initial commit / add all books

1 files changed, 28 insertions, 0 deletions

diff --git a/3760/CH6/EX6.64/Ex6_64.sce b/3760/CH6/EX6.64/Ex6_64.sce
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+clc;

+v=3300; // rated voltage of induction motor

+p=6; // number of poles

+f=50; // frequency

+t=3.2; // stator to rotor turns

+r=0.1; // rotor resistance

+x=1; // rotor leakage reactance

+R=t^2*r; // rotor resistance referred to stator

+X=t^2*x; // rotor reactance referred to stator

+ws=(4*%pi*f)/p; // synchronous speed

+disp('case a');

+is=(v/sqrt(3))/(sqrt(R^2+X^2)); 

+printf('Starting current at rated voltage is %f A\n',is);

+Ts=(3*is^2*R)/ws; 

+printf('Starting torque at rated voltage is %f Nm\n',Ts);

+disp('case b');

+is=50; // starting current

+// is=Vp/(sqrt((R+rex)^2+X^2) where rex is external resistance and Vp is phase voltage

+// solving above equation we get a quadratic equation in rex whose terms are

+t1=1;

+t2=2*R; 

+t3=(R^2+X^2)-((v/sqrt(3))/is)^2;

+p=[ t1 t2 t3 ];

+rex=roots(p);  

+printf('External resistance referred to rotor is %f ohms\n',rex(2)/t^2);

+Ts=(3*is^2*(R+rex(2)))/ws; 

+printf('Starting torque under new condition is %f Nm\n',Ts);

+