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diff --git a/1445/CH7/EX7.1/Ex7_1.sce b/1445/CH7/EX7.1/Ex7_1.sce
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index 000000000..c88808117
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+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 1
+
+disp("CHAPTER 7");
+disp("EXAMPLE 1");
+
+//VARIABLE INITIALIZATION
+I_0=10;                        //no load current in Amperes
+pf=0.25;                       //power factor
+v1=400;                        //in Volts
+f=50;                          //in Hertz
+
+//SOLUTION
+
+//solution (a)
+//magnetizing component
+//Iphi=I0.sin theta
+theta=acos(pf);                 //taking value of theta from the given power factor
+I_phi=I_0*sin(theta);         
+disp(sprintf("(a) The magnetizing component of no load current is %.2f A",I_phi));
+
+//solution (b)
+//iron loss
+//Pc=V1.Ic
+//Ic=I0.cos theta & also Ic=I0.pf as pf=cos theta
+p_c=v1*I_0*pf;
+disp(sprintf("(b) The iron loss is %d W",p_c));
+
+//solution (c)
+N1=500;                     // number of turns in primary given
+phi_m=v1/(sqrt(2)*%pi*f*N1);
+disp(sprintf("(c) The maximum value of flux in the core is %.2f mWb",phi_m*1000));
+
+//END
+
diff --git a/1445/CH7/EX7.10/Ex7_10.sce b/1445/CH7/EX7.10/Ex7_10.sce
new file mode 100644
index 000000000..d9018d0ec
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+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 10
+
+disp("CHAPTER 7");
+disp("EXAMPLE 10");
+
+//6600/220 V single phase transformer
+//VARIABLE INITIALIZATION
+v1=6600;                        //primary voltage in Volts
+v2=220;                         //secondary voltage in Volts
+coreA=0.05;                     //core section m^2
+fluxD=1.2;                      //flux density in wm/m^2
+f=50;                           //Hz
+
+//SOLUTION
+//E1=sqrt(2).pi.f.N1.φm
+//flux density = Phimax/core area
+phiM=coreA*fluxD;
+N1=v1/(4.44*f*phiM);    //4.44=sqrt(2).pi
+N1=round(N1);
+//
+//N2=N1.E2/E1
+N2=N1*(v2/v1);
+N2=round(N2);
+disp(sprintf("The no. of turns on HT side is %d",N1));
+disp(sprintf("The no. of turns on LT side is %d",N2));
+disp(" "); 
+// 
+//END
+
diff --git a/1445/CH7/EX7.11/Ex7_11.sce b/1445/CH7/EX7.11/Ex7_11.sce
new file mode 100644
index 000000000..df17e61c0
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+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 11
+
+disp("CHAPTER 7");
+disp("EXAMPLE 11");
+
+//2200/220 V 44 kVA transformer with 50 turns in the secondary
+//VARIABLE INITIALIZATION
+va=44000;                       //
+v1=2200;                        //primary voltage in Volts
+v2=220;                         //secondary voltage in Volts
+N2=50;                          //turns in secondary coil
+
+//SOLUTION
+// N1/N2=V1/V2
+N1=N2*(v1/v2);
+disp("SOLUTION (a)");
+disp(sprintf("The no. of turns on HT side is %f",N1));
+//
+//since losses are negligible, input=output, V1.I1=V2.I2
+I1=va/v1;
+I2=va/v2;
+disp("SOLUTION (b)");
+disp(sprintf("The primary full load current is %.0f Amp",I1));
+disp(sprintf("The secondary full load current is %.0f Amp",I2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.12/Ex7_12.sce b/1445/CH7/EX7.12/Ex7_12.sce
new file mode 100644
index 000000000..980b54bd2
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+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 12
+
+disp("CHAPTER 7");
+disp("EXAMPLE 12");
+
+//no load cuurent of transformer ia 10A at pf of 0.25 lagging when connected to 400V, 50 Hz supply
+//VARIABLE INITIALIZATION 
+v1=400;                         //primary voltage in Volts
+f=50;                           //Hz
+Io=10;                          //in Amp no load current
+pf =0.25;                       //lagging
+N1=500;                         //given
+
+//SOLUTION
+//magnetizing component of no load current
+// N1/N2=V1/V2
+//Iphi=Io.sin phi0
+//pf=cos phi0
+phi0=acos(pf);
+Iphi=Io*sin(phi0);
+disp("SOLUTION (a)");
+disp(sprintf("The magnetic component of no load current is %f Amp",Iphi));
+//
+//iron loss
+//Pi=ironloss=power input on no load
+//Pi=Wo=V1.Io.cos phi0
+ironLoss=v1*Io*pf;
+disp("SOLUTION (b)");
+disp(sprintf("The iron loss on no load is %.0f W",ironLoss));
+//
+//maximum flux in the core
+//E1=sqrt(2).pi.f.N1.φm
+//E1=V1
+phiM=v1/(4.44*f*N1);
+disp("SOLUTION (c)");
+disp(sprintf("The value of flux in the core is %5.4f mWb",phiM*1000));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.13/Ex7_13.sce b/1445/CH7/EX7.13/Ex7_13.sce
new file mode 100644
index 000000000..047444eca
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+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 13
+
+disp("CHAPTER 7");
+disp("EXAMPLE 13");
+//230/115 V single phase transformer
+//VARIABLE INITIALIZATION 
+v1=230;                           //primary voltage in Volts
+v2=115;
+f=50;                             //Hz
+Io=2;                            //in Amp no load current
+pf0 =0.28;                       //lagging 
+I2=20;                           //
+pf2=0.8;                         //lagging
+
+//SOLUTION
+// 
+//given power factors in primary and secondary
+// I1.N1=I2.N2
+phi0=acos(pf0);
+phi2=acos(pf2);
+//let Ix and Iy be the components of I0 and I'1 along X and Y axes
+//then
+//Ix=Io.sin phi0 + I'2.sin phi2
+//
+//Ix=Io.cos phi0 + I'2.cos phi2
+I_dash_2=I2*v2/v1;
+Ix=Io*sin(phi0)+I_dash_2*sin(phi2);
+Iy=Io*cos(phi0)+I_dash_2*cos(phi2);
+I1=sqrt(Ix^2+Iy^2);
+disp(sprintf("The current taken by primary is %.1f Amp",I1));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.14/Ex7_14.sce b/1445/CH7/EX7.14/Ex7_14.sce
new file mode 100644
index 000000000..4f635a60b
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@@ -0,0 +1,51 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 14
+
+disp("CHAPTER 7");
+disp("EXAMPLE 14");
+
+//1100/110 V 22 kVA single phase transformer
+//VARIABLE INITIALIZATION
+va=22000;                       //apparent power
+v1=1100;                        //primary voltage in Volts
+v2=110;                         //secondary voltage in Volts
+R1=2;                           //in Ohms
+R2=0.02;                        //in Ohms
+X1=5;                           //in Ohms
+X2=0.045;                       //in Ohms 
+
+//SOLUTION
+//N1/N2=v1/v2;
+
+R_dash_2=R2*((v1/v2)^2);
+X_dash_2=X2*((v1/v2)^2);
+disp("SOLUTION (a)");
+disp(sprintf("The equivalent resistance of secondary referred to primary is %.1fΩ",R_dash_2));
+disp(sprintf("The equivalent reactance of secondary referred to primary is %.1f Ω",X_dash_2));
+//
+R_e1=R_dash_2+R1;
+X_e1=X_dash_2+X1;
+disp("SOLUTION (b)");
+disp(sprintf("The total resistance referred to primary is %.1f Ω",R_e1));
+disp(sprintf("The total reactance referred to primary is %.1f Ω",X_e1));
+//
+R_dash_1=R1*((v2/v1)^2);
+X_dash_1=X1*((v2/v1)^2);
+disp("SOLUTION (c)");
+disp(sprintf("The equivalent resistance of secondary referred to secondary is %.2f Ω",R_dash_1));
+disp(sprintf("The equivalent reactance of secondary referred to secondary is %.2f Ω",X_dash_1));
+//
+R_e2=R_dash_1+R2;
+X_e2=X_dash_1+X2;
+disp("SOLUTION (d)");
+disp(sprintf("The total resistance referred to secondary is %.3f Ω",R_e2));
+disp(sprintf("The total reactance referred to secondary is %.3f Ω",X_e2));
+//
+I1=va/v1;
+I2=va/v2;
+copperLoss=R1*I1^2+R2*I2^2;
+disp("SOLUTION (e)");
+disp(sprintf("The total copper loss is %4.0f W",copperLoss));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.15/Ex7_15.sce b/1445/CH7/EX7.15/Ex7_15.sce
new file mode 100644
index 000000000..62b09f20e
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+++ b/1445/CH7/EX7.15/Ex7_15.sce
@@ -0,0 +1,38 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 15
+
+disp("CHAPTER 7");
+disp("EXAMPLE 15");
+//20kVA single phase transformer
+//VARIABLE INITIALIZATION
+va=20000;                        //apparent power
+v1=2000;                         //primary voltage in Volts
+v2=200;                          //secondary voltage in Volts
+R1=2.5;                          //in Ohms
+R2=0.04;                         //in Ohms
+X1=8;                            //in Ohms
+X2=0.07;                         //in Ohms 
+pf2=0.8;
+
+//SOLUTION
+//N1b/N2=v1/v2;
+I2=va/v2;
+phi2=acos(pf2);
+//
+R_dash_1=R1*((v2/v1)^2);
+X_dash_1=X1*((v2/v1)^2);
+//
+R_e2=R_dash_1+R2;
+X_e2=X_dash_1+X2;
+//disp(sprintf("The total resistance referred to secondary is %f Ω",R_e2));
+//disp(sprintf("The total reactance referred to secondary is %f Ω",X_e2));
+//
+//R=ercosphi2+vx.sinphi2
+//E2=V2+I2.R
+V2=v2-(I2*R_e2*pf2+I2*X_e2*sin(phi2));
+%reg=(v2-V2)*100/v2;
+disp(sprintf("The secondary terminal voltage is %.2f V",V2));
+disp(sprintf("The percent regulation at full load is %.2f",%reg));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.16/Ex7_16.sce b/1445/CH7/EX7.16/Ex7_16.sce
new file mode 100644
index 000000000..99cf22818
--- /dev/null
+++ b/1445/CH7/EX7.16/Ex7_16.sce
@@ -0,0 +1,47 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 16
+
+disp("CHAPTER 7");
+disp("EXAMPLE 16");
+
+//Values from the previous example.
