logo
  • Home
  • Rank
  • Tests
  • About
  • Training
  • Programming
  • CS
  • IT
  • IS
  • ECE
  • EEE
  • EE
  • Civil
  • Mechanical
  • Chemical
  • Metallurgy
  • Instrumentation
  • Aeronautical
  • Aerospace
  • Biotechnology
  • Agriculture
  • MCA
  • BCA
  • Internship
  • Contact

Electrical Machines Multiple Choice Questions | MCQs | Quiz

Electrical Machines Interview Questions and Answers
Practice Electrical Machines questions and answers for interviews, campus placements, online tests, aptitude tests, quizzes and competitive exams.

Get Started

•   Energy Principles
•   Singly Magnetic System
•   Reluctance Motor
•   Doubly Magnetic System
•   Synchronous Machines
•   Singly Electric Systems
•   Torque Equations
•   Rotating Machines Terms
•   Rotating Magnetic Field-1
•   Rotating Magnetic Field-2
•   Rotating EM - 1
•   Rotating EM - 2
•   Rotating EM - 3
•   Generated Emfs
•   Losses and Efficiency-1
•   Losses and Efficiency-2
•   Machine Ratings
•   Cooling(Loss Dissipation)
•   Machine Applications
•   Commutator Action
•   Armature Generation
•   DC Machines Torque
•   DC Machines Circuits
•   Excitation Methods
•   MMF & Flux Waveforms
•   Compensation Winding
•   DC Machines Testing
•   DC Machine Applications
•   Generator Characteristics
•   Rotating Amplifiers
•   Motors Characteristics
•   DC Motors Basics
•   DC Motors Speed Control
•   DC Motors Magnet
•   EMF Polygon - 1
•   EMF Polygon - 2
•   Non-Salient Machines
•   Distributed Windings
•   Synchronous Machines
•   Flux & MMF Phasors
•   Synchronous Operation
•   Synchronous Controls
•   Salient Pole Machines
•   Characteristics
•   Xd & Xq Measurement
•   Applications
•   Cylindrical Rotor
•   Voltage Regulation
•   Alternator Characteristics
•   Motors Phasor Diagram
•   Motor Power Factor
•   Motors Basics
•   Inductive Impedance - 1
•   Inductive Impedance - 2
•   Efficiency
•   Losses & Efficiency
•   Power & Torque
•   Synchronous Stability
•   Damper Winding
•   Induction Motor
•   Operation Principles
•   MMF Phasors & Waves
•   Rotor Frequency
•   EMF, Current & Power
•   Induction Motor Phasor
•   Equivalent Circuit
•   Circuit Analysis
•   Motor Characteristics
•   Circuit Parameters
•   Three Phase Motor
•   Induction Generator
•   Polyphase Induction
•   Induction Diagrams
•   Polyphase Motors - 1
•   Polyphase Motors - 2
•   Armature Windings
•   Transformer Construction
•   Ideal Two Winding
•   Phasor Diagrams
•   Transformer Circuit
•   Open & Short Circuit Test
•   Voltage Regulation
•   Transformer Efficiency
•   Single Phase
•   Magnetically Coupled
•   Three Phase Transformer
•   Autotransformers

« Prev Page
Next Page »

Electrical Machines Questions and Answers – Action of Commutator

Posted on May 19, 2017 by Manish

This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Action of commutator”.

1. Commutator is a
a) rotating segment to which brushes are attached
b) stationary segment to which rotating brushes are attached
c) rotating segment to which rotating brush segment is attached
d) any of the mentioned
View Answer

Answer: a
Explanation: Commutator is a rotating segment to which brushes are attached.
advertisement

2. Commutator action is analogous to _________ in analog electronics.
a) full wave rectifier
b) half wave rectifier
c) comparator
d) amplifier
View Answer

Answer: a
Explanation: Commutator converts the alternating voltage induced at the armature to the unidirectional voltage at the slip rings.

3. Inductive kick is
a) reactance voltage in commutator segments
b) reactance voltage in shorted commutator segments
c) impulsive voltage in commutator segments
d) none of the mentioned
View Answer

Answer: a
Explanation: Inductive kick is the name given to the reactance voltage which occurs at the commutation taking place in the commutator.It occurs due to the high circulating current during the commutation.

4. Inductive kick causes
a) sparking at the brushes of the machine
b) similar problems when neutral phase shift takes place in the armature
c) large current to flow in the equalizer rings
d) none of the mentioned
View Answer

Answer: a
Explanation: Inductive kick is the name given to the reactance voltage which occurs at the commutation taking place in the commutator.It occurs due to the high circulating current during the commutation.

5. Operation of a dc machine will
a) not be affected by commutating poles
b) be affected by commutating poles
c) be affected significantly upto 30% spread of commutating poles
d) none of the mentioned
View Answer

Answer: a
Explanation: Commutating poles are placed under the armature poles and it compensates only poles under these regions.
advertisement

6. A 200 V dc machine working at rated speed. Voltage across the commutating terminals should ideally be
a) zero
b) 2 V
c) 1 V
d) 200 V
View Answer

Answer: a
Explanation: The commutating poles undergoing commutation should have zero voltage across it so that there is no reactive voltage induced.
So it will not cause large circulating current in the winding.

