22523 Industrial AC Machines Mcqs for MSBTE Online Exams With Answer & MSBTE Solution
22523 Industrial AC Machines Mcqs for Electrical Engineering PDF
Welcome Diploma and degree students to mypractically. Get Industrial AC Machines Mcqs For Electrical Engineering Students PDF.
This important and major post is helpful and beneficial for MSBTE Electrical Engineering Diploma and Degree Students.
In this article you will get MSBTE Electrical Engineering 22523 Industrial AC Machines Mcqs Pdf.
By getting this IAM Industrial AC Machine Mcqs, you will easily get more marks for MSBTE Exams.
In this post we have added MSBTE unit wise and chapter wise Industrial AC Machines Mcqs for Electrical Engineering MCQs Pdf, so if you like it make sure you will share with your MSBTE diploma & degree Students
{tocify} $title={Table of Contents}
Industrial AC Machine Question Bank for Multiple Choice Questions
01 – THREE PHASE INDUCTION MOTOR Marks:-20
Content of Chapter:-
1.1 Working principle: production of RMF, Synchronous speed, rotor speed and slip.
1.2 Constructional details of 3-Ph induction motor: Squirrel cage induction motor and Slip ring induction motor
1.3 Rotor quantities: frequency, induced emf, Power factor at starting and running condition.
1.4 Characteristics of torque versus slip (speed), Torques: Starting, full load and maximum with relations
among them.
1.5 Induction motor as a generalized transformer with phasor diagram
1.6 Four quadrant operation, Power flow diagram
1.7 Starters: need and types; Stator resistance, auto transformer, star delta, rotor resistance and soft starter
1.8 Speed control methods: stator voltage, Pole changing, rotor resistance and VVVF
1.9 Motor selection for different applications as per the load torque-speed requirements
1.10Maintenance of three phase induction motors
1. The frame of induction motor is usually made of
(A) Cast Iron
(B) Bronze
(C) Silicon Steel
(D) Aluminum
Answer: - Option A
2. In an induction motor, no-load the slip is generally
(A) Less than 1%
(B) 5 %
(C) 4 %
(D) 2 %
Answer: - Option A
3. The shaft of induction motor is made up of
(A) Stainless steel
(B) Carbon steel
(C) Cast Iron
(D) Aluminum
Answer: - Option B
4. Brushes of an slip ring induction motor is usually made up of
(A) Aluminium
(B) Carbon
(C) Phosphorus Bronze
(D) Cast Iron
Answer: - Option B
5. A 3-phase 440 V, 50 Hz induction motor has 8% slip. The frequency of rotor current will be
(A) 50 Hz
(B) 25 Hz
(C) 4 Hz
(D) 2 Hz
Answer: - Option C
6. The starting torque of an induction motor is maximum when rotor resistance per phase is
…………… rotor reactance/phase.