+//VARIABLE INITIALIZATION
+va=20000;                        //apparent power
+v1=2000;                         //primary voltage in Volts
+v2=200;                          //secondary voltage in Volts
+R1=2.5;                          //in Ohms
+R2=0.04;                         //in Ohms
+X1=8;                            //in Ohms
+X2=0.07;                         //in Ohms 
+pf2=0.8;
+
+//SOLUTION
+//N1/N2=v1/v2;
+I2=va/v2;
+phi2=acos(pf2);
+
+//
+R_dash_1=R1*((v2/v1)^2);
+X_dash_1=X1*((v2/v1)^2);
+//
+R_e2=R_dash_1+R2;
+X_e2=X_dash_1+X2;
+//disp(sprintf("The total resistance referred to secondary is %f Ω",R_e2));
+//disp(sprintf("The total reactance referred to secondary is %f Ω",X_e2));
+//
+//power factor angle at which regulation is zero is given by tan.phi2=-Re2/Xe2
+phi2=atan(-R_e2/X_e2);
+disp(sprintf("The PF at which the regulation is zero is %.3f",cos(phi2)));
+//
+//power factor angle at which regulation is maximum is given by tan.phi2=Xe2/Re2
+phi2=atan(X_e2/R_e2);
+disp(sprintf("The PF at which the regulation is maximum is %.3f",cos(phi2)));
+//R=ercosphi2+vx.sinphi2
+//E2=V2+I2.R
+
+V2=v2-(I2*R_e2*cos(phi2)+I2*X_e2*sin(phi2));
+%reg=(v2-V2)*100/v2;
+disp(sprintf("The maximum value of percent regulation is %.2f ",%reg));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.17/Ex7_17.sce b/1445/CH7/EX7.17/Ex7_17.sce
new file mode 100644
index 000000000..7ae2f47e6
--- /dev/null
+++ b/1445/CH7/EX7.17/Ex7_17.sce
@@ -0,0 +1,43 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 17
+
+disp("CHAPTER 7");
+disp("EXAMPLE 17");
+
+//200kVA single phase transformer
+//VARIABLE INITIALIZATION 
+va=200000;                      //
+ironLoss=1000;                  // Watts
+cuLoss=2000;                    //Watts
+pf=0.8;
+//
+//SOLUTION
+// 
+Pout=va*pf;                     //Full load output
+loss=ironLoss+cuLoss;
+Pin=Pout+loss;                  //INPUT=OUTPUT+LOSS
+eff=Pout*100/Pin;
+disp("SOLUTION (a)");
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); 
+//
+//at half load
+Pout=va*pf/2;
+loss=ironLoss+cuLoss*(1/2)^2;       // ironloss is independent of output
+Pin=Pout+loss;
+eff=Pout*100/Pin;
+disp("SOLUTION (b)");
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); 
+//
+//fraction x of copperloss=ironloss for maximum efficiency
+//x^2.cuLoss=ironLoss
+x=sqrt(ironLoss/cuLoss);
+Pout=x*va*pf;
+loss=ironLoss+cuLoss*x^2;
+Pin=Pout+loss;
+eff=Pout*100/Pin;
+disp("SOLUTION (c)");
+disp(sprintf("The percent efficiency at %f load is %.2f ",x,eff)); 
+
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.18/Ex7_18.sce b/1445/CH7/EX7.18/Ex7_18.sce
new file mode 100644
index 000000000..5d9e22bf4
--- /dev/null
+++ b/1445/CH7/EX7.18/Ex7_18.sce
@@ -0,0 +1,47 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 18
+
+disp("CHAPTER 7");
+disp("EXAMPLE 18");
+
+//400kVA distribution transformer variously loaded during day
+//VARIABLE INITIALIZATION 
+va=400000;                      //
+ironLoss=1500;                  // Watts
+cuLoss=4000;                    //Watts
+//during the day frommidnight to midnight is as below:
+h1=6;                           //first 6 hours from midnight to 6 hrs
+load1=0;
+pf1=0;
+h2=6;                           //next 6 hours from 6 am to noon
+load2=100000;                   //kVA converted to VA
+pf2=0.8;
+h3=5;                           //next from noon to 5 pm  
+load3=400000;
+pf3=0.8;
+h4=3;                           //next from  5 pm to 8 pm  
+load4=300000;
+pf4=0.7;
+h5=4;                           //next from  8 pm to midnight
+load5=200000;
+pf5=0.85;
+//
+//SOLUTION
+// 
+//energy loss at any load=(VA output/VA rated)^2 .Full load cuLoss
+loss1=h1*load1;
+loss2=h2*(load2/va)^2*cuLoss;
+loss3=h3*(load3/va)^2*cuLoss;
+loss4=h4*(load4/va)^2*cuLoss;
+loss5=h5*(load5/va)^2*cuLoss;
+//loss in 24 hours
+loss24=loss1+loss2+loss3+loss4+loss5;
+//disp(sprintf("The all day loss is %f ",loss24)); 
+Pout=h1*load1*pf1+h2*load2*pf2+h3*load3*pf3+h4*load4*pf4+h5*load5*pf5;
+//disp(sprintf("The all day energy output is %f ",Pout)); 
+Pin=Pout+ironLoss*24+loss24;
+eff=Pout*100/Pin;
+disp(sprintf("The all day percent efficiency is %.2f ",eff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.19/Ex7_19.sce b/1445/CH7/EX7.19/Ex7_19.sce
new file mode 100644
index 000000000..5673a8c80
--- /dev/null
+++ b/1445/CH7/EX7.19/Ex7_19.sce
@@ -0,0 +1,70 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 19
+
+disp("CHAPTER 7");
+disp("EXAMPLE 19");
+
+//Open circuit and short circuit test on 10 kVA transformer 500/250 V 50 Hz single phase transformer
+//VARIABLE INITIALIZATION
+va=10000;                           //apparent power
+v1=500;                             //primary voltage in Volts
+v2=250;                             //secondary voltage in Volts
+f=50;
+//open circuit parameters
+Voc=500;
+Io=2;
+Wi=100;                            // watts HT side
+Woc=Wi;                             //just another nomenclature
+//short circuit test
+Vsc=25;
+Isc=20;
+Wc=90;                             // watts HT side 
+//
+pf=0.8;
+//SOLUTION  
+//open circuit
+phi0=acos(Woc/(v1*Io));
+Ic=Io*cos(phi0);
+Iphi=Io*sin(phi0);
+Rc=v1/Ic;
+X=v1/Iphi;
+disp("SOLUTION (a)");
+disp(sprintf("The value of Ic is %.2f Amp",Ic));
+disp(sprintf("The value of IΦ is %.2f Amp",Iphi));
+disp(sprintf("The value of Rc is %.0f Ohm",Rc));
+disp(sprintf("The value of X is %.0fΩ",X));
+//
+//short circuit
+phisc=acos(Wc/(Vsc*Isc));
+pf1=cos(phisc);
+R_e1=Vsc*pf1/Isc;
+Z_e1=Vsc/Isc;
+X_e1=sqrt(Z_e1^2-R_e1^2); 
+disp(sprintf("The value of Power factor is %.3f",pf1));
+disp(sprintf("The value of Re1 is %.3f Ohm",R_e1));
+disp(sprintf("The value of Ze1 is %.3f Ohm",Z_e1));
+disp(sprintf("The value of Xe1 is %.3fΩ",X_e1)); 
+//
+//Regulation and efficiency
+//% Regulation 
+I1=va/v1;
+phi=acos(pf);
+//R=ercosphi2+vx.sinphi2
+//E2=V2+I2.R
+%reg=(Isc*R_e1*pf+Isc*X_e1*sin(phi))*100/v1; 
+disp("SOLUTION (c(i))");
+disp(sprintf("The percent regulation at full load is %.2f",%reg));
+//
+//Efficiency
+//full load output at pf=0.8
+Pout=va*pf;
+ironLoss=Wi;
+cuLoss=Wc;
+loss=ironLoss+cuLoss;
+Pin=Pout+loss;
+eff=Pout*100/Pin;
+disp("SOLUTION (c(ii))");
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.2/Ex7_2.sce b/1445/CH7/EX7.2/Ex7_2.sce
new file mode 100644
index 000000000..df6d083dd
--- /dev/null
+++ b/1445/CH7/EX7.2/Ex7_2.sce
@@ -0,0 +1,42 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 2
+
+disp("CHAPTER 7");
+disp("EXAMPLE 2");
+//
+//400/200V transformer
+//VARIABLE INITIALIZATION
+v1=400;                         //primary voltage in Volts
+v2=200;                         //secondary voltage in Volts
+I0=1;                           //in Amperes
+pf1=0.4;                        //power factor in degrees  on no load
+I2=50;                          //secondary current in Amperes
+pf2=0.8;                        //secondary supplies lagging power factor in degrees
+
+//SOLUTION
+//primary current is given by
+//I1=I0+I2
+//function to convert from polar to rectangular form
+function [x,y]=pol2rect(mag,angle1);
+x=mag*cos(angle1);
+y=mag*sin(angle1);
+endfunction;
+//
+phi_0=acos(pf1);                // cosine inverse of the power factor which is given
+phi=acos(pf2);                  // cosine inverse of the power factor which is given
+I2_dash=(v2*I2)/v1;             //v1.i1=v2.i2
+//I0=1 < phi_0 in polar format
+[x0,y0]=pol2rect(I0,-phi_0); 
+[x2_dash,y2_dash]=pol2rect(I2_dash,-phi); 
+I1_x=x0+x2_dash;                //x-component of I1
+I1_y=y0+y2_dash;                //y-component of I1
+disp(sprintf("The primary current in reactangular form is (%.3f-j%.2f) A",I1_x,-I1_y));
+//
+//function to convert from rectangular form to polar form
+function [I,angle]=rect2pol(x,y);
+I=sqrt((x^2)+(y^2));           
+angle=atan(y/x)*(180/%pi);     //to convert the angle from radians to degrees
+endfunction;
+[I,angle]=rect2pol(I1_x,I1_y);        // converting current from rectangular to polar form
+disp(sprintf("The primary current in polar form is (%.3f <%.2f) A",I,angle));
+//END
diff --git a/1445/CH7/EX7.20/Ex7_20.sce b/1445/CH7/EX7.20/Ex7_20.sce
new file mode 100644
index 000000000..0c5f59379
--- /dev/null
+++ b/1445/CH7/EX7.20/Ex7_20.sce
@@ -0,0 +1,44 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 20
+
+disp("CHAPTER 7");
+disp("EXAMPLE 20");
+
+//4 kVA 200/400 V 50 hz single phase transformer
+//VARIABLE INITIALIZATION
+va=4000;                            //apparent power
+v1=200;                             //primary voltage in Volts
