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Diffstat (limited to '3731/CH6/EX6.2')
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diff --git a/3731/CH6/EX6.2/Ex6_2.sce b/3731/CH6/EX6.2/Ex6_2.sce new file mode 100644 index 000000000..9944263ea --- /dev/null +++ b/3731/CH6/EX6.2/Ex6_2.sce @@ -0,0 +1,75 @@ +//Chapter 6:Induction Motor Drives +//Example 2 +clc; + +//Variable Initialization +//Ratings of the Delta connected Induction motor +f=50 //frequency in HZ +Vl=2200 //line voltage in V +P=8 //number of poles +N=735 //rated speed in rpm + +//Parameters referred to the stator +Xr_=0.55 // rotor winding reactance in ohm +Xs=0.45 // stator winding reactance in ohm +Rr_=0.1 // resistance of the rotor windings in ohm +Rs=0.075 // resistance of the stator windings in ohm + +//Solution +Ns=120*f/P //synchronous speed in rpm +s=(Ns-N)/Ns //full load slip +x=sqrt((Rs+Rr_/s)**2+(Xs+Xr_)**2) //total impedance +Ip=(Vl)/x //full load phase current +Il=sqrt(3)*Ip //full load line current +Wms=2*%pi*Ns/60 +Tl=(1/Wms)*(3*Ip**2*Rr_/s) //full load torque + +//(i)if the motor is started by star-delta switching +y=sqrt((Rs+Rr_)**2+(Xs+Xr_)**2) +Ist=(Vl/sqrt(3))/y //Maximum line current during starting +Tst=(1/Wms)*(3*Ist**2*Rr_) //Starting torque +ratio1=Tst/Tl //ratio of starting torque to full load torque +z=Rs+sqrt(Rs**2+(Xs+Xr_)**2) +Tmax=3/(2*Wms)*(Vl/sqrt(3))**2/z //maximum torque +ratio2=Tmax/Tl //ratio of maximum torque to full load torque + +//(ii) If the motor is started using auto transformer +y=sqrt((Rs+Rr_)**2+(Xs+Xr_)**2) +Ist1=Vl*sqrt(3)/y //starting current direct online +aT=sqrt(2*Il/Ist1) //transofrmation ratio +Ilst=2*Il/aT //starting motor line current +Ipst=Ilst/sqrt(3) //starting motor phase current +Tst1=(1/Wms)*(3*Ipst**2*Rr_) //starting torque + +//(iii) If motor is started using part winding method +Rs_=2*Rs +Xs_=2*Xs +y=sqrt((Rs_+Rr_)**2+(Xs_+Xr_)**2) +Ist2=(Vl*sqrt(3))/y //starting line current +Ip=Ist2/sqrt(3) //starting phase current +Tst2=(1/Wms)*(3*Ip**2*Rr_) //starting torque + +//(iv) motor is started using series reactors in line +Rs_=Rs/3 ; Rr_=Rr_/3 +Xs_=Xs/3 ; Xr_=Xr_/3 +Il=2*Il //line current at start +x=(Vl/sqrt(3))**2/(Il**2) //x=(Rs_+Rr_)**2+(Xs_+Xr_+Xe)**2 +y=x-(Rs_+Rr_)**2 //y=(Xs_+Xr_+Xe)**2 +z=sqrt(y) //z=(Xs_+Xr_+Xe) +Xe=z-Xs_-Xr_ + + +//Results + +mprintf("(i)Maximum value of line current during starting Ist:%d A",Ist) +mprintf("\nRatio of starting torque to full load torque :%.3f",ratio1) +mprintf("\nRatio of maximum torque to full load torque :%.2f\n",ratio2) +mprintf("\n(ii)Transformation ratio aT:%.3f",aT) +mprintf("\nStarting torque :%d N-m\n",Tst1) +//Answer for the starting torque in the book is wrong due to accuracy + +mprintf("\n(iii)Maximum line current during starting :%d A",Ist2) +mprintf("\nStarting torque :%d N-m\n",Tst2) +//Answer for the starting torque in the book is wrong due to accuracy + +mprintf("\n(iv)Value of the reactor Xe:%.3f ohm",Xe) |