Top 250+ Solved Control of Electric Drives MCQ Questions Answer
Q. Which electromagnet is preferred for noiseless operation
a. DC operated
b. AC operated
c. Any of the above.
d. all
Q. For high frequency choppers the device that is preferred is
a. Thyristor
b. TRIAC
c. Transistor
d. GTO.
Q. The number of operations per hour in case of class IV contactor will be around
a. 100
b. 600
c. 900
d. 1200.
Q. In case of contactors, the duty in which the main contacts remain closed for a period bearing a definition relation to the no-load periods, is known as
a. Standard duty
b. Intermittent duty
c. Temporary duty
d. Un-interrupted duty.
Q. In case of contactors the ratio of the in service period to the entire period, expressed as a percentage is known as
a. duty
b. load factor
c. class of contact
d. none of the above.
Q. A class I contactor should be mechanically sound to withstand
a. 0.05 million times
b. 0.25 million times
c. 1.2 million times
d. 5.0 million times.
Q. Which of the following pair is used for frequency converters ?
a. Squirrel cage induction motor and synchronous motor
b. Wound rotor induction motor and synchronous motor
c. Wound rotor induction motor and squirrel cage induction motor
d. Any of the above.
Q. Belted wound rotor induction motors are preferred for
a. machine tools
b. gyratory crushers
c. belt conveyor
d. water pumps.
Q. The cooling time constant is usually
a. equal to the heating time constant
b. more than heating time constant
c. none of these.
d. all
Q. A motor of less than full load power rating can be used if the load is
a. continuous duty
b. short time duty
c. intermittent periodic duty
d. none of these.
Q. Pole changing method of speed control is used in
a. slip ring induction motor
b. dc shunt motor
c. dc series motor
d. squirrel cage induction motor.
Q. To save the energy during braking
a. dynamic braking is used
b. plugging is used
c. regenerative braking is used
d. mechanical braking is use
Q. To get speed higher than the base speed of the dc shunt motor
a. armature resistance control is used
b. field resistance control is used
c. armature voltage control is used
d. none of these.
Q. Rotor resistance speed control is used in
a. squirrel cage induction motor
b. synchronous motor
c. slip ring induction motor
d. dc shunt motor.
Q. Effect of friction torque is more pronounced
a. when the drive is running on full speed
b. when the drive is being started
c. when the drive is being stopped
d. when the drive at half of its normal spee