING COMPLEX ALGEBRA
+
+V_RL_N = (V_RL_L)/sqrt(3) ; // line-to-neutral reference voltage in V
+I = (p/(sqrt(3)*V_RL_L*pf))*( pf - %i*sind(acosd(pf))) ; // Line current in amperes
+IZ = I*z_t ;
+V_SL_N = V_RL_N + IZ // Line to neutral voltage at sending end in volts
+V_SL_L = sqrt(3)*V_SL_N ; // Line to line voltage at sending end in volts
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.1 : SOLUTION :-") ;
+disp("METHOD I : USING COMPLEX ALGEBRA") ; 
+printf("\n (a) Line-to-neutral voltage at sending end , V_SL_N = %.f<%.1f V \n",abs(V_SL_N),atand( imag(V_SL_N),real(V_SL_N) )) ;
+printf("\n i.e Line-to-neutral voltage at sending end , V_SL_N = %.f V \n",abs(V_SL_N)) ;
+printf("\n     Line-to-line voltage at sending end , V_SL_L = %.f<%.1f V \n",abs(V_SL_L),atand( imag(V_SL_L),real(V_SL_L) )) ;
+printf("\n i.e Line-to-line voltage at sending end , V_SL_L = %.f V \n",abs(V_SL_L)) ;
+printf("\n (b) load angle , δ = %.1f degree \n",atand( imag(V_SL_L),real(V_SL_L) )) ;
+printf("\n") ;
+
+
+// CALCULATIONS
+// METHOD II : USING THE CURRENT AS REFERENCE PHASOR
+theta_R = acosd(pf) ; 
+V1 = V_RL_N*cosd(theta_R) + abs(I)*real(z_t) ; // unit is volts
+V2 = V_RL_N*sind(theta_R) + abs(I)*imag(z_t) ; // unit is volts
+V_SL_N2 = sqrt( (V1^2) + (V2^2) ) ; // Line to neutral voltage at sending end in volts/phase
+V_SL_L2 = sqrt(3) * V_SL_N2 ; // Line to line voltage at sending end in volts
+theta_s = atand(V2/V1) ; 
+delta = theta_s - theta_R ; 
+
+// DISPLAY RESULTS
+disp("METHOD II : USING THE CURRENT AS REFERENCE PHASOR");
+printf("\n (a) Line-to-neutral voltage at sending end , V_SL_N = %.f V \n",V_SL_N2) ;
+printf("\n     Line-to-line voltage at sending end , V_SL_L = %.f V \n",V_SL_L2) ;
+printf("\n (b) load angle , δ = %.1f degree \n",delta) ;
+printf("\n") ;
+
+// CALCULATIONS
+// METHOD III : USING THE RECEIVING-END VOLTAGE  AS REFERENCE PHASOR
+// for case (a)
+V_SL_N3 = sqrt( (V_RL_N + abs(I) * real(z_t) * cosd(theta_R) + abs(I) * imag(z_t) * sind(theta_R))^2 + (abs(I)*imag(z_t) * cosd(theta_R) - abs(I) * real(z_t) * sind(theta_R))^2) ;
+V_SL_L3 = sqrt(3)*V_SL_N3 ;
+
+// for case (b)
+delta_3 = atand( (abs(I)*imag(z_t) * cosd(theta_R) - abs(I) * real(z_t) * sind(theta_R))/(V_RL_N + abs(I) * real(z_t) * cosd(theta_R) + abs(I) * imag(z_t) * sind(theta_R)) ) ;
+
+// DISPLAY RESULTS
+disp("METHOD III : USING THE RECEIVING END VOLTAGE  AS REFERENCE PHASOR") ;
+printf("\n (a) Line-to-neutral voltage at sending end , V_SL_N = %.f V \n",V_SL_N3) ;
+printf("\n     Line-to-line voltage at sending end , V_SL_L = %.f V \n",V_SL_L3) ;
+printf("\n (b) load angle , δ = %.1f degree \n",delta_3) ;
+printf("\n") ;
+
+// CALCULATIONS
+// METHOD IV : USING POWER RELATIONSHIPS
+P_4 = 9 ; // load in MW (Given)
+P_loss = 3 * (abs(I))^2 * real(z_t) * 10^-6 ; // Power loss in line in MW
+P_T = P_4 + P_loss ; // Total input power to line in MW
+Q_loss = 3 * (abs(I))^2 * imag(z_t) * 10^-6 ; // Var loss of line in Mvar lagging
+Q_T = ( (P_4*sind(theta_R))/cosd(theta_R) ) + Q_loss ; // Total megavar input to line in Mvar lagging
+S_T = sqrt( (P_T^2)+(Q_T^2) ) ; // Total megavoltampere input to line
+// for case (a)
+V_SL_L4 = S_T*10^6/(sqrt(3) * abs(I)) ; // line to line voltage in volts
+V_SL_N4 = V_SL_L4/sqrt(3) ; // Line to line neutral in volts
+
+// for case (b)
+theta_S4 = acosd(P_T/S_T) ; // Lagging
+delta_4 = theta_s - theta_R ; 
+
+// DISPLAY RESULTS
+disp("METHOD IV : USING POWER RELATIONSHIPS");
+printf("\n (a) Line-to-neutral voltage at sending end , V_SL_N = %.f V \n",V_SL_N4) ;
+printf("\n (a) Line-to-line voltage at sending end , V_SL_L = %.f V \n",V_SL_L4) ;
+printf("\n (b) load angle , δ = %.1f degree \n",delta_4) ;
+printf("\n");
+
+// CALCULATIONS
+// METHOD V : Treating 3-Φ line as 1-Φ line having having V_S and V_R represent line-to-line voltages not line-to-neutral voltages
+// for case (a)
+I_line = (p/2)/(V_RL_L * pf) ; // Power delivered is 4.5 MW
+R_loop = 2*real(z_t) ;
+X_loop = 2*imag(z_t) ;
+V_SL_L5 = sqrt( (V_RL_L * cosd(theta_R) + I_line*R_loop)^2 + (V_RL_L * sind(theta_R) + I_line * X_loop)^2) ; // line to line voltage in V
+V_SL_N5 = V_SL_L5/sqrt(3) ; // line to neutral voltage in V
+
+// for case (b)
