ELECTRIC TRACTION | NCERTBOOKSPDF.COM

Objective Questions

Short notes

Objective questions (Answers are given below)

Diesel electric traction has comparatively limited
overload capacity because
(a) diesel electric locomotive is heavier than a
plain electric locomotive
(b) diesel engine has shorter life span
(c) diesel engine is a constant-kW output
prime mover
(d) regenerative braking cannot be employed.
The most vital factor against electric traction
is the
(a) necessity of providing a negative booster
(b) possibility of electric supply failure
(c) high cost of its maintenance
(d) high initial cost of laying out overhead
electric supply system.
The direct current system used for tramways
has a voltage of about ………….volt.
(a) 750
(b) 1500
(c) 3000
(d) 2400
In electric traction if contact voltage exceeds
1500 V, current collection is invariably via a
(a) contact rail
(b) overhead wire
(c) third rail
(d) conductor rail.
For the single-phase ac system of track
electrification, low frequency is desirable
because of the following advantages
(a) it improves commutation properties of ac
motors
(b) it increases ac motor efficiency
(c) it increases ac motor power factor
(d) all of the above.
In Kando system of track electrification,
………………is converted into ………….
(a) 1-phase ac, dc
(b) 3-phase ac, 1-phase ac
(c) 1-phase ac, 3-phase ac
(d) 3-phase ac, dc.
The main reason for choosing the composite
1-phase ac-to-dc system for all future track
electrification in India is that it
(a) needs less number of sub-stations
(b) combines the advantages of high-voltage
ac distribution at 50 Hz with dc series traction
motors
(c) provides flexibility in the location of substations
(d) requires light overhead catenary.
Ordinary, tramway is the most economical
means of transport for
(a) very dense traffic of large city
(b) medium traffic densities
(c) rural services
(d) suburban services.
Unlike a tramway, a trolleybus requires no
(a) overhead contact wire
(b) driving axles
(c) hand brakes
(d) running rail.

The current collector which can be used at
different speeds under all wind conditions and
stiffness of OHE is called ………………….
collector.
(a) trolley
(b) bow
(c) pantograph
(d) messenger.
The speed/time curve for city service has
no…………………… period.
(a) coasting
(b) free-running
(c) acceleration
(d) braking.
For the same value of average speed, increase
in the duration of stops…………. speed.
(a) increases the schedule
(b) increases the crest
(c) decreases the crest
(d) decreases the schedule.
A train weighing 490 tonne and running at 90
km/h has a mass of ………….. kg and a speed
of …………….. m/s.
(a) 50,000, 25
(b) 490,000, 25
(c) 490, 25
(d) 50, 324.
A train has a mass of 500 tonne. Its weight is
(a) 500 t.wt
(b) 500,000 kg-wt
(c) 4,900,000 newton
(d) all of the above
(e) none of the above.
The free-running speed of a train does NOT
depend on the
(a) duration of stops
(b) distance between stops
(c) running time
(d) acceleration.
A motor coach weighing 100 tonnes is to be
given an acceleration of 1.0 km/h/s on an
ascending gradient of 1 percent. Neglecting
rotational inertia and train resistance, the
tractive force required is ……………. newton.
(a) 109,800
(b) 37,580
(c) 28,760
(d) 125,780.
In a train, the energy output of the driving
axles in used for
(a) accelerating the train
(b) overcoming the gradient
(c) overcoming train resistance
(d) all of the above.
Longer coasting period for a train results in
(a) higher acceleration
(b) higher retardation
(c) lower specific energy consumption
(d) higher schedule speed.
Tractive effort of an electric locomotive can be
increased by
(a) increasing the supply voltage
(b) using high kW motors
(c) increasing dead weight over the driving
axles
(d) both (b) and (c) (e)both (a) and (b).
Skidding of a vehicle always occurs when
(a) braking effort exceeds its adhesive weight
(b) it negotiates a curve
(c) it passes over points and crossings
(d) brake is applied suddenly.
Which of the following is an advantage of
electric traction over other methods of traction?
(a) Faster acceleration
(b) No pollution problems
(c) Better braking action
(d) All of the above
Which of the following is the voltage for
single phase A.C. system?
(a) 22 V
(b) 440 V
(c) 5 kV
(d) 15 kV
(e) None of the above
Long distance railways use which of the
following?
(a) 200 V D.C.
(b) 25 kV single phase A.C.
(c) 25 kV two phace A.C.
(d) 25 kV three phase A.C.
The speed of a locomotive is controlled by
(a) flywheel
(b) gear box
(c) applying brakes
(d) regulating steam flow to engine

