initial commit / add all books

1 files changed, 20 insertions, 0 deletions

diff --git a/3760/CH4/EX4.48/Ex4_48.sce b/3760/CH4/EX4.48/Ex4_48.sce
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+clc;

+v=230; // rated voltage of dc shunt motor

+ra=0.4; // armature circuit resistance

+rf=115; // field resistance

+n1=800; // initial speed 

+n2=1000; // final speed

+ia1=20; // armature current at n=800 rpm

+// torque at both speed is same therefore f1*ia1=f2*ia2 where f=field flux therefore

+Ea1=v-ia1*ra; // counter EMF at 800rpm

+// ia2=ia1*k where k=f1/f2 now writing Ea2(counter EMF at 1000rpm) in terms of k and finding value of k by solving quadratic equation in k whose terms are

+t1=ia1*ra*n1;

+t2=-v*n1;

+t3=Ea1*n2;

+p=[ t1 t2 t3];

+k=roots(p);

+if1=v/rf; // initial field current

+if2=if1/k(2); // final field current correponding to n=1000rpm

+rs=v/if2; // new shunt field circuit resistance

+re=rs-rf;

+printf('Resistance that must be inserted in shunt field circuit is %f ohms\n',floor(re));