+theta_S5 = atand((V_RL_L * sind(theta_R) + I_line * X_loop)/(V_RL_L * cosd(theta_R) + I_line*R_loop)) ;
+delta_5 = theta_S5 - theta_R ;
+
+// DISPLAY RESULTS
+disp("METHOD V : TREATING 3-Φ LINE AS 1-Φ LINE") ;
+printf("\n (a) Line to neutral voltage at sending end , V_SL_N = %.f V \n",V_SL_N5) ;
+printf("\n (a) Line to line voltage at sending end , V_SL_L = %.f V \n",V_SL_L5) ;
+printf("\n (b) load angle , δ = %.1f degree \n",delta_5) ;
+printf("\n") ;
+
+printf("\n NOTE : ERROR : Change in answer because root(3) = 1.73 is considered in Textbook ") ;
+printf("\n But here sqrt(3) = 1.7320508 is considered \n") ;
diff --git a/1820/CH4/EX4.10/Example4_10.sce b/1820/CH4/EX4.10/Example4_10.sce
new file mode 100755
index 000000000..153a1adca
--- /dev/null
+++ b/1820/CH4/EX4.10/Example4_10.sce
@@ -0,0 +1,27 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.10 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+Z_1 = 10 * exp(%i*(30)*%pi/180) ; // Impedance in Ω
+Z_2 = 40 * exp(%i*(-45)*%pi/180) ; // Impedance in Ω
+
+// CALCULATIONS
+P = [1 ,Z_1 ; 0 , 1]; // For network 1
+Y_2 = 1/Z_2 ; // unit is S
+Q = [1 0 ; Y_2 1]; // For network 2
+EQ = P * Q ;
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.10 : SOLUTION :-") ;
+printf("\n Equivalent A , B , C , D constants are \n") ;
+printf("\n A_eq = %.3f<%.1f \n",abs( EQ(1,1) ),atand( imag(EQ(1,1)),real(EQ(1,1)) )) ;
+printf("\n B_eq = %.3f<%.1f \n",abs( EQ(1,2) ),atand( imag(EQ(1,2)),real(EQ(1,2)) )) ;
+printf("\n C_eq = %.3f<%.1f \n",abs( EQ(2,1) ),atand( imag(EQ(2,1)),real(EQ(2,1)) )) ;
+printf("\n D_eq = %.3f<%.1f \n",abs( EQ(2,2 )),atand( imag(EQ(2,2)),real(EQ(2,2)) )) ;
diff --git a/1820/CH4/EX4.11/Example4_11.sce b/1820/CH4/EX4.11/Example4_11.sce
new file mode 100755
index 000000000..3c4882fb6
--- /dev/null
+++ b/1820/CH4/EX4.11/Example4_11.sce
@@ -0,0 +1,38 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.11 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+Z_1 = 10*exp(%i*(30)*%pi/180) ; // Impedance in Ω
+Z_2 = 40*exp(%i*(-45)*%pi/180) ; // Impedance in Ω
+Y_2 = 1/Z_2 ;
+A_1 = 1 ;
+B_1 = Z_1 ;
+C_1 = 0 ;
+D_1 = 1 ;
+A_2 = 1 ;
+B_2 = 0 ;
+C_2 = Y_2 ;
+D_2 = 1 ;
+
+// CALCULATIONS
+P = [A_1 B_1 ; C_1 D_1]; // For network 1
+Q = [A_2 B_2 ; C_2 D_2]; // For network 2
+A_eq = ( A_1*B_2 + A_2*B_1 )/( B_1 + B_2 ) ; // Constant A
+B_eq = ( B_1*B_2 )/(B_1 + B_2) ; // Constant B
+C_eq = C_1 + C_2 + ( (A_1 - A_2) * (D_2 -D_1)/(B_1 + B_2) ) ; // Constant C
+D_eq = ( D_1*B_2 + D_2*B_1 )/(B_1+B_2) ; // Constant D
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.11 : SOLUTION :-") ;
+printf("\n Equivalent A , B , C , D constants are \n") ;
+printf("\n A_eq = %.2f<%.f \n",abs(A_eq),atand( imag(A_eq),real(A_eq) )) ;
+printf("\n B_eq = %.2f<%.f \n",abs(B_eq),atand( imag(B_eq),real(B_eq) )) ;
+printf("\n C_eq = %.3f<%.f \n",abs(C_eq),atand( imag(C_eq),real(C_eq) )) ;
+printf("\n D_eq = %.2f<%.f \n",abs(D_eq),atand( imag(D_eq),real(D_eq) )) ;
diff --git a/1820/CH4/EX4.12/Example4_12.sce b/1820/CH4/EX4.12/Example4_12.sce
new file mode 100755
index 000000000..e97d48289
--- /dev/null
+++ b/1820/CH4/EX4.12/Example4_12.sce
@@ -0,0 +1,51 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.12 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+Z = 2.07 + 0.661 * %i ; // Line impedance in Ω
+V_L = 2.4 * 10^3 ; // Line voltage in V
+p = 200 * 10^3; // Load in VA
+pf = 0.866 ; // Lagging power factor
+
+// CALCULATIONS
+// for case (a)
+A = 1 ;
+B = Z ;
+C = 0 ;
+D = A ;
+theta = acosd(pf) ;
+S_R = p * ( cosd(theta) + %i * sind(theta) ) ; // Receiving end power in VA
+I_L1 = S_R/V_L ;
+I_L = conj(I_L1) ;
+I_S = I_L ; // sending end current in A
+I_R = I_S ; // Receiving end current in A
+
+// for case (b)
+Z_L = V_L/I_L ; // Impedance in Ω
+V_R = Z_L * I_R ;
+V_S = A * V_R + B * I_R ; // sending end voltage in V
+P = [A B ;C D] * [V_R ; I_R] ;
+
+// for case (c)
+V_S = P(1,1) ;
+I_S = P(2,1) ;
+Z_in = V_S/I_S ; // Input impedance in Ω
+
+// for case (d)
+S_S = V_S * conj(I_S) ;
+S_L = S_S - S_R ; // Power loss of line in VA
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.12 : SOLUTION :-") ;
+printf("\n (a) Sending-end current , I_S = %.2f<%.2f A \n",abs(I_S),atand( imag(I_S),real(I_S) )) ;
