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// Example 5.20
// Computation of (a) Resistance of the resistors required to limit the locked
// rotor current to 3 times rated current (b) Stator voltage per phase at
// locked rotor (c) Expected minimum locked rotor torque when starting as a
// percent of rated torque
// Page No. 235
clc;
clear all;
close;
// Given data
Ilr=3*78; // Locked rotor current
Vbranch=132.79; // Branch voltage
Rlr=0.2549; //Locked rotor resistance
Xlr=0.0978; //Locked rotor impedance
f=60; //Frequency of motor
Zlr=0.273;
// (a) Resistance of the resistors required to limit the locked rotor current
// to 3 times rated current
Rex=sqrt((Vbranch^2/Ilr^2)-(Rlr^2))-Xlr;
// (b) Stator voltage per phase at locked rotor
IZlr=Ilr*Zlr;
VT1_N=IZlr;
// (c) Expected minimum locked rotor torque when starting as a percent of
// rated torque
// From table 5.1 --> Minimum locked rotor torque = 150% rated torque
// Display result on command window
printf("\n Resistance of the resistors required = %0.4f Ohm ",Rex);
printf("\n Stator voltage per phase at locked rotor = %0.2f V ",VT1_N);
disp('Expected minimum locked rotor torque = 1.5 Trated');
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