initial commit / add all books

29 files changed, 558 insertions, 0 deletions

diff --git a/1067/CH20/EX20.03/20_03.sce b/1067/CH20/EX20.03/20_03.sce
new file mode 100755
index 000000000..2e320ea7b
--- /dev/null
+++ b/1067/CH20/EX20.03/20_03.sce
@@ -0,0 +1,13 @@
+clear;

+clc;

+rating=25e6;

+vb=11e3;

+x=.16/4;

+faultMVA=rating*1e-6/x;

+mprintf("the fault MVA from method 1=%dMVA",faultMVA);

+//method 2

+Ifault=1/(x*%i);

+Ib=rating/(sqrt(3)*vb);

+Isc=Ib*25;

+MVA=sqrt(3)*vb*Isc/1e6;

+mprintf("\n the fault MVA from method 2=%dMVA",MVA);

diff --git a/1067/CH20/EX20.04/20_04.sce b/1067/CH20/EX20.04/20_04.sce
new file mode 100755
index 000000000..e873b3368
--- /dev/null
+++ b/1067/CH20/EX20.04/20_04.sce
@@ -0,0 +1,26 @@
+clear;

+clc;

+R=3e6;

+Rb=6000e3;

+vb1=11e3;

+vb2=22e3;

+X=.15;

+x=.15*Rb/R;

+xeq=x/2;

+MVA=Rb/xeq;

+Ifault=MVA/(sqrt(3)*vb1*%i);

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+Imod=round(Imod/10)*10;

+mprintf("for fault on generator side \n Fault MVA=%dMVA \n Fault current=%d/_%dAmp",MVA/1e6,Imod,Iangle);

+x2=.05;

+Xeq=x2+xeq;

+MVA=Rb/Xeq;

+Ifault=MVA/(1.734*vb2*%i);

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+mprintf("\nfor fault on transmission side \n Fault MVA=%dMVA \n Fault current=%d/_%dAmp(lag)",MVA/1e6,Imod,Iangle);

diff --git a/1067/CH20/EX20.05.a/20_5_a.sce b/1067/CH20/EX20.05.a/20_5_a.sce
new file mode 100755
index 000000000..50a541318
--- /dev/null
+++ b/1067/CH20/EX20.05.a/20_5_a.sce
@@ -0,0 +1,36 @@
+clear;

+clc;

+R=3e6;

+Rb=6e6;

+vb2=11e3;

+vb3=66e3;

+x=.2;

+Xg=x*Rb/R;

+xt=.05;

+xl=vb3^2/Rb;

+xl1=20*.1/xl;

+xl2=xl1*4;

+

+X1=Xg+xt+xl2;

+X2=Xg+xt+xl1;

+X=inv(inv(X1)+inv(X2));

+Ifaultpu=1/(X*%i);

+Ifault=Ifaultpu*Rb/(sqrt(3)*vb3);

+MVA=sqrt(3)*vb3*Ifault*%i;

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+MVA=fix(MVA/1e5)*1e5;

+Imod=fix(Imod);

+mprintf("\n Fault MVA=%fMVA \n Fault current=%d/_%dAmp",MVA/1e6,Imod,Iangle);

+//another method

+MVA=Rb/X;

+Ifault=MVA/(sqrt(3)*vb3*%i);

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+MVA=fix(MVA/1e5)*1e5;

+Imod=fix(Imod);

+mprintf("\n \n from second method\nFault MVA=%fMVA \n Fault current=%d/_%dAmp",MVA/1e6,Imod,Iangle);

diff --git a/1067/CH20/EX20.05.b/20_5_b.sce b/1067/CH20/EX20.05.b/20_5_b.sce
new file mode 100755
index 000000000..9b9ec95c4
--- /dev/null
+++ b/1067/CH20/EX20.05.b/20_5_b.sce
@@ -0,0 +1,18 @@
+clear;

+clc;

+v1=66e3;

+v2=11e3;

+x2=.461;

+x1=.4527;

+If=229;

+I1=If*x2/(x1+x2);

