1 files changed, 33 insertions, 0 deletions
diff --git a/3760/CH4/EX4.40/Ex4_40.sce b/3760/CH4/EX4.40/Ex4_40.sce
new file mode 100644
index 000000000..3976a0aba
--- /dev/null
+++ b/3760/CH4/EX4.40/Ex4_40.sce
@@ -0,0 +1,33 @@
+clc;
+v=200; // rated voltage of shunt motor
+i=22; // rated current of dc shunt motor
+n1=1000; // speed at which motor is running
+rf=100; // field resistance
+ra=0.1; // armature resistance
+n2=800; // reduced speed at which motor is to run
+iF=v/rf; // field current
+ia=i-iF; // armature current
+disp('case a');
+// load torque is independent of speed
+Ea1=v-ia*ra; // counter EMF at 1000 rpm
+rg=(v-ia*ra-(n2*Ea1)/n1)/ia; 
+printf('Additional resistance inserted in armature circuit is %f ohms\n',rg);
+printf('Loss in additional resistance is %f W\n',ia^2*rg);
+disp('case b');
+// load torque is directly proportional to speed
+ia2=(n2/n1)*ia; // armature current at 800 rpm
+rg=(v-ia2*ra-(n2*Ea1)/n1)/ia2; 
+printf('Additional resistance inserted in armature circuit is %f ohms\n',rg);
+printf('Loss in additional resistance is %f W\n',ia2^2*rg);
+disp('case c');
+// load torque varies as the square of speed
+ia2=(n2/n1)^2*ia; // armature current at 800 rpm
+rg=(v-ia2*ra-(n2*Ea1)/n1)/ia2; 
+printf('Additional resistance inserted in armature circuit is %f ohms\n',rg);
+printf('Loss in additional resistance is %f W\n',ia2^2*rg);
+disp('case d');
+// load torque varies as the cube of speed
+ia2=(n2/n1)^3*ia; // armature current at 800 rpm
+rg=(v-ia2*ra-(n2*Ea1)/n1)/ia2; 
+printf('Additional resistance inserted in armature circuit is %f ohms\n',rg);
+printf('Loss in additional resistance is %f W\n',ia2^2*rg);