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// Example 5.3
// Computation of (a) Speed at which maximum torque is developed (b) Maximum
// torque that the machine can develop (c) Rated shaft torque (d) Which NEMA
// design fits this motor?
// Page No. 184
clc;
clear;
close;
// Given data
f=60; // Frequency in Hz
p=4; // Number of poles
hp=40; // Horsepower
n=1751; // Rated speed of machine
v=460/sqrt(3); // Voltage
s=0.1490; // Slip
R2=0.153; // Rotor resistance
R1=0.102;
X1=0.409; // Rotor reactance
X2=0.613;
// (a) Speed at which maximum torque is developed
STDmax=R2/(sqrt(R1^2+(X1+X2)^2));
ns=120*f/p; //stator spped
nr=ns*(1-s);
// (b) Maximum torque that the machine can develop
TDmax=(21.12*v^2)/(2*ns*(sqrt(R1^2+(X1+X2)^2)+R1));
// (c) Rated shaft torque
TDshaft=hp*5252/n;
// Display result on command window
printf("\n Speed at which maximum torque is developed = %0.0f r/min ",nr);
printf("\n Maximum torque that the machine can develop = %0.1f lb-ft ",TDmax);
printf("\n Rated shaft torque = %0.1f lb-ft ",TDshaft);
printf("\n Maximum torque is developed at slip of 0.1490 and \n hence machine is placed in design A category ");
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