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Practice Test: Question Set - 06

1. 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) All of the above

2. In a level compounded D.C. generator, full load terminal voltage is
    (A) Negligibly low
    (B) Equal to no-load terminal voltage
    (C) More than no-load terminal voltage
    (D) Less than no-load terminal voltage

3. Two generators are running in parallel. One of the generators may run as motor for which of the following reasons?
    (A) The direction of that generator is reversed
    (B) The speed of that generator is increased
    (C) The field of that generator is weakened
    (D) That generator takes large share of loads

4. The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is
    (A) 2
    (B) 4
    (C) 6
    (D) 8

5. 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

6. For a D.C. generator when the number of poles and the number of armature conductors is 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

7. If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be
    (A) Demagnetization only
    (B) Cross magnetization as well as magnetization
    (C) Cross-magnetization as well as demagnetizing
    (D) Cross magnetization only

8. In the case of lap winding resultant pitch is
    (A) Multiplication of front and back pitches
    (B) Division of front pitch by back pitch
    (C) Sum of front and back pitches
    (D) Difference of front and back pitches

9. Two generators A and B have 6 poles each. Generator A has wave wound armature while generator B has lap wound armature. The ratio of the induced e.m.f. is generator A and B will be
    (A) 2 : 3
    (B) 3 : 1
    (C) 3 : 2
    (D) 1 : 3

10. 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
    (A) Interpoles
    (B) Dummy coils
    (C) Compensating winding
    (D) Shifting of axis of brushes

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