A three-phase synchronous motor rated at 1.2 MW with a power factor of 0.87 leading and an efficiency of 90% is connected to an 11 kV supply. The synchronous reactance of the motor is 1.5 Q2/phase. Calculate the per-unit reactance of the motor to its own base.

A three-phase induction motor is supplied from a 50 Hz supply and runs at 1200 rev/min when the slip is 4%. Determine the synchronous speed.

T-a. The direction of rotation of a single-phase split-phase motor can be change by........ a) reversing the connection of the start winding b) reversing the connection of the run winding c) reversing the connection of the start and run winding at the same time d) "a" or "b", not "c" T-b. Single-phase split-phase motors using an electrolytic capacitor in the start winding circuit should not be cycled more than about__________ time per hour. a) 8 b) 12 c) 24 d) none of the above T-c. When replacing the capacitor in a capacitor-start induction-run motor, one must be sure to replace the bad capacitor with__________ . a) a smaller one b) one of the same size c) a larger one d) none of the above

A three-phase induction motor operates at a slip of 3% and has a rotor copper loss of 300W. The rotational loss is 1500W. Determine (a) the airgap power and (b) the power output.