+v2=400;                             //secondary voltage in Volts
+f=50;
+R_e1=0.15;
+Pi=60;                              //core losses iron core
+pf1=0.9;                            //power factor of primary
+pf2=0.8;                            //power factor of secondary
+
+//SOLUTION  
+//Copper loss on full load
+R_e2=(v2/v1)^2*R_e1;
+I1=va/v1;
+I2=va/v2;
+Pcu=I2^2*R_e2;                      //cu losses
+disp("SOLUTION (i)");
+disp(sprintf("The value of Copper Losses at full load is %.0f W",Pcu)); 
+//
+//efficiency
+Pout=va*pf1;
+Pin=Pout+Pi+Pcu;
+eff=Pout*100/Pin;
+disp("SOLUTION (ii)");
+disp(sprintf("The percent efficiency at full load %f PF is %.2f",pf1,eff)); 
+//
+//
+//efficiency at half load
+Pout=va*pf2/2;
+Pin=Pout+Pi+Pcu*(1/2)^2;
+eff=Pout*100/Pin;
+disp("SOLUTION (ii)");
+disp(sprintf("The percent efficiency at half load %f PF is %.2f",pf2,eff)); 
+  
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.21/Ex7_21.sce b/1445/CH7/EX7.21/Ex7_21.sce
new file mode 100644
index 000000000..7135f11c4
--- /dev/null
+++ b/1445/CH7/EX7.21/Ex7_21.sce
@@ -0,0 +1,36 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 21
+
+disp("CHAPTER 7");
+disp("EXAMPLE 21");
+
+//250/125 V 5kVA single phase transformer
+//VARIABLE INITIALIZATION
+va=5000;                            //apparent power
+v1=250;                             //primary voltage in Volts
+v2=125;                             //secondary voltage in Volts
+R1=0.2;                             //resistance of primary
+X1=0.75;                            //leakage reactance of primary
+R2=0.05;                            //resistance of secondary
+X2=0.2;                             //leakage reactance of secondary
+pf=0.8;                             //power factor (leading)
+
+//SOLUTION  
+R_e2=(v2/v1)^2*R1+R2;
+X_e2=(v2/v1)^2*X1+X2;
+I1=va/v1;
+I2=va/v2;
+//
+//at full load leading
+phi=acos(pf);
+%reg=(I2*R_e2*pf-I2*X_e2*sin(phi))*100/v2; 
+disp("SOLUTION (i)");
+disp(sprintf("The percent regulation at full load is %.2f",%reg));
+//
+//%R=(E2-V2).100/E2
+V2=v2-%reg*v2/100;
+disp("SOLUTION (ii)");
+disp(sprintf("The secondary terminal voltage at full load is %.2f V",V2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.22/Ex7_22.sce b/1445/CH7/EX7.22/Ex7_22.sce
new file mode 100644
index 000000000..8262bd109
--- /dev/null
+++ b/1445/CH7/EX7.22/Ex7_22.sce
@@ -0,0 +1,29 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 22
+
+disp("CHAPTER 7");
+disp("EXAMPLE 22");
+
+//6600/400 V single phase transformer
+//VARIABLE INITIALIZATION 
+v1=6600;                             //primary voltage in Volts
+v2=400;                             //secondary voltage in Volts
+R1=2.5;                             //primary resistance
+R2=0.01;                            //secondary resistance
+
+//SOLUTION 
+//while finding equivalent resistance referrd to primary
+//transfer R2 resistance to  R'2
+R_dash_2=R2*(v1/v2)^2;
+R_e1=R1+R_dash_2;
+//
+//to find total equivalent resistance referred to secondary
+//first calculate R'1
+R_dash_1=R1*(v2/v1)^2;
+R_e2=R2+R_dash_1;
+//
+disp(sprintf("The total equivalent resistance referred to primary is %.6f Ω",R_e1));
+disp(sprintf("The total equivalent resistance referred to secondary is %.6f Ω",R_e2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.23/Ex7_23.sce b/1445/CH7/EX7.23/Ex7_23.sce
new file mode 100644
index 000000000..c794f2e98
--- /dev/null
+++ b/1445/CH7/EX7.23/Ex7_23.sce
@@ -0,0 +1,79 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 23
+
+disp("CHAPTER 7");
+disp("EXAMPLE 23");
+
+//33kVA 2200/220 V 50Hz single phase transformer
+//VARIABLE INITIALIZATION 
+va=33000;
+v1=2200;                             //primary voltage in Volts
+v2=220;                              //secondary voltage in Volts
+f=50;                               // frequency in Hz
+R1=2.4;                             //primary winding (High Voltage side) resistance
+X1=6;                               //primary winding (High Voltage side)leakage reactance
+R2=0.03;                            //secondary winding (Low Voltage side) resistance
+X2=0.07;                            //secondary winding (Low Voltage side)leakage reactance
+
+//SOLUTION 
+// 
+//Primary resistance and leakage reactance referred to secondary
+//R'1 & X'1
+//Secondary resistance and leakage reactance referred to primary
+//R'2 & X'2
+//Equivalent resistance & leakage reactance referred to primary
+//Re1 & Xe1
+//Equivalent resistance & leakage reactance referred to secondary
+//Re2 & Xe2
+//
+R_dash_2=R2*(v1/v2)^2;
+R_e1=R1+R_dash_2;
+X_dash_2=X2*(v1/v2)^2;
+X_e1=X1+X_dash_2;
+//
+R_dash_1=R1*(v2/v1)^2;
+R_e2=R2+R_dash_1;
+X_dash_1=X1*(v2/v1)^2;
+X_e2=X2+X_dash_1;
+
+disp("SOLUTION (a)");
+disp(sprintf("The primary resistance referred to secondary %.2f Ω",R_dash_1));
+disp(sprintf("The primary leakage reactance referred to secondary %.2f Ω",X_dash_1));
+//
+disp("SOLUTION (b)");
+disp(sprintf("The secondary resistance referred to secondary %.2f Ω",R_dash_2));
+disp(sprintf("The secondary leakage reactance referred to secondary %.2f Ω",X_dash_2));
+//
+disp("SOLUTION (C(i))");
+disp(sprintf("The equivalent resistance referred to primary %.2f Ω",R_e1));
+disp(sprintf("The equivalent leakage reactance referred to primary %.2f Ω",X_e1));
+//
+disp("SOLUTION (C(ii))");
+disp(sprintf("The equivalent resistance referred to secondaryy %.2f Ω",R_e2));
+disp(sprintf("The equivalent leakage reactance referred to secondary %.2f Ω",X_e2));
+//
+//Ohmic load
+I1=va/v1;                   // primary full load current
+I2=va/v2;                   // secondary full load current
+oLoss=I2^2*R_e2;            //ohmic loss
+disp("SOLUTION (d)");
+disp(sprintf("The ohmic loss at full load %.0f W",oLoss));
+//
+//Voltage to be applied on the HV side
+//to obtain short circuit currnet of 160 A in L.V side winding
+Z_e1=sqrt(R_e1^2+X_e1^2);               // equivalent leakage impedance
+//voltage to be applied on HV side is equivalent leakage reactance x primary current
+//relationship between current and voltage in transformer 
+//I1/I2=V2/V1
+//Given V2=220 V, V1=2200 V, I2=160 Amp
+//Therefore, I1=I2.(V2/V1)
+I1=160*(v2/v1);
+V=I1*Z_e1;                      //160*(v2/v1)*Z_e1;
+//Power Input 
+P=(I1)^2*R_e1                  //P=I^2.R
+disp("SOLUTION (e)");
+disp(sprintf("The voltage to be applied on HV side is %.2f V",V));
+disp(sprintf("The power input is %.1f W",P));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.24/Ex7_24.sce b/1445/CH7/EX7.24/Ex7_24.sce
new file mode 100644
index 000000000..6a74149b1
--- /dev/null
+++ b/1445/CH7/EX7.24/Ex7_24.sce
@@ -0,0 +1,61 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 24
+
+disp("CHAPTER 7");
+disp("EXAMPLE 24");
+
+//10kVA 2500/250 V single phase transformer
+//VARIABLE INITIALIZATION 
+va=10000;
+v1=2500;                             //primary voltage in Volts
+v2=250;                              //secondary voltage in Volts
+R1=4.8;                              //primary HV side winding resistance
+X1=11.2;                            //primary HV side winding leakage reactance
+R2=0.048;                           //secondary LV side winding resistance
+X2=0.112;                           //secondary LV side winding leakage reactaance
+
+//SOLUTION 
+// 
+//Primary resistance and leakage reactance referred to secondary
+//R'1 & X'1
+//Secondary resistance and leakage reactance referred to primary
+//R'2 & X'2
+//Equivalent resistance & leakage reactance referred to primary
+//Re1 & Xe1
+//Equivalent resistance & leakage reactance referred to secondary
+//Re2 & Xe2
+//
+R_dash_2=R2*(v1/v2)^2;
+R_e1=R1+R_dash_2;
+X_dash_2=X2*(v1/v2)^2;
+X_e1=X1+X_dash_2;
+//
+R_dash_1=R1*(v2/v1)^2;
+R_e2=R2+R_dash_1;
+X_dash_1=X1*(v2/v1)^2;
+X_e2=X2+X_dash_1;
+//leakage impedence
+//The transformer leakage impedance=z0=Re2+j.Xe2
+//Therefore:
+z0=R_e2+X_e2*%i;
+//Further Given
+//the LV winding side is connected to load impedance of 5+j.3.5 Ohm
+//The power factor 0.8 lagging on LV side
+//applied load is
+Zl=5+3.5*%i;
+//total impedence in series
+//The leakage impedance and load impedance are in series, therefore, total impedance is sum of the two
+//
+Z=z0+Zl;
+magZ=sqrt(real(Z)^2+imag(Z)^2);
+magZl=sqrt(real(Zl)^2+imag(Zl)^2);
+//V2=I2.Zl
+I2=v2/magZ;
+V2=I2*magZl
+disp("SOLUTION (a)");
+disp(sprintf("The secondary terminal voltage is %.0f V",V2)); 
+//
+//part (b) and (c) of the problem cannot be solved mathematically alone.