+printf("\n (b) Sending-end voltage , V_S = %.2f<%.2f V \n",abs(V_S),atand( imag(V_S),real(V_S) )) ;
+printf("\n (c) Input impedance , Z_in = %.2f<%.2f Ω \n",abs(Z_in),atand( imag(Z_in),real(Z_in) )) ;
+printf("\n (d) Real power loss in line , S_L = %.2f W \n",real(S_L)) ;
+printf("\n     Reactive power loss in line , S_L = %.2f var \n",imag(S_L)) ;
diff --git a/1820/CH4/EX4.13/Example4_13.sce b/1820/CH4/EX4.13/Example4_13.sce
new file mode 100755
index 000000000..4d710fa45
--- /dev/null
+++ b/1820/CH4/EX4.13/Example4_13.sce
@@ -0,0 +1,49 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.13 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+KV = 345 ; // Transmission line voltage in kV
+V_R = KV ;
+V_S = KV ; 
+x_L = 0.588 ;// Inductive reactance in Ω/mi/phase 
+b_c = 7.20*10^-6 ;// susceptance S phase to neutral per phase
+l = 200 ;// Total line length in mi
+
+// CALCULATIONS
+// for case (a)
+x_C = 1/b_c ;// Ω/mi/phase
+Z_C = sqrt(x_C * x_L) ;
+SIL = KV^2/Z_C ; // Surge impedance loading in MVA/mi . [1MVA = 1MW]
+SIL1 = (KV^2/Z_C) * l ; // Surge impedance loading of line in MVA . [1MVA = 1MW]
+
+// for case (b)
+delta = 90 ; // Max 3-Φ theoretical steady-state power flow limit occurs for δ = 90 degree
+X_L = x_L * l ; // Inductive reactance Ω/phase 
+P_max = V_S * V_R * sind(delta)/(X_L) ;
+
+// for case (c)
+Q_C = V_S^2 * (b_c * l/2) + V_R^2 *( b_c * l/2) ; // Total 3-Φ magnetizing var in Mvar
+
+// for case (d)
+g = %i * sqrt(x_L/x_C) ; // rad/mi
+g_l = g * l ; // rad
+V_R_oc = V_S / cosh(g_l) ; // Open-circuit receiving-end voltage in kV
+X_C = x_C * 2 / l ;
+V_R_oc1 = V_S * ( - %i * X_C/( - %i * X_C + %i * X_L) ) ; // Alernative method to find Open-circuit receiving-end voltage in kV
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.13 : SOLUTION :-") ;
+printf("\n (a) Total 3-Φ SIL of line , SIL = %.2f MVA/mi \n",SIL) ;
+printf("\n     Total 3-Φ SIL of line for total line length , SIL = %.2f MVA \n",SIL1) ;
+printf("\n (b) Maximum 3-Φ theortical steady-state power flow limit , P_max = %.2f MW \n",P_max) ;
+printf("\n (c) Total 3-Φ magnetizing var generation by line capacitance , Q_C = %.2f Mvar \n",Q_C) ;
+printf("\n (d) Open-circuit receiving-end voltage if line is open at receiving end , V_R_oc = %.2f kV \n",V_R_oc) ;
+printf("\n    From alternative method ,") ;
+printf("\n     Open-circuit receiving-end voltage if line is open at receiving end , V_R_oc = %.2f kV \n",V_R_oc1) ;
diff --git a/1820/CH4/EX4.14/Example4_14.sce b/1820/CH4/EX4.14/Example4_14.sce
new file mode 100755
index 000000000..3a10b0ae2
--- /dev/null
+++ b/1820/CH4/EX4.14/Example4_14.sce
@@ -0,0 +1,58 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.14 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+KV = 345 ; // Transmission line voltage in kV
+V_R = KV ; // Sending end voltage in kV
+x_L = 0.588 ;// Inductive reactance in Ω/mi/phase 
+b_c = 7.20*10^-6 ;// susceptance S phase to neutral per phase
+l = 200 ;// Total line length in mi
+per = 60/100 ; // 2 shunt reactors absorb 60% of total 3-Φ magnetizing var
+cost = 10 ; // cost of each reactor is $10/kVA
+
+// CALCULATIONS
+// For case (a)
+x_C = 1/b_c ;// Ω/mi/phase
+Z_C = sqrt(x_C * x_L) ;
+SIL = KV^2/Z_C ; // Surge impedance loading in MVA/mi
+SIL1 = (KV^2/Z_C) * l ; // Surge impedance loading of line in MVA . [1MVA = 1MW]
+
+// For case (b)
+delta = 90 ; // Max 3-Φ theoretical steady-state power flow limit occurs for δ = 90 degree
+V_S = V_R ; // sending end voltage in kV
+X_L = x_L * l ; // Inductive reactance Ω/phase 
+P_max = V_S * V_R * sind(delta)/(X_L) ;
+
+// For case (c)
+Q_C = V_S^2 * (b_c * l/2) + V_R^2 *( b_c * l/2) ; // Total 3-Φ magnetizing var in Mvar
+Q = (1/2) * per * Q_C ; // 3-Φ megavoltampere rating of each reactor . Q = (1/2)*Q_L
+
+// For case (d)
+Q_L1 = Q * 10^3 ; // Total 3-Φ magnetizing var in Kvar
+T_cost = Q_L1 * cost ; // Cost of each reactor in $
+
+// For case (e)
+g = %i * sqrt(x_L * (1-per)/x_C) ; // rad/mi
+g_l = g * l ; // rad
+V_R_oc = V_S/cosh(g_l) ; // Open circuit receiving-end voltage in kV
+X_L = x_L *l ; 
+X_C = (x_C * 2) / (l * (1 - per)) ;
+V_R_oc1 = V_S * ( -%i*X_C/(-%i*X_C + %i*X_L) ) ; // Alernative method to find Open-circuit receiving-end voltage in kV
