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MCQs

Dc Motors

Total Questions : 240 | Page 24 of 24 pages
Question 231. The power mentioned on the name plate of an electric motor indicates
  1.    The gross power
  2.    The output power available at the shaft
  3.    The power drawn in kW
  4.    The power drawn in kVA
 Discuss Question
Answer: Option B. -> The output power available at the shaft
Question 232. If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
  1.    Of lower H.P. should be selected
  2.    Can be used for 50°C ambient temperature also
  3.    Of higher H.P. should be selected
  4.    Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor
 Discuss Question
Answer: Option D. -> Is to be de-rated by a factor recommended by manufacturer and select the next higher H.P. motor
Question 233. D.C. generators are normally designed for maximum efficiency around
  1.    All of these
  2.    Full load
  3.    Rated r.p.m.
  4.    Rated voltage
 Discuss Question
Answer: Option B. -> Full load
Question 234. In D.C. motor which of the following can sustain the maximum temperature rise?
  1.    Field winding
  2.    Slip rings
  3.    Commutator
  4.    Armature winding
 Discuss Question
Answer: Option A. -> Field winding
Question 235. In variable speed motor
  1.    Same commutating field is needed at low speed than at high speed
  2.    A stronger commutating field is needed at low speed than at high speed
  3.    A weaker commutating field is needed at low speed than at high speed
  4.    None of these
 Discuss Question
Answer: Option C. -> A weaker commutating field is needed at low speed than at high speed
Question 236. For a D.C. shunt motor if the excitation is changed
  1.    Torque and power both will change
  2.    Torque will remain constant
  3.    Torque will change but power will remain constant
  4.    Torque, power and speed, all will change
 Discuss Question
Answer: Option C. -> Torque will change but power will remain constant
Question 237. If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
  1.    Dynamic braking
  2.    None of these
  3.    Plugging
  4.    Regenerative
 Discuss Question
Answer: Option C. -> Plugging
Question 238. Which method of braking is generally used in elevators?
  1.    Rheostat braking
  2.    Regenerative braking
  3.    None of these
  4.    Plugging
 Discuss Question
Answer: Option D. -> Plugging
Question 239. If a D.C. motor is to be selected for conveyors, which rriotor would be preferred ?
  1.    Series motor
  2.    Differentially compound motor
  3.    Cumulative compound motor
  4.    Shunt motor
 Discuss Question
Answer: Option A. -> Series motor
Question 240. Which of the following motor is preferred for operation in highly explosive atmosphere?
  1.    Air motor
  2.    Shunt motor
  3.    Series motor
  4.    Battery operated motor
 Discuss Question
Answer: Option A. -> Air motor

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