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.25/Ex7_25.sce b/1445/CH7/EX7.25/Ex7_25.sce
new file mode 100644
index 000000000..acb81a060
--- /dev/null
+++ b/1445/CH7/EX7.25/Ex7_25.sce
@@ -0,0 +1,66 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 25
+
+disp("CHAPTER 7");
+disp("EXAMPLE 25");
+
+//15kVA 2200/110 V transformer
+//VARIABLE INITIALIZATION 
+va=25000;                             //power rating
+v1=2200;                             //primary voltage in Volts
+v2=110;                              //secondary voltage in Volts
+f=50;
+R1=1.75;
+X1=2.6;
+R2=0.0045;
+X2=0.0075; 
+
+//SOLUTION 
+// 
+//Primary resistance and leakage reactance referred to secondary
+//R'1 & X'1
+//Secondary resistance and leakage reactance referred to primary
+//R'2 & X'2
+//Equivalent resistance & leakage reactance referred to primary
+//Re1 & Xe1
+//Equivalent resistance & leakage reactance referred to secondary
+//Re2 & Xe2
+//
+R_dash_2=R2*(v1/v2)^2;
+R_e1=R1+R_dash_2;
+X_dash_2=X2*(v1/v2)^2;
+X_e1=X1+X_dash_2;
+//
+R_dash_1=R1*(v2/v1)^2;
+R_e2=R2+R_dash_1;
+X_dash_1=X1*(v2/v1)^2;
+X_e2=X2+X_dash_1;
+//
+Z_e1=R_e1+X_e1*%i;
+Z_e2=R_e2+X_e2*%i;
+magZ_e1=sqrt(real(Z_e1)^2+imag(Z_e1)^2);
+magZ_e2=sqrt(real(Z_e2)^2+imag(Z_e2)^2);
+//
+//
+disp("SOLUTION (a)");
+disp(sprintf("The equivalent resistance referred to primary %.2f Ω",R_e1));
+disp("SOLUTION (b)");
+disp(sprintf("The equivalent resistance referred to secondaryy %.5f Ω",R_e2));
+disp("SOLUTION (c)");
+disp(sprintf("The equivalent leakage reactance referred to primary %.1f Ω",X_e1));
+disp("SOLUTION (d)");
+disp(sprintf("The equivalent leakage reactance referred to secondary %.3f Ω",X_e2));
+disp("SOLUTION (e)");
+disp(sprintf("The equivalent impedance referred to primary %.5f Ω",magZ_e1));
+disp("SOLUTION (f)");
+disp(sprintf("The equivalent impedance referred to secondary %.5f Ω",magZ_e2));
+//
+//primary and secondary full load current and voltage relationship with power rating
+I1=va/v1;           //primary current
+I2=va/v2;           //secondary current
+cuLoss=I2^2*R_e2;   //copper loss     or also as I1^2.R1 + I2^2.R2
+disp("SOLUTION (d)");
+disp(sprintf("The copper loss at full load %f W",cuLoss)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.26/Ex7_26.sce b/1445/CH7/EX7.26/Ex7_26.sce
new file mode 100644
index 000000000..7fed48bc9
--- /dev/null
+++ b/1445/CH7/EX7.26/Ex7_26.sce
@@ -0,0 +1,68 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 26
+
+disp("CHAPTER 7");
+disp("EXAMPLE 26");
+
+//open circuit & short circuit test
+//10 kVA 500/250 V 50 Hz single phase 
+//VARIABLE INITIALIZATION
+va=10000;                           //apparent power
+v1=500;                             //primary voltage in Volts
+v2=250;                             //secondary voltage in Volts
+f=50;                               // frequency
+//open circuit parameters
+Voc=500;
+Io=2;
+Wi=100;                            // watts HT side
+Woc=Wi;                             //just to keep symbology
+//short circuit test
+Vsc=25;
+Isc=20;
+Wc=90;                             // watts HT side 
+//
+pf=0.8;
+//SOLUTION  
+//open circuit
+phi0=acos(Woc/(v1*Io));
+Ic=Io*cos(phi0);
+Iphi=Io*sin(phi0);
+Rc=v1/Ic;
+X=v1/Iphi;
+disp("SOLUTION (a)");
+disp(sprintf("The value of Ic is %.2f Amp",Ic));
+disp(sprintf("The value of IΦ is %.2f Amp",Iphi));
+disp(sprintf("The value of Rc is %.2f Ohm",Rc));
+disp(sprintf("The value of X is %.2fΩ",X));
+//
+//short circuit
+phisc=acos(Wc/(Vsc*Isc));
+pf1=cos(phisc);
+R_e1=Vsc*pf1/Isc;
+Z_e1=Vsc/Isc;
+X_e1=sqrt(Z_e1^2-R_e1^2); 
+disp(sprintf("The value of Power factor is %f",pf1));
+disp(sprintf("The value of Re1 is %f Ohm",R_e1));
+disp(sprintf("The value of Ze1 is %f Ohm",Z_e1));
+disp(sprintf("The value of Xe1 is %fΩ",X_e1)); 
+//
+I1=va/v1;
+phi=acos(pf);
+//R=er.cos phi2+vx.sin phi2
+//E2=V2+I2.R
+%reg=(Isc*R_e1*pf+Isc*X_e1*sin(phi))*100/v1; 
+disp("SOLUTION (c(i))");
+disp(sprintf("The percent regulation at full load is %.2f",%reg));
+//
+//full load output at pf=0.8
+Pout=va*pf;                 // Output Power
+ironLoss=Wi;
+cuLoss=Wc;
+loss=ironLoss+cuLoss;
+Pin=Pout+loss;              //Input Power
+eff=Pout*100/Pin;           //efficiency
+disp("SOLUTION (c(ii))");
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.27/Ex7_27.sce b/1445/CH7/EX7.27/Ex7_27.sce
new file mode 100644
index 000000000..b72abacee
--- /dev/null
+++ b/1445/CH7/EX7.27/Ex7_27.sce
@@ -0,0 +1,73 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 27
+
+disp("CHAPTER 7");
+disp("EXAMPLE 27");
+
+//200kVA 1100/400 V delta star distribution transformer
+//three phase
+//VARIABLE INITIALIZATION
+va=200000;                           //apparent power
+v1=11000;                             //primary voltage in Volts
+v2=400;                             //secondary voltage in Volts
+f=50;                               // frequency
+//open circuit test parameters
+V3=400;
+I3=9;
+W3=1500;                            //load in watts HT side
+//short circuit test parameters
+Vsc=350;
+Isc=20;
+Wc=2100;                             //load in watts HT side 
+//
+pf=0.8;
+//SOLUTION  
+Voc=V3/sqrt(3);                     //per phase applied voltage in open circiut
+Io=9;                               //per phase exciting current.= I3
+Wi=W3/3;                            // per phase core loss in watts HT side
+Pc=Wi;                              //core losses
+//power factor Pc=V1.Io.cos phi0  //v1=Voc  
+//open circuit test performed on LV side
+phi0=acos(Wi/(Voc*Io));
+Ic=Io*cos(phi0);                    //core loss current
+Iphi=Io*sin(phi0);                  //magnetising current
+Rc=Voc/Ic;                          //Core loss resistance
+X=Voc/Iphi;                         //
+disp("SOLUTION (a)");
+disp(sprintf("The value of Ic is %.0f Amp",Ic));
+disp(sprintf("The value of IΦ is %.2f Amp",Iphi));
+disp(sprintf("The value of Rc is %.2f Ohm",Rc));
+disp(sprintf("The value of X is %.2fΩ",X));
+//
+//core loss resistance referred to hv side
+Rch=Rc*(v1/Voc)^2;
+XphiH=X*(v1/Voc)^2;
+disp(sprintf("The value of Rch is %.2f kΩ",Rch/1000));
+disp(sprintf("The value of XΦh is %.2f KΩ",XphiH/1000));
+//short circuit
+//This test performed on HV side
+//first find rated current
+Isc=va/(3*v1);
+Psc=Wc/3;                           //ohmic loss per phase
+phisc=acos(Wc/(Vsc*Isc));
+pf1=cos(phisc);
+R_e1=Psc/Isc^2;
+Z_e1=Vsc/Isc;
+X_e1=sqrt(Z_e1^2-R_e1^2); 
+disp(sprintf("The value of ohmic loss per phase is %.0f W",Psc));
+disp(sprintf("The value of Re1 is %.2f Ohm",R_e1));
+disp(sprintf("The value of Ze1 is %.2f Ohm",Z_e1));
+disp(sprintf("The value of Xe1 is %.2fΩ",X_e1)); 
+//
+//efficiency at half load
+pf=1;                                   //unity power factor
+Pout=(va/3)*(1/2)*pf;
+//core losses=Pc
+//cuLosses ohmic loss =Psc
+Pin=Pout+Pc+(1/2)^2*Psc;
+eff=Pout*100/Pin;
+disp(sprintf("The efficiency at half load is %.2f",eff)); 
+ 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.28/Ex7_28.sce b/1445/CH7/EX7.28/Ex7_28.sce
new file mode 100644
index 000000000..022c5502e
--- /dev/null
+++ b/1445/CH7/EX7.28/Ex7_28.sce
@@ -0,0 +1,97 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 28
+
+disp("CHAPTER 7");
+disp("EXAMPLE 28");
+
+//10 kVA 2500/250 V single phase transformer
+//open circuit and short circuit tests
+//VARIABLE INITIALIZATION
+va=10000;                             //apparent power
+v1=2500;                              //primary voltage in Volts
+v2=250;                               //secondary voltage in Volts
+f=50;
+//open circuit parameters
+Voc=250;
+Io=0.8;
+Wi=50;                               // watts HT side
+//short circuit test
+Vsc=60;
+Isc=3;
+Wc=45;                             // watts HT side 
+//
+//loads
+pf=0.8;
+//SOLUTION 
+//Open circuit test conducted on lv because 250 V during this test  is equal to rated voltage on lv side.  
