D.C. Generators MCQ

Test your knowledge with important D.C. Generators MCQ and their applications. These MCQs are beneficial for competitive exams too. Explore 30 + more D.C. Generators MCQs at Bissoy

• Number of tapings for each equalizer ring is equal to
  ক

  Number of pole pairs

  খ

  Number of poles

  গ

  Number of parallel paths

  ঘ

  Number of commutator segments
• In a D.C. machine stray loss is the sum of
  ক

  Total copper loss and mechanical loss

  খ

  Armature copper loss and iron loss

  গ

  Shunt field copper loss and mechanical loss

  ঘ

  Iron loss and mechanical loss
• The voltage drop for which of the following types of brush can be expected to be least?
  ক

  Graphite brushes

  খ

  Carbon brushes

  গ

  Metal graphite brushes

  ঘ

  None of the above
• In a four-pole D.C. machine
  ক

  All the four poles are north poles

  খ

  Alternate poles are north and south

  গ

  All the four poles are south poles

  ঘ

  Two north poles follow two south poles
• In D.C. generators, current to the external circuit from armature is given through
  ক

  Commutator

  খ

  Solid connection

  গ

  Slip rings

  ঘ

  None of above
• The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is
  ক

  2

  খ

  4

  গ

  6

  ঘ

  8
• Inter-pole flux should be sufficient to
  ক

  Neutralize the commutating self induced e.m.f.

  খ

  Neutralize the armature reaction flux

  গ

  Neutralize both the armature reaction flux as well as commutating e.m.f. induced in the coil

  ঘ

  Perform none of the above functions
• In D.C. generators the polarity of the interpoles
  ক

  Is the same as that of the main pole ahead

  খ

  Is the same as that of the immediately preceding pole

  গ

  Is opposite to that of the main pole ahead

  ঘ

  Is neutral as these poles do not play part in generating e.m.f.
• An exciter for a turbo generator is a
  ক

  Separately excited generator

  খ

  Shunt generator

  গ

  Series generator

  ঘ

  Compound generator
• As a result of armature reaction, the reduction in the total mutual air gap flux in a D.C. generator is approximately
  ক

  40 percent

  খ

  25 percent

  গ

  10 percent

  ঘ

  5 percent
• In a D.C. generator the critical resistance refers to the resistance of
  ক

  Brushes

  খ

  Field

  গ

  Armature

  ঘ

  Load
• While applying Fleming's right-hand rule to and the direction of induced e.m.f., the thumb points towards
  ক

  Direction of induced e.m.f.

  খ

  Direction of flux

  গ

  Direction of motion of the conductor if forefinger points in the direction of generated e.m.f.

  ঘ

  Direction of motion of conductor, if forefinger points along the lines of flux
• The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage
  ক

  Will be less than 250 V

  খ

  Will always be 250 V

  গ

  May be greater or less than 250 V

  ঘ

  None of the above
• In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralized by all of the following except
  ক

  Interpoles

  খ

  Dummy coils

  গ

  Compensating winding

  ঘ

  Shifting of axis of brushes
• If residual magnetism is present in a D.C. generator, the induced e.m.f. at zero speed will be
  ক

  Zero

  খ

  Small

  গ

  The same as rated voltage

  ঘ

  High
• Magnetic field in a D.C. generator is produced by
  ক

  Electromagnets

  খ

  Permanent magnets

  গ

  Both (A) and (B)

  ঘ

  None of the above
• In a D.C. generator the ripples in the direct e.m.f. generated are reduced by
  ক

  Using conductor of annealed copper

  খ

  Using commutator with large number of segments

  গ

  Using carbon brushes of superior quality

  ঘ

  Using equalizer rings
• The armature core of a D.C. generator is usually made of
  ক

  Silicon steel

  খ

  Copper

  গ

  Nonferrous material

  ঘ

  Cast-iron
• When two D.C. generators are running in parallel an equalizer bar is used
  ক

  To increase the series flux

  খ

  To increase the generated e.m.f.

  গ

  To reduce the combined effect of armature reaction of both the machines

  ঘ

  So that the two identical machines will pass approximately equal currents to the load
• When two D.C. series generators are running in parallel, an equalizer bar is used
  ক

  To increase the speed and hence generated e.m.f.

  খ

  To increase the series flux

  গ

  So that two similar machines will pass approximately equal currents to the load

  ঘ

  To reduce the combined effect of armature reaction of both machines
• For a D.C. machines laboratory following type of D.C. supply will be suitable
  ক

  Rotary converter

  খ

  Mercury are rectifier

  গ

  Induction motor D.generator set

  ঘ

  Synchronous motor D.C. generator set
• The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except
  ক

  Armature reaction

  খ

  Armature resistance drop

  গ

  Field weakening due to armature reaction and armature

  ঘ

  Commutation
• The main factor which leads to unstable parallel operation of flat and over compounded generators is
  ক

  their rising voltage characteristics

  খ

  unequal number of turns in their series field windings

  গ

  unequal speed regulation of their primemovers

  ঘ

  unequal series field resistances
• To avoid formation of grooves in the commutator of a D.C. machine
  ক

  The brushes of opposite polarity should track each other

  খ

  The brushes of same polarity should track each other

  গ

  Brush position has no effect on the commutator grooving

  ঘ

  All of the above
• D.C. generator generally preferred for charging automobile batteries is
  ক

  Series generator

  খ

  Shunt generator

  গ

  Long shunt compound generator

  ঘ

  Any of the above
• The number of brushes in a commutator depends on
  ক

  Speed of armature

  খ

  Type of winding

  গ

  Voltage

  ঘ

  Amount of current to be collected
• Which of the following generating machine will offer constant voltage on all loads?
  ক

  Self-excited generator

  খ

  Separately excited generator

  গ

  Level compounded generator

  ঘ

  All of the above
• In lap winding, the number of brushes is always
  ক

  Double the number of poles

  খ

  Same as the number of poles

  গ

  Half the number of poles

  ঘ

  Two
• Open circuited armature coil of a D.C. machine is
  ক

  Identified by the scarring of the commutator segment to which open circuited coil is connected

  খ

  Indicated by a spark completely around the commutator

  গ

  Both (A) and (B)

  ঘ

  None of the above
• Which of the following components of a D.C, generator plays vital role for providing direct current of a D.C. generator?
  ক

  Dummy coils

  খ

  Commutator

  গ

  Eye bolt

  ঘ

  Equalizer rings