Main traction system used in India are, those
using
(a) electric locomotives
(b) diesel engine locomotives
(c) steam engine locomotives
(d) diesel electric locomotives
(e) all of the above
In India diesel locomotives are manufactured
at
(a) Ajmer
(b) Varanasi
(c) Bangalore
(d) Jamalpur
For diesel locomotives the range of
horsepower is
(a) 50 to 200
(b) 500 to 1000
(c) 1500 to 2500
(d) 3000 to 5000
……. locomotive has the highest operational
availability.
(a) Electric
(b) Diesel
(c) Steam
The horsepower of steam locomotives is
(a) upto 1500
(b) 1500 to 2000
(c) 2000 to 3000
(d) 3000 to 4000
The overall efficiency of steam locomotive is
around
(a) 5 to 10 percent
(b) 15 to 20 percent
(c) 25 to 35 percent
(d) 35 to 45 percent
In tramways which of the following motors is
used?
(a) D.C. shunt motor
(b) D.C. series motor
(c) A.C. three phase motor
(d) A.C. single phase capacitor start motor
In a steam locomotive electric power is
provided through
(a) overhead wire
(b) battery system
(c) small turbo-generator
(d) diesel engine generator
Which of the following drives is suitable for
mines where explosive gas exists?
(a) Steam engine
(b) Diesel engine
(c) Battery locomotive
(d) Any of the above
In case of locomotives the tractive power is
provided by
(a) single cylinder double acting steam
engine
(b) double cylinder, single acting steam
engine
(c) double cylinder, double acting steam
engine
(d) single stage steam turbine
Overload capacity of diesel engines is usually
restricted to
(a) 2 percent
(b) 10 percent
(c) 20 percent
(d) 40 percent
In case of steam engines the steam pressure is
(a) 1 to 4 kgf/cm2
(b) 5 to 8 kgf/cm2
(c) 10 to 15 kgf/cm2
(d) 25 to 35 kgf/cm2
The steam engine provided on steam
locomotives is
(a) single acting condensing type
(b) single acting non-condensing type
(c) double acting condensing type
(d) double acting non-condensing type
Electric locomotives in India are manufactured
at
(a) Jamalpur
(b) Bangalore
(c) Chittranjan
(d) Gorakhpur
The wheels of a train, engine as well as bogies,
are slightly tapered to
(a) reduce friction
(b) increase friction
(c) facilitate braking
(d) facilitate in taking turns
Automatic signalling is used for which of the
following trains?

(a) Mail and express trains
(b) Superfast trains
(c) Suburban and Urban electric trains
(c) All trains