(A) Equal to
(B) Inductance only More than
(C) Less than
(D) None of the above
Answer: - Option A
7. For higher efficiency of 3-phase induction motor, the slip should be
(A) Unity
(B) Large
(C) As small as possible
(D) Very large
Answer:-Option C
8. The shaft of an induction motor must be of
(A) Hollow
(B) Solid
(C) Flexible
(D) None of the above
Answer: - Option A
9. Which of the following component is usually fabricated out of silicon steel?
(A) Shaft
(B) Bearings
(C) Stator core
(D) None of the above
Answer: Option C
10. The efficiency of an induction motor is about
(A) 100 %
(B) 80-90 %
(C) 50 %
(D) 25 %
Answer: - Option B
11. Slip rings of an induction motor is usually made up of
(A) Aluminium
(B) Copper
(C) Phosphor Bronze
(D) Steel
Answer: - Option C
12. The crawling in the induction motor is caused by
(A) High Load
(B) Low Voltage supply
(C) Harmonic developed in the motor
(D) Improper design of machine
Answer: - Option C
13. An induction Motor is
(A) Self-starting with high torque
(B) Self-starting with zero torque
(C) Self-starting with low torque
(D) Not self-starting
Answer: - Option C
14. If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed,
the phenomenon will be termed as
(A) Humming
(B) Hunting
(C) Cogging
(D) Crawling
Answer: - Option D
15. Which of the following motor has high starting torque?
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option A
16. Rotor resistance speed control method is not applicable in
(A) Slip Ring induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: Option B
17. If the terminal voltage of an induction motor is decreased then current
(A) Decreased
(B) Increased
(C) Remain same
(D) None of the above
Answer: - Option A
18. As compared to DOL starting method the star delta starting method should have
(A) High torque
(B) Low starting current
(C) High starting current
(D) Smooth acceleration
Answer: - Option B
19. In a three-phase induction motor, the number of poles in the rotor winding is always
(A) Equal to the number of poles in the stator
(B) More than the number of poles in the stator
(C) Less than the number of poles in the stator
(D) Zero
Answer: - Option A
20. At standstill condition the value of slip is
(A) 0
(B) Infinity
(C) One
(D) two
Answer: - Option C
21. An induction motor is analogous to
(A) Auto-transformer
(B) Two windings transformer with secondary short circuited
(C) Two windings transformer with secondary open circuited
(D) Synchronous motor
Answer: - Option B
22. No load test of 3-phase induction motor used to determine
(A) Variable loss
(B) Constant loss
(C) Eddy current loss only
(D) Hysteresis loss only
Answer: - Option B
23. Which of the following losses are negligible in blocked rotor test?
(A) Mechanical losses
(B) Iron losses
(C) Both 1 & 2
(D) None of the above
Answer: - Option C
24. In induction generator operation the slip is always
(A) Positive
(B) Negative
(C) Infinite
(D) Zero
Answer: - Option B
25. The value of power factor of an induction motor operating at no load is
(A) 0.9 lagging
(B) Unity
(C) 0.2 lead
(D) 0.2 lag
Answer: - Option D
26. If an induction machine is run at above the synchronous speed it acts as
(A) Synchronous Motor
(B) Synchronous Generator
(C) Induction Generator
(D) None of the above
Answer: - Option C
27. A small air gap in 3 phase induction motor helps to
(A) Reduce cogging effect
(B) Reduce Crawling effect
(C) Reduce Magnetizing effect
(D) All of the above
Answer: - Option C
28. Three phase induction motor works on
(A) A.C supply only
(B) D.C supply only
(C) A.C or D.C supply
(D) None of the above
Answer: - Option A
29. A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor current will be
(A) 50 Hz
(B) 25 Hz
(C) 5 Hz
(D) 2 Hz
Answer: - Option D
30. When Rotor speed is equal to synchronous speed then slip is
(A) 0
(B) Infinity
(C) One
(D) two
Answer: - Option A
31. When Rotor speed is equal to 0 then slip is
(A) 0
(B) Infinity
(C) Unity
(D) two
Answer: - Option C
32. Three phase induction motor works on the principle of
(A) Faradays law
(B) Flemings Rule
(C) Amperes law
(D) Lenz´s law
Answer: - Option A
33. The synchronous speed for a 4 pole 50 Hz induction motor is
(A) 3000 RPM
(B) 6000 RPM
(C) 1500 RPM
(D) 2000 RPM
Answer: - Option C
34. The per unit slip induction motor for a rotor frequency of 5 Hz and supply frequency 50 Hz is
(A) 0.1
(B) 0.5
(C) 0.2
(D) 1
Answer: - Option A
35. The synchronous speed for a 6 pole 50 Hz induction motor is
(A) 1000 RPM
(B) 6000 RPM
(C) 1500 RPM
(D) 2000 RPM
Answer: - Option A
36. The per unit slip induction motor for a rotor frequency of 4 Hz and supply frequency 50 Hz is
(A) 0.01
(B) 0.05
(C) 0.08
(D) 1
Answer: - Option C
37. The synchronous speed for a 12 pole 60 Hz induction motor is
(A) 3000 RPM
(B) 600 RPM
(C) 1500 RPM
(D) 2000 RPM
Answer: - Option B
38. The motor which is mostly preferred for Lifts is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option A
39. The motor which is mostly preferred for Cranes is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option A
40. The motor which is mostly preferred for Lathe Machines is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Synchronous Motors
(D) None of the above
Answer: - Option B
41. The motor which is mostly preferred for Printing Machines is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Synchronous Motors
(D) None of the above
Answer: - Option B
42. The motor which is mostly preferred for Drilling Machines is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Synchronous Motors
(D) None of the above
Answer: - Option B
43. The motor which is mostly preferred for Milling Machines is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Synchronous Motors