+I1=va/v1;                            //full rated current on hv side
+Psc0=Wc*(I1/Isc)^2;                  //ohmic loss/ cu loss at full load rated current
+Pc=Wi;                               // core losses
+// 1/4 load
+Psc=(1/4)^2*Psc0;
+Pout=va*pf*(1/4);
+Pin=Pout+Pc+Psc;
+eff=Pout*100/Pin;
+disp("SOLUTION (a)");
+disp(sprintf("The efficiency at 1/4 load is %.2f",eff));
+//
+// 1/2 load
+Psc=(1/2)^2*Psc0;
+Pout=va*pf*(1/2);
+Pin=Pout+Pc+Psc;
+eff=Pout*100/Pin; 
+disp(sprintf("The efficiency at 1/2 load is %.2f",eff));
+//
+// full load
+Psc=(1/1)^2*Psc0;
+Pout=va*pf*(1/1);
+Pin=Pout+Pc+Psc;
+eff=Pout*100/Pin;
+disp(sprintf("The efficiency at full load is %.2f",eff));
+//
+// 1 1/4 = 5/4 load
+Psc=(5/4)^2*Psc0;
+Pout=va*pf*(5/4);
+Pin=Pout+Pc+Psc;
+eff=Pout*100/Pin;
+disp(sprintf("The efficiency at 1 1/4 or 5/4 load is %.2f",eff));
+//
+//maximum efficiency at x, but then ohmic loss=core loss
+x=sqrt(Pc/Psc0);
+Pout=va*x*pf;
+Pin=Pout+Pc+Pc;                             //Ohmic losses = core losses at max efficiency
+eff=Pout*100/Pin;
+disp("SOLUTION (b)");
+disp(sprintf("The maximum efficiency  is %.2f",eff));
+//
+//short circuit test performed on lv side 
+phisc=acos(Wc/(Vsc*Isc));
+pf1=cos(phisc);
+R_e1=Vsc*pf1/Isc;
+Z_e1=Vsc/Isc;
+X_e1=sqrt(Z_e1^2-R_e1^2);  
+disp("SOLUTION (c)");
+disp(sprintf("The value of Re1 is %.2f Ohm",R_e1));
+disp(sprintf("The value of Ze1 is %.2f Ohm",Z_e1));
+disp(sprintf("The value of Xe1 is %.2fΩ",X_e1)); 
+//
+//ee, ex;
+er=I1*R_e1/v1;
+ex=I1*X_e1/v1;
+disp(sprintf("The value of Er is %.3f pu",er));
+disp(sprintf("The value of Ex is %.3f",ex)); 
+//
+phi=acos(pf);
+//R=ercosphi2+vx.sinphi2
+//E2=V2+I2.R
+%reg=(I1*R_e1*pf+I1*X_e1*sin(phi))*100/v1; //same as using er and ex
+disp(sprintf("The percent regulation at full load lagging is %.2f",%reg));
+%reg1=(I1*R_e1*pf-I1*X_e1*sin(phi))*100/v1; //same as using er and ex
+disp(sprintf("The percent regulation at full load leading is %.2f",%reg1));
+V21=(1-%reg/100)*v2;
+V22=(1-%reg1/100)*v2;
+disp(sprintf("The secondary terminal voltage at full load lagging is %.2f",V21));
+disp(sprintf("The secondary terminal voltage at full load leading is %.2f",V22));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.29/Ex7_29.sce b/1445/CH7/EX7.29/Ex7_29.sce
new file mode 100644
index 000000000..5e8b2f759
--- /dev/null
+++ b/1445/CH7/EX7.29/Ex7_29.sce
@@ -0,0 +1,59 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 29
+
+disp("CHAPTER 7");
+disp("EXAMPLE 29");
+
+//20kVA 4000/1000 V single phase transformer
+//VARIABLE INITIALIZATION
+va=200000;                             //apparent power
+v1=4000;                              //primary voltage in Volts
+v2=1000;                               //secondary voltage in Volts
+f=50;                                   // frequency in Hz
+//loads
+pf=1;                                   //power factor is unity
+eff=0.97;                               // at full load and at 60% of full load
+nlpf=0.5;                               //no load pf
+lpf=0.8                                 //lagging pf
+reg=0.05;                               //%regulation at 0.8 pf
+//
+//SOLUTION  
+loss=(1-eff)*va/eff;                    //=Pc+Pcu losses
+//simultaneous equation to be solved
+//eq 1: Pc+Pcu=loss;
+//fractipon of copper/ ohmic losses
+f=(0.6)^2;                              // 60% of full load
+//the 2nd equation is Pc+f*Pcu=loss
+//now the matrix
+M=[1,1;1,f];
+A=[loss,loss*0.6];
+Mi=inv(M);
+Ans=A*inv(M);
+Pc=Ans(1,1);
+Pcu=Ans(1,2);
+//disp(sprintf("The Pc is %f",Pc));
+//disp(sprintf("The Pcu is %f",Pcu));
+//LV side
+R_e2=Pcu/va;
+//from %reg find X_e2
+phi=acos(lpf);
+X_e2=(reg-R_e2*cos(phi))/sin(phi);
+//in oms units
+R_e2=R_e2*v2^2/va;                       // in ohms
+X_e2=X_e2*v2^2/va;                       // in ohms
+disp(sprintf("The Re2 is %.3f Ω",R_e2));
+disp(sprintf("The Xe2 is %.3f Ω",X_e2));
+//
+Rc=v2^2/Pc; 
+Ie2=Pc/(v2*0.25);
+Ic=Pc/v2;
+Iphi=sqrt(Ie2^2-Ic^2);
+Xphi=v2/Iphi;
+disp(sprintf("The Rc is %.2f Ω",Rc));
+disp(sprintf("The Ie2 is %.3f A",Ie2)); 
+disp(sprintf("The Ic is %.3f A",Ic));
+disp(sprintf("The Iphi is %.4f A",Iphi)); 
+disp(sprintf("The Xphi is %.2f Ω",Xphi)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.3/Ex7_3.sce b/1445/CH7/EX7.3/Ex7_3.sce
new file mode 100644
index 000000000..870db87c8
--- /dev/null
+++ b/1445/CH7/EX7.3/Ex7_3.sce
@@ -0,0 +1,72 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 3
+
+disp("CHAPTER 7");
+disp("EXAMPLE 3");
+//
+//2300/230 V 50 Hz transformer
+//VARIABLE INITIALIZATION 
+v1=2300;                             //primary voltage in Volts
+v2=230;                              //secondary voltage in Volts
+f=50;
+R1=0.286;
+X1=0.73;
+R_dash_2=0.319;
+X_dash_2=0.73;
+Rc=250;
+Xphi=1250;
+Zl=0.387+0.29*%i;
+//
+//SOLUTION 
+Z_e1=(R1+R_dash_2)+(X1+X_dash_2)*%i;
+Z_dash_l=(v1/v2)^2*Zl;
+// 
+I_dash_1=v1/(Z_dash_l+Z_e1);
+//[mag,angle]=rect2pol(real(I_dash_1),imag(I_dash_1));
+//disp(sprintf("The  current is %f <%f  A",mag,angle));
+//impedance of shunt branch
+Zm=Rc*(Xphi*%i)/(Rc+Xphi*%i);
+//[mag,angle]=rect2pol(real(Zm),imag(Zm));
+//disp(sprintf("The  Zm is %f <%f  A",mag,angle));
+I0=v1/Zm;
+//[mag,angle]=rect2pol(real(I0),imag(I0));
+//disp(sprintf("The  I0 is %f <%f  A",mag,angle));
+//
+//primary current
+I1=I0+I_dash_1;
+function [mag,angle]=rect2pol(x,y);
+mag=sqrt((x^2)+(y^2));            //z is impedance & the resultant of x and y
+angle=atan(y/x)*(180/%pi);      //to convert the angle from radians to degrees
+endfunction;
+[mag,angle]=rect2pol(real(I1),imag(I1));
+theta1=angle;
+disp("SOLUTION (i)");
+disp(sprintf("The primay current in rectangulr form is %.3f -j%.2f  A",real(I1),-imag(I1)));
+disp(sprintf("The primay current in polar form is %.3f <%.2f  A",mag,angle));
+//
+//input power
+Pin=v1*I1; ;                            //=I1.cos(theta1)
+//disp(sprintf("The  input power is %.3f kW",Pin/1000));
+//output power
+V_dash_2=I_dash_1*Z_dash_l; 
+[mag,angle]=rect2pol(real(V_dash_2),imag(V_dash_2));
+theta2=angle;
+//disp(sprintf("The  V_dash_2 is %.2f <%.2f  A",mag,angle));
+//
+Pout= V_dash_2*I_dash_1;                //I_dash_1.cos(theta1)
+//disp(sprintf("The  output power is %.3f kW",real(Pout)/1000));
+//Efficiency
+disp("SOLUTION (ii)");
+disp(sprintf("The  Efficiency is %.2f kW",Pout*100/Pin));// text Book answer is 78.75%
+//Losses
+Pc=v1*I0;                               //core loss
+loss=Pin-Pout;
+Pcu=loss-Pc;                            //copper loss
+disp(sprintf("The  core loss is %.2f kW",Pc/1000));//text book answer is 0.8 kW
+disp(sprintf("The  copper loss is %.2f kW",Pcu/1000));//text book answer is 1..38 kW
+//efficiency
+//eff=Pout*100/Pin;
+//disp(sprintf("The  percent efficiency is %f W",eff));
+disp(" "); 
+// The answers from V_dash_2 calculation onward do not match with the book on page 7.21 and 7.22
+//END
diff --git a/1445/CH7/EX7.30/Ex7_30.sce b/1445/CH7/EX7.30/Ex7_30.sce
new file mode 100644
index 000000000..7d78d4b84
--- /dev/null
+++ b/1445/CH7/EX7.30/Ex7_30.sce
@@ -0,0 +1,23 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 30
+
+disp("CHAPTER 7");
+disp("EXAMPLE 30");
+
+//6600/440 V single phase transformer
+//VARIABLE INITIALIZATION 
+v1=6600;                                //primary voltage in Volts
+v2=440;                                 //secondary voltage in Volts
+e_r=0.02;                               //equivalent resistance
+e_x=0.05;                               //equivalent reactance
+pf=0.8;                                 //power factor
+//
+//SOLUTION  
+//worked out differently a bit from the text book in terms of the steps
+phi=acos(pf);                           //phase angle
+reg=e_r*cos(phi)+e_x*sin(phi);          //voltage regulation
+V2=v2*(1-reg);                          //secondary terminal voltage
+disp(sprintf("The secondary terminal voltage is %.2f V",V2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.31/Ex7_31.sce b/1445/CH7/EX7.31/Ex7_31.sce
new file mode 100644
index 000000000..0150a59be
--- /dev/null
+++ b/1445/CH7/EX7.31/Ex7_31.sce
@@ -0,0 +1,29 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 31
+