The efficiency of diesel locomotives is nearly
(a) 20 to 25 percent
(b) 30 to 40 percent
(c) 45 to 55 percent
(d) 60 to 70 percent
The speed of a superfast train is
(a) 60 kmph
(b) 75 kmph
(c) 100 kmph
(d) more than 100 kmph
The number of passenger coaches that can be
attached to a diesel engine locomotive on
broad gauge is usually restricted to
(a) 5
(b) 10
(c) 14
(d) 17
Which of the following state capitals is not on
broad gauge track?
(a) lucknow
(b) Bhopal
(c) Jaipur
(d) Chandigarh
Which of the following is the advantage of
electric braking?
(a) It avoids wear of track
(b) Motor continues to remain loaded during
braking
(c) It is instantaneous
(d) More heat is generated during braking
Which of the following braking systems on the
locomotives in costly?
(a) Regenerative braking on electric locomotives
(b) Vacuum braking on diesel locomotives
(c) Vacuum braking on steam locomotives
(d) All braking systems are equally costly
Tractive effort is required to
(a) overcome the gravity component of train
mass
(b) overcome friction, windage and curve
resistance
(c) accelerate the train mass
(d) do all of the above
For given maximum axle load tractive efforts
of A.C. locomotive will be
(a) less than that of D.C. locomotive
(b) more than that of D.C. locomotive
(c) equal to that of D.C. locomotive
(d) none of the above
Co-efficient of adhesion reduces due to the
presence of which of the following?
(a) Sand on rails
(b) Dew on rails
(c) Oil on the rails
(d) both (b) and (c)
Due to which of the following co-efficient of
adhesion improves?
(a) Rust on the rails
(b) Dust on the rails
(c) Sand on the rails
(d) All of the above
Quadrilateral speed-time curve pertains to
which of the following services?
(a) Main line service
(b) Urban service
(c) Sub-urban service
(d) Urban and sub-urban service
Which of the following is the disadvantage of
electric traction over other systems of traction?
(a) Corrosion problems in the underground
pip work
(b) Short time power failure interrupts traffic
for hours
(c) High capital outlay in fixed installations
beside route limitation
(d) Interference with communication lines
(e) All of the above
Co-efficient of adhesion is
(a) high in case of D.C. traction than in the
case of A.C. traction
(b) low in case of D.C. traction that in the
case of A.C. traction
(c) equal in both A.C. and D.C. traction
(d) any of the above
Speed-time curve of main line service differs
from thoseof urban and suburban services on
following account
(a) it has longer free running period
(b) it has longer coasting period

The rate of acceleration on suburban or urban
services is restricted by the consideration of
(a) engine power
(b) track curves
(c) passanger discomfort
(d) track size
The specific energy consumption of a train
depends on which of the following?
(a) Acceleration and retardation
(b) Gradient
(c) Distance covered
(d) all of the above
The friction at the track is proportional to
(a) 1/speed
(b) 1/(speed)2
(c) speed
(d) none of the above
The air resistance to the movement of the train
is proportional to
(a) speed
(b) (speed)2
(c) (speed)3
(d) 1/speed
The normal value of adhesion friction is
(a) 0.12
(b) 0.25
(c) 0.40
(d) 0.75
The pulsating torque exerted by steam
locomotives causes which of the following?
(a) Jolting and skidding
(b) Hammer blow
(c) Pitching
(d) All of the above
Which of the following braking systems is
used on steam locomotives?
(a) Hydraulic system
(b) Pneumatic system
(c) Vacuum system
(d) None of the above
Vacuum is created by which of the following?
(a) Vacuum pump
(b) Ejector
(c) Any of the above
(d) None of the above
The resistance encountered by a train in
motion is on account of
(a) resistance offered by air
(b) friction at the track
(c) friction at various parts of the rolling stock
(d) all of the above
Battery operated trucks are used in
(a) steel mills
(b) power stations
(c) narrow gauge traction
(d) factories for material transportation
……. method can bring the locomotive todead
stop.
(a) Plugging braking
(b) Rheostatic braking
(c) Regenerative braking
(d) None of the above
The value of co-efficient of adhesion will be
high when rails are
(a) greased
(b) wet
(c) sprayed with oil
(d) cleaned with sand
The voltage used for suburban trains in D.C.
system is usually
(a) 12 V
(b) 24 V
(c) 220 V
(d) 600 to 750 V
For three-phase induction motors which of the
following is the least efficient method of speed
control?
(a) Cascade control
(b) Pole changing
(c) Rheostatic control
(d) Combination of cascade and pole
changing
Specific energy consumption becomes
(a) more on steeper gradient
(b) more with high train resistance
(c) less if distance between stops is more
(d) all of the above
In main line service as compared to urban and
suburban service