(D) None of the above
Answer: - Option B
44. The motor which is mostly preferred for Hoists is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option A
45. The motor which is mostly preferred for Crushers is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option A
46. Resistance of Earth connections of a three phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Yearly
Answer: - Option D
47. Induction motor will operate in plugging mode when slip is
(A) 0
(B) Infinity
(C) Greater than one
(D) Negative
Answer: - Option C
48. The motor which is mostly preferred for Blowers is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option B
49. The motor which is mostly preferred for Pumps is
(A) Slip ring Induction motor
(B) Squirrel cage induction motor
(C) Both 1 & 2
(D) None of the above
Answer: - Option B
50. Induction motor will operate in motoring mode when slip is
(A) Between 0 to 1
(B) Infinity
(C) Greater than one
(D) Negative
Answer: - Option C
02 – SINGLE PHASE INDUCTION MOTOR Marks:-14
Content of Chapter:-
2.1 Double field revolving theory, Principle of making these motors self-start.
2.2 Construction and working: Resistance start induction run, capacitor start capacitor run, shaded pole,
repulsion type series motor, universal motor, Hysteresis motor
2.3 Torque-speed characteristics for all of the above motors
2.4 Motor selection for different application as per the load torque-speed requirements
2.5 Maintenance of 1-Ph induction motor
1. Which of the following motor will have relatively higher power factor
(A) Capacitor start motor
(B) Shaded pole motor
(C) Capacitor run motor
(D) Split phase motor
Answer: - Option C
2. A centrifugal switch is used to disconnect ‘starting winding when the motor has
(A) Picked up 10% speed
(B) Picked up 20% speed
(C) Picked up 5 – 10% speed
(D) Picked up 50 – 75% speed
Answer: - Option D
3. The motor which is mostly preferred for household mixer is
(A) Repulsion Motor
(B) Reluctance Motor
(C) Hysteresis Motor
(D) Universal Motor
Answer: - Option D
4. A shaded pole motor does not possess
(A) Commutator
(B) Centrifugal switch
(C) Capacitor
(D) All of the above
Answer: - Option D
5. Which motor is normally free from mechanical and magnetic vibrations?
(A) Capacitance motor
(B) Hysteresis motor
(C) Reluctance motor
(D) Split phase motor
Answer: - Option B
6. The speed/load characteristics of a universal motor is same as that of
(A) D.C. series motor
(B) D.C. shunt motor
(C) A.C. motor
(D) None of the above
Answer: - Option A
7. The motor which is mostly preferred for timing devices is
(A) Repulsion Motor
(B) Shaded pole motor
(C) Hysteresis Motor
(D) Universal Motor
Answer: - Option C
8. The motor which is mostly preferred for compressors is
(A) Capacitor start Capacitor run motor
(B) Shaded pole motor
(C) Universal Motor
(D) Hysteresis Motor
Answer: - Option A
9. If a single-phase induction motor runs slower than normal, the most likely defect is
(A) Short circuit winding
(B) Open circuit winding
(C) Worn bearing
(D) All of the above
Answer: - Option C
10. The power factor of a single-phase induction motor is usually
(A) Always Lagging
(B) Always Leading
(C) Unity
(D) None of the above
Answer: - Option A
11. In a split-phase motor
(A) Both starting and running windings are connected through a centrifugal switch
(B) Centrifugal switch is used to control supply voltage
(C) The running winding is connected through a centrifugal switch
(D) The starting winding is connected through a centrifugal switch
Answer: - Option D
12. If the centrifugal switch does not open at 70 to 80 percent of the synchronous speed of the
motor, it can
(A) Damage to the starting winding
(B) Overloading of running winding
(C) Damage to the centrifugal switch
(D) None of the above
Answer: - Option A
13. In a capacitor start a single-phase motor, when the capacitor is replaced by a resistance
(A) Motor will consume less power
(B) Motor will continue to run in the same direction
(C) Motor may get burn
(D) None of the above
Answer: - Option C
14. If the capacitor of a single-phase motor is short-circuited
(A) The motor will not start
(B) The motor will run in the same direction at a reduced speed
(C) The motor will run in the reverse direction
(D) None of the above
Answer: - Option A
15. In a ceiling fan employing capacitor run motor
(A) Primary winding surrounds the secondary winding
(B) Secondary winding surrounds the primary winding
(C) Either 1 or 2
(D) None of the above
Answer: - Option B
16. In a split-phase motor the main winding is made up of
(A) Thick wire placed at the top of the slots
(B) Thick wire placed at the bottom of the slots
(C) Thin wire placed at the top of the slots
(D) Thin wire placed at the bottom of the slots
Answer: - Option B
17. The rotor of a hysteresis motor is made of
(A) Copper
(B) Cast iron
(C) Aluminium
(D) Chrome steel
Answer: - Option D
18. A hysteresis motor works on the principle of
(A) Eddy current loss
(B) Magnetization of rotor
(C) Hysteresis loss
(D) Electromagnetic induction
Answer: - Option B
19. The motor which is mostly preferred for Traction purposes is
(A) Universal Motor
(B) Hysteresis Motor
(C) A.C Series Motor
(D) Repulsion Motor
Answer: - Option C
20. In a two-value capacitor motor, the capacitor used for running purposes is
(A) Paper spaced oil-filled type
(B) Air capacitor
(C) Ceramic type
(D) None of the above
Answer: - Option A
21. The motor which is mostly preferred for tape recorders is
(A) Universal Motor
(B) Repulsion Motor
(C) Series Motor
(D) Hysteresis Motor
Answer: - Option D
