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authorprashantsinalkar2017-10-10 12:27:19 +0530
committerprashantsinalkar2017-10-10 12:27:19 +0530
commit7f60ea012dd2524dae921a2a35adbf7ef21f2bb6 (patch)
treedbb9e3ddb5fc829e7c5c7e6be99b2c4ba356132c /3760/CH4/EX4.42
parentb1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b (diff)
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+clc;
+N=1000; // speed of dc series motor
+v=250; // supply from mains
+i=50; // current drawn from mains
+r=0.6; // armature + field resistance
+rg=4.4; // additional resistance
+// field flux is proportional to armature current
+Ea1=v-i*r; // counter EMF at 1000 rpm
+// Ea2=v-(n2/20)*(r+rg) where Ea2 is counter EMf at speed n2 . taking ratio of Ea2/Ea1 we obtain a quadratic equation in n2 whose terms are given by
+t1=(Ea1*i)/N;
+t2=(N*i)*((r+rg)/(N/i));
+t3=-(N*i*v);
+p=[ t1 t2 t3];
+n=roots(p);
+printf('New speed of motor is %f rpm',ceil(n(2)));
+