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// Example 5.19
// Computation of (a) Locked rotor current per phase and minimum locked rotor
// torque when starting (b) Locked rotor current per phase when motor is delta
// connected (c) Code letter
// Page No.233
clc;
clear all;
close;
// Given data
V=460; // Rated Voltage
Z=0.547; // Locked rotor impedance
n=1750; // Speed of machine
hp=60; // Horsepower rating of device
f=60; // Frequency of motor
// (a) Locked rotor current per phase and minimum locked rotor torque
Vphase=V/sqrt(3); // Voltage/phase
Ilr1=Vphase/Z; // Locked rotor current/phase
Trated=hp*5252/(n); // Rated torque
Tlr=1.4*Trated; // Locked rotor torque
T2=Tlr*(Vphase/V)^2;
// (b) Locked rotor current per phase when motor is delta connected
Ilr=V/Z; // Locked rotor current/phase
Il=Ilr*sqrt(3); // Line current
// (c) Code letter
Slr=sqrt(3)*V*Il/1000; // Code letter at rated voltage
kVA=Slr/f;
// Display result on command window
printf("\n Locked rotor current per phase = %0.1f A",Ilr1);
printf("\n Minimum locked rotor torque = %0.0f lb-ft",T2);
printf("\n Locked rotor current per phase when motor is delta connected = %0.0f A ",Il);
printf("\n Code letter = %0.1f",kVA);
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