ELECTRICIAN IN ENGLISH Quiz - 834


In D.C. machines the residual magnetism is of the order of
  
    2 to 3 per cent
    50 to 75 per cent
    20 to 25 per cent
    10 to 15 per cent

2 to 3 per cent

In a D.C. shunt motor under the conditions of maximum power the current in the armature will be
  
    more than full-load current
    rated full-load current
    almost negligible
    less than full-load current

more than full-load current

In case-the conditions for maximum power for a D.C. motor are established the efficiency of the motor will be
  
    anywhere between 75% and 90%
    less than 50%
    1
    around 90%

less than 50%

In D.C. motor which of the following can sustain the maximum temperature rise?
  

    Field winding
    Slip rings
    Commutator
    Armature winding

Field winding

The speed of a D.C. series motor is
  
    proportional to field current
    proportional to the square of the armature current
    proportional to the armature current
    inversely proportional to the armature current

inversely proportional to the armature current

By looking at which part of the motor it can be easily confirmed that a particular motor is D.C. motor?
  
    Frame
    Shaft
    Commutator
    Stator

Commutator

Which of the following load normally needs starting torque more than the rated torque?
  
    Conveyors
    Centrifugal pumps
    Air compressors
    Blowers

Conveyors

The starting resistance of a D.C. motor is generally
  
    low
    1000 Q
    around 500 Q
    infinitely large

low

In a D.C. series motor if the armature current is reduced by 50% the torque of the motor will be e toqual
  
    10% of the previous value
    25% of the previous value
    100% of the previous value
    50% of the previous value

25% of the previous value

The current drawn by the armature of D.C. motor is directly proportional to
  
    the torque required
    the speed of the motor
    the voltage across the terminals
    none of the above

the torque required


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