+I2=If*x1/(x1+x2);

+I=I1+I2;

+Ig1=I1*v1/v2;

+Ig1=fix(Ig1);

+I1=round(I1*10)/10;

+I2=round(I2*10)/10;

+mprintf("the fault current supplied by each transformer is\n I1=%fA\nI2=%fA\nI3=I1+I2=%dA\n",I1,I2,I);

+I2=fix(I2);

+Ig2=I2*v1/v2;

+mprintf("the fault current supplied by each generator \n Ig1=%dA\n Ig2=%dA\n",Ig1,Ig2);

diff --git a/1067/CH20/EX20.06/20_6.sce b/1067/CH20/EX20.06/20_6.sce
new file mode 100755
index 000000000..0d79fadd5
--- /dev/null
+++ b/1067/CH20/EX20.06/20_6.sce
@@ -0,0 +1,22 @@
+clear;

+clc;

+r=6e6;

+v1=11e3;

+v2=66e3;

+xg=.1;

+xt=.09;

+z=4+(1*%i);

+zb=v2^2/r;

+zpu=z/zb;

+E=1;

+Ifault=E/(zpu+((xg+xt)*%i));

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Ib=r/(sqrt(3)*v2);

+i=Imod*Ib;

+igb=r/(sqrt(3)*v1);

+ig=igb*Imod;

+i=fix(i);

+ig=fix(ig);

+mprintf("the base current on HT side = %dA\n the current from generator = %dA",i,ig);

diff --git a/1067/CH20/EX20.07/20_7.sce b/1067/CH20/EX20.07/20_7.sce
new file mode 100755
index 000000000..f7838aab6
--- /dev/null
+++ b/1067/CH20/EX20.07/20_7.sce
@@ -0,0 +1,29 @@
+clear;

+clc;

+r1=20e6;

+rb=30e6;

+v1=11e3;

+v2=110e3;

+x1g=.2*rb/r1;

+x1t=.08*rb/r1;

+x2g=.2;

+x2t=.1;

+xl=.516;

+x0=xl/2;

+x1=x1g+x1t;

+x2=x2g+x2t;

+x=inv(inv(x2)+inv(x1));

+z=x+x0;

+E=1;

+isc=E/z;

+ig1=isc*x2/(x1+x2);

+ig2=isc*x1/(x1+x2);

+i=ig1+ig2;

+ib=rb/(1.7355*v1);

+ig1=fix(ig1*1000)/1000;

+Ig1=ig1*ib;

+ib=fix(ib);

+ig2=fix(ig2*100)/100;

+Ig2=ig2*ib;

+Ig2=fix(Ig2);

+mprintf("the current taken from G1=%dA(lagging)\n the current taken from G2=%dA(lagging)",Ig1,Ig2);

diff --git a/1067/CH20/EX20.08/20_8.sce b/1067/CH20/EX20.08/20_8.sce
new file mode 100755
index 000000000..1cddc0db8
--- /dev/null
+++ b/1067/CH20/EX20.08/20_8.sce
@@ -0,0 +1,37 @@
+clear;

+clc;

+r=25e6;

+rb=5e6;

+v1=6.6e3;

+v2=25e3;

+xs=.2;

+xt=.3;

+Xs=xs*r/rb;

+Xt=xt*r/rb;

+Z=.125;

+v=1;

+I=v/(Z);

+ib=r/(1.7355*v1);

+ib=fix(ib);

+i=ib*8;

+ig=I*.25/.5;

+im=I-ig;

+it=3*1+im;

+Ia=ib*it;

+Imom=1.6*Ia;

+xt=.15;

+Zth=.375*.25/(.375+.25);

+I=v/xt;

+igen=I*.375/.625;

+imot=.25*I*.25/.625;

+itot=igen+(3*imot);//symm breaking current

+ibr=itot*1.1;//asymm breaking current

+is=itot*ib;

+ia=ibr*ib*1.01;

+ia=fix(ia/100)*100;

+rbreaking=1.739*v1*ia;

