DC Machines MCQ

Test your knowledge with important DC Machines MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30+ more DC Machines MCQs on Bissoy. Bissoy App

• In current commutation, in chopper circuit we use _____________
  ক

  2 auxiliary thyristors

  খ

  2 diodes

  গ

  1 auxiliary thyristor

  ঘ

  2 auxiliary thyristors and 2 diodes
• In voltage commutation, in chopper circuit we use _____________
  ক

  2 auxiliary thyristors

  খ

  2 diodes

  গ

  1 auxiliary thyristor

  ঘ

  Many diodes
• Which of the following is not the method of auxiliary commutation?
  ক

  Voltage commutation

  খ

  Resistance commutation

  গ

  Current commutation

  ঘ

  Load commutation
• What is the formula for step up chopper?
  ক

  V(1-α)

  খ

  V/(1-α)

  গ

  αV

  ঘ

  v/α
• How output voltage of chopper can be varied?
  ক

  By using constant frequency system

  খ

  By using variable frequency system

  গ

  By using constant and variable frequency systems

  ঘ

  By using constant or variable frequency systems
• The average value of chopper output waveform is given by _____________
  ক

  αV

  খ

  V/α

  গ

  α2V

  ঘ

  V/α2
• Which of the following correctly suits with chopper?
  ক

  Thyristor in series with load

  খ

  Thyristor in parallel with load

  গ

  Thyristor switch in series with load

  ঘ

  Thyristor switch in parallel with load
• Which of the following statement is not true regarding to DC chopper?
  ক

  Cheap

  খ

  Fast response

  গ

  Regeneration

  ঘ

  AC to DC control
• Which of the following method is employed when regenerative braking is necessary?
  ক

  DC chopper

  খ

  Variable resistor

  গ

  Inverter rectifier

  ঘ

  Motor-generator
• Which of the following method is adopted for controlling a DC motor?
  ক

  Resistance control

  খ

  Motor-generator set

  গ

  Inverter Rectifier

  ঘ

  DC chopper
• Three phase converters are employed for _______________
  ক

  Large kW motors

  খ

  Small kW motors

  গ

  In all motors

  ঘ

  Never used
• Which converter/s can be used for DC series motor control?
  ক

  Semi-converters

  খ

  Half-wave converter

  গ

  Full-converter

  ঘ

  Semi converters and full converter
• Dual converter operates in _________________
  ক

  1

  খ

  2

  গ

  3

  ঘ

  4
• Full-converter can be used in DC motor for regenerative braking in ______________
  ক

  Constant operation

  খ

  Variable operation

  গ

  Inversion operation

  ঘ

  Opposite operation
• How many thyristors are required for full converter?
  ক

  1

  খ

  2

  গ

  3

  ঘ

  4
• How many quadrants does full-converter work?
  ক

  One

  খ

  Half

  গ

  Two

  ঘ

  Can be any
• Which of the following is the effect of non-uniform armature current?
  ক

  Ratio of peak to average and rms to average armature current decreases

  খ

  Ratio of peak to average and rms to average armature current increases

  গ

  Ratio of peak to average increases and rms to average armature current decreases

  ঘ

  Ratio of peak to average decreases and rms to average armature current increases
• When armature current becomes discontinuous?
  ক

  Small firing angles

  খ

  Large firing angles

  গ

  Infinite firing angle

  ঘ

  Does not depend on firing angle
• How many thyristors does we need in semi-converter?
  ক

  1

  খ

  2

  গ

  3

  ঘ

  Many
• can’t be used when regeneration is required.
  ক

  True

  খ

  False
• How many thyristors does we need in half wave converter?
  ক

  1

  খ

  2

  গ

  3

  ঘ

  Many
• Half wave converters are used for controlling DC motor of ________________
  ক

  Below 400 W

  খ

  400 W – 4000W

  গ

  More than 4000W

  ঘ

  Anywhere
• BLDC can be used instead ____________
  ক

  Synchronous motor

  খ

  Normal brushed DC motor

  গ

  Induction motor

  ঘ

  Air motor
• Typical brushless motor doesn’t have ______________
  ক

  Commutator

  খ

  Permanent magnet

  গ

  Electronic controller

  ঘ

  Fixed armature
• Construction of BLDC is exactly similar to the ______________
  ক

  Conventional DC motor

  খ

  Induction motor

  গ

  Permanent magnet synchronous motor

  ঘ

  Totally different construction
• In medical fields which DC motor is widely used?
  ক

  PMDC

  খ

  BLDC

  গ

  Brushed DC motor

  ঘ

  Cannot be determined
• In BLDC motor driver module, we do not require ______________
  ক

  SCRs

  খ

  Power transistors

  গ

  FETs

  ঘ

  Transistors
• Which of the following is not an advantage of BLDC motor over conventional DC motor.
  ক

  Less maintenance

  খ

  Long life

  গ

  No risk of explosion or possibility of RF radiation

  ঘ

  Low cost
• By electronic circuitry BLDC can be controlled for both constant and variable torque operation.
  ক

  True

  খ

  False
• In BLDC motor field winding is kept on _______________
  ক

  Stator

  খ

  Rotor

  গ

  Can be placed anywhere

  ঘ

  Absent