initial commit / add all books

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diff --git a/3760/CH1/EX1.28/Ex1_28.sce b/3760/CH1/EX1.28/Ex1_28.sce
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+clc;

+P=10000; // rated power of transformer in VA

+E1=2500; // primary side voltage

+E2=250; // secondary side voltage

+pf=0.8; // power factor

+//initialising the results of open circuit test

+vo=250; // open circuit voltage

+io=0.8; //no load current

+po=50; // open circuit voltage

+// initialising the results of open circuit test

+vsc=60; // short circuit voltage

+isc=3; // short circuit current

+psc=45; // power dissipated in test

+ifl=P/E1; // full load current on primary side

+poh=psc*(ifl/isc)^2; // ohmic losses at full load current

+disp('case a(1)');

+n=(1-(po+(poh/4^2))/(po+(poh/4^2)+(P*pf)/4))*100; // efficiency at 1/4 load

+printf('efficiency at 1/4 load is %f percent\n',n); 

+disp('case a(2)');

+n=(1-(po+(poh/2^2))/(po+(poh/2^2)+(P*pf)/2))*100; // efficiency at 1/2 load

+printf('efficiency at 1/2 load is %f percent\n',n); 

+disp('case a(3)');

+n=(1-(po+(poh/1^2))/(po+(poh/1^2)+(P*pf)/1))*100; // efficiency at full load

+printf('efficiency at full load is %f percent\n',n);

+disp('case a(4)');

+n=(1-(po+((poh*5^2)/4^2))/(po+((poh*5^2)/4^2)+(P*pf*5)/4))*100; // efficiency at 1*1/4 load

+printf('efficiency at 5/4 load is %f percent\n',n);  

+// let maximum efficiency occurs at x times the rated KVA

+// maximum efficiency occurs when core loss becomes equal to ohmic losses

+x=sqrt(po/poh); 

+nm=(x*P)/1000; // VA output at maximum

+nmax=(1-(2*po)/(nm*1000*pf+2*po))*100; 

+printf('KVA load at which maximum efficiency occurs is %f KVA\n',nm);

+printf('Maximum efficiency is %f percent\n',nmax);

+// from short circuit test

+reh=psc/isc^2; // total resistance referred to h v side

+zeh=vsc/isc; // total impedance referred to h v side

+xeh=sqrt(zeh^2-reh^2); // total leakage reactance referred to h v side

+er=(ifl*reh)/E1; //p u resistance

+ex=(ifl*xeh)/E1; // p u reactance

+vr=(er*pf+ex*sqrt(1-pf^2))*100; // p u voltage regulation

+printf(' p u voltage regulation for lagging power factor is %f percent\n',vr);

+dv=E2*(vr/100); // voltage drop in series impedance

+v2=E2-dv;

+printf('secondary terminal voltage for lagging power factor of 0.8 is %f v\n',v2);

+// voltaage regulation for leading power factor

+vr=(er*pf-ex*sqrt(1-pf^2))*100; // p u voltage regulation

+printf(' p u voltage regulation for leading power factor is %f percent\n',vr);

+dv=E2*(vr/100); // voltage drop in series impedance

+v2=E2-dv;

+printf('secondary terminal voltage for leading power factor of 0.8 is %f v\n',v2);