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.14 : SOLUTION :-") ;
+printf("\n (a) Total 3-phase SIL of line , SIL = %.2f MVA/mi \n",SIL) ;
+printf("\n     Total 3-Φ SIL of line for total line length , SIL = %.2f MVA \n",SIL1) ;
+printf("\n (b) Maximum 3-phase theortical power flow , P_max = %.2f MW \n",P_max) ;
+printf("\n (c) 3-phase MVA rating of each reactor , (1/2)Q_L = %.2f MVA \n",Q) ;
+printf("\n (d) Cost of each reactor at $10/kVA = $ %.2f \n",T_cost) ;
+printf("\n (e) Open circuit receiving voltage , V_Roc= %.2f kV \n",V_R_oc) ;
+printf("\n    From alternative method ,") ;
+printf("\n     Open-circuit receiving-end voltage if line is open at receiving end , V_R_oc = %.2f kV \n",V_R_oc1) ;
diff --git a/1820/CH4/EX4.15/Example4_15.sce b/1820/CH4/EX4.15/Example4_15.sce
new file mode 100755
index 000000000..93ac6eccf
--- /dev/null
+++ b/1820/CH4/EX4.15/Example4_15.sce
@@ -0,0 +1,55 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.15 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+D_12 = 26 ; // distances in feet
+D_23 = 26 ; // distances in feet
+D_31 = 52 ; // distances in feet
+d = 12 ; // Distance b/w 2 subconductors in inches
+f = 60 ; // frequency in Hz
+kv = 345 ; // voltage base in kv
+p = 100 ; // Power base in MVA
+l = 200 ; // length of line in km
+
+// CALCULATIONS
+// For case (a)
+D_S = 0.0435 ; // from A.3 Appendix A . Geometric mean radius in feet
+D_bS = sqrt(D_S * 0.3048 * d * 0.0254) ; // GMR of bundled conductor in m .[1 ft = 0.3048 m ; 1 inch = 0.0254 m]
+D_eq = (D_12 * D_23 * D_31 * 0.3048^3)^(1/3) ; // Equ GMR in meter
+L_a = 2 * 10^-7 * log(D_eq/D_bS); // Inductance in H/meter
+
+// For case (b)
+X_L = 2 * %pi * f * L_a ; // inductive reactance/phase in ohms/m 
+X_L0 = X_L * 10^3 ; // inductive reactance/phase in ohms/km 
+X_L1 = X_L0 * 1.609 ;// inductive reactance/phase in ohms/mi [1 mi = 1.609 km]
+
+// For case (c)
+Z_B = kv^2 / p ; // Base impedance in Ω
+X_L2 = X_L0 * l/Z_B ; // Series reactance of line in pu
+
+// For case (d)
+r = 1.293*0.3048/(2*12) ; // radius in m . outside diameter is 1.293 inch given in A.3
+D_bsC = sqrt(r * d * 0.0254) ;
+C_n = 55.63 * 10^-12/log(D_eq/D_bsC) ; // capacitance of line in F/m
+
+// For case (e)
+X_C = 1/( 2 * %pi * f * C_n ) ; // capacitive reactance in ohm-m
+X_C0 = X_C * 10^-3 ; // capacitive reactance in ohm-km
+X_C1 = X_C0/1.609 ; // capacitive reactance in ohm-mi
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.15 : SOLUTION :-") ;
+printf("\n (a) Average inductance per phase , L_a = %.4e H/m \n",L_a) ;
+printf("\n (b) Inductive reactance per phase , X_L = %.4f Ω/km \n",X_L0) ;
+printf("\n     Inductive reactance per phase , X_L = %.4f Ω/mi \n",X_L1) ;
+printf("\n (c) Series reactance of line , X_L = %.4f pu \n",X_L2) ;
+printf("\n (d) Line-to-neutral capacitance of line , C_n = %.4e F/m \n",C_n);
+printf("\n (e) Capacitive reactance to neutral of line , X_C = %.3e Ω-km \n",X_C0) ;
+printf("\n     Capacitive reactance to neutral of line , X_C = %.3e Ω-mi \n",X_C1) ;
diff --git a/1820/CH4/EX4.2/Example4_2.sce b/1820/CH4/EX4.2/Example4_2.sce
new file mode 100755
index 000000000..e6b80c945
--- /dev/null
+++ b/1820/CH4/EX4.2/Example4_2.sce
@@ -0,0 +1,33 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+// EXAMPLE : 4.2 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+// for case (a)
+V_S = 14803 ; // sending end phase voltage at no load in volts . From exa 4.1
+V_R = 13279.056 ; // receiving end phase voltage at full load in volts . From exa 4.1
+
+// for case (b)
+I_R = 265.78785 ; // Line current in amperes . From exa 4.1
+z_t = 2.48+%i*6.57 ; // Total impedance in ohm/phase
+pf = 0.85 ; // power factor
+theta_R = acosd(pf) ;
+
+// CALCULATIONS
+// for case (a)
+V_reg1 = ( (V_S - V_R)/V_R )*100 ; // percentage voltage regulation using equ 4.29
+
+// for case (b)
+V_reg2 = (I_R * ( real(z_t) * cosd(theta_R) + imag(z_t) * sind(theta_R) )/ V_R)*100 ; // percentage voltage regulation using equ 4.31
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.2 : SOLUTION :-") ;
+printf("\n (a) Percentage of voltage regulation using equ 4.29 = %.1f \n",V_reg1) ;
+printf("\n (b) Percentage of voltage regulation using equ 4.31 = %.1f \n",V_reg2) ;
+
