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

None

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

to decrease the coenergy at constant mmf.

to decrease the stored energy at constant flux.

to increase the stored energy at constant flux

to decrease the stored energy at constant mmf

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

reduce the reluctance of the magnetic path.

permit mechanical clearance

increase fiux density in the air gap.

avoid saturation of field

None

For a linear electromagnetic circuit,the following statement is true

coenergy is zero.

field energy is lesser than the coenergy

field energy is equal to the coenergy

field energy is greater than the coenergy

None

The commutator of a dc motor serves the purpose of

reducing friction

avoiding arc at the brushes

converting dc into ac.

changing ac to dc

None

The commutator pitch for simplex lap winding is

+1 or -1

average pitch

-1

None

Armature of a dc machine is made of

non-ferrous material

silicon steel

conducting material

insulating material.

None

Laminated yoke in dc motor can reduce

temperature rise.

speed regulation

iron loss.

sparking on load.

None

Minimum number of coils for 400v,6-poles lap connected dc machine for a maximum voltage of 15v between adjacent commutator segments should be

400

299

160

None

The field coils of a dc generator are usually made of

carbon

cast iron

mica.

copper.

None

In a dc motor the windage loss is proportional to

square of the flux density.

square of the armature speed.

square of the supply voltage

supply voltage

None

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

damping winding.

commutator.

armature.

field winding.

None

Wave winding is employed in a dc machine of

low current & low voltage reting

low current & high voltage rating.

high current & low voltage rating

high current & high voltage rating

None

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

copper loss and stray load loss.

core loss and mechanical loss

core loss and stray load loss.

copper and mechanical losses

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

reluctance torque.

starting torque.

hysteresis torque.

synchronizing torque.

None

Wave winding is composed of

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

any even number of conductors

any odd number of conductors

that even number which is exactly multiple of poles

None

The commutator pitch for simplex wave winding is equal to

+1 or -1

half average pitch

twice average pitch

average pitch

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

Width of a carbon brush should be equal to

the width of more than 3 commutator segments

the width of 2 to 3 commutator segment

less than the width of one commutator segment

the width of 1to 2 commutator segment

None

A homopolar generator usually has

high voltage and high current

low voltage and high current

low voltage and low current

high voltage and low current

None

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AC and DC Machines

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