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+//Chapter 5:Dc Motor Drives
+//Example 7
+clc;
+
+//Variable Initialization
+
+//Ratings of the DC series motor which operated under dynamic braking
+Ra=0.5         //total resistance of armature and field windings in ohms
+Rf=10          //field resistance in ohms
+T=500          //overhauling load torque in N-m
+N=600          //speed at the overhauling torque T in rpm
+
+//Nagnetisation curve at a speed of 500 rpm
+N1=500    //speed in rpm
+Ia=[20, 30, 40, 50, 60, 70, 80]       //armature current in A
+E =[215,310,381,437,482,519,550]     //back emf in V
+
+//Solution
+Wm1=2*%pi*N1/60
+disp(Ia,"Armature current : in A")
+Ke_flux=E / Wm1     //Ke*flux=constant
+disp(Ke_flux,"Ke_flux :")
+T=[]
+for i=1:7
+T($+1)=(Ke_flux(i))*(Ia(i))   //torque
+end
+disp(T,"Torque  :in N-m")
+
+
+//Results
+//Plotting the values of Ke*flux vs Ia and T vs Ia
+subplot(2,1,1)
+plot(Ia,Ke_flux,'y')
+xlabel('Armature current I_a')
+ylabel('Ke*flux')
+title('Ke*flux vs Ia')
+xgrid(2)
+
+subplot(2,1,2)
+plot(T,Ia)
+xlabel('Torque T')
+ylabel('Armature current I_a')
+title('T vs Ia')
+xgrid(2)
+
+mprintf("\nFrom the plot we can see that at the given torque T=500 N-m the current Ia is 56 A, and Ke*flux is 8.9 at Ia=56 A")
+Ke_flux=8.9    //value of Ke*flux at T=500 N-m from the plot
+Ia=56          //value of Ia at at T=500 N-m from the plot
+Wm=2*%pi*N/60
+E=Ke_flux*Wm   //required emf
+x=E/Ia         //x=Ra+Rb
+Rb=x-Ra        //required braking resistance
+mprintf("\nHence the rquired braking resistance is %.3f ohm",Rb)