Top 250+ Solved Electrical and Electronics Engineering MCQ Questions Answer
Q. Under running condition, the rotor reactance is proportional to
a. induced emf
b. rotor current
c. slip
d. supply voltage
Q. Under running condition , the rotor resistance is proportional to
a. induced emf
b. rotor current
c. slip
d. none of these
Q. Power factor of rotor of three phase induction motor depends on
a. rotor resistance
b. speed of rotor
c. rotor reactance
d. all of these
Q. The function of starter is
a. to start the motor
b. to start and stop the motor
c. to limit the starting current
d. to limit the applied the voltage
Q. When three phase induction motor is started with star-delta starter, during starting stator is connected
a. in star
b. in delta
c. in star or delta
d. none of these
Q. When three phase induction motor is started with star-delta starter, during normal running condition, stator is connected
a. in star
b. in delta
c. in star or delta
d. none of these
Q. The torque developed by three phase induction motor is approximately proportional to
a. square of applied voltage
b. applied voltage
c. half of applied voltage
d. double of appled voltage
Q. The rotor of an induction motor can't run at synchronous speed, if it did so then
a. rotor emf would be zero
b. rotor current would be zero
c. rotor torque would be zero
d. all of these
Q. A 3-phase , 50 Hz , 4-pole squirrel cage induction motor has its stator rewound for 6 poles without any alternations in the rotor. The motor would now run at a speed
a. less than 1000 rpm
b. less than 1500 rpm
c. less than 3000 rpm
d. zero rpm
Q. If the input voltage and the frequency of supply is halved, to the 3-phase induction motor
a. the maximum torque is halved
b. the maximum torque remains the same
c. the air-gap flux is halved
d. none of these
Q. The speed of the slip ring induction motor can be easily controlled by
a. changing supply frequency
b. changing number of poles
c. changing the resistance of the rotor winding
d. all of these
Q. A 440V, 20HP, 3phase motor operates at full load, 88% efficiency and 0.65 power factor lagging, the current drawn by motor is
a. 59.28a
b. 0.0458a
c. 34.22 a
d. 26.50a
Q. Thermal relays are used in DOL starter of Three Phase I.M. to
a. protect the motor from high temperature
b. protect the motor from overloading
c. protect the motor from short circuit
d. none of the above