+disp("CHAPTER 7");
+disp("EXAMPLE 31");
+
+//single phase transformer having 400 primary and 1000 secondary turns
+//VARIABLE INITIALIZATION 
+N1=400;
+N2=1000;
+coreA=60;                                //net core area in cm^2
+v1=500;                                  //primary voltage in Volts 
+f=50;                                    //frequency
+
+//
+//SOLUTION  
+//v1=E1=4.44.Φm.N1.f Volts
+phiM=v1/(4.44*N1*f);
+//flux density Bm=Φm/area
+Bm=phiM/coreA;                          //lines per cm
+//voltage per turn
+vpt=v1/N1;
+v2=N2*vpt;
+//
+disp(sprintf("The maximum flux density is %.3fx10^-5 Wb per cm^2",Bm*10^5));//text book anser is 9383 lines per cm^2
+disp(sprintf("The secondary voltage is %.0f V",v2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.32/Ex7_32.sce b/1445/CH7/EX7.32/Ex7_32.sce
new file mode 100644
index 000000000..05a91a7ea
--- /dev/null
+++ b/1445/CH7/EX7.32/Ex7_32.sce
@@ -0,0 +1,62 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 32
+
+disp("CHAPTER 7");
+disp("EXAMPLE 32");
+
+//50 kVA 4400/220 V single phase transformer
+//VARIABLE INITIALIZATION 
+va=50000;
+v1=4400;                             //primary voltage in Volts
+v2=220;                              //secondary voltage in Volts
+f=50;
+R1=3.45;
+X1=5.2;
+R2=0.0009;
+X2=0.015; 
+
+//SOLUTION 
+// 
+//Primary resistance and leakage reactance referred to secondary
+//R'1 & X'1
+//Secondary resistance and leakage reactance referred to primary
+//R'2 & X'2
+//Equivalent resistance & leakage reactance referred to primary
+//Re1 & Xe1
+//Equivalent resistance & leakage reactance referred to secondary
+//Re2 & Xe2
+//
+R_dash_2=R2*(v1/v2)^2;
+R_e1=R1+R_dash_2;
+X_dash_2=X2*(v1/v2)^2;
+X_e1=X1+X_dash_2;
+//
+R_dash_1=R1*(v2/v1)^2;
+R_e2=R2+R_dash_1;
+X_dash_1=X1*(v2/v1)^2;
+X_e2=X2+X_dash_1;
+//
+Z_e1=R_e1+X_e1*%i;
+Z_e2=R_e2+X_e2*%i;
+magZ_e1=sqrt(real(Z_e1)^2+imag(Z_e1)^2);
+magZ_e2=sqrt(real(Z_e2)^2+imag(Z_e2)^2);
+//
+disp("SOLUTION (i)");
+disp(sprintf("The equivalent resistance referred to primary %.4f Ω",R_e1));//text book answer is 7.05 ohm
+disp("SOLUTION (ii)");
+disp(sprintf("The equivalent resistance referred to secondaryy %.4f Ω",R_e2));
+disp("SOLUTION (iii)");
+disp(sprintf("The equivalent leakage reactance referred to primary %.4f Ω",X_e1)); 
+disp(sprintf("The equivalent leakage reactance referred to secondary %.4f Ω",X_e2));
+disp("SOLUTION (iv)");
+disp(sprintf("The equivalent impedance referred to primary %.4f Ω",magZ_e1)); // text book answer is 13.23 ohm
+disp(sprintf("The equivalent impedance referred to secondary %.4f Ω",magZ_e2));//text book answer is 0.0331 ohm
+//
+I1=va/v1;
+I2=va/v2;
+Pcu=I2^2*R_e2;
+disp("SOLUTION (d)");
+disp(sprintf("The copper loss at full load %.0f W",Pcu)); 
+disp(" "); 
+//The answers in the book on page 7.77 are wrong for all but Xe1 and Xe2 values.
+//END
diff --git a/1445/CH7/EX7.33/Ex7_33.sce b/1445/CH7/EX7.33/Ex7_33.sce
new file mode 100644
index 000000000..35ea4a24d
--- /dev/null
+++ b/1445/CH7/EX7.33/Ex7_33.sce
@@ -0,0 +1,66 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 33
+
+disp("CHAPTER 7");
+disp("EXAMPLE 33");
+
+// 5kVA 400/200 V 50 Hz single phase transformer
+//open ciruit and short circuit tests
+//VARIABLE INITIALIZATION
+va=5000;                             //apparent power
+v1=400;                             //primary voltage in Volts
+v2=200;                             //secondary voltage in Volts
+f=50;
+//no load parameters
+Voc=400;
+Io=1;
+Woc=50;                             // watts HT side
+//short circuit test
+Vsc=12;
+Isc=10;
+Wc=40;                             // watts HT side 
+//
+pf=0.8;
+//SOLUTION  
+//no load condition
+phi0=acos(Woc/(v1*Io));
+Ic=Io*cos(phi0);
+Iphi=Io*sin(phi0);
+Rc=v1/Ic;
+X=v1/Iphi;
+disp("SOLUTION (i)");
+disp(sprintf("The value of Ic is %f Amp",Ic));
+disp(sprintf("The value of IΦ is %f Amp",Iphi));
+//disp(sprintf("The value of Rc is %f Ohm",Rc));
+//disp(sprintf("The value of X is %fΩ",X));
+//
+//short circuit
+phisc=acos(Wc/(Vsc*Isc));
+pf1=cos(phisc);
+R_e1=Vsc*pf1/Isc;
+Z_e1=Vsc/Isc;
+X_e1=sqrt(Z_e1^2-R_e1^2);  
+disp(sprintf("The value of Re1 is %.2f Ohm",R_e1));
+disp(sprintf("The value of Ze1 is %.2f Ohm",Z_e1));
+disp(sprintf("The value of Xe1 is %.2fΩ",X_e1)); 
+//
+I1=va/v1;
+phi=acos(pf);
+//R=ercosphi2+vx.sinphi2
+//E2=V2+I2.R
+%reg=(I1*R_e1*pf+I1*X_e1*sin(phi))*100/v1; 
+disp("SOLUTION (c(i))");
+disp(sprintf("The percent regulation at full load is %.3f",%reg));
+//
+//full load output at pf=0.8
+Pout=va*pf;                 //output power
+ironLoss=Woc;
+cuLoss=Wc;
+loss=ironLoss+cuLoss;
+Pin=Pout+loss;              // input power
+eff=Pout*100/Pin;
+disp("SOLUTION (c(ii))");
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); // not calculated in the text book
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.34/Ex7_34.sce b/1445/CH7/EX7.34/Ex7_34.sce
new file mode 100644
index 000000000..eaf48effe
--- /dev/null
+++ b/1445/CH7/EX7.34/Ex7_34.sce
@@ -0,0 +1,41 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 35
+
+disp("CHAPTER 7");
+disp("EXAMPLE 35");
+
+//single phase 50 hz, 200kVA, 11kVA/230 V
+//open circuit and short circuit tests
+//VARIABLE INITIALIZATION
+va=200000;                              //apparent power
+v1=11000;                               //primary voltage in Volts
+v2=230;                                 //secondary voltage in Volts
+Woc=1600;                               //watts also equals core losses
+Wc=2600;                               //watts, also equals cu losses
+f=50;
+//no load parameters
+//day cycle given
+h1=8;                                   // hours
+load1=160000;                           //load in watts
+pf1=0.8;                                //power factor
+h2=6;
+load2=100000;
+pf2=1;
+h3=10;
+load3=0;
+pf3=0;
+//SOLUTION  
+//24 hr energy output
+Pout=load1*h1*pf1+load2*h2*pf2+load3*h3*pf3;
+Pc24=Woc*24;                            // 24 hours Pc loss
+//cu loss= hours.(kva output/kva rated)^2.Full load Cu loss
+Pcu24=h1*(load1/va)^2*Wc+h2*(load2/va)^2*Wc+h3*(load3/va)^2*Wc;
+Pin=Pout+Pc24+Pcu24; 
+eff=Pout*100/Pin;
+//disp(sprintf("The value Pout is %f",Pout));
+//disp(sprintf("The value Pc is %f",Pc24));
+//disp(sprintf("The value Pcu is %f",Pcu24));
+disp(sprintf("The percent efficiency at full load is %.2f",eff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.35/Ex7_35.sce b/1445/CH7/EX7.35/Ex7_35.sce
new file mode 100644
index 000000000..1d5f68a38
--- /dev/null
+++ b/1445/CH7/EX7.35/Ex7_35.sce
@@ -0,0 +1,46 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 36
+
+disp("CHAPTER 7");
+disp("EXAMPLE 36");
+
+// 100kVA 50 Hz 440/11000 V single phase transformer
+//VARIABLE INITIALIZATION
+va=100000;                               //apparent power
+v1=440;                                  //primary voltage in Volts
+v2=11000;                                //secondary voltage in Volts
+f=50;                                    // efficiency
+//loads
+pf=1;                                    //power factor at half load current
+eff1=0.985;                              // at full load at 0.8pf
+eff2=0.99;                               //at half full load at unity pf
+pf1=0.8;                                 // power factor at full load current 
+pf2=1;                                   //  
+//
+//SOLUTION  
+loss1=(1-eff1)*va*pf1/eff1;                    //=Pc+Pcu losses
+loss2=(1-eff2)*va*(1/2)*pf2/eff2;                    //=Pc+Pcu losses
+//simultaneous equation to be solved
+//eq 1: Pc+Pcu=loss;
+//fractipon of copper/ ohmic losses
+f=(1/2)^2;                              // 60% of full load
+//the 2nd equation is Pc+f*Pcu=loss
+//now the matrix
+M=[1,1;1,f];                            //Pc+Pcu=loss1; Pc+(1/2)^2*Pcu=loss2: 1,1,; 1,f
+A=[loss1,loss2];
+Mi=inv(M);
+Ans=A*inv(M);
+Pc=Ans(1,1);
+Pcu=Ans(1,2);
+disp(sprintf("The Pc is %.1f W",Pc));
+disp(sprintf("The Pcu is %.1f W",Pcu));
+//
+//maximumefficiency at farction x times the full load;and then f.Pcu=Pc
+x=sqrt(Pc/Pcu);
+disp(sprintf("The maximum efficiency would occur at a load of  %.0f kVA",x*va/1000));
+I1=va/v1;
+I1maxEff=I1*x;