22. Starting winding of a single-phase motor of a refrigerator is disconnected from the circuit by
means of
(A) Magnetic Relay
(B) Centrifugal switch
(C) Thermal Relay
(D) None of the above
Answer: - Option B
23. The direction of rotation of a hysteresis motor is determined by
(A) Retentivity of the rotor material
(B) Position of shaded Pole with respect to the main pole
(C) Interchanging the supply leads
(D) None of the above
Answer: - Option B
24. Capacitor-start single phase induction motor is switched on to supply with its capacitor
replaced by an inductor of equivalent reactance value then the
(A) Motor will not start
(B) Motor will Start and run
(C) Small KW motor can start but large KW motor will not start
(D) None of the above
Answer: - Option C
25. The motor which is mostly preferred for toys is
(A) Universal Motor
(B) Repulsion Motor
(C) Series Motor
(D) Shaded Pole Motor
Answer: - Option D
26. The motor which is mostly preferred for large commercial Refrigerators is
(A) Universal Motor
(B) Hysteresis Motor
(C) Series Motor
(D) Capacitor start Motor
Answer: - Option D
27. The motor which is mostly preferred for Washing Machines is
(A) Universal Motor
(B) Repulsion Motor
(C) Series Motor
(D) Resistance start induction run motor
Answer: - Option D
28. The motor which is mostly preferred for Ceiling fans is
(A) Universal Motor
(B) Hysteresis Motor
(C) Series Motor
(D) Permanent split capacitor motor
Answer: - Option D
29. The motor which is mostly preferred for film projectors is
(A) Universal Motor
(B) Repulsion Motor
(C) Series Motor
(D) Shaded pole motor
Answer: - Option D
30. The single phase motor which is mostly preferred for hoists is
(A) Universal Motor
(B) Repulsion Motor
(C) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option C
31. The single phase motor which is mostly preferred for Vacuum cleaners is
(A) Universal Motor
(B) Repulsion Motor
(C) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option A
32. The single phase motor which is mostly preferred for Oil burners is
(A) Universal Motor
(B) Resistance start induction run motor
(C) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option B
33. The single phase motor which is mostly preferred for Photo copying machines is
(A) Universal Motor
(B) Resistance start induction run motor
(C) Shaded Pole Motor
(D) Capacitor start capacitor run motor
Answer: - Option C
34. The single phase motor which is mostly preferred for Sewing machines is
(A) Universal Motor
(B) Repulsion Motor
(C) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option A
35. The single phase motor which is mostly preferred for Coffee grinders is
(A) Universal Motor
(B) Repulsion Motor
(B) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option A
36. The single phase motor which is mostly preferred for Electric shavers is
(A) Universal Motor
(B) Repulsion Motor
(C) A.C Series Motor
(D) Capacitor start capacitor run motor
Answer: - Option A
37. The motor which is mostly preferred for Teleprinters is
(A) Universal Motor
(B) Hysteresis Motor
(C) A.C Series Motor
(D) Permanent split capacitor motor
Answer: - Option B
38. The motor which is mostly preferred for Air conditioners is
(A) Universal Motor
(B) Hysteresis Motor
(C) A.C Series Motor
(D) Capacitor start motor
Answer: - Option D
39. The motor which is mostly preferred for gramophones is
(A) Universal Motor
(B) Shaded pole motor
(C) Repulsion Motor
(D) Capacitor start motor
Answer: - Option B
40. The motor which is mostly preferred for Advertising displays is
(A) Universal Motor
(B) Capacitor run motor
(C) Shaded pole motor
(D) Capacitor start motor
Answer: - Option C
41. Which of the following motor has relatively higher starting torque
(A) Capacitor run motor
(B) Resistance start induction run motor
(C) Shaded pole motor
(D) Capacitor start motor
Answer: - Option D
42. Which of the following motor has relatively poor starting torque
(A) Capacitor start motor
(B) Capacitor run motor
(C) Shaded pole motor
(D) Resistance start induction run motor
Answer: - Option C
43. Oil level in bearings of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Yearly
Answer: - Option B
44. Conductor of Insulation of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Yearly
Answer: - Option D
45. Capacitor and centrifugal switch of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Half – Yearly
Answer: - Option D
46. The direction of rotation of the universal motor can be reversed by reversing the flow of current
through
(A) Field winding
(B) Armature winding
(C) Either 1 or 2
(D) None of the above
Answer: - Option B
47. Starter switch and fuses of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Half – Yearly
Answer: - Option B
48. Oil in the sleeve bearings of a single phase induction motor must be replaced
(A) Daily
(B) Weekly
(C) Monthly
(D) Half – Yearly
Answer: - Option D
49. Air gap of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Yearly
Answer: - Option D
50. Loose connections of a single phase induction motor must be checked
(A) Daily
(B) Weekly
(C) Monthly
(D) Yearly
Answer: - Option B
03 – THREE PHASE ALTERNATORS Marks:-16
Content of Chapter:-
3.1 Principle of working moving and stationary armatures
3.2 Constructional details : Parts and their functions, rotor construction, Winding: single and double layer
3.3 E.M.F. equation of alternator with numerical considering short pitch factor and distribution factor
3.4 Alternator loading: factors affecting the terminal voltage of alternator, armature resistance and leakage
reactance drop.