(a) distance between the stops is more
(b) maximum speed reached is high
(c) acceleration and retardation rates are low
(d) all of the above

Locomotive having monomotor bogies
(a) has better co-efficient of adhesion
(b) are suited both for passanger as well as
freight service
(c) has better riding qualities due to the
reduction of lateral forces
(d) has all above qualities
Series motor is not suited for traction duty due
to which of the following account?
(a) Less current drain on the heavy load torque
(b) Current surges after temporary switching
off supply
(c) self relieving property
(d) Commutating property at heavy load
When a bogie negotiates a curve, reduction in
adhesion occurs resulting in sliding. Thus
sliding is acute when
(a) wheel base of axles is more
(b) degree of curvature is more
(c) both (a) and (b)
(c) none of the above
Energy consumption in propelling the train is
required for which of the following?
(a) Work against the resistance to motion
(b) Work against gravity while moving up
the gradient
(c) Acceleration
(d) All of the above
An ideal traction system should have ……..
(a) easy speed control
(b) high starting tractive effort
(c) equipment capable of with standing large
temporary loads
(d) all of the above
……. have maximum unbalanced forces
(a) Diesel shunters
(b) Steam locomotives
(c) Electric locomotives
(d) Diesel locomotives
Specific energy consumption is affected by
which of the following factors?
(a) Regardation and acceleration values
(b) Gradient
(c) Distance between stops
(d) All of the above
In case of ……. free running and coasting
periods are generally long.
(a) main-line service
(b) urban wervice
(c) sub-urban service
(d) all of the above
Overhead lines for power supply to tramcars
are at a minimum height of
(a) 3 m
(b) 6 m
(c) 10 m
(d) 20 m
The return circuit for tram cars is through …….
(a) neutral wire
(b) rails
(c) cables
(d) common earthing
Specific energy consumption is least in ……..
service.
(a) main line
(b) urban
(c) suburban
Locomotives with monometer bogies have
(a) uneven distribution of tractive effect
(b) suitability for passanger as well as freight
service
(c) lot of skidding
(d) low co-efficient of adhesion
……. was the first city in India to adopt electric
traction.
(a) Delhi
(b) Madras
(c) Calcutta
(d) Bombay
……. frequency is not common in low
frequency traction system
(a) 40 Hz
(b) 25 Hz
(c) 16Hz
For 25 kV single phase system power supply
frequency is …….
(a) 60 Hz
(b) 50 Hz
(c) 25 Hz
(d) 16 2/3 Hz

