# Power Electronic Controlled Drives 6

Electrical Engineering MCQ Question Papers: Campus Placement

Subject: Power Electronic Controlled Drives 6

Part 6: List for questions and answers of Power Electronic Controlled Drives

Q1. The earth wire should not be thinner than a

a) 20 swg wire

b) 16 swg wire

c) 10 swg wire

d) 8 swg wire

Q2. In automobiles the sound is produced by horn due to

a) Magnetostriction

b) Vibrating diaphragm

c) Moving coil

d) Oscillating coil

Q3. The current drawn by a 6 v horn is roughly

a. a

b) 1a

c) a

d) 20 a

Q4. The hours are rated for

a) Continuous operation

b) Intermittent operation

c) Both (a) and (b) above

d) None of the above

Q5. Continuous operation of automobile horn will

a) Help in charging the battery

b) Improve mileage

c) Damage the operating coil

d) Change the tone

Q6. In a constant power type load

a) Torque is proportional to speed

b) Torque is proportional to square of speed

c) Torque is inversely proportional to speed

d) Torque is independent of speed

Q7. According to fan laws

a) v1/v2 = (d1/d2) * (rpm1/rpm2)

b) v1/v2 = (d1/d2)^2 * (rpm1/rpm2)

c) v1/v2 = (d1/d2)^3 * (rpm1/rpm2)

d) v1/v2 = (d1/d2)^3 * (rpm1/rpm2)

Q8.According to fan laws when p is the power d is the diameter. N is the rpm and d is the density, then

a) p1/p2 = (d1/d2)^2 * (n1/n2)^3 * (d1/d2)

b) p1/p2 = (d1/d2)^3 * (n1/n2)^2 * (d1/d2)

c) p1/p2 = (d1/d2)^4 * (n1/n2)^3 * (d1/d2)

d) p1/p2 = (d1/d2)^5 * (n1/n2)^3 * (d1/d2)

Q9. 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

Q10. Belted wound rotor induction motors are preferred for

a) Machine tools

b) Gyratory crushers

c) Belt conveyor

d) Water pumps

Q11. The cooling time constant is usually

a) Equal to the heating time constant

b) Equal to the heating time variable

c) More than heating time constant

d) None of these

Q12.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

Q13. 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

Q14.To save the energy during braking

a) Dynamic braking is used

b) Plugging is used

c) Regenerative braking is used

d) Mechanical braking is used

Q15. 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

Q16. Rotor resistance speed control is used in

a) Squirrel cage induction motor

b) Synchronous motor

c) Slip ring induction motor

d) Dc shunt motor

Q17. 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 speed

Q18. The equilibrium speed of a motor load system is obtained

a) When motor torque equals the load torque

b) When motor torque is less than the load torque

c) When motor torque is more than the load torque

d) None of the these

Q19. Most commonly used ac motor is

a) Synchronous motor

b) Slip ring induction motor

c) Squirrel cage induction motor

d) Ac commutator induction motor

Q20. The motor commonly used in computers and digital systems is

a) Dc shunt motor

b) Induction motor

c) Stepper motor

d) Synchronous motor

Part 6: List for questions and answers of Power Electronic Controlled Drives