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// Example 5.10
// Determine (a) Range of rotor speed (b) Required rheostat resistance
// Page No. 198
clc;
clear;
close;
// Given data
F=60; // Frequency of motor
P=14; // Number of poles
SL=0.395; // Low speed point
SH=0.02; // High speed point
Stdmax=0.74; // Value at which TD is maximum (from curve B)
R1=0.403; // Motor resistance
R2=0.317;
X1=1.32; // Motor reactance
X2=1.32;
a=3.8; // Ratio of stator turns/phase to rotor turns/phase
// (a) Range of rotor speed
ns=120*F/P; // Speed
nrl=ns*(1-SL); // Rotor low speed
nrh=ns*(1-SH); // Rotor high speed
// (b) Required rheostat resistance
Rrhe=Stdmax*(sqrt(R1^2+(X1+X2)^2))-R2;
Rehereq=Rrhe/a^2;
// Display result on command window
printf("\n Low range of rotor speed = %0.0f r/min",nrl);
printf("\n High range of rotor speed = %0.0f r/min",nrh);
printf("\n Required rheostat resistance = %0.3f Ohm/phase",Rehereq);
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