Polyphase Induction Motors

A. rotor current
B. rotor power factor
C. rotor e.m.f.
D. shaft diameter

A. Air motor
B. Induction motor
C. D.C. shunt motor
D. Synchronous motor

A. graphite
B. grease
C. mineral oil
D. molasses

A. efficiency
B. power factor
C. frequency
D. output

A. leakage reactance
B. power factor on short circuit
C. short-circuit current under rated voltage
D. all of the above

A. noload test
B. blocked rotor test
C. stator resistance test
D. all of the above

A. to reduce the magnetic hum and locking tendency of the rotor
B. to increase the tensile strength of the rotor bars
C. to ensure easy fabrication
D. none of the above

A. at the unit value of slip
B. at the zero value of slip
C. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
D. at the value of the slip which makes the rotor reactance half of the rotor

A. The slip of the motor will be 5%
B. The rotor will not run
C. The rotor will run at very high speed
D. The torque produced will be very large

A. external inductance to the rotor
B. external resistance to the rotor
C. external capacitance to the rotor
D. both resistance and inductance to rotor