A 473 V (line-line), 60 Hz, 3 phase, wye connected, 4 pole induction motor is running at rated voltage, speed, and current. The actual machine speed is 1733 rpm. The stator resistance and leakage reactance can be neglected. When the motor runs at no load, with no core losses, the speed is approximately 1800 rpm with a stator line current of 8 A. The rotor resistance referred to the stator R'r is 0.7 Ohm, and the rotor leakage reactance referred to the stator X'ir is 1.6 Ohm. (a) What is the frequency of the rotor currents at this operating point?
(b) What is the rated line current?
(c) What is the starting line current if started at full voltage?
(d) What is the rated torque?