Rotor EMF, Current and Power MCQ

Test your knowledge with important Rotor EMF, Current and Power MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30+ more Rotor EMF, Current and Power MCQs on Bissoy. Bissoy App

• For a constant load torque, the supply voltage of a squirrel cage induction motor is reduced by a factor of 0.5, its rotor current is modified by a factor is?
  ক

  2

  খ

  0.5

  গ

  4

  ঘ

  0.25
• If a 400 V, 50 hz star connected, 3-phase squirrel cage induction motor is operated from 400V and 75 Hz supply. The torque that the motor can now provide while drawing rated current from the supply will _________
  ক

  reduce

  খ

  increase

  গ

  remains same

  ঘ

  increases or reduces based on the rotor resistance.
• A three phase induction motor is connected to 400V, 50 hz supply. If the stator to rotor turn ratio is 2, the standstill rotor induced voltage per phase is?
  ক

  115.5 V

  খ

  231 V

  গ

  346 V

  ঘ

  200 V
• In a three phase induction motor, voltage between the slip rings at standstill is 50 V. At full load the slip is 0.04. The voltage between slip rings at full load is?
  ক

  2V

  খ

  50V

  গ

  20V

  ঘ

  5V
• A 3-phase induction motor is operating at slip ‘s’. If the slip is reversed, its slip at the instant will be _________
  ক

  2-s

  খ

  zero

  গ

  2+s

  ঘ

  1-s
• In an induction motor slip will be negative when the _________
  ক

  rotor rotates at speed more than synchronous speed and in the direction of the rotation of stator field

  খ

  stator magnetic field and rotor rotate in opposite direction

  গ

  rotor rotates at speed less than synchronous speed and in the opposite direction of the rotation of stator field

  ঘ

  rotor rotates at speed more than synchronous speed and in the opposite direction of the rotation of stator field
• The mmf produced by the current of the three phase induction motor _________
  ক

  is standstill with respect to stator mmf

  খ

  rotates at the speed of rotor in air gap

  গ

  rotates at slip speed with respect to stator mmf

  ঘ

  rotates at synchronous speed with respect to rotor
• the three phase supply is fed to the rotor and it is running at its normal operating conditions. Then the synchronous speed can be defined as speed at which?
  ক

  stator magnetic field rotates

  খ

  rotor magnetic field rotates

  গ

  rotor rotates

  ঘ

  flux is set up in the rotor
• If the three phase supply is fed to the stator and it is running at its normal operating conditions. Then the synchronous speed can be defined as speed at which?
  ক

  stator magnetic field rotates

  খ

  rotor magnetic field rotates

  গ

  rotor rotates

  ঘ

  flux is set up in the rotor
• The voltage actually used to set up the working flux in the three phase induction motor is _________
  ক

  equal to applied voltage

  খ

  less than applied voltage

  গ

  more than applied voltage

  ঘ

  equal to rotor induced emf.
• The rotor of the induction motor must never run at synchronous speed because then the relative speed between the rotating flux and rotor will be _________
  ক

  zero and hence torque will be zero

  খ

  zero, and torque will be maximum

  গ

  maximum and hence, torque will be zero

  ঘ

  maximum, and torque will also be zero
• Two of the supply terminals to a three phase induction motor gets interchanges while regular scheduling work. When the machine is switched on, then it will _________
  ক

  rotate in opposite direction

  খ

  rotate in same direction

  গ

  not start

  ঘ

  get heated and winding will burn
• In an induction motor, when the number of stator slots is equal to an integral multiple of rotor slots?
  ক

  machine will fail to start

  খ

  machine will get heated

  গ

  high starting torque will be achieved

  ঘ

  discontinuity in torque slip characteristic
• Rotor leakage reactance for a three phase slip ring induction motor with slip ‘s’ is?
  ক

  s(x2)

  খ

  (x2)/s

  গ

  x2

  ঘ

  (x2)(s2)