1 files changed, 46 insertions, 0 deletions
diff --git a/3760/CH6/EX6.45/Ex6_45.sce b/3760/CH6/EX6.45/Ex6_45.sce
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+clc;
+v=400; // rated voltage of motor
+m=3; // number of phases
+r=2; // ratio of leakage reactance of stator to leakage reactance of rotor
+ns=1000; // synchronous speed
+n=960; // speed of motor
+f=50; // frequency 
+// no load test results
+Vo=400; // applied voltage
+io=7.5; // no load current
+pfo=0.135; // power factor
+// blocked rotor test
+vb=150; // applied voltage
+ib=35; // current
+pfb=0.44; // power factor
+znl=Vo/(io*sqrt(3)); // no load impedance
+rnl=znl*pfo; // no load resistance
+xnl=sqrt(znl^2-rnl^2); // no load reactance
+zbr=vb/(ib*sqrt(3)); // block rotor test impedance
+Rbr=zbr*pfb; // block rotor resistance 
+xbr=sqrt(zbr^2-Rbr^2); // block rotor reactance
+x2=xbr/3; // leakage reactance of rotor
+x1=x2*2; // leakage reactance of stator
+xm=xnl-x1; // magnetising reactance
+r1=Rbr/2; // stator resistance/rotor resistance
+V1=v/sqrt(3); // per phase stator voltage
+Ve=(V1*xm)/(x1+xm); // thevenin voltage
+Re=(r1*xm)/(x1+xm); // thevenin resistance
+Xe=(x1*xm)/(x1+xm); // thevenin resistance
+lr=sqrt(3)*v*io*pfo-m*io^2*r1; // rotational losses
+s=(ns-n)/ns; // slip
+ir=Ve/(Re+(r1/s)+%i*(Xe+x2)); // rotor current at slip
+Pm=m*abs(ir)^2*r1*((1-s)/s);
+disp('case a');
+Psh=Pm-lr; 
+printf('Mechanical power output is %f KW\n',Psh/1000);
+disp('case b');
+wr=((2*%pi*f)*(1-s))/m; // speed at which motor is running
+T=Psh/wr; 
+printf('Net torque is %f Nm\n',T);
+disp('case c');
+lor=(Pm*s)/(1-s); // rotor/stator ohmic losses
+Tl=lor*2+lr; // total losses
+pi=Tl+Psh; // input power 
+ne=Psh/pi;
+printf('Efficiency of motor is %f percent',ne*100);