3.5 Armature reaction at various power factors and synchronous impedance.
3.6 Voltage regulation: Direct loading and synchronous impedance method.
3.7 Maintenance of alternator.
1. The output frequency of an alternator depends on
(A) Type of winding
(B) Number of poles and Rotational speed
(C) Numbers of poles only
(D) Rotational speed only
Answer: - Option B
2. The power factor of an alternator depends on
(A) Speed of Motor
(B) Core losses
(C) Armature losses
(D) Type of load
Answer: - Option D
3. Which type of rotor is best for a turbo-alternator?
(A) Salient pole type
(B) Cylindrical rotor type
(C) Salient pole & cylindrical rotor
(D) Non-salient pole type
Answer: - Option B
4. An alternator is said to be over-excited when it is operating at
(A) Leading Power Factor
(B) Lagging Power Factor
(C) Unity Power Factor
(D) Leading & Lagging PF
Answer: - Option B
5. The function of damper winding in an alternator is to
(A) Damp oscillation
(B) Provide stability
(C) Eliminate Hunting
(D) All option are correct
Answer: - Option D
6. If the input to the prime mover of an alternator is kept constant but the excitation is changed,
then the
(A) The active component of the output is changed
(B) The power factor remains constant
(C) Reactive components of the output are changed
(D) The power factor is reduced
Answer: - Option C
7. When an alternator is running on no-load the power supplied by the prime mover of an alternator
goes to
(A) Meets copper loss and winding loss in an armature
(B) Meet no-load looses
(C) Meet iron losses
(D) Produce E.M.F in the armature winding
Answer: - Option B
8. When the power factor of an alternator is unity then the armature flux will be
(A) Demagnetizing
(B) Cross-magnetizing
(C) Zero
(D) Operating at high RPM
Answer: - Option B
9. If the frequency of an alternator increase then
(A) Its speed increases
(B) Its speed decreases
(C) Speed will remain constant
(D) None of the above
Answer: - Option A
10. In an alternator zero power factor method is used to find the
(A) Synchronous impedance
(B) Efficiency
(C) Armature resistance
(D) Voltage regulation
Answer: - Option D
11. The frequency of voltage generated in large alternators is
(A) 50 Hz
(B) 100 Hz
(C) In kilo cycles
(D) In mega cycles
Answer: - Option A
12. An alternator coupled to which prime mover will usually have the highest
rotating speed
(A) Steam engine
(B) Reciprocating diesel engine
(C) Francis turbine
(D) Steam turbine
Answer: - Option D
13. In an alternator the voltage generated per phase is proportional to
(A) Number of turns in coil
(B) Flux per pole
(C) Frequency of waveform
(D) All of the above
Answer: - Option D
14. When a three-phase alternator supplies capacitive load, armature reaction
flux will be
(A) Opposing the main magnectic field
(B) Helping the main magnetic field
(C) Either (a) or (b)
