1 files changed, 28 insertions, 0 deletions
diff --git a/3760/CH4/EX4.54/Ex4_54.sce b/3760/CH4/EX4.54/Ex4_54.sce
new file mode 100644
index 000000000..9b83a4ecc
--- /dev/null
+++ b/3760/CH4/EX4.54/Ex4_54.sce
@@ -0,0 +1,28 @@
+clc;
+v=230; // rated voltage of dc shunt motor
+n=1000; // rated speed of motor
+rf=115; // field resistance
+ra=0.5; // armature resistance
+ia=4; // no load armature current
+k=(v-ia*ra)/(2*%pi*n/60); // constant term in formula of back EMF
+disp('case a');
+t=80; // load torque
+ia2=t/k; // armature load current
+Ea2=v-ia2*ra; // counter EMF corresponding to load armature current
+printf('Armature current for given load is %f A\n',ia2);
+n2=(Ea2*60)/(k*2*%pi);
+printf('Speed of motor at given load is %f rpm\n',n2);
+disp('case b');
+pd=8000; // power developed by motor
+n3=1250; // speed at power is developed
+// determining value of armature current corresponding to power by solving quadratic equation whose terms are
+t1=ra;
+t2=-v;
+t3=pd;
+p=[ t1 t2 t3];
+ia3=roots(p);
+Ea3=v-ia3(2)*ra; // counter EMF for load armature current
+k1=k/(v/rf); // constant term in formula of back EMF for field current = 1 A
+ifn=(Ea3*60)/(2*%pi*n3*k1);
+rfn=v/ifn;
+printf('External resistance that must be inserted in series with field winding is %f ohms',rfn-rf);