+rbreaking=fix(rbreaking/1e6)*1e6;

+Imom=round(Imom/10)*10;

+ia=round(ia);

+is=fix(is/100)*100;

+mprintf("the subtransient fault current If= %d/_-90A\nsubtansient current in breaker A=%dA\n the momentary current = %dA\n,the current to be interrupted asymmetric=%dA \n symmetric interrupting current=%dA\n the rating of the CB in kva=%dkVA",i,Ia,Imom,ia,is,rbreaking/1e3);

diff --git a/1067/CH20/EX20.09/20_9.sce b/1067/CH20/EX20.09/20_9.sce
new file mode 100755
index 000000000..1c4a991b6
--- /dev/null
+++ b/1067/CH20/EX20.09/20_9.sce
@@ -0,0 +1,13 @@
+clc;

+clear;

+rb=100e6;

+rf=1e6;

+v=3.3e3;

+x=rf/rb;

+xpu=.6;

+xtot=x+xpu;

+rf2=rf/xtot;

+rf2=round(rf2/1e4)*1e4;

+If=rf2/(1.72*v);

+If=fix(If);

+mprintf("the fault level is=%fMVA\n the fault current=%dA",rf2/1e6,If);;

diff --git a/1067/CH20/EX20.1/20_01.sce b/1067/CH20/EX20.1/20_01.sce
new file mode 100755
index 000000000..6cec8cacd
--- /dev/null
+++ b/1067/CH20/EX20.1/20_01.sce
@@ -0,0 +1,38 @@
+clear;

+clc;

+V=6.6e3;

+r=5e6;

+X=.12;

+F=r/X;

+I=(F/V)/(%i*sqrt(3));

+Ir=real(I);

+Ii=imag(I);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+F=fix(F/1e5)*1e5;

+Imod=fix(Imod);

+mprintf("Method 1 \nthe value of fault MVA=%fMVA \n the fault current is = %d /_%d A\n",(F/1e6),Imod,Iangle);

+//method 2

+Vbase=V/sqrt(3);

+Ifaultpu=1/(X*%i);

+Ibase=r/(Vbase*3);

+Ifault=Ifaultpu*Ibase;

+P=sqrt(3)*Ifault*V;

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Pr=real(P);

+Pi=imag(P);

+Pmod=sqrt((Pr^2)+(Pi^2));

+Pangle=atand(Pr/Pi)-90;

+Pmod=fix(Pmod/1e5)*1e5;

+Imod=fix(Imod);

+mprintf("From method 2\n the value of fault MVA=%f /_%d MVA \n the fault current is = %d A",(Pmod/1e6),Pangle,Imod);

+//method 3

+v1=6.4e3;

+I=(v1/V)/X;

+Ifault=Ibase*I;

+p=sqrt(3)*Ifault*v1;//the difference in result is due to erroneous calculation in textbook.

+p=round(p/1e5)*1e5;

+mprintf("\nthe new fault current at 6.4kV is = %fA \n the newfault power at service voltage is =%fMVA",Ifault,p/1e6);

+disp("the difference in result is due to erroneous calculation in textbook.");

diff --git a/1067/CH20/EX20.10/20_10.sce b/1067/CH20/EX20.10/20_10.sce
new file mode 100755
index 000000000..d41be83d2
--- /dev/null
+++ b/1067/CH20/EX20.10/20_10.sce
@@ -0,0 +1,7 @@
+clear;

+clc;

+r=500e3;

+x=4.75/100;

+fault=r/x;

+fault=fix(fault/1e5)*1e5;

+mprintf("the fault level on LT side=%dkVA",fault/1e3);

diff --git a/1067/CH20/EX20.11/20_11.sce b/1067/CH20/EX20.11/20_11.sce
new file mode 100755
index 000000000..f51eefbe0
--- /dev/null
+++ b/1067/CH20/EX20.11/20_11.sce
@@ -0,0 +1,14 @@
+clc;

+clear;

+r1=75e6;

+r2=150e6;

+rb=r1+r2;

+rf=rb;

+x=.05;

