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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