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//CHAPTER 10- THREE-PHASE INDUCTION MACHINES
//Example 12
disp("CHAPTER 10");
disp("EXAMPLE 12");
//VARIABLE INITIALIZATION
v=440; //line voltage in Volts
I=1200; //line current in Amperes
eff=0.85; //full load efficiency
pow_fact=0.8; //full load power factor
//SOLUTION
//solution (a)
I_fl1=I/5; //starting current at rated voltage is 5 times the rated full-load current
p1=sqrt(3)*v*I_fl1*pow_fact*eff;
disp(sprintf("(a) The maximum permissible kW rating when the motor when it starts at full voltage is %.3f kW",p1/1000));
//solution (b)
x=0.8; //voltage is stepped down to 80%
I_fl2=I/((x^2)*5);
p2=sqrt(3)*v*I_fl2*pow_fact*eff;
disp(sprintf("(b) The maximum permissible kW rating when the motor is used with an auto-transformer is %.3f kW",p2/1000));
//solution (c)
I_fl3=I/((0.578^2)*5); //since a star-delta is equivalent to an auto-transformer starter with 57.8% tapping
p3=sqrt(3)*v*I_fl3*pow_fact*eff;
disp(sprintf("(c) The maximum permissible kW rating when the motor is used with star-delta starter is %.3f kW",p3/1000));
//The answers are slightly different due to precision of floating point numbers
//END
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