+xn=x*rb/1e6;

+xeq=rb/rf;

+X=xn+xeq;

+fault=rb/X;

+f=rb/xn;

+fault=round(fault/1e4)*1e4

+mprintf("fault level on LT sid eof transformer=%fMVA \n fault level when source of reactance is neglected=%fMVA",fault/1e6,f/1e6);

diff --git a/1067/CH20/EX20.12/20_12.sce b/1067/CH20/EX20.12/20_12.sce
new file mode 100755
index 000000000..7401eabb9
--- /dev/null
+++ b/1067/CH20/EX20.12/20_12.sce
@@ -0,0 +1,10 @@
+clear;

+clc;

+rb=100e6;

+r1=50e6;

+r2=rb;

+x1=rb/r1;

+x2=rb/r2;

+xeq=inv(inv(x1)+inv(x2));

+f=rb/xeq;

+mprintf("the fault level on the line =%dMVA",f/1e6);

diff --git a/1067/CH20/EX20.13/20_13.sce b/1067/CH20/EX20.13/20_13.sce
new file mode 100755
index 000000000..7b5bc6638
--- /dev/null
+++ b/1067/CH20/EX20.13/20_13.sce
@@ -0,0 +1,15 @@
+clear;

+clc;

+x=.23;

+r=3750e3;

+v=6600;

+res=.866;

+x1=x*(v^2)/r;

+z=sqrt((res^2)+(x1^2));

+i=1.1*v/(sqrt(3)*z);

+f=res/x1;

+x=1.38;

+i=round(i/100)*100

+is=sqrt(2)*x*i;

+is=round(is/10)*10;

+mprintf("initial short circuit current=%dA \n peak short circuit current=%dA",i,is);

diff --git a/1067/CH20/EX20.14/20_14.sce b/1067/CH20/EX20.14/20_14.sce
new file mode 100755
index 000000000..360be08a2
--- /dev/null
+++ b/1067/CH20/EX20.14/20_14.sce
@@ -0,0 +1,26 @@
+clear;

+clc;

+rb=75000e3;

+ro=50e6;

+v1=11e3;

+v2=66e3;

+xa=.25*rb/ro;

+xb=.75;

+xt=.1;

+v=1;

+xeq=inv(inv(xa)+inv(xb))+xt;

+i=v/xeq;

+i=round(i*100)/100;

+ia=i*xb/(xa+xb);

+ib=i*xa/(xa+xb);

+ia=round(ia*100)/100;

+ilt=rb/(sqrt(3)*v1);

+iht=rb/(sqrt(3)*v2);

+i=i*iht;

+i=fix(i)

+ia=ia*ilt;

+ilt=rb/(1.73*v1);

+ib=ib*ilt;

+ia=round(ia);

+ib=round(ib/10)*10;

+mprintf("sub transient current generator A=%dA \n generator B=%dA \n HT side=%dA",ia,ib,i);

diff --git a/1067/CH20/EX20.15/20_15.sce b/1067/CH20/EX20.15/20_15.sce
new file mode 100755
index 000000000..78a8293c9
--- /dev/null
+++ b/1067/CH20/EX20.15/20_15.sce
@@ -0,0 +1,25 @@
+clear;

+clc;

+x=1;

+e=1;

+i=e/x;

+r=7.5e6;

+v=6.6e3;

+i=r/(sqrt(3)*v);

+i=fix(i);

+x2=.09;

+i2=e/x2;

+I2=i2*i;

+I2=fix(I2/10)*10

+idc=sqrt(2)*I2;

+mc=idc*2;

+x3=.15;

+i3=e/x3;

+I3=i3*i;

+ib=I3*1.4;

+Mva=sqrt(3)*v*ib;

+idc=round(idc/1e2)*1e2;

+mc=round(mc/1e2)*1e2;

+I3=round(I3/10)*10;

