Electric Traction MCQ

81. A locomotive exerts a tractive effort of 40,000 N in pulling a train at 60 kmph on a level track. If the same train is to be halted at the same speed but on gradient, the tractive effort required will be at 60,000 N. The output delivered by the motor will be more if it is driven by

(a) a 3-phase induction motor.
(b) a dc series motor.
(c) an ac series motor.
(d) equal in all the three cases.

82. When two or more motors are used for traction service, the method of speed control used will be

(a) rheostatic control.
(c) field control.
(b) series-parallel control.
(d) motor generator control.

83. The advantage(s) of series-parallel starting is/are

(a) small energy loss and higher efficiency.
(b) economical speed control.
(c) higher reliability of operation.
(d) all of the above.

84. Parallel operation of traction motors is easier with

(a) dc shunt motors.
(b) dc series motors.
(c) induction motors.
(d) none of these.

85. In motor-generator locomotive control

(a) rheostatic control is used.
(b) series parallel control is used.
(c) the output voltage of generator is regulated by means of field control from exciter.
(d) any one of the above method is used.

86. In metadyne control.

(a) current throughout the accelerating period remains constant.
(b) tractive effort developed is uniform.
(c) there is no wastage of energy in starting rheostat.
(d) all of the above.

87. The method of speed control adopted in 25 kV, single-phase, 50 Hz traction is

(a) tap changing control of transformer.
(b) reduced current method.
(c) series-parallel control.
(d) rheostatic control.

88. The preferable method of speed control of linear induction motor is

(a) variable flux control.
(b) PAM control.
(c) variable frequency and constant voltage control.
(d) variable frequency and variable voltage control.

89. Which of the following braking systems on the locomotives is costly ?

(a) Vacuum braking on steam locomotives.
(b) Vacuum braking on diesel locomotives.
(c) Regenerative braking on electric locomotives.
(d) All braking systems are equally costly.

90. Braking system employed in diesel electric traction is

(a) hydraulic type.
(b) vacuum type.
(c) regenerative type.
(d) any of these.

91. The type of braking used in electric traction is

(a) mechanical braking.
(b) vacuum brake system.
(c) electropneumatic braking.
(d) both (a) and (c).

92. Vacuum is created by

(a) vacuum pumps.
(b) ejector.
(c) vacuum pump or ejector.
(d) none of the above.

93. Bearings employed for supporting axles of rolling stock are

(a) bush bearings.
(b) roller bearings.
(c) ball bearings.
(d) journal bearings.

94. The wheels of a train, engine as well as bogies, are slightly tapered so as to

(a) reduce friction.
(b) increase friction.
(c) facilitate in taking turns.
(d) facilitate braking.

95. Bo-Bo locomotives have two bogies with

(a) two driving axles with individual drive motors.
(b) two driving axles with group drives.
(c) four driving axles with individual drive motors.
(d) four driving axles with group drives.

96. A locomotive for Indian Railways has been designated as WAM. In this W indicates that

(a) the locomotive is to run on metre gauge track.
(b) the locomotive is to operate on broad gauge track.
(c) the locomotive is for goods trains only.
(d) the locomotive is only for shunting duty.

97. Locomotives with manometer bogies

(a) are suited both for passengers as well as freight service.
(b) have better coefficient of adhesion.
(c) have better riding qualities owing to reduction of lateral forces.
(d) all of the above.

98. Factor(s) affecting the design of rolling stock is/are

(a) environmental condition.
(b) vibrations and shocks.
(c) unbalanced and fluctuating supply voltages for auxiliaries.
(d) all of the above.

99. In
electric traction if contact voltage exceeds 1,500 V, current collection is invariably by

(a) a contact rail.
(b) a conductor rail.
(c) overhead wire.
(d) third rail.

100. Conductor rail system of supply is

(a) cheap and easy to repair and inspection.
(b) suitable for heavy current collection at voltages up to 1,200 V.
(c) universally used for all ac railways.
(d) both (a) and (b).