+printf("\n NOTE : ERROR : The question is with respect to values given in Exa 4.1 not 4.5 \n") ;
diff --git a/1820/CH4/EX4.3/Example4_3.sce b/1820/CH4/EX4.3/Example4_3.sce
new file mode 100755
index 000000000..28ce14e24
--- /dev/null
+++ b/1820/CH4/EX4.3/Example4_3.sce
@@ -0,0 +1,23 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.3 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+Z_xy = 0.09 + %i*0.3 ; // Mutual impedance between two parallel feeders in Ω/mi per phase
+Z_xx = 0.604*exp(%i*50.4*%pi/180) ; // Self impedance of feeders in Ω/mi per phase
+Z_yy = 0.567*exp(%i*52.9*%pi/180) ; // Self impedance of feeders in Ω/mi per phase
+
+// SOLUTION
+Z_2 = Z_xx - Z_xy ; // mutual impedance between feeders
+Z_4 = Z_yy - Z_xy ; // mutual impedance between feeders
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.3 : SOLUTION :-") ;
+printf("\n  Mutual impedance at node 2 , Z_2 = %.3f + j%.3f Ω\n",real(Z_2),imag(Z_2)) ;
+printf("\n  Mutual impedance at node 4 , Z_4 = %.3f + j%.3f Ω\n",real(Z_4),imag(Z_4)) ;
diff --git a/1820/CH4/EX4.4/Example4_4.sce b/1820/CH4/EX4.4/Example4_4.sce
new file mode 100755
index 000000000..87957ca66
--- /dev/null
+++ b/1820/CH4/EX4.4/Example4_4.sce
@@ -0,0 +1,60 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.4 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+V = 138*10^3 ; // transmission line voltage in V
+P = 49*10^6 ; // load power in Watts
+pf = 0.85 ; // lagging power factor
+Z = 95 * exp(%i*78*%pi/180) ; // line constants in Ω
+Y = 0.001 * exp(%i*90*%pi/180) ; // line constants in siemens
+
+// CALCULATIONS
+V_RL_N = V/sqrt(3) ;
+theta_R = acosd(pf) ; 
+I_R = P/(sqrt(3)*V*pf)*( cosd(theta_R) - %i*sind(theta_R) ) ; // receiving end current in ampere
+
+// for case (a)
+// A,B,C,D constants for nominal-T circuit representation
+A = 1 + (1/2)*Y*Z ; 
+B = Z + (1/4)*Y*Z^2 ;
+C = Y ;
+D = A ;
+
+// for case (b)
+P = [A B ; C D] * [V_RL_N ; I_R] ;
+V_SL_N = P(1,1) ; // Line-to-neutral Sending end voltage in V
+V_SL_L = sqrt(3) * abs(V_SL_N) * exp(%i* ( atand( imag(V_SL_N),real(V_SL_N) ) + 30 )* %pi/180) ; // Line-to-line voltage in V
+// NOTE that an additional 30 degree is added to the angle since line to line voltage is 30 degree ahead of its line to neutral voltage
+
+
+// for case (c)
+I_S = P(2,1); // Sending end current in A
+
+// for case (d)
+theta_s = atand( imag(V_SL_N),real(V_SL_N) ) - atand( imag(I_S),real(I_S) ) ;
+
+// for case (e)
+n = (sqrt(3) * V * abs(I_R) * cosd(theta_R)/(sqrt(3) * abs(I_S) * abs(V_SL_L) * cosd(theta_s) ))*100 ; // Efficiency
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.4 : SOLUTION :-") ;
+printf("\n (a) A constant of line , A = %.4f<%.1f \n",abs(A),atand( imag(A),real(A) )) ;
+printf("\n     B constant of line , B = %.2f<%.1f Ω \n",abs(B),atand( imag(B),real(B) )) ;
+printf("\n     C constant of line , C = %.3f<%.1f S \n",abs(C),atand( imag(C),real(C) )) ;
+printf("\n     D constant of line , D = %.4f<%.1f \n",abs(D),atand( imag(D),real(D) )) ;
+printf("\n (b) Sending end line-to-neutral voltage , V_SL_N = %.1f<%.1f V \n",abs(V_SL_N),atand( imag(V_SL_N),real(V_SL_N) )) ;
+printf("\n     Sending end line-to-line voltage , V_SL_L = %.1f<%.1f V \n",abs(V_SL_L),atand( imag(V_SL_L),real(V_SL_L) )) ;
+printf("\n (c) sending end current , I_S = %.2f<%.1f A \n",abs(I_S),atand( imag(I_S),real(I_S) )) ;
+printf("\n (d) sending end power factor , cosθ_s = %.3f \n",cosd(theta_s)) ;
+printf("\n (e) Efficiency of transmission , η = %.2f Percentage \n",n) ;
+
+printf("\n NOTE : From A = 0.9536<0.6 , magnitude is 0.9536 & angle is 0.6 degree") ;
+printf("\n ERROR : Change in answer because root(3) = 1.73 is considered in Textbook ") ;
+printf("\n But here sqrt(3) = 1.7320508 is considered \n") ;
diff --git a/1820/CH4/EX4.5/Example4_5.sce b/1820/CH4/EX4.5/Example4_5.sce
new file mode 100755
index 000000000..14c4be030
--- /dev/null
+++ b/1820/CH4/EX4.5/Example4_5.sce
@@ -0,0 +1,59 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.5 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+V = 138*10^3 ; // Transmission line voltage in V
+P = 49*10^6 ; // load power in Watts
+pf = 0.85 ; // lagging power factor
+Z = 95 * exp(%i*78*%pi/180) ; // line constants in Ω