+Mva=fix(Mva/1e4)*1e4

+mprintf("sustained short circuit current=%dA\ninitial symmetric SC current=%fkA\nmaximum dc component=%fkA\nmaking capacity required=%fkA\ntransient short circuit current=%fkA\n interrupting capacity required=%fMVA,Asymmetric",i,I2/1e3,idc/1e3,mc/1e3,I3/1e3,Mva/1e6);

diff --git a/1067/CH20/EX20.16.a/20_16_a.sce b/1067/CH20/EX20.16.a/20_16_a.sce
new file mode 100755
index 000000000..8b832bf81
--- /dev/null
+++ b/1067/CH20/EX20.16.a/20_16_a.sce
@@ -0,0 +1,23 @@
+clear;

+clc;

+rb=2e6;

+r=1.2e6;

+x=7*rb/r;

+v=6.6e3;

+i=rb/v;

+zb=v/i;

+r=1200e3;

+rb=2000e3;

+v=6.6e3;

+i=rb/v;

+x=.1;

+z0=v*x/i;

+x1=7*rb/r;

+z1=v*x1/(100*i);

+z2=2;

+z=z0+z1+z2;

+ish=v/z;

+zb=round(zb*10)/10;

+ish=round(ish/10)*10;

+mprintf("the shortcircuit current by direct ohmic method=%fA\n",ish);

+mprintf("the base impedence=%fohm",zb);

diff --git a/1067/CH20/EX20.16.b/20_16_b.sce b/1067/CH20/EX20.16.b/20_16_b.sce
new file mode 100755
index 000000000..50bbc50f7
--- /dev/null
+++ b/1067/CH20/EX20.16.b/20_16_b.sce
@@ -0,0 +1,19 @@
+clear;

+clc;

+rb=2e6;

+r=1.2e6;

+x=7*rb/r;

+x1=10;

+x2=11.7;

+v=6.6e3;

+i=rb/v;

+zb=v/i;

+r=1200e3;

+rb=2000e3;

+v=6.6e3;

+xt=.117;

+xf=2/zb*100;

+xtot=xf+x1+x2;

+ish=i*100/xtot;

+ish=round(ish/10)*10;

+mprintf("the short circuit current by percentage reactance method=%fA",ish);

diff --git a/1067/CH20/EX20.16.c/20_16_c.sce b/1067/CH20/EX20.16.c/20_16_c.sce
new file mode 100755
index 000000000..bf393b462
--- /dev/null
+++ b/1067/CH20/EX20.16.c/20_16_c.sce
@@ -0,0 +1,10 @@
+clear;

+clc;

+x1=5;

+x2=10;

+x3=11.7;

+x4=9.1;

+i=303;

+xt=x1+x2+x3+x4;

+ish=303*100/xt;

+mprintf("the SHORT CIRCUIT CURRENT=%dA",ish)

diff --git a/1067/CH20/EX20.17.a/20_17_a.sce b/1067/CH20/EX20.17.a/20_17_a.sce
new file mode 100755
index 000000000..6d0f19865
--- /dev/null
+++ b/1067/CH20/EX20.17.a/20_17_a.sce
@@ -0,0 +1,15 @@
+clear;

+clc;

+v=3.3e3;

+rb=3e6;

+r1=1e6;

+r2=1.5e6;

+x1=10;

+x2=20;

+X1=x1*rb/r1;

+X2=x2*rb/r2;

+x=inv(inv(X1)+inv(X2));

+kva=rb*100/x;

+ish=kva/(1.7388*v);

+ish=round(ish);

+printf("the value of short circuit current=%dA",ish);

diff --git a/1067/CH20/EX20.17.b/20_17_b.sce b/1067/CH20/EX20.17.b/20_17_b.sce
new file mode 100755
index 000000000..426481b0e
--- /dev/null
+++ b/1067/CH20/EX20.17.b/20_17_b.sce
@@ -0,0 +1,17 @@
+clear;

+clc;

+v=3.3e3;

+rb=3e6;

+r1=1e6;

+r2=1.5e6;

+x1=10;

+x2=20;

+X1=x1*rb/r1;

+X2=x2*rb/r2;

+x=inv(inv(X1)+inv(X2));