7. For a four pole, 16 slot armature with two coil-side/slot having lap connected progressive winding has single turn coils. Then number of commutator segment is
a) 16
b) 32
c) 4
d) 8
View Answer

Answer: a
Explanation: Commmutator segment is equal to number of coil slots.

8. For a four pole, 16 slot armature with two coil-side/slot having wave connected progressive winding has single turn coils. The commutator pitch for the machine should be
a) 1
b) -1
c) +1 and 1
d) none of the mentioned
View Answer

Answer: a
Explanation: Commutator pitch for the wave connected progressive winding should be 1.

9. The brushes in dc machine are normally placed electrically in interpolar region, to
a) make an angle of 90 deg. electrical
b) make an angle of 90 deg. mechanical
c) make an angle of 0 deg. electrical
d) none of the mentioned
View Answer

Answer: a
Explanation: To obtain proper commutation without any sparks, the magnetic neutral axis and geometrical neutral axis should be aligned to each other,such that coils undergoing commutation experience zero emf across them.

10. The armature rotation in the dc machine and the magnetic field are independent of each other and obey laws of conservation of energy.
a) True
b) False
View Answer

Answer: a
Explanation: The armature rotation does not affect the stored magnetic energy at the steady state of operation.
advertisement

11. Under commutation results
a) sparking at the trailing edge of brush
b) sparking at the leading edge of brush
c) sparking at the middle of brush
d) any of the mentioned
View Answer

Answer: a
Explanation: Under commutation takes place when the commutation speed is slow and it takes more time than critical defined time for commutation. Because of this the trailing edge of the brush still remains under the commutation.

12. While the operation of dc motor, there are sparkings at the commutation observed. These can be happening due to
a) under commutation
b) over commutation
c) too rapid reversal of the current
d) any of the mentioned
View Answer

Answer: d
Explanation: The over commutation, over commutation or rapid reversal of the current, any of these reasons can lead to sparking at the brushes.

Sanfoundry Global Education & Learning Series – Electrical Machines.
To practice all areas of Electrical Machines, here is complete set of 1000+ Multiple Choice Questions and Answers.

« Prev Page - Electrical Machines Questions and Answers – Machine Applications
» Next Page - Electrical Machines Questions and Answers – EMF Generated in the Armature

« Pulp & Paper Questions and Answers – Solid Wood Measurement
Pulp & Paper Questions and Answers – Wood Chip Measurement »
advertisement

Deep Dive @ Sanfoundry:

  1. Electric Circuits Questions and Answers
  2. Power Electronics Questions and Answers
  3. Electrical & Electronics Engineering Questions and Answers
  4. Electrical Engineering Questions and Answers
  5. Theory of Machines Questions and Answers
  6. Electrical Measurements Questions and Answers
  7. Basic Electrical Engineering Questions and Answers
  8. Electrical Engineering Questions and Answers
  9. DC Machines Questions and Answers
  10. Electrical Machines Questions and Answers
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer and SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage & Cluster Administration, Advanced C Programming, SAN Storage Technologies, SCSI Internals and Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him below:
LinkedIn | Facebook | Twitter | Google+

Best Careers

Developer Tracks
SAN Developer
Linux Kernel Developer
Linux Driver Developer
Linux Network Developer

Live Training Photos
Mentoring
Software Productivity
GDB Assignment
Sanfoundry is No. 1 choice for Deep Hands-ON Trainings in SAN, Linux & C, Kernel Programming. Our Founder has trained employees of almost all Top Companies in India such as VMware, Citrix, Oracle, Motorola, Ericsson, Aricent, HP, Intuit, Microsoft, Cisco, SAP Labs, Siemens, Symantec, Redhat, Chelsio, Cavium, ST-Micro, Samsung, LG-Soft, Wipro, TCS, HCL, IBM, Accenture, HSBC, Mphasis, Tata-Elxsi, Tata VSNL, Mindtree, Cognizant and Startups.

Best Trainings

SAN I - Technology
SAN II - Admin
Linux Fundamentals
Advanced C Training
Linux-C Debugging
System Programming
Network Programming
Linux Threads
Kernel Programming
Kernel Debugging
Linux Device Drivers

Best Reference Books

Computer Science Books
Algorithm & Programming Books
Electronics Engineering Books
Electrical Engineering Books
Chemical Engineering Books
Civil Engineering Books
Mechanical Engineering Books
Industrial Engineering Books
Instrumentation Engg Books
Metallurgical Engineering Books
All Stream Best Books

Questions and Answers

1000 C Questions & Answers
1000 C++ Questions & Answers
1000 C# Questions & Answers
1000 Java Questions & Answers
1000 Linux Questions & Answers
1000 Python Questions
1000 PHP Questions & Answers
1000 Hadoop Questions
Cloud Computing Questions
Computer Science Questions
All Stream Questions & Answers

India Internships

Computer Science Internships
Instrumentation Internships
Electronics Internships
Electrical Internships
Mechanical Internships
Industrial Internships
Systems Internships
Chemical Internships
Civil Internships
IT Internships
All Stream Internships

About Sanfoundry

About Us
Copyright
Terms
Privacy Policy
Jobs
Bangalore Training
Online Training
Developers Track
Mentoring Sessions
Contact Us
Sitemap
© 2011 Sanfoundry. All Rights Reserved.