+Y = 0.001 * exp(%i*90*%pi/180) ; // line constants in siemens
+
+// CALCULATIONS
+V_RL_N = V/sqrt(3) ;
+theta_R = acosd(pf) ;
+I_R = P/(sqrt(3)*V*pf) * ( cosd(theta_R) - %i*sind(theta_R) ) ; // Receiving end current in A
+
+// for case (a)
+// A,B,C,D constants for nominal-π circuit representation
+A = 1 + (1/2)*Y*Z ;
+B = Z ;
+C = Y + (1/4)*(Y^2)*Z ;
+D = 1 + (1/2)*Y*Z ;
+
+// for case (b)
+P = [A B ; C D] * [V_RL_N ; I_R] ;
+V_SL_N = P(1,1) ; // Line-to-neutral Sending end voltage in V
+V_SL_L = sqrt(3) * abs(V_SL_N) * exp(%i* ( atand( imag(V_SL_N),real(V_SL_N) ) + 30 )* %pi/180) ; // Line-to-line voltage in V
+// NOTE that an additional 30 degree is added to the angle since line-to-line voltage is 30 degree ahead of its line-to-neutral voltage
+
+
+// for case (c)
+I_S = P(2,1); // Sending end current in A
+
+// for case (d)
+theta_s = atand( imag(V_SL_N),real(V_SL_N) ) - atand( imag(I_S),real(I_S) ) ;
+
+// for case (e)
+n = (sqrt(3) * V * abs(I_R) * cosd(theta_R)/(sqrt(3) * abs(I_S) * abs(V_SL_L) * cosd(theta_s) ))*100 ; // Efficiency
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.5 : SOLUTION :-") ;
+printf("\n (a) A constant of line , A = %.4f<%.1f \n",abs(A),atand( imag(A),real(A) )) ;
+printf("\n     B constant of line , B = %.2f<%.1f Ω \n",abs(B),atand( imag(B),real(B) )) ;
+printf("\n     C constant of line , C = %.3f<%.1f S \n",abs(C),atand( imag(C),real(C) )) ;
+printf("\n     D constant of line , D = %.4f<%.1f \n",abs(D),atand( imag(D),real(D) )) ;
+printf("\n (b) Sending end line-to-neutral voltage , V_SL_N = %.1f<%.1f V \n",abs(V_SL_N),atand( imag(V_SL_N),real(V_SL_N) )) ;
+printf("\n     Sending end line-to-line voltage , V_SL_L = %.1f<%.1f V \n",abs(V_SL_L),atand( imag(V_SL_L),real(V_SL_L) )) ;
+printf("\n (c) sending end current , I_S = %.2f<%.1f A \n",abs(I_S),atand( imag(I_S),real(I_S) )) ;
+printf("\n (d) sending end power factor , cosθ_s = %.3f \n",cosd(theta_s)) ;
+printf("\n (e) Efficiency of transmission , η = %.2f Percentage \n",n) ;
+
+printf("\n NOTE : ERROR : Change in answer because root(3) = 1.73 is considered in Textbook ") ;
+printf("\n But here sqrt(3) = 1.7320508 is considered \n") ;
diff --git a/1820/CH4/EX4.6/Example4_6.sce b/1820/CH4/EX4.6/Example4_6.sce
new file mode 100755
index 000000000..9cb1d61fd
--- /dev/null
+++ b/1820/CH4/EX4.6/Example4_6.sce
@@ -0,0 +1,91 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.6 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+V_RL_L = 138*10^3 ; // transmission line voltage in V
+R = 0.1858 // Line constant in Ω/mi
+f = 60 // frequency in Hertz
+L = 2.60*10^-3 // Line constant in H/mi
+C = 0.012*10^-6 // Line constant in F/mi
+pf = 0.85 // Lagging power factor
+P = 50*10^6 // load in VA
+l = 150 // length of 3-Φ transmission line in mi
+
+// CALCULATIONS
+z = R + %i*2*%pi*f*L ; // Impedance per unit length in Ω/mi
+y = %i*2*%pi*C*f ; // Admittance per unit length in S/mi
+g = sqrt(y*z) ; // Propagation constant of line per unit length
+g_l = real(g) * l + %i * imag(g) * l ; // Propagation constant of line
+Z_c = sqrt(z/y) ; // Characteristic impedance of line
+V_RL_N = V_RL_L/sqrt(3) ;
+theta_R = acosd(pf) ; 
+I_R = P/(sqrt(3)*V_RL_L)*( cosd(theta_R) - %i*sind(theta_R) ) ; // Receiving end current in A
+
+// for case (a)
+// A,B,C,D constants of line
+A = cosh(g_l) ;
+B = Z_c * sinh(g_l) ;
+C = (1/Z_c) * sinh(g_l) ;
+D = A ;
+
+// for case (b)
+P = [A B ; C D] * [V_RL_N ; I_R] ;
+V_SL_N = P(1,1) ; // Line-to-neutral Sending end voltage in V
+V_SL_L = sqrt(3) * abs(V_SL_N) * exp(%i* ( atand( imag(V_SL_N),real(V_SL_N) ) + 30 )* %pi/180) ; // Line-to-line voltage in V
+// NOTE that an additional 30 degree is added to the angle since line-to-line voltage is 30 degree ahead of its line-to-neutral voltage
+
+// for case (c)
+I_S = P(2,1); // Sending end current in A
+
+// for case (d)
+theta_s = atand( imag(V_SL_N),real(V_SL_N) ) - atand( imag(I_S),real(I_S) ) ; // Sending-end pf
+
+// For case (e)
+P_S = sqrt(3) * abs(V_SL_L) * abs(I_S) * cosd(theta_s) ; // Sending end power
+
+// For case (f)
+P_R = sqrt(3)*abs(V_RL_L)*abs(I_R)*cosd(theta_R) ; // Receiving end power
+P_L = P_S - P_R ; // Power loss in line
+
+// For case (g)
