A 460-V, four-pole, 75-hp, 60-Hz, Y connected, three phase induction motor develops its full load induced torque at 1.2 percent slip when operating at 60 Hz and 460 V. The per phase circuit model impedances of the motor are,
R1 = 0.058ohms Xm = 18ohms
X1 = 0.32 ohms X2 = 0.386 ohms
Mechanical, core and stray losses can be neglected in this problem.
a. Find value for rotor resistance R2 (there will be two values for R2. Choose the larger one).
b. Find Tmax, Smax and rotor at maximum torque for this motor.
c. Find the starting torque of this motor.
For the motor in the question above, write a MATLAB code to plot the motor's torque vs speed curve for the two values of R2. Explain why the larger value should be selected.