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Diffstat (limited to '3731/CH6/EX6.4')
| -rw-r--r-- | 3731/CH6/EX6.4/Ex6_4.sce | 53 |
1 files changed, 53 insertions, 0 deletions
diff --git a/3731/CH6/EX6.4/Ex6_4.sce b/3731/CH6/EX6.4/Ex6_4.sce new file mode 100644 index 000000000..7ec27cbb1 --- /dev/null +++ b/3731/CH6/EX6.4/Ex6_4.sce @@ -0,0 +1,53 @@ +//Chapter 6:Induction Motor Drives +//Example 4 +clc; + +//Variable Initialization + +//Ratings of the motor are same as that in Ex-6.3 +f=50 // frequency in HZ +Vl=400 //line voltage in V +P=6 // number of poles + +//Parameters referred to the stator +Xr_=2 // rotor winding reactance in ohm +Xs=Xr_ // stator winding reactance in ohm +Rr_=1 // resistance of the rotor windings in ohm +Rs=Rr_ // resistance of the stator windings in ohm +N=950 //full load speed in rpm +SR=2.3 //stator to rotor turns ratio + +//Solution +Ns=120*f/P //synchronous speed in rpm +Wms=2*%pi*Ns/60 +s=(Ns-N)/Ns //full load slip +x=sqrt((Rs+Rr_/s)**2+(Xs+Xr_)**2) +Irf_=(Vl/sqrt(3))/x //full load current +Tf=(1/Wms)*3*Irf_**2*Rr_/s //full load torque + +//(i)initial braking current and torque +S=2-s //during plugging at 950rpm +y=sqrt((Rs+Rr_/S)**2+(Xs+Xr_)**2) +Ir_=(Vl/sqrt(3))/y //initial braking current +ratio1=Ir_/Irf_ +T=(1/Wms)*3*Ir_**2*Rr_/S //initial braking torque +ratio2=T/Tf + +//(ii)when an external resistance is connected such +//that maximum braking current is 1.5 times the full load current +Ir_=1.5*Irf_ +x=(Vl/sqrt(3))/Ir_ //x=sqrt((Rs+(Rr_+Re_)/S)**2+(Xs+Xr_)**2) +y=x**2 //y=(Rs+(Rr_+Re_)/S)**2+(Xs+Xr_)**2 +z=y-(Xs+Xr_)**2 //z=(Rs+(Rr_+Re_)/S)**2 +a=sqrt(z) //a=(Rs+(Rr_+Re_)/S) +b=(a-Rs)*S //b=(Rr_+Re_) +Re_=b-Rs +Re=Re_/SR**2 +T=(1/Wms)*3*Ir_**2*(Rr_+Re_)/S //initial braking torque +ratio=T/Tf + + +//Results +mprintf("(i)Ratio of initial braking current to full load current is:%.1f",ratio1) +mprintf("\nRatio of initial braking torque to full load torque is:%.2f\n",ratio2) +mprintf("\n(ii)Ratio of initial braking torque to full load torque when the resistance is added is:%.3f",ratio) |