• Electrical Engineering Reference

# 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

Question 2

How many methods to obtain Sparkless commutation?

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

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

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

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

Question 6

The insulating material used between the commutator segments is normally _______

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

Question 7

If Time taken > Tc, then known as?

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

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

Question 9

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

A. TRUE
B. FALSE
C. Can be true or false
D. Can not say