//CHAPTER 10- THREE-PHASE INDUCTION MACHINES //Example 2 disp("CHAPTER 10"); disp("EXAMPLE 2"); //VARIABLE INITIALIZATION P=6; //number of poles f1=60; //frequency in Hertz N_r1=1140; //in rpm //SOLUTION N_s=(120*f1)/P; s1=(N_s-N_r1)/N_s; //slip at full load //solution (a) N_r2=0; s2=(N_s-N_r2)/N_s; disp(sprintf("(a) At standstill, the slip is %f %%",s2*100)); if(s2>1) disp("Since the slip is greater than 100%, the motor operates as brake"); end; if(s2<0) disp("Since the slip is negative, the motor operates as generator"); end; f2=s2*f1; disp(sprintf("And the frequency is %d Hz",f2)); if(f2<0) disp("Since frequency is negative, phase sequence of voltage induced in rotor winding is reversed"); end; //solution (b) N_r3=500; s3=(N_s-N_r3)/N_s; disp(sprintf("(b) At %d rpm, the slip is %f %%",N_r3,s3*100)); if(s3>1) disp("Since the slip is greater than 100%, the motor operates as brake"); end; if(s3<0) disp("Since the slip is negative, the motor operates as generator"); end; f3=s3*f1; disp(sprintf("And the frequency is %d Hz",f3)); if(f3<0) disp("Since frequency is negative, phase sequence of voltage induced in rotor winding is reversed"); end; //solution (c) N_r4=500; s4=(N_s+N_r4)/N_s; //as motor runs in opposite direction disp(sprintf("(c) At %d rpm, the slip is %f %%",N_r4,s4*100)); if(s4>1) disp("Since the slip is greater than 100%, the motor operates as brake"); end; if(s4<0) disp("Since the slip is negative, the motor operates as generator"); end; f4=s4*f1; disp(sprintf("And the frequency is %d Hz",f4)); if(f4<0) disp("Since frequency is negative, phase sequence of voltage induced in rotor winding is reversed"); end; //solution (d) N_r5=2000; s5=(N_s-N_r5)/N_s; disp(sprintf("(d) At %d rpm, the slip is %f %%",N_r5,s5*100)); if(s5>1) disp("Since the slip is greater than 100%, the motor operates as brake"); end; if(s5<0) disp("Since the slip is negative, the motor operates as generator"); end; f5=s5*f1; disp(sprintf("And the frequency is %d Hz",f5)); if(f5<0) disp("Since frequency is negative, phase sequence of voltage induced in rotor winding is reversed"); end; //END