Test your knowledge of AC and DC machines with this online MCQ quiz by MCQTrip. See how well you understand the basics of AC and DC machines and challenge yourself to get the highest score. Twenty (20) MCQ questions from our test bank will be randomly shown for every attempt. Passing mark for this test is 70%.

Objectives: To provide an online quiz that tests the user’s knowledge of AC and DC machines.

Welcome to your DC Machines MCQ practice assessment.

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Laminated yoke in dc motor can reduce

iron loss.

temperature rise.

sparking on load.

speed regulation

None

Armature of a dc machine is made of

insulating material.

conducting material

non-ferrous material

silicon steel

None

The number of parallel paths for a 4-pole duplex lap winding will be

None

For a 4-pole machine wave winding is impossible with — armature conductors

None

The commutator pitch for simplex wave winding is equal to

half average pitch

twice average pitch

average pitch

+1 or -1

None

Wave winding is composed of

that even number which is exactly multiple of poles

any odd number of conductors

any even number of conductors

that even number which is exact multiple of poles +or- 2

None

A homopolar generator usually has

low voltage and high current

low voltage and low current

high voltage and low current

high voltage and high current

None

The developed electromagnetic force and/or torqe in electromechanical energy conversion system act in a direction that tends

to decrease the stored energy at constant flux.

to decrease the coenergy at constant mmf.

to increase the stored energy at constant flux

to decrease the stored energy at constant mmf

None

Which of the following are the variable losses in a rotating machine?

core loss and stray load loss.

copper loss and stray load loss.

copper and mechanical losses

core loss and mechanical loss

None

In a dc machine armature windind,the number of commutator segments is equal to the number of armature

coils

turns

conductors

coils sides

None

In electromechanical energy conversion devices(e.g. generators and motors),a small air gap is left between the stator and the rotor ignored to

avoid saturation of field

permit mechanical clearance

reduce the reluctance of the magnetic path.

increase fiux density in the air gap.

None

Wave winding is employed in a dc machine of

high current & low voltage rating

low current & high voltage rating.

high current & high voltage rating

low current & low voltage reting

None

In a dc motor the windage loss is proportional to

square of the flux density.

supply voltage

square of the armature speed.

square of the supply voltage

None

In a dc generator,the ripples in the direct emf generated are reduced by employing

equalizer rings

graphite brushes

commutator with large number of segments

carbon brushes

None

The field coils of a dc generator are usually made of

mica.

copper.

carbon

cast iron

None

A rotating electrical machine having its self inductance of both the stator and the rotor winding, independent of rotor position will definitely not developed

starting torque.

reluctance torque.

hysteresis torque.

synchronizing torque.

None

Width of a carbon brush should be equal to

the width of 2 to 3 commutator segment

the width of more than 3 commutator segments

the width of 1to 2 commutator segment

less than the width of one commutator segment

None

The teeth in the armature of a dc machine are something skewed.This is done to reduce

vibrations.

copper loss.

eddy current loss.

hysteresis loss.

None

Reluctance torque in rotating machines is present,when

reluctance seen by the working mmf varies.

air gap is not uniform.

reluctance seen by stator mmf varies.

reluctance seen by rotor mmf varies.

None

Which of the following is not a part of dc machine?

damping winding.

commutator.

field winding.

armature.

None

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AC and DC Machines

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