(D) None of the above
Answer: - Option B
15. A 10 pole AC generator rotates at 1200 rpm. The frequency of AC voltage in cycles per second
will be
(A) 120
(B) 60
(C) 160
(D) 100
Answer: - Option D
16. The output frequency of an alternator depends on
(A) Type of winding
(B) Number of poles and Rotational speed
(C) Numbers of poles only
(D) Rotational speed only
Answer: - Option B
17. The number of electrical degrees passed through in one revolution of a six-pole alternator is
(A) 3600
(B) 720
(C) 1080
(D) 1000
Answer: - Option C
18. The number of electrical degrees passed through in one revolution of a ten-pole alternator is
(A) 3600
(B) 720
(C) 1800
(D) 1000
Answer: - Option C
19. When an alternator is running on no-load the power supplied by the prime mover of an
alternator goes to
(A) Meets copper loss and winding loss in an armature
(B) Meet no-load looses
(C) Meet iron losses
(D) Produce E.M.F in the armature winding
Answer: - Option B
20. The power factor of an alternator depends on
(A) Speed of Motor
(B) Core losses
(C) Armature losses
(D) Type of load
Answer: - Option D
21. A 6 pole AC generator rotates at 800 rpm. The frequency of AC voltage in cycles per second will
be
(A) 120
(B) 40
(C) 160
(D) 100
Answer: - Option B
22. A 12 pole AC generator rotates at 1600 rpm. The frequency of AC voltage in cycles per second
will be
(A) 120
(B) 80
(C) 160
(D) 100
Answer: - Option C
23. The number of electrical degrees passed through in one revolution of a four-pole alternator is
(A) 3600
(B) 720
(C) 1800
(D) 1000
Answer: - Option B
24. The number of electrical degrees passed through in one revolution of a eight-pole alternator is
(A) 3600
(B) 720
(C) 1440
(D) 1000
Answer: - Option C
25. The active power of an alternator can be varied by
(A) Increasing field excitation
(B) Changing prime mover speed
(C) Decreasing field excitation
(D) Decreasing Frequency
Answer: - Option B
26. Alternators are usually designed to generate which type of ac voltage?
(A) With fixed frequency
(B) With variable frequency
(C) Fixed current
(D) Fixed power factor
Answer: - Option A
27. Turbo alternators have rotors of
(A) Small diameter and long axial length
(B) Large diameter and long axial length
(C) Large diameter and small axial length
(D) Small diameter and axial length
Answer: - Option A
28. In an alternator, if the winding is short pitch by 60 degrees electrical its pitch
factor will be
(A) 0.866
(B) 1
(C) 0.75
(D) 0.28
Answer: - Option A
29. In an alternator, if the winding is short pitch by 120 degrees electrical its
pitch factor will be
(A) 0.866
(B) 1
(C) 0.75
(D) 0.5
Answer: - Option D
30. In an alternator, if the winding is short pitch by 30 degrees electrical its
pitch factor will be
(A) 0.866
(B) 1
(C) 0.75
(D) 0.96
Answer: - Option D
31. In an alternator, if the winding is short pitch by 90 degrees electrical its
pitch factor will be
(A) 0.866
(B) 1
(C) 0.707
(D) 0.5
Answer: - Option C
32. In an alternator, if the winding is short pitch by 150 degrees electrical its
pitch factor will be
(A) 0.258
(B) 1
(C) 0.75
(D) 0.5
Answer: - Option A
33. The number of electrical degrees passed through in one revolution of a fourteen-pole alternator
is
(A) 3600
(B) 2520
(C) 1800
(D) 1000
Answer: - Option B
34. The number of electrical degrees passed through in one revolution of a twelve-pole alternator is
(A) 3600
(B) 2160
(C) 1800
(D) 1000
Answer: - Option B
35. The number of electrical degrees passed through in one revolution of a sixteen-pole alternator
is
(A) 3600
(B) 720
(C) 2880
(D) 1000
Answer: - Option C
04 – SYNCHRONOUS MOTORS Marks:-12
Content of Chapter:-
4.1 Principle of working/ operation, significance of load angle.
4.2 Torque: Starting torque, running torque, pull in torque, pull out torque.
4.3 Synchronous motor on load with constant excitation (numerical), effect of excitation at constant load
(numerical).
4.4 V-curve and inverted V-curve.
4.5 Hunting and phase swinging.
4.6Method of starting of synchronous motor.
4.7 Losses in synchronous motors and efficiency (no numerical).
4.8 Applications areas.
1. In the synchronous motor, the V curve is drawn between
(A) Field current on X-axis and armature current on Y-axis
(B) Field current on Y-axis and armature current on X-axis
(C) Field current on Y-axis and Power factor on X-axis
(D) Field current on X-axis and Power factor on Y-axis
Answer: - Option A
2. In the synchronous motor, the inverted V curve is drawn between
(A) Field current on X-axis and armature current on Y-axis
(B) Field current on Y-axis and armature current on X-axis
(C) Field current on Y-axis and Power factor on X-axis
(D) Field current on X-axis and Power factor on Y-axis
Answer: - Option D
3. For power factor correction, synchronous motors operate at
(A) No load with over-excited fields
(B) No load with under-excited fields
(C) Normal load with minimum excitation
(D) Normal load with zero excitation
Answer: - Option A
4. What happens if the field winding of the synchronous motor is
short- circuited?
