A. graphite
B. paper
C. mica
D. insulating varnish
Related Mcqs:
- The commutator segments are connected to the armature conductors by means of___________?
A. copper lugs
B. resistance wires
C. insulation pads
D. brazing - In case of D.C. machine winding, number of commutator segments is equal to______________?
A. number of armature coils
B. number of armature coil sides
C. number of armature conductors
D. number of armature turns - The material for commutator brushes is generally_______________?
A. mica
B. copper
C. cast iron
D. carbon - In D.C. generators, the brushes on commutator remain in contact with conductors which_________________?
A. lie under south pole
B. lie under north pole
C. lie under interpolar region
D. are farthest from the poles - To avoid formation of grooves in the commutator of a D.C. machine?
A. the brushes of opposite polarity should track each other
B. the brushes of same polarity should track each other
C. brush position has no effect on the commutator grooving
D. None - The number of brushes in a commutator depends on______________?
A. speed of armature
B. type of winding
C. voltage
D. amount of current to be collected - For both lap and wave windings, there are as many commutator bars as the number of_____________?
A. slots
B. armature conductors
C. winding elements
D. poles - The field coils of D.C. generator are usually made of_____________?
A. mica
B. copper
C. cast iron
D. carbon - The following constitute short-circuit in the armature winding.
A. Insulation failure between two commutator bars
B. Insulation failure between two turns of a coil
C. Two of more turns of the same coil getting grounded
D. All of the above - D.C. generator generally preferred for charging automobile batteries is______________?
A. series generator
B. shunt generator
C. long shunt compound generator
D. any of’the above