+disp(sprintf("The current at maximum efficeincy is %.0f A",I1maxEff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.36/Ex7_36.sce b/1445/CH7/EX7.36/Ex7_36.sce
new file mode 100644
index 000000000..860243a80
--- /dev/null
+++ b/1445/CH7/EX7.36/Ex7_36.sce
@@ -0,0 +1,46 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 36
+
+disp("CHAPTER 7");
+disp("EXAMPLE 36");
+
+//100kVA 50 Hz 440/1100 V single phase transformer
+//VARIABLE INITIALIZATION
+va=100000;                               //apparent power
+v1=440;                                  //primary voltage in Volts
+v2=11000;                                //secondary voltage in Volts
+f=50;                                   // frequency
+//loads
+pf=1;                                    //power factor unity
+eff1=0.985;                              // at full load at 0.8pf
+eff2=0.99;                               //at half full load at unity pf
+pf1=0.8;                                 // power factor
+pf2=1;                                   //power factor
+//
+//SOLUTION  
+loss1=(1-eff1)*va*pf1/eff1;                    //=Pc+Pcu losses
+loss2=(1-eff2)*va*(1/2)*pf2/eff2;                    //=Pc+Pcu losses
+//simultaneous equation to be solved
+//eq 1: Pc+Pcu=loss;
+//fractipon of copper/ ohmic losses
+f=(1/2)^2;                              // 60% of full load
+//the 2nd equation is Pc+f*Pcu=loss
+//now the matrix
+M=[1,1;1,f];                            //Pc+Pcu=loss1; Pc+(1/2)^2*Pcu=loss2: 1,1,; 1,f
+A=[loss1,loss2];
+Mi=inv(M);
+Ans=A*inv(M);
+Pc=Ans(1,1);
+Pcu=Ans(1,2);
+disp(sprintf("The Pc is %.1f W",Pc));
+disp(sprintf("The Pcu is %.1f W",Pcu));
+//
+//maximumefficiency at farction x times the full load;and then f.Pcu=Pc
+x=sqrt(Pc/Pcu);
+disp(sprintf("The maximum efficiency would occur at a load of  %.0f kVA",x*va/1000));
+I1=va/v1;
+I1maxEff=I1*x;
+disp(sprintf("The current at maximum efficeincy is %.0f A",I1maxEff)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.37/Ex7_37.sce b/1445/CH7/EX7.37/Ex7_37.sce
new file mode 100644
index 000000000..b4d21103f
--- /dev/null
+++ b/1445/CH7/EX7.37/Ex7_37.sce
@@ -0,0 +1,40 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 37
+
+disp("CHAPTER 7");
+disp("EXAMPLE 37");
+
+//500 kVA 3300/500 V 50 hz single phase transformer
+//VARIABLE INITIALIZATION
+va=500000;                                  //apparent power
+v1=3300;                                    //primary voltage in Volts
+v2=500;                                     //secondary voltage in Volts
+f=50;
+//loads
+pf=1;                                       //power factor unity
+eff=0.97;                                   // at 3/4 full load at unity pf
+pf2=0.8;                                    //power factor
+//
+//SOLUTION  
+I1=va/v1;
+loss=(1-eff)*va*(3/4)*pf/eff;              //=Pc+Pcu losses at 3/4 load
+//since the eff value is maximum, Pcu=Pc; therefore, 2*Pc=loss
+Pc=loss/2;
+//(3/4)^2*Pcu=Pc;  
+f=(3/4)^2;                                 //3/4 load
+//Pcu=Pc/f
+Pcu=Pc/f;
+//disp(sprintf("The Pc is %f W",Pc));
+//disp(sprintf("The Pcu is %f W",Pcu));
+//
+R_e1=Pcu/I1^2;
+disp(sprintf("The value of Re1 is %.3f W",R_e1));
+//10% impedance
+Z_e1=v1*0.1/I1;
+X_e1=sqrt(Z_e1^2-R_e1^2);
+phi=acos(0.8);
+%reg=(I1*R_e1*cos(phi)+I1*X_e1*sin(phi))*100/v1;
+disp(sprintf("The percent regulation at full load 0.8 pf is %.2f W",%reg));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.38/Ex7_38.sce b/1445/CH7/EX7.38/Ex7_38.sce
new file mode 100644
index 000000000..080504a42
--- /dev/null
+++ b/1445/CH7/EX7.38/Ex7_38.sce
@@ -0,0 +1,31 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 38
+
+disp("CHAPTER 7");
+disp("EXAMPLE 38");
+
+//220/115 V 25 Hz single phase transformer
+//VARIABLE INITIALIZATION
+v1=220;                                    //primary voltage in Volts
+v2=115;                                     //secondary voltage in Volts
+f1=25;                                      //frequency rating of the transformer in Hz
+f2=50;                                      //frequency of the connected load
+//loads
+V=440                                       // i Volts
+We1=100;                                     //in Watts at 220 V, eddy losses
+Pc1=2*We1;                                    //Total iron losses which equals We+Wh due to eddy and hysteresis
+Wh1=Pc1-We1;
+//
+//SOLUTION  
+//since we know that We=kh.f.B^1.6 and Wh=Ke.Kf^2.f^2.B^2
+//since all being constant exept frequency, we may take We2/We1=f2^2/f1^2
+//and Wh2/Wh1=f2/f1
+//flux density in both cases is same as in second case voltage and frquency both are doubled
+//find values for We2 and Wh2, whence Pc2=We2+Wh2
+We2=f2^2*We1/f1^2;
+Wh2=f2*Wh1/f1;
+Pc2=We2+Wh2;
+disp(sprintf("The total no load losses at 400 V is %.0f W",Pc2));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.39/Ex7_39.sce b/1445/CH7/EX7.39/Ex7_39.sce
new file mode 100644
index 000000000..0d9677643
--- /dev/null
+++ b/1445/CH7/EX7.39/Ex7_39.sce
@@ -0,0 +1,41 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 39
+
+disp("CHAPTER 7");
+disp("EXAMPLE 39");
+
+//220/440 v 50 Hz transformer
+//VARIABLE INITIALIZATION
+v1=220;                                             //primary voltage in Volts
+v2=440;                                             //secondary voltage in Volts
+f1=50;                                              //rated frequency in Hz
+
+//loads
+V=110;
+f2=25;                                              //frquency of the applied load
+//say, else computation may not be possible using computer
+Pout1=100;                                              //in watt, just assumed for computational purposes for the 220V supply
+We1=0.01*Pout1;                                         //in Watts at 220 V, eddy losses which are 1% of the output at 220V
+Wh1=0.01*Pout1;                                         //in Watts at 220 V, hysteresis losses which are 1% of the output at 220V
+//Pc1=We1+Wh1;                                          //Total iron losses which equals We+Wh due to eddy and hysteresis
+Pcu1=0.01*Pout1;                                        //copper losses 
+//
+//SOLUTION  
+//since on connecting to half the power ie 110V, the output would get halved
+Pout2=Pout1/2;
+xPcu=Pcu1/Pout2;
+disp(sprintf("The copper losses at 110 V would be %.0f percent of the output",xPcu*100));
+//now coming to frequency dependant losses ie eddy and hysteresis 
+//since we know that We=kh.f.B^1.6 and Wh=Ke.Kf^2.f^2.B^2
+//since all being constant exept frequency, we may take We2/We1=f2^2/f1^2
+//and Wh2/Wh1=f2/f1
+//find values for We2 and Wh2, whence Pc2=We2+Wh2
+We2=f2^2*We1/f1^2;
+Wh2=f2*Wh1/f1;
+xWe=We2/Pout2;
+xWh=Wh2/Pout2;
+disp(sprintf("The eddy losses at 110 V would be %.2f percent of the output",xWe*100));
+disp(sprintf("The hysteresis losses at 110 V would be %.2f percent of the output",xWh*100)); 
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.4/Ex7_4.sce b/1445/CH7/EX7.4/Ex7_4.sce
new file mode 100644
index 000000000..4f6586072
--- /dev/null
+++ b/1445/CH7/EX7.4/Ex7_4.sce
@@ -0,0 +1,38 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 4
+
+disp("CHAPTER 7");
+disp("EXAMPLE 4");
+
+//10kVA Transformer with 50 turns on primary and 10 turns on secondary
+//connected to 440 V 50Haz supply
+//VARIABLE INITIALIZATION
+va=10*1000;                   //apparent power, converting kVA to VA
+N1=50;                        //number of turns on primary side
+N2=10;                        //number of turns on secondary side
+v1=440;                       //primary voltage in Volts
+f=50;                         //in Hertz
+
+//SOLUTION 
+
+//solution (a)
+//K=N2/N1=V2/V1
+v2=v1*(N2/N1);
+disp(sprintf("(a) The secondary voltage on no load is %d V",v2));
+
+//solution (b)
+//Current on Full load
+//primary side I1=VA/V1
+//secondary side I2=VA/V2
+I1=va/v1;
+disp(sprintf("(b) The full load primary current is %.4f A",I1));
+I2=va/v2;
+disp(sprintf("The full load secondary current is %.4f A",I2));
+
+//solution (c)
+//As per EMF equation
+//E2=sqrt(2).pi.f.phimax.N2
+phi_m=v2/(sqrt(2)*%pi*f*N2);
+disp(sprintf("(c) The maximum value of the flux is %.3f mWb",phi_m*1000));