(A) First, starts as induction motor then run as synchronous motor
(B) Not start
(C) Motor will burn out
(D) Run as induction motor
Answer: - Option D
5. The speed regulation of a synchronous motor is
(A) 100%
(B) 50%
(C) 25%
(D) 0%
Answer: - Option D
6. The negative phase sequence in a three phase synchronous motor
exists when the motor is
(A) Supplied with an unbalanced voltage
(B) Supplied with an unbalanced load
(C) Unbalanced system fault
(D) All of the above
Answer: - Option D
7. A synchronous motor working at leading power factor can be used as
(A) Synchronous induction motor
(B) Static condenser
(C) Synchronous condenser
(D) None of the above
Answer: - Option C
8. In a synchronous motor, the magnitude of back emf depends
on ________
(A) Flux density
(B) DC excitation
(C) Load on the motor
(D) Speed of the rotor
Answer: - Option B
9. The maximum value of torque that a synchronous motor, can develop
without losing its synchronism, is known as
(A) Pull out torque
(B) Breaking torque
(C) Slip torque
(D) Non-synchronizing torque
Answer: - Option A
10. In a synchronous motor if the back emf generated in the armature at no
load is approximately equal to the applied voltage, then the
(A) The torque generated is maximum
(B) Motor is fully loaded
(C) Excitation is 100%
(D) No Excitation at all
Answer: - Option C
11. In a synchronous motor, the armature current has large values for
(A) High excitation
(B) Low excitation
(C) Both high and low excitation
(D) None of the above
Answer: - Option C
12. The construction of a synchronous motor resembles which of the
following machine
(A) Differential compound motor
(B) Alternator
(C) DC series motor
(D) Induction motor
Answer: - Option B
13. The synchronous motors are not self-starting because
(A) The direction of torque on the rotor reverses after every half cycle.
(B) Slip is not present in synchronous machine
(C) Starting winding is not present in the synchronous machine
(D) DC excitation is used
Answer: - Option A
14. Due to which one of the following reasons a synchronous motor fails to
pull into synchronism after applying D.C. field current?
(A) Low short circuit ratio
(B) High field current
(C) High core losses
(D) Low field current
Answer: - Option D
15. The direction of rotation of the synchronous motor can be reversed by reversing
(A) Field winding
(B) The polarity of the rotor poles
(C) Supply phase sequence
(D) None of the above
Answer: - Option C
16. In synchronous motor out of the following losses, which one will have the highest proportion?
(A) Stator copper losses
(B) Iron losses
(C) Eddy current losses
(D) Friction and windage losses
Answer: - Option B
17. The speed of a synchronous motor
(A) Increases as load increases
(B) Adjusts itself to new equilibrium speed whenever load changes.
(C) Always remains constant
(D) Reduces as load increases
Answer: - Option B
18. Which of the following devices can be used as a phase advancer?
(A) Synchronous motor working at lagging power factor
(B) Synchronous motor working at leading power factor
(C) Squirrel cage induction motor
(D) Slip ring induction motor
Answer: - Option B
19. The maximum speed variation in a 3-phase synchronous motor is
(A) 5%
(B) Zero
(C) 10%
(D) 3%
Answer: - Option B
20. If the field of a synchronous motor is underexcited, the power factor will be
(A) Lagging
(B) Leading
(C) Zero
(D) None of the above
Answer: - Option A
21. The damper winding in a synchronous motor is provided for
(A) Starting torque only
(B) Reduce eddy currents
(C) Prevent hunting and provide the starting torque.
