A 15 hp, 209 V, three-phase, six-pole, Y-connected induction motor has the following parameter values per phase:
The motor slip at full load is 3%, and the efficiency is 90%.
a. Calculate the starting current. (Ignore the magnetizing current.)
b. Determine the starting torque.
c. Determine the maximum torque.
d. Calculate the value of the resistance that should be added to the rotor circuit
to reduce the starting current by 50%.
e. What is the starting torque in part (d)?
f. Calculate the value of the resistance that should be added to the rotor circuit
to increase the starting torque to maximum.
g. What is the starting current in part (f)?
a. Starting current (ignoring the Io)
For an equivalent Y-connected motor, the phase and line currents are the same,
thus the starting line current is also 224.39 A
b. Starting torque
Keep in mind that large slip approximation cannot be used due to the large
resistive values of the motor.
c. Maximum Torque:
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