Top 150+ Solved DC Generators MCQ Questions Answer
Q. Laminations of core are generally made of
a. case iron
b. carbon
c. silicon steel
d. stainless steel
Q. Which of the following could be lamina-proximately the thickness of laminations of a D.C.machine ?
a. 0.005 mm
b. 0.05 mm
c. 0.5 m
d. 5 m
Q. The armature of D.C. generator is laminated to
a. reduce the bulk
b. provide the bulk
c. insulate the core
d. reduce eddy current loss
Q. The resistance of armature winding depends on
a. length of conductor
b. cross-sectional area of the conductor
c. number of conductors
d. all of the above
Q. The commutator segments are connected to the armature conductors by means of
a. copper lugs
b. resistance wires
c. insulation pads
d. brazing
Q. In a commutator
a. copper is harder than mica
b. mica and copper are equally hard
c. mica is harder than copper
d. none of the above
Q. In D.C. generators the pole shoes are fastened to the pole core by
a. rivets
b. counter sunk screws
c. brazing
d. welding
Q. Satisfactory commutation of D.C. machines requires
a. brushes should be of proper grade and size
b. brushes should smoothly run in the holders
c. smooth, concentric commutator properly undercut
d. all of the above
Q. Fleming's right-hand rule regarding direction of induced e.m.f., correlates
a. magnetic flux, direction of current flow and resultant force
b. magnetic flux, direction of motion and the direction of e.m.f. induced
c. magnetic field strength, induced voltage and current
d. magnetic flux, direction of force and direction of motion of conductor
Q. While applying Fleming's right-hand rule to And the direction of induced e.m.f., thethumb points towards
a. direction of induced e.m.f.
b. direction of flux
c. direction of motion of the conductor if forefinger points in the direction of generated e.m.f.
d. direction of motion of conductor, if forefinger points along the lines of flux
Q. The bearings used to support the rotor shafts are generally
a. ball bearings
b. bush bearings
c. magnetic bearmgs
d. needle bearings
Q. In D.C. generators, the cause of rapid brush wear may be
a. severe sparking
b. rough commutator surface
c. imperfect contact
d. any of the above
Q. In lap winding, the number of brushes is always
a. double the number of poles
b. same as the number of poles
c. half the number of poles
d. two
Q. For a D.C. generator when the number of poles and the number of armature conductorsis fixed, then which winding will give the higher e.m.f. ?
a. Lap winding
b. Wave winding
c. Either of (a) and (b) above
d. Depends on other features of design