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Commutation - DC Machines MCQs

Commutation MCQs : This section focuses on the "Commutation" in DC Machines. These Multiple Choice Questions (MCQs) should be practiced to improve the DC Machines skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

___________ the change that takes place in a winding element during the period of a short circuit by a brush.

A. Excitation
B. Commutation
C. Generator
D. Motors

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Question 2

How many methods to obtain Sparkless commutation?

A. 1
B. 2
C. 3
D. 4

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Question 3

The time required to change the current through a coil from Ic to -Ic is called?

A. Commutation Period
B. Commutation Time
C. Commutation Set
D. Commutation Count

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Question 4

Commutation is delayed due to __________

A. Leakage reactance
B. Effect of armature reaction
C. Because of other factors
D. Leakage reactance and armature reaction

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Question 5

For a DC machine, in a commutator ________

A. Copper is harder than mica
B. Mica and copper are equally hard
C. Mica is harder than copper
D. Cannot be determined

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Question 6

The insulating material used between the commutator segments is normally _______

A. Graphite
B. Mica
C. Paper
D. Air gap

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Question 7

If Time taken > Tc, then known as?

A. under commutation
B. delayed commutation
C. Both A and B
D. accelerated commutation

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Question 8

Which are the methods for getting an ideal commutation?

A. Resistance commutation
B. Voltage commutation
C. Current commutation
D. Both A and B

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Question 9

If Time taken < Tc , then over or accelerated commutation.

C. Can be true or false
D. Can not say

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Question 10

If the current reversal is completed by the end of commutation period, it is called ideal commutation.

A. Yes
B. No
C. Can be yes or no
D. Can not say

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