A. Graphite brushes
B. Carbon brushes
C. Metal graphite brushes
D. None of the above
Related Mcqs:
- 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 - A sinusoidal voltage of 5 Hz is applied to the field of a shunt generator. The armature voltage wave will_____________?
A. will be zero
B. will be of 5 Hz
C. will be of 5 xiVHz
D. will be of v Hz 5 - The terminal voltage of a series generator is 150 V when the load current is 5 A. If the load current is increased to 10 A, the terminal voltage will be____________?
A. 150 V
B. less than 150 V
C. greater than 150 V
D. none of the above - Which of the following generator will have negligible terminal voltage while running on no-load?
A. Series generator
B. Shunt generator
C. Compound generator
D. Separately excited generator - The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except:_____________?
A. armature reaction
B. armature resistance drop
C. field weakening due to armature reaction and armature
D. commutation - Which of the following generating machine will offer constant voltage on all loads?
A. Self-excited generator
B. Separately excited generator
C. Level compounded generator
D. All of the above - Following energized winding of a D.C. machine should not be opened as it would produce high inductive voltage which may be dangerous to personnel and may cause its own insulation failure.
A. Series field
B. Compensating field
C. Inter pole field
D. Shunt field - A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be_____________?
A. zero
B. about 2 V
C. about 50 V
D. 220 V - Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be_____________________?
A. 270 V
B. 267.5 V
C. 265 V
D. 257.4 V - The open circuit voltage of a compound generator is 250 V. At full load the terminal voltage____________?
A. will be less than 250 V
B. will always be 250 V
C. may be greater or less than 250 V
D. none of the above