+kva=rb*100/x;

+ish=kva/(sqrt(3)*v);

+rx=10e6;

+x2=rb*100/rx;

+r=inv(inv(X1)-inv(X2))-30;

+printf("the reactance of generator to be converted=%dpercent",r);

diff --git a/1067/CH20/EX20.18.a/20_18a.sce b/1067/CH20/EX20.18.a/20_18a.sce
new file mode 100755
index 000000000..97d369ca4
--- /dev/null
+++ b/1067/CH20/EX20.18.a/20_18a.sce
@@ -0,0 +1,11 @@
+clear;

+clc;

+r1=3e6;

+x=10;

+r=150e6;

+rb=9e6;

+x1=x*rb/r1;

+xc=inv(2*inv(x1));

+xt=rb*100/r;

+x=(inv(inv(xt)-inv(xc)))-5;

+printf("the reactance that should be added= %d percent",x);

diff --git a/1067/CH20/EX20.18.b/20_18b.sce b/1067/CH20/EX20.18.b/20_18b.sce
new file mode 100755
index 000000000..18f1a908e
--- /dev/null
+++ b/1067/CH20/EX20.18.b/20_18b.sce
@@ -0,0 +1,13 @@
+clear;

+clc;

+z=4000;

+zb=9;

+x1=zb/z*100;

+x2=5;

+x3=30;

+x4=30;

+x=inv(inv(x1+x2)+inv(x3)+inv(x4));

+x=round(x*100)/100;

+fault=zb*1e3/x*100;

+fault=fix(fault/1e3)*1e3;

+mprintf("the new fault level of generator bus=%dMVA",fault/1e3);

diff --git a/1067/CH20/EX20.19/20_19.sce b/1067/CH20/EX20.19/20_19.sce
new file mode 100755
index 000000000..5552054e1
--- /dev/null
+++ b/1067/CH20/EX20.19/20_19.sce
@@ -0,0 +1,23 @@
+clear;

+clc;

+rb=20e6;

+r=10e6;

+v1=11e3;

+v2=66e3;

+x1=5;

+X1=x1*rb/r;

+xa=20;

+xb=20;

+xc=20;

+xd=20;

+xbus=25;

+xtr=X1;

+xcd=inv(inv(xc)+inv(xd));

+xab=inv(inv(xa)+inv(xb));

+xcdbus=xcd+xbus;

+xn=inv(inv(xab)+inv(xcdbus));

+xth=xtr+xn;

+mva=rb/xth*100;

+i=mva/(1.745*v2);

+i=round(i);

+printf("the SC MVA=%fMVA \n the SC current=%dA",mva/1e6,i);

diff --git a/1067/CH20/EX20.2/20_02.sce b/1067/CH20/EX20.2/20_02.sce
new file mode 100755
index 000000000..da746575a
--- /dev/null
+++ b/1067/CH20/EX20.2/20_02.sce
@@ -0,0 +1,20 @@
+clear;

+clc;

+V=3000e3;

+r1=30;

+r=5000e3;

+vb2=11e3;

+vb3=33e3;

+x=.2;

+Xt=.05*r/V;

+Xl=r1*r/(vb3^2);

+xtotal=(x+Xt+Xl)*%i;

+MVA=r*%i*1e-6/xtotal;

+Ifault=MVA*1e6/(sqrt(3)*vb3*%i);

+Ir=real(Ifault);

+Ii=imag(Ifault);

+Imod=sqrt((Ir^2)+(Ii^2));

+Iangle=atand(Ir/Ii)-90;

+Imod=round(Imod);

+MVA=round(MVA*10)/10;

+mprintf("the value of falut current = %d/_%d Amp \n fault MVA =%f MVA",Imod,Iangle,MVA);

diff --git a/1067/CH20/EX20.20.b/20_20_b.sce b/1067/CH20/EX20.20.b/20_20_b.sce
new file mode 100755
index 000000000..5aeb2f57c
--- /dev/null
+++ b/1067/CH20/EX20.20.b/20_20_b.sce
@@ -0,0 +1,12 @@
+clear;

