D.C. Generators MCQ Questions & Answers

91

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

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Answer & Solution

Answer: Option C

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92

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

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Answer & Solution

Answer: Option A

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93

The main factor which leads to unstable parallel operation of flat and over compounded generators is

A) their rising voltage characteristics B) unequal number of turns in their series field windings C) unequal speed regulation of their primemovers D) unequal series field resistances

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Answer & Solution

Answer: Option A

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94

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

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Answer & Solution

Answer: Option D

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95

For a D.C. machines laboratory following type of D.C. supply will be suitable

A) Rotary converter B) Mercury are rectifier C) Induction motor D.C. generator set D) Synchronous motor D.C. generator set

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Answer & Solution

Answer: Option C

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96

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

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Answer & Solution

Answer: Option C

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97

When two D.C. generators are running in parallel an equalizer bar is used

A) To increase the series flux B) To increase the generated e.m.f. C) To reduce the combined effect of armature reaction of both the machines D) So that the two identical machines will pass approximately equal currents to the load

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Answer & Solution

Answer: Option D

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98

The armature core of a D.C. generator is usually made of

A) Silicon steel B) Copper C) Nonferrous material D) Cast-iron

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Answer & Solution

Answer: Option A

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99

In a D.C. generator the ripples in the direct e.m.f. generated are reduced by

A) Using conductor of annealed copper B) Using commutator with large number of segments C) Using carbon brushes of superior quality D) Using equalizer rings

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Answer & Solution

Answer: Option C

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100

Magnetic field in a D.C. generator is produced by

A) Electromagnets B) Permanent magnets C) Both (A) and (B) D) None of the above

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Answer & Solution

Answer: Option C

Solution:

In a D.C. generator, the magnetic field is essential for the generation of electricity through electromagnetic induction.

Most commonly, this magnetic field is produced by electromagnets which are created by field windings supplied with direct current.

However, in small D.C. generators or specific applications, permanent magnets can also be used to produce the magnetic field.

Therefore, depending on the type and size of the generator, both electromagnets and permanent magnets may be used.

Hence, the correct answer is Option C: Both (A) and (B)

D.C. Generators MCQ Questions & Answers | Electrical Engineering