Power for lighting in passenger coach, in a
long distance electric train, is provided
(a) directly through overhead electric
(b) through individual generator of bogie and
batteries
(c) through rails
(d) through locomotive
In India, electrification of railway track was
done for the first time in which of the
following years?
(a) 1820–1825
(b) 1880–1885
(c) 1925–1932
(d) 1947–1954
Suri transmission is …….
(a) electrical-pneumatic
(b) mechanical-electrical
(c) hydro-mechanical
(d) hydro-pneumatic
In case of a steam engine an average coat
consumption per km is nearly
(a) 150 to 175 kg
(b) 100 to 120 kg
(c) 60 to 80 kg
(d) 28 to 30 kg
Which of the following happens in Kando
system?
(a) Three phase A.C. is converted into D.C.
(b) Single phase A.C. is converted into D.C.
(c) Single phase supply is converted into three
phase system
(d) None of the above
For which of the following locomotives the
maintenance requirements are the least?
(a) Steam locomotives
(b) Diesel locomotives
(c) Electric locomotives
(d) Equal in all of the above
Which of the following methods is used to
control speed of 25 kV, 50 Hz single phase
traction?
(a) Reduced current method
(b) Tapchanging control of transformer
(c) Series parallel operation of motors
(d) All of the above
If the co-efficient of adhesion on dry rails is
0.26, which of the following could be the value
for wet rails?
(a) 0.3
(b) 0.26
(c) 0.225
(d) 0.16
……. watt-hours per tonne km is usually the
specific energy consumption for suburban
services.
(a) 15–20
(b) 50–75
(c) 120–150
(d) 160–200
The braking retardation is usually in the range
(a) 0.15 to 0.30 km phps
(b) 0.30 to 0.6 km phps
(c) 0.6 to 2.4 km phps
(d) 3 to 5 km phps
(e) 10 to 15 km phps
The rate of acceleration on suburban or urban
service is in the range
(a) 0.2 to 0.5 km phps
(b) 1.6 to 4.0 km phps
(c) 5 to 10 km phps
(d) 15 to 25 km phps
The coasting retardation is around
(a) 0.16 km phps
(b) 1.6 km phps
(c) 16 km phps
(d) 40 km phps
which of the following track is electrified
(a) Delhi–Bombay
(b) Delhi–Madras
(c) Delhi–Howrah
(d) Delhi–Ahmedabad
……. is the method of braking in which motor
armature remains connected to the supply and
draws power from it producing torque
opposite to the direction of motion.
(a) Rheostatic braking
(b) Regerative braking
(c) Plugging
For 600 V D.C. line for tramcars, brack is
connected to …….
(a) positive of the supply
(b) negative of the supply
(c) mid voltage of 300 V
(d) none of the above

(c) 2. (d) 3. (a) 4. (b) 5. (d) 6. (c) 7. (b) 8. (a) 9. (d) 10. (c) 11.(b) 12. (d) 13. (b) 14. (d) 15. (a) 16. (b) 17. (d) 18. (c) 19. (d) 20. (a) 21.(d) 22. (d) 23. (b) 24. (d) 25. (e) 26. (b) 27. (c) 28. (a) 29. (a) 30. (a) 31.(b) 32. (c) 33. (c) 34. (c) 35. (b) 36. (c) 37. (d) 38. (c) 39. (d) 40. (c) 41.(a) 42. (d) 43. (d) 44. (c) 45. (a) 46. (a) 47. (d) 48. (b) 49. (d) 50. (d) 51.(d) 52. (e) 53. (b) 54. (d) 55. (c) 56. (d) 57. (c) 58. (b) 59. (b) 60. (a) 61.(c) 62. (c) 63. (d) 64. (d) 65. (a) 66. (d) 67. (d) 68. (c) 69. (d) 70. (d) 71.(d) 72. (b) 73. (c) 74. (d) 75. (d) 76. (b) 77. (d) 78. (a) 79. (c) 80. (b) 81.(a) 82. (b) 83. (d) 84. (a) 85. (b) 86. (b) 87. (c) 88. (c) 89. (d) 90. (c) 91.(c) 92. (b) 93. (d) 94. (b) 95. (d) 96. (b) 97. (a) 98. (c) 99. (c) 100. (b)

Visit Here for other basic electrical engineering MCQ and Notes

ELECTRIC CURRENT AND OHM’S LAW- Questions, MCQ and Short notes

DC NETWORK THEOREMS- Questions, MCQ and Short notes

WORK, POWER AND ENERGY- Questions, MCQ and Short notes

ELECTROSTATICS- Questions, MCQ and Short notes

CAPACITANCE- Questions, MCQ and Short notes

MAGNETISM AND ELECTROMAGNETISM- Questions, MCQ and Short notes

ELECTROMAGNETIC INDUCTION- Questions, MCQ and Short notes

MAGNETIC HYSTERESIS- Questions, MCQ and Short notes

ELECTROCHEMICAL POWER SOURCES- Questions, MCQ and Short notes

ELECTRICAL INSTRUMENTS AND MEASUREMENTS- Questions, MCQ and Short notes

A.C. FUNDAMENTALS- Questions, MCQ and Short notes