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//Chapter 5:DC Motor Drives
//Example 4
clc;
//Variable Initialization
//The ratings of the motor are same as that of Ex-5.2
V1=220 //rated voltage in V
Ia1=100 //rated current in A
N1=1000 //speed in rpm clockwise
N2=800 //given speed during the dynamic braking in rpm
Ra=0.05 //armature resistance in ohms
Rs=0.05 //field resistance in ohms
//Solution
T2 = 2 //dynamic torque is twice the rated torque
Ia2=Ia1*sqrt(T2) //since T=Kf*Ia**2
E1=V1-Ia1*(Ra+Rs)
E2=(Ia2/Ia1)*(N2/N1)*E1 //since E=Ke*Ia*N
Rb=E2/Ia2-(Ra+Rs) //since E2=Ia2(Rb+Ra+Rs) during braking
//Results
mprintf("\n Braking current Ia2: %.1f A",Ia2)
mprintf("\n Required braking resistance Rb: %.2f ohm",Rb)
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