(D) Reduce the noise level
Answer: - Option C
22. If the field of a synchronous motor is Overexcited, the power factor will be
(A) Lagging
(B) Leading
(C) Zero
(D) None of the above
Answer: - Option B
23. A Synchronous motor can operate at
(A) Unity power factor
(B) Leading power factor
(C) Lagging power factor
(D) Leading as well as lagging power factor
Answer: - Option D
24. The motor which is mostly preferred for centrifugal pump is
(A) Universal Motor
(B) Repulsion Motor
(C) Synchronous Motor
(D) Shaded Pole Motor
Answer: - Option C
25. The motor which is mostly preferred for belt driven reciprocating compressors is
(A) Synchronous Motor
(B) Repulsion Motor
(C) Universal Motor
(D) Shaded Pole Motor
Answer: - Option A
26. The motor which is mostly preferred for blowers is
(A) Universal Motor
(B) Repulsion Motor
(C) Synchronous Motor
(D) Shaded Pole Motor
Answer: - Option C
27. The motor which is mostly preferred for line shafts is
(A) Synchronous Motor
(B) Repulsion Motor
(C) Universal Motor
(D) Shaded Pole Motor
Answer: - Option A
28. The motor which is mostly preferred for vacuum pumps is
(A) Universal Motor
(B) Repulsion Motor
(C) Synchronous Motor
(D) Shaded Pole Motor
Answer: - Option C
29. The motor which is mostly preferred for rubber mills is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
30. The motor which is mostly preferred for paper mills is
(A) Synchronous Motor
(B) Repulsion Motor
(C) Universal Motor
(D) Shaded Pole Motor
Answer: - Option A
31. The motor which is mostly preferred for rolling mills is
(A) Universal Motor
(B) Repulsion Motor
(C) Synchronous Motor
(D) Shaded Pole Motor
Answer: - Option C
32. The motor which is mostly preferred for pulp grinders is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
33. The motor which is mostly preferred for textile mill is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
34. The motor which is mostly preferred for power factor correction device is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
35. The motor which is mostly used as phase advancers is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
36. The motor which is mostly used as phase modifiers is
(A) Universal Motor
(B) Repulsion Motor
(C) Shaded Pole Motor
(D) Synchronous Motor
Answer: - Option D
05 – FRACTIONAL HP MOTORS Marks:-20
Content of Chapter:-
5.1 Construction and working: synchronous Reluctance motor, BLDC, Switched Reluctance motor, permanent
magnet synchronous motors, stepper motors, AC and DC servomotors.
5.2 Torque speed characteristics of above motors.
5.3 Application of above motors.
1. The motor which is mostly preferred for electric power steering is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Servo Motor
(D) Synchronous Reluctance Motor
Answer: - Option A
2. The motor which is mostly preferred for compressors is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option A
3. The motor which is mostly preferred for food processors is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option A
4. The motor which is mostly preferred for Vacuum Cleaners is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option A
5. The motor which is mostly preferred for Serial Printers is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option B
6. The motor which is mostly preferred for floppy disc drives is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option B
7. The motor which is mostly preferred for Space-craft is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option B
8. The motor which is mostly preferred for Numerical control of machine tools is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option B
9. The motor which is mostly preferred for Process control systems is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option B
10. The motor which is mostly preferred for Cryogenic coolers is
(A) Switched Reluctance Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) BLDC Motor
Answer: - Option D
11. The motor which is mostly preferred for Artificial Heart Pumps is
(A) BLDC Motor
(B) Stepper Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option A
12. The motor which is mostly preferred for Hard Disc Drive is
(A) BLDC Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option A
13. The motor which is mostly preferred for elevators is
(A) BLDC Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Permanent Magnet Synchronous Motor
Answer: - Option D
14. The motor which is mostly preferred for traction is
(A) Permanent Magnet Synchronous Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option A
15. The motor which is mostly preferred for glass industry is
(A) Permanent Magnet Synchronous Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option A
16. The motor which is mostly preferred for steel rolling mills is
(A) Permanent Magnet Synchronous Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option A
17. The motor which is mostly preferred for fibre spinning mills is
(A) Permanent Magnet Synchronous Motor
(B) Switched Reluctance Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option A
18. The maximum stepping rate of variable reluctance stepper motor is upto __________ pulses per
seconds
(A) 120
(B) 12
(C) 12000
(D) 1200
Answer: - Option D
19. The maximum stepping rate of permanent magnet stepper motor is upto __________ pulses per
seconds
(A) 120
(B) 300
(C) 3000
(D) 1200
Answer: - Option C
21. Which of the following motor has low inertia?
(A) Permanent Magnet Synchronous Motor
(B) Servo Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option B
22. Which of the following motor has high speed of response?
(A) Permanent Magnet Synchronous Motor
(B) Servo Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option B
23. Which of the following motor has linear torque speed characteristics?
(A) Permanent Magnet Synchronous Motor
(B) Servo Motor
(C) Synchronous Reluctance Motor
(D) Stepper Motor
Answer: - Option B
24. The motor which is mostly preferred for remote positioning devices is
(A) Switched Reluctance Motor
(B) Permanent Magnet Synchronous Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option D
25. The motor which is mostly preferred for Robotics is
(A) Switched Reluctance Motor
(B) Permanent Magnet Synchronous Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option D
26. The motor which is mostly preferred for food tracking and guidance systems is
(A) Switched Reluctance Motor
(B) Permanent Magnet Synchronous Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option D
27. The motor which is mostly preferred for self-balancing recorders is
(A) Switched Reluctance Motor
(B) Permanent Magnet Synchronous Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option D
28. The motor which is mostly preferred for machine tools is
(A) Switched Reluctance Motor
(B) Permanent Magnet Synchronous Motor
(C) Synchronous Reluctance Motor
(D) Servo Motor
Answer: - Option D