A420 vll, 60 hz, 3-phase, y-connected, 4 pole induction motor is running at rated voltage and current. the rotor speed is 1720 rpm. the stator resistance and leakage reactance may be neglected. when the motor runs at no load, the speed is approximately 1800 rpm and the stator line current (magnitude) is 5 amps. the rotor resistance referred to the stator (rr) is 0.8 ohms. the rotor leakage reactance referred to the stator (xir) is 2.0 ohms.
(a) what is the frequency of the rotor current at this operating point (1720 rpm)?
(b) what is the rated line current magnitude?
(c) what is the starting line current magnitude if started at full rated voltage?
(d) what is the rated torque?
(e) what is the maximum possible torque this motor can deliver?
(f) what is the rotor speed (in rpm) at which this maximum torque occurs?