+clc;

+g=20;

+v=11e3;

+r=20e6;

+n=4;

+x=.4;

+x1=g/(n-1);

+z=((x1/x)-(x1))/1.33;

+R=(z/100)*(v^2)/r;

+R=round(R*1000)/1000;

+printf("the value of reactance=%fohms",R);

diff --git a/1067/CH20/EX20.21/20_21.sce b/1067/CH20/EX20.21/20_21.sce
new file mode 100755
index 000000000..ee76fef74
--- /dev/null
+++ b/1067/CH20/EX20.21/20_21.sce
@@ -0,0 +1,37 @@
+clear;

+clc;

+xst=20;

+xtr=28;

+xs=250;

+xt=15;

+v1=25e3;

+r1=500e6/.8;

+v2=220e3;

+rb=600e6;

+vb=25e3;

+xf=rb/r1;

+xst=xst*xf/100;

+xtr=xtr*xf/100;

+xs=xs*xf/100;

+xt=xt/100;

+xeqs=inv(inv(xst)+inv(xt));

+xeqt=inv(inv(xtr)+inv(xt));

+xeg=inv(inv(xs)+inv(xt));

+e=1;

+xeqs=round(xeqs*1000)/1e3;

+is=e/xeqs;

+is=round(is);

+it=e/xeqt;

+ig=e/xeg;

+i1=is*xt/(xt+xst);

+i2=is*xst/(xst+xt);

+ib=rb/(1.726*22.2*1e3);

+Is=is*ib;

+i1=round(i1*10)/10;

+Is=round(Is/1e3)*1e3;

+i2=fix(i2*100)/0100;

+I1=i1*ib;

+I2=i2*ib;

+I1=fix(I1/1e2)*1e2;

+I2=fix(I2/1e2)*1e2;

+mprintf("total subtransient current T-off=%fkA\nsubtransient current on generator side=%fkA\n subtransient current on transformer side=%fkA",Is/1e3,I1/1e3,I2/1e3);

diff --git a/1067/CH20/EX20.22/20_22.sce b/1067/CH20/EX20.22/20_22.sce
new file mode 100755
index 000000000..71bb1a396
--- /dev/null
+++ b/1067/CH20/EX20.22/20_22.sce
@@ -0,0 +1,11 @@
+clc;

+clear;

+mvan=6800e6;

+v=132e3;

+mvac=200e6;

+mvae=mvan-mvac;

+n=mvan/(sqrt(3)*v);

+e=mvae/(1.681*v);

+e=fix(e/10)*10;

+n=fix(n/10)*10;

+printf("normal fault current=%f/_-90 kA\nEffective fault current=%f/_-90 kA",n/1e3,e/1e3);

diff --git a/1067/CH20/EX20.23/20_23.sce b/1067/CH20/EX20.23/20_23.sce
new file mode 100755
index 000000000..49d221a84
--- /dev/null
+++ b/1067/CH20/EX20.23/20_23.sce
@@ -0,0 +1,11 @@
+clear;

+clc;

+v=400e3;

+mvan=30000e6;

+mw=1500e6;

+mvac=600e6;

+n=mvan/mw;

+mvae=mvan-mvac;////the difference in result is due to erroneous calculation in textbook.

+e=mvae/mw;

+mprintf("the SC raio=%d\neffective fault level=%fMVA\neffective circuit level of HVDC system(ESCR)=%f",n,mvae/1e6,e);

+disp('the difference in result is due to erroneous calculation in textbook.');

diff --git a/1067/CH20/EX20.24/20_24.sce b/1067/CH20/EX20.24/20_24.sce
new file mode 100755
index 000000000..37112e7e7
--- /dev/null
+++ b/1067/CH20/EX20.24/20_24.sce
@@ -0,0 +1,7 @@
+clear;

+clc;

+s=1;

+xt=5;

+m=s/xt*100;

+n=2*s/xt*100;

+mprintf("fault level on lt side=%dMVA\n fault level on HT side=%dMVA",m,n);