+n = (P_R/P_S)*100 ; // Transmission line efficiency
+
+// For case (h)
+reg = (( abs(V_SL_N) - V_RL_N )/V_RL_N )*100 ; // Percentage of voltage regulation
+
+// For case (i)
+Y = y * l ; // unit is S
+I_C = (1/2) * Y * V_SL_N ; // Sending end charging current in A
+
+// For case (j)
+Z = z * l ;
+V_RL_N0 = V_SL_N - I_C*Z ;
+V_RL_L0 = sqrt(3) * abs(V_RL_N0) * exp(%i* ( atand( imag(V_RL_N0),real(V_RL_N0) ) + 30 )* %pi/180) ; // Line-to-line voltage at receiving end in V
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.6 :SOLUTION :-") ;
+printf("\n (a) A constant of line , A = %.4f<%.2f \n",abs(A),atand( imag(A),real(A) )) ;
+printf("\n     B constant of line , B = %.2f<%.2f Ω \n",abs(B),atand( imag(B),real(B) )) ;
+printf("\n     C constant of line , C = %.5f<%.2f S \n",abs(C),atand( imag(C),real(C) )) ;
+printf("\n     D constant of line , D = %.4f<%.2f \n",abs(D),atand( imag(D),real(D) )) ;
+printf("\n (b) Sending end line-to-neutral voltage , V_SL_N = %.2f<%.2f V \n",abs(V_SL_N),atand( imag(V_SL_N),real(V_SL_N) )) ;
+printf("\n     Sending end line-to-line voltage , V_SL_L = %.2f<%.2f V \n",abs(V_SL_L),atand( imag(V_SL_L),real(V_SL_L) )) ;
+printf("\n (c) sending-end current , I_S = %.2f<%.2f A \n",abs(I_S),atand( imag(I_S),real(I_S) )) ;
+printf("\n (d) sending-end power factor , cosθ_s = %.4f \n",cosd(theta_s)) ;
+printf("\n (e) sending-end power , P_S = %.5e W \n",P_S) ;
+printf("\n (f) Power loss in line , P_L = %.5e W \n",P_L) ;
+printf("\n (g) Transmission line Efficiency , η = %.1f Percentage\n",n) ;
+printf("\n (h) Percentage of voltage regulation = %.1f Percentage \n",reg) ;
+printf("\n (i) Sending-end charging current at no load , I_C = %.2f A \n",abs(I_C)) ;
+printf("\n (j) Receiving-end voltage rise at no load ,V_RL_N = %.2f<%.2f V \n",abs(V_RL_N0),atand(imag(V_RL_N0),real(V_RL_N0)));
+printf("\n     Line-to-line voltage at receiving end at no load ,V_RL_L = %.2f<%.2f V \n",abs(V_RL_L0),atand(imag(V_RL_L0),real(V_RL_L0)));
+
+printf("\n NOTE : ERROR : Change in answer because root(3) = 1.73 is considered in Textbook & change in α & β values ") ;
+printf("\n But here sqrt(3) = 1.7320508 is considered \n") ;
diff --git a/1820/CH4/EX4.7/Example4_7.sce b/1820/CH4/EX4.7/Example4_7.sce
new file mode 100755
index 000000000..c4ab75628
--- /dev/null
+++ b/1820/CH4/EX4.7/Example4_7.sce
@@ -0,0 +1,50 @@
+
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.7 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+R = 0.1858 // Line constant in Ω/mi
+f = 60 // frequency in Hertz
+L = 2.60*10^-3 // Line constant in H/mi
+C = 0.012*10^-6 // Line constant in F/mi
+l = 150 // length of 3-Φ transmission line in mi
+
+// CALCULATIONS
+z = R + %i*2*%pi*f*L ; // Impedance per unit length in Ω/mi
+y = %i*2*%pi*C*f ; // Admittance per unit length in S/mi
+g = sqrt(y*z) ; // Propagation constant of line per unit length
+g_l = real(g) * l + %i * imag(g) * l ; // Propagation constant of line
+Z_c = sqrt(z/y) ; // Characteristic impedance of line
+
+A = cosh(g_l) ;
+B = Z_c * sinh(g_l) ;
+C = (1/Z_c) * sinh(g_l) ;
+D = A ;
+Z_pi = B ;
+Y_pi_by2 = (A-1)/B ; // Unit in Siemens
+Z = l * z ; // unit in ohms
+Y = y * l ;
+Y_T = C ;
+Z_T_by2 = (A-1)/C ; // Unit in Ω
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.7 : SOLUTION :-") ;
+printf("\n FOR EQUIVALENT-π CIRCUIT ") ;
+printf("\n   Z_π = B = %.2f<%.2f Ω \n",abs(Z_pi),atand( imag(Z_pi),real(Z_pi) )) ;
+printf("\n   Y_π/2 = %.6f<%.2f S \n",abs(Y_pi_by2),atand( imag(Y_pi_by2),real(Y_pi_by2) )) ;
+printf("\n FOR NOMINAL-π CIRCUIT ") ;
+printf("\n   Z = %.3f<%.2f Ω \n",abs(Z),atand( imag(Z),real(Z) )) ;
+printf("\n   Y/2 = %.6f<%.1f S \n",abs(Y/2),atand( imag(Y/2),real(Y/2) )) ;
+printf("\n FOR EQUIVALENT-T CIRCUIT ") ;
+printf("\n   Z_T/2 = %.2f<%.2f Ω \n",abs(Z_T_by2),atand( imag(Z_T_by2),real(Z_T_by2) )) ;
+printf("\n   Y_T = C = %.5f<%.2f S \n",abs(Y_T),atand( imag(Y_T),real(Y_T) )) ;
+printf("\n FOR NOMINAL-T CIRCUIT ") ;
+printf("\n   Z/2 = %.2f<%.2f Ω \n",abs(Z/2),atand( imag(Z/2),real(Z/2) )) ;
+printf("\n   Y = %.6f<%.1f S \n",abs(Y),atand( imag(Y),real(Y) )) ;
diff --git a/1820/CH4/EX4.8/Example4_8.sce b/1820/CH4/EX4.8/Example4_8.sce
new file mode 100755
index 000000000..1e2071f42
--- /dev/null