+
+//END 
diff --git a/1445/CH7/EX7.40/Ex7_40.sce b/1445/CH7/EX7.40/Ex7_40.sce
new file mode 100644
index 000000000..a78c44b1d
--- /dev/null
+++ b/1445/CH7/EX7.40/Ex7_40.sce
@@ -0,0 +1,22 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 40
+
+disp("CHAPTER 7");
+disp("EXAMPLE 40");
+
+//Given
+//transformer on no load has a core loss 50W, draws a current of 2 A (RMS) and induced emf 220 V(RMS)
+//VARIABLE INITIALIZATION
+loss=50;                       //core loss in Watts
+I0=2;                          //no load current in Amperes
+v0=220;                        //induced emf in Volts 
+                             
+//SOLUTION
+pf=loss/(v0*I0);
+I_c=I0*pf;                     //core loss component
+I_phi=I0*sin(acos(pf));        //magnetizing component
+disp(sprintf("The magnetizing component, I_c= %.4f A,",I_phi));
+disp(sprintf("The core loss component, I_Φ= %.4f A,",I_c));
+
+//END  
+
diff --git a/1445/CH7/EX7.41/Ex7_41.sce b/1445/CH7/EX7.41/Ex7_41.sce
new file mode 100644
index 000000000..ffab26d2c
--- /dev/null
+++ b/1445/CH7/EX7.41/Ex7_41.sce
@@ -0,0 +1,32 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 41
+
+disp("CHAPTER 7");
+disp("EXAMPLE 41");
+
+//3-phase 550/440 V star connected transformer supplies a load of 400kW
+//VARIABLE INITIALIZATION
+v1=550;                         //primary voltage in Volts
+v2=440;                         //secondary voltage in Volts
+p=400*1000;                     //load in Watts
+pf=0.8;                         //power factor(lagging)
+
+//SOLUTION
+
+//solution (a)
+I2=p/(sqrt(3)*v2*pf);           //current on secondary side
+I1=I2*(v2/v1);                 //since I1:I2=N2:N1
+I=I2-I1;                       //in sections Oa, Ob and Oc
+disp(sprintf("(a) The current flowing in sections Oa, Ob and Oc is %.0f A",I));
+disp(sprintf("The current flowing in sections aA, bB and cC is %.0f A",I1));
+
+//solution (b)
+//power transferred by transformer action = Pin.(1-k)
+p_o=p*(1-(v2/v1));             //k=v2/v1
+disp(sprintf("(b) The power transferred by transformer action %.0f kW",p_o/1000));
+
+//solution (c)
+p_d=p-p_o;
+disp(sprintf("(c) The power conducted directly %d kW",p_d/1000)); 
+
+//END                                               
diff --git a/1445/CH7/EX7.5/Ex7_5.sce b/1445/CH7/EX7.5/Ex7_5.sce
new file mode 100644
index 000000000..cd6b7f3b3
--- /dev/null
+++ b/1445/CH7/EX7.5/Ex7_5.sce
@@ -0,0 +1,31 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 5
+
+disp("CHAPTER 7");
+disp("EXAMPLE 5");
+
+//single phase transformer
+//350 primary and 1050 secondary turns
+//VARIABLE INITIALIZATION
+N1=350;                       //number of turns on primary side
+N2=1050;                      //number of turns on secondary side
+v1=400;                       //primary voltage in Volts
+f=50;                         //in Hertz
+ar=50/10000;                  //cross-sectional area of core in m^2
+
+//SOLUTION
+
+//solution (i)
+//emf1=sqrt(2).pi.f.Phimax.N1
+//Phimax=Bm.Area, Bm=flux density
+//Bm=e1/sqrt(2).pi.A.f.N1
+Bm=v1/(sqrt(2)*%pi*ar*f*N1);
+disp(sprintf("(i) The maximum flux density is %.4f Wb/m^2",Bm));
+
+//solution (ii)
+//e2/e1=n2/n1=K
+K=N2/N1;
+e2=K*v1;
+disp(sprintf("(ii) The induced emf in the secondary winding is %d V",e2));
+
+//END 
diff --git a/1445/CH7/EX7.6/Ex7_6.sce b/1445/CH7/EX7.6/Ex7_6.sce
new file mode 100644
index 000000000..2abcb8cf9
--- /dev/null
+++ b/1445/CH7/EX7.6/Ex7_6.sce
@@ -0,0 +1,37 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 6
+
+disp("CHAPTER 7");
+disp("EXAMPLE 6");
+
+//2200/20V 50Hz single phase transformer
+//VARIABLE INITIALIZATION
+v1=2200;                           //primary voltage in Volts
+v2=220;                            //secondary voltage in Volts
+I=0.6;                             //exciting current in Amperes
+p_c=361;                           //core loss in Watts
+I2=60;                             //load current in Amperes
+pf=0.8;                            //power factor
+
+//SOLUTION
+
+//solution (a)
+//core loss components
+I1=p_c/v1;                         //vertical component of I0
+I_phi=sqrt((I^2)-(I1^2));          //horizontal component of I0
+disp(sprintf("(a) The core loss component is %.3f A",I1));
+disp(sprintf("And the magnetising component is %.3f A",I_phi));
+
+//solution (b)
+//I1.N1=I2.N2
+I1_dash=(v2/v1)*I2;
+theta=acos(pf);
+I1_x=I1_dash*sin(theta)+I_phi;     //horizontal component of I0
+I1_y=I1_dash*pf+I1;                //vertical component of I0
+I1_res=sqrt((I1_x^2)+(I1_y^2));    //primary current
+pf_p=I1_y/I1_res;                  //primary power factor
+disp(sprintf("(b) The primary current is %.3f A",I1_res));
+disp(sprintf("And the power factor is %.3f A",pf_p));
+
+//END
+
diff --git a/1445/CH7/EX7.8/Ex7_8.sce b/1445/CH7/EX7.8/Ex7_8.sce
new file mode 100644
index 000000000..e53aed921
--- /dev/null
+++ b/1445/CH7/EX7.8/Ex7_8.sce
@@ -0,0 +1,66 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 8
+
+disp("CHAPTER 7");
+disp("EXAMPLE 8");
+
+//23 kVA 2300/230 V 60 Hz step down transformer
+
+//VARIABLE INITIALIZATION
+va=23000;                       //apparent power
+v1=2300;                        //primary voltage in Volts
+v2=230;                         //secondary voltage in Volts
+r1=4;                           //primary resistance in Ohms
+r2=0.04;                        //secondary resistance in Ohms
+X1=12;                          //leakage reactance primary in Ohms
+X2=0.12;                        //leake reactance in secondary in Ohms
+pf=0.866;                       //power factor(leading)
+
+//SOLUTION
+//assume voltage across load be 230 V
+//V'1=I2.(Re2+jXe2)+V2
+//Re2=R'1+R2
+//R'1=R1.(N2/N1)^2
+//Xe2=X'1+X2
+//X'1=X1.(N2/N1)^2
+//Ze2=Re2+j.Xe2
+r1_dash=r1*((v2/v1)^2);
+r_e2=r1_dash+r2;
+X1_dash=X1*((v2/v1)^2);
+X_e2=X1_dash+X2;
+//
+//disp(sprintf("The value of Re2 %f and Xe2 %f",r_e2,X_e2));
+I2=0.75*(va/v2);                //since transformer operates at 75% of its rated load
+//
+function [x,y]=pol2rect(mag,angle);
+x=mag*cos(angle*(%pi/180));         //to convert the angle from degrees to radians
+y=mag*sin(angle*(%pi/180));
+endfunction;
+[x,y]=pol2rect(I2,-30);
+I_dash_2=x+y*%i;
+//disp(sprintf("The value %f %f",real(I_dash_2),imag(I_dash_2)));
+//
+Z_e2=r_e2+X_e2*%i;              //in rect coordinates
+//disp(sprintf("The value %f %f",real(Z_e2),imag(Z_e2)));
+//
+V_dash_1=v2+I_dash_2*Z_e2;
+//disp(sprintf("The value %f %f",real(V_dash_1),imag(V_dash_1)));
+//
+function [mag,angle]=rect2pol(x,y);
+mag=sqrt((x^2)+(y^2));            //z is impedance & the resultant of x and y
+angle=atan(y/x)*(180/%pi);      //to convert the angle from radians to degrees
+endfunction;
+//
+[magV1,angleV1]=rect2pol(real(V_dash_1),imag(V_dash_1));
+//disp(sprintf("The value %f <%f",magV1,angleV1));
+//
+//Pin=V'1.I2.cos theta1
+//Pout=V2.I2.cos theta2
+Pin=magV1*I2*cos((30+angleV1)*%pi/180);
+Pout=v2*I2*cos(30*%pi/180);
+eff=Pout*100/Pin;
+//
+disp(sprintf("The efficiency of the transformer is %.2f",eff));
+disp(" "); 
+// 
+//END
diff --git a/1445/CH7/EX7.9/Ex7_9.sce b/1445/CH7/EX7.9/Ex7_9.sce
new file mode 100644
index 000000000..4a53d3b70
--- /dev/null
+++ b/1445/CH7/EX7.9/Ex7_9.sce
@@ -0,0 +1,36 @@
+//CHAPTER 7- SINGLE PHASE TRANSFORMER
+//Example 9
+
+disp("CHAPTER 7");
+disp("EXAMPLE 9");
+
+//11000/400 V distribution transformer
+//VARIABLE INITIALIZATION 
+v1=11000;                       //primary voltage in Volts
+v2=400;                         //secondary voltage in Volts
+Io=1;                           //primary current in Amp
+pf=0.24                         //power factor lagging
+
+//SOLUTION
+//core loss current
+//Ic=Io.cos phi
+//Ic=Io.pf
+Ic=Io*pf;
+disp("SOLUTION (a)");
+disp(sprintf("The value of core loss current is %.2f Amp",Ic));
+//
+//magnetizing current
+//Iphi=sqrt(Io^2-Ic^2)
+Iphi=sqrt(Io^2-Ic^2);
+disp("SOLUTION (b)");
+disp(sprintf("The value ofmagnetizing current is %.3f Amp",Iphi));
+//
+//Iron Loss
+//Iron loss=primary voltage X core loss current
+IronLoss=v1*Ic;
+disp("SOLUTION (c)");
+disp(sprintf("The iron loss  is %.0f W",IronLoss));
+disp(" "); 
+// 
+//END
+