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// Example 4.3
// Determine (a) Synchronous speed (b) Slip (c) Rotor impedance (d) Rotor current
// (e) Rotor current if changing the shaft load resulted in 1.24 percenr slip
// (f) Speed for the condition in (e)
// Page No. 146
clc;
clear;
close;
// Given data
fs=60; // Frequency
p=6; // Number of poles
nr=1164; // Rotor speed
Rr=0.10; // Equivalent resistance
Xbr=0.54; // Equivalent reactance
Ebr=150; // Blocked rotor voltage per phase
s1=0.0124; // Percent slip
// (a) Synchronous speed
ns=120*fs/p; // Speed
// (b) Slip
s=(ns-nr)/ns;
// (c) Rotor impedance
Zr=(Rr/s)+%i*Xbr;
// Complex to Polar form...
Zr_Mag=sqrt(real(Zr)^2+imag(Zr)^2); // Magnitude part
Zr_Ang=atan(imag(Zr),real(Zr))*180/%pi; // Angle part
// (d) Rotor current
Ir_Mag=Ebr/Zr_Mag; // Magnitude
Ir_Ang=0-Zr_Ang; // Angle
// (e) Rotor current if changing the shaft load resulted in 1.24 percent slip
Zrnew=Rr/s1+%i*Xbr;
// Complex to Polar form...
Zrnew_Mag=sqrt(real(Zrnew)^2+imag(Zrnew)^2); // Magnitude part
Zrnew_Ang=atan(imag(Zrnew),real(Zrnew))*180/%pi; // Angle part
Irnew_Mag=Ebr/Zrnew_Mag; // Magnitude
Irnew_Ang=0-Zrnew_Ang; // Angle
// (f) Speed for the condition in (e)
nr=ns*(1-s1);
// Display result on command window
printf("\n Synchronous speed = %0.0f r/min ",ns);
printf("\n Slip = %0.3f ",s);
printf("\n Rotor impedance magnitude = %0.2f Ohm ",Zr_Mag);
printf("\n Rotor impedance angle = %0.2f deg ",Zr_Ang);
printf("\n Rotor current magnitude = %0.1f Ohm ",Ir_Mag);
printf("\n Rotor current angle = %0.1f deg ",Ir_Ang);
printf("\n Rotor current magnitude by changing the shaft load = %0.1f Ohm ",Irnew_Mag);
printf("\n Rotor current angle by changing the shaft load = %0.2f deg ",Irnew_Ang);
printf("\n New rotor speed = %0.0f r/min ",nr);
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