Questions and Answers on DC Generators - Set 02 - ObjectiveBooks

Questions and Answers on DC Generators - Set 02

Practice Test: Question Set - 02

1. In a D.C. machine stray loss is the sum of
    (A) Total copper loss and mechanical loss
    (B) Armature copper loss and iron loss
    (C) Shunt field copper loss and mechanical loss
    (D) Iron loss and mechanical loss

2. 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

3. In a separately excited generator supplying rated load the armature reaction:
    (A) Is always present
    (B) Is always absent
    (C) May be sometimes present
    (D) None of the above

4. When two D.C. series generators are running in parallel, an equalizer bar is used
    (A) To increase the speed and hence generated e.m.f.
    (B) To increase the series flux
    (C) So that two similar machines will pass approximately equal currents to the load
    (D) To reduce the combined effect of armature reaction of both machines

5. A D.C. generator works on the principle of
    (A) Lenz's law
    (B) Ohm's law
    (C) Faraday's law of electromagnetic induction
    (D) None of the above

6. 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

7. In a D.C. generator the critical resistance can be increased by
    (A) Increasing its field resistance
    (B) Decreasing its field resistance
    (C) Increasing its speed
    (D) Decreasing its speed

8. 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

9. 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

10. A D.C. welding generator has
    (A) Lap winding
    (B) Wave moving
    (C) Duplex winding
    (D) Any of the above

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