Explore topic-wise MCQs in Design Electrical Machines.

This section includes 20 Mcqs, each offering curated multiple-choice questions to sharpen your Design Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.

The design of commutator and the brushes of DC machines are interconnected.

A. true
B. false
Answer» B. false
Discussion
2.

What should be the range for the width of the commutator in a good design?

A. < 4 mm
B. > 4 mm
C. 3-4 mm
D. < 3 mm
Answer» C. 3-4 mm
Discussion
3.

The diameter of the commutator should be 0.2-0.4 times the main diameter for a good design.

A. true
B. false
Answer» C.
Discussion
4.

What is the formula for finding out the width of the commutator of the DC machines?

A. width of the commutator = 3.14*(Diameter of the commutator)
B. width of the commutator = 3.14*(Diameter of the commutator)*(Number of armature coils)
C. width of the commutator = 3.14*(Diameter of the commutator) / (Number of armature coils)
D. width of the commutator = Number of armature coils / 3.14*(Diameter of the commutator)
Answer» D. width of the commutator = Number of armature coils / 3.14*(Diameter of the commutator)
Discussion
5.

What factor does the diameter of the commutator depend on?

A. length of the commutator
B. speed of the commutator
C. peripheral speed of the commutator
D. opening of the commutator
Answer» D. opening of the commutator
Discussion
6.

WHAT_IS_THE_FORMULA_FOR_FINDING_OUT_THE_WIDTH_OF_THE_COMMUTATOR_OF_THE_DC_MACHINES??$

A. width of the commutator = 3.14*(Diameter of the commutator)
B. width of the commutator = 3.14*(Diameter of the commutator)*(Number of armature coils)
C. width of the commutator = 3.14*(Diameter of the commutator) / (Number of armature coils)
D. width of the commutator = Number of armature coils / 3.14*(Diameter of the commutator)
Answer» D. width of the commutator = Number of armature coils / 3.14*(Diameter of the commutator)
Discussion
7.

What should be the range for the width of the commutator in a good design?$

A. < 4 mm
B. > 4 mm
C. 3-4 mm
D. < 3 mm
Answer» C. 3-4 mm
Discussion
8.

The_diameter_of_the_commutator_should_be_0.2-0.4_times_the_main_diameter_for_a_good_design?$

A. true
B. false
Answer» C.
Discussion
9.

What is the formula for total commutator loss for DC machine?

A. brush contact loss + brush friction loss
B. brush contact loss – brush friction loss
C. brush contact loss * brush friction loss
D. brush contact loss / brush friction loss
Answer» B. brush contact loss ‚Äö√Ñ√∂‚àö√ë‚àö¬® brush friction loss
Discussion
10.

What is the formula for brush contact loss of DC machines?

A. brush contact loss = armature current + brush contact voltage
B. brush contact loss = armature current – brush contact voltage
C. brush contact loss = armature current * brush contact voltage
D. brush contact loss = (armature current + brush contact voltage) / 2
Answer» D. brush contact loss = (armature current + brush contact voltage) / 2
Discussion
11.

What is the formula for calculation of brush current of DC machine for wave winding?

A. brush Current = 2*(Armature Current) / P
B. brush Current = (Armature Current) / P
C. brush Current = Armature Current
D. brush Current = P/2*(Armature Current)
Answer» D. brush Current = P/2*(Armature Current)
Discussion
12.

The_design_of_commutator_and_the_brushes_of_DC_machines_are_interconnected?

A. true
B. false
Answer» B. false
Discussion
13.

What is the other name for commutator segment pitch of DC machines?

A. width of the commutator
B. length of the commutator
C. breadth of the commutator
D. height of the commutator
Answer» B. length of the commutator
Discussion
14.

For a DC machine, given Diameter of the commutator= 0.48 m, Speed = 600 rpm. What is the voltage across the commutator?

A. 15 V
B. 15.5 V
C. 15.2 V
D. 15.1 V
Answer» E.
Discussion
15.

What factor does the diameter of the commutator depends on?

A. length of the commutator
B. speed of the commutator
C. peripheral speed of the commutator
D. opening of the commutator
Answer» D. opening of the commutator
Discussion
16.

What is the total number of design steps for the brushes in DC machines?

A. 4
B. 3
C. 5
D. 6
Answer» D. 6
Discussion
17.

What is the total number of design steps available for the commutators in DC machines?

A. 4
B. 3
C. 2
D. 5
Answer» B. 3
Discussion
18.

Which material is commonly used in brushes?

A. copper
B. carbon
C. silicon
D. steel
Answer» C. silicon
Discussion
19.

What is the use of brushes in DC machines?

A. to connect the parts of the machine to the external circuit
B. to conduct current between moving parts
C. to conduct current between stationary wires and moving parts
D. used for smooth conduction of current
Answer» D. used for smooth conduction of current
Discussion
20.

What is a commutator in DC machines?

A. electrical device which reverses the current direction between the rotor and external circuit
B. mechanical device which reverses the current direction between the rotor and external circuit
C. electrical device which allows the current flow between the rotor and external circuit
D. mechanical device which allows the current flow between the rotor and external circuit
Answer» B. mechanical device which reverses the current direction between the rotor and external circuit
Discussion