+++ b/1820/CH4/EX4.8/Example4_8.sce
@@ -0,0 +1,65 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.8 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+V_RL_L = 138*10^3 ; // transmission line voltage in V
+R = 0.1858 // Line constant in Ω/mi
+f = 60 // frequency in Hertz
+L = 2.60*10^-3 // Line constant in H/mi
+C = 0.012*10^-6 // Line constant in F/mi
+pf = 0.85 // Lagging power factor
+P = 50*10^6 // load in VA
+l = 150 // length of 3-Φ transmission line in mi
+
+// CALCULATIONS
+// For case (a)
+z = R + %i*2*%pi*f*L ; // Impedance per unit length in Ω/mi
+y = %i*2*%pi*C*f ; // Admittance per unit length in S/mi
+g = sqrt(y*z) ; // Propagation constant of line per unit length
+
+// For case (b)
+lamda = (2 * %pi)/imag(g) ; // Wavelength of propagation in mi
+V = lamda * f ; // Velocity of propagation in mi/sec
+
+ // For case (c)
+Z_C = sqrt(z/y) ;
+V_R = V_RL_L/sqrt(3) ;
+theta_R = acosd(pf) ; 
+I_R = P/(sqrt(3)*V_RL_L) * ( cosd(theta_R) - %i*sind(theta_R) ) ; // Receiving end current in A
+V_R_incident = (1/2)*(V_R + I_R*Z_C) ; // Incident voltage at receiving end in V
+V_R_reflected = (1/2)*(V_R - I_R*Z_C) ; // Reflected voltage at receiving end in V
+
+// For case (d)
+V_RL_N = V_R_incident + V_R_reflected ; // Line-to-neutral voltage at receiving end in V
+V_RL_L = sqrt(3)*V_RL_N // Receiving end Line voltage in V
+
+// For case (e)
+g_l = real(g) * l + %i * imag(g) * l ; // Propagation constant of line
+a = real(g) ; // a = α is the attenuation constant
+b = imag(g) ; // b = β is the phase constant
+V_S_incident = (1/2) * (V_R+I_R*Z_C) * exp(a*l) * exp(%i*b*l) ; // Incident voltage at sending end in V
+V_S_reflected = (1/2) * (V_R-I_R*Z_C) * exp(-a*l) * exp(%i*(-b)*l) ; // Reflected voltage at sending end in V
+
+// For case (f)
+V_SL_N = V_S_incident + V_S_reflected ; // Line-to-neutral voltage at sending end in V
+V_SL_L = sqrt(3)*V_SL_N ; // sending end Line voltage in V
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.8 : SOLUTION :-") ;
+printf("\n (a) Attenuation constant , α = %.4f Np/mi \n",real(g)) ;
+printf("\n     Phase change constant, β = %.4f rad/mi \n",imag(g)) ;
+printf("\n (b) Wavelength of propagation = %.2f mi \n",lamda) ;
+printf("\n     velocity of propagation = %.2f mi/s \n",V) ;
+printf("\n (c) Incident voltage receiving end , V_R(incident) = %.2f<%.2f V \n",abs(V_R_incident),atan(imag(V_R_incident),real(V_R_incident))*(180/%pi));
+printf("\n     Receiving end reflected voltage , V_R(reflected) = %.2f<%.2f V \n",abs(V_R_reflected),atan(imag(V_R_reflected),real(V_R_reflected))*(180/%pi)) ;
+printf("\n (d) Line voltage at receiving end , V_RL_L = %d V \n",V_RL_L) ;
+printf("\n (e) Incident voltage at sending end , V_S(incident) = %.2f<%.2f V \n",abs(V_S_incident),atan(imag(V_S_incident),real(V_S_incident))*(180/%pi)) ;
+printf("\n     Reflected voltage at sending end , V_S(reflected) = %.2f<%.2f V \n",abs(V_S_reflected),atan(imag(V_S_reflected),real(V_S_reflected))*(180/%pi)) ;
+printf("\n (f) Line voltage at sending end , V_SL_L = %.2f V \n",abs(V_SL_L)) ;
diff --git a/1820/CH4/EX4.9/Example4_9.sce b/1820/CH4/EX4.9/Example4_9.sce
new file mode 100755
index 000000000..c30e58801
--- /dev/null
+++ b/1820/CH4/EX4.9/Example4_9.sce
@@ -0,0 +1,26 @@
+// ELECTRIC POWER TRANSMISSION SYSTEM ENGINEERING ANALYSIS AND DESIGN
+// TURAN GONEN
+// CRC PRESS
+// SECOND EDITION
+
+// CHAPTER : 4 : OVERHEAD POWER TRANSMISSION
+
+// EXAMPLE : 4.9 :
+clear ; clc ; close ; // Clear the work space and console
+
+// GIVEN DATA
+L = 2.60 * 10^-3 ; // Inductance of line in H/mi
+R = 0.1858 ; // Resistance of line in Ω/mi
+C = 0.012 * 10^-6 ; // Capacitance in F/mi
+kV = 138 ; // Transmission line voltage in kV
+Z_c1 = 469.60085 // Characteristic impedance of line in Ω . Obtained from example 4.6
+
+// CALCULATIONS
+Z_c = sqrt(L/C) ; // Approximate value of surge Impedance of line in ohm
+SIL =  kV^2/Z_c ; // Approximate Surge impedance loading in MW
+SIL1 = kV^2/Z_c1 ; // Exact value of SIL in MW
+
+// DISPLAY RESULTS
+disp("EXAMPLE : 4.9 : SOLUTION :-") ;
+printf("\n Approximate value of SIL of transmission line , SIL_app = %.3f MW\n",SIL) ;
+printf("\n Exact value of SIL of transmission line , SIL_exact = %.3f MW\n",SIL1) ;