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MCQ in Power Generators (Cells and Batteries) Part 3 | ECE Board Exam
MCQ in Power Generators (Cells and Batteries) Part 3 | ECE Board
Exam
Engr 4 Years Ago
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(Last Updated On: August 9, 2018)
This is the Multiples Choice Questions Part 3 of the Series in Power Generators, Sources, Principles and
Applications as one of the Electronics Engineering topic. In Preparation for the ECE Board Exam make sure to
expose yourself and familiarize in each and every questions compiled here taken from various sources including
but not limited to past Board Exam Questions in Electronics Engineering eld, Electronics Books, Journals and
other Electronics References.
MCQ Topic Outline included in ECE Board Exam Syllabi
MCQ in Cells and Batteries
MCQ in Electric Generator
MCQ in Electronic Power Supply
MCQ in Voltage Regulation
MCQ in Photovoltaic/Thermoelectric Generator
MCQ in Distribution Transformer
MCQ in Uninterrupted Power Supply (UPS)
MCQ in Float-Battery System
MCQ in Converters
MCQ in Inverters
Continue Practice Exam Test Questions Part 3 of the Series
Choose the letter of the best answer in each questions.
101. The synchronous reactance of an alternator _________ as the iron is saturated
A. decreases
B. remains the same
C. increases
D. becomes doubled
View Answer:
Answer: Option A
Solution:
102. A 4 pole dc machine has magnetic circuits
A. 2
B. 4
C. 8
D. 6
View Answer:
Answer: Option B
Solution:
103. The current in armature conductors of a dc machine is
A. pure dc
B. ac
C. pulsating dc
D. pure dc plus pulsating dc
View Answer:
Answer: Option B
Solution:
104. The ac armature winding of an alternator operates at __________ the field of winding
A. the same voltage as
B. much higher voltage than
C. much lesser voltage than
D. half the voltage than
View Answer:
Answer: Option B
Solution:
105. Why are the field poles and the armature of a dc machine laminated?
A. to reduce the weight of the machine
B. to reduce eddy current
C. to decrease the speed
D. to reduce armature reaction
View Answer:
Answer: Option B
Solution:
106. The back emf or counter emf in a dc motor
A. opposes the applied voltage
B. aids the armature current
C. aids the supplied voltage
D. opposes the armature current
View Answer:
Answer: Option A
Solution:
107. The synchronous reactance of an alternator is due to
A. leakage flux
B. armature reaction
C. dc field excitation
D. hysteresis loss
View Answer:
Answer: Option B
Solution:
108. Back emf in a dc motor is maximum at
A. no load
B. half full load
C. full load
D. three fourth full load
View Answer:
Answer: Option A
Solution:
109. The mechanical power developed in a dc motor is maximum when back emf is equal to _____ the applied
voltage
A. twice
B. one third
C. one half
D. one fourth
View Answer:
Answer: Option C
Solution:
110. The core type transformer is generally suitable for
A. high voltage and small output
B. low voltage and high output
C. high voltage and high output
D. low voltage and low output
View Answer:
Answer: Option A
Solution:
111. The transformer that should never have the secondary open circuited when primary is energized is
A. power transformer
B. auto transformer
C. voltage transformer
D. current transformer
View Answer:
Answer: Option D
Solution:
112. The field winding of an armature is _________ excited
A. dc
B. ac
C. both ac and dc
D. battery
View Answer:
Answer: Option A
Solution:
113. The salient pole construction for field structure of an alternator is generally used for _________ machine
A. 2 pole
B. 8 pole
C. 4 pole
D. 6 pole
View Answer:
Answer: Option B
Solution:
114. When the speed of a dc motor increases, its armature current
A. increases
B. remains the same
C. decreases
D. becomes infinite
View Answer:
Answer: Option C
Solution:
115. The frequency of emf generated in an 8 pole alternator at 900 rpm is
A. 50 hz
B. 120 hz
C. 60 hz
D. 240 hz
View Answer:
Answer: Option C
Solution:
116. In case if a 4 pole machine, 1 mechanical degree corresponds to ________ electrical degree
A. 2
B. 8
C. 4
D. 6
View Answer:
Answer: Option A
Solution:
117. The torque developed by a dc motor is directly proportional to
A. flux per pole x armature current
B. armature resistance x applied voltage
C. armature resistance x armature current
D. flux per pole x applied voltage
View Answer:
Answer: Option A
Solution:
118. AC machine in which the torque is produced by the interaction of currents in the stator and currents induced in
the motor by transformer action
A. squirrel cage motor
B. stepper motor
C. synchronous motor
D. induction motor
View Answer:
Answer: Option D
Solution:
119. Machine in which torque is produced by the interaction of ac current in the stator and dc currents in the rotor
turning synchronism
A. synchronous motor
B. induction motor
C. squirrel cage motor
D. stepper motor
View Answer:
Answer: Option A
Solution:
120. The main drawback of a dc shunt generator is that
A. terminal voltage drops considerably with load
B. shunt field circuit has high resistance
C. generated voltage is small
D. it is expensive
View Answer:
Answer: Option A
Solution:
121. DC machines which are subjected to abrupt changes of load are provided with
A. interpole windings
B. compensating winding
C. equalizers
D. copper brushes
View Answer:
Answer: Option B
Solution:
122. The shaft torque in a dc motor is less than total armature torque because of _________ in the motor
A. copper losses
B. iron and friction losses
C. field losses
D. hysteresis loss
View Answer:
Answer: Option B
Solution:
123. Armature reaction in a dc motor is increased
A. When the armature current increases
B. when the armature current decreases
C. when the field current increases
D. by interpole
View Answer:
Answer: Option A
Solution:
124. An ideal transformer is one which
A. has no losses and leakage reactance
B. does not work
C. has the same number of primary and secondary turns
D. has the same primary and secondary voltage
View Answer:
Answer: Option A
Solution:
125. If a power transformer is operated at very high frequencies then
A. primary reactance is too much increased
B. primary will draw large power
C. core losses will be excessive
D. core loss is negligible
View Answer:
Answer: Option C
Solution:
126. With respect to the direction of rotation, interpoles on a dc motor must have the same polarity as the main
poles
A. ahead of them
B. in parallel with them
C. behind them
D. beside them
View Answer:
Answer: Option C
Solution:
127. The open circuit test on a transformer is always made on
A. low voltage winding
B. high voltage winding
C. either low or high voltage
D. neither low or high voltage
View Answer:
Answer: Option A
Solution:
128. In the short circuit test in a transformer, __________ winding is generally short circuited
A. high voltage
B. low voltage
C. either low or high voltage
D. neither low nor high voltage
View Answer:
Answer: Option B
Solution:
129. In a dc motor, the brushes are shifted from the mechanical neutral panel in a direction opposite to the rotation
to
A. decreased speed
B. reduced sparking
C. increase speed
D. produce flat characteristics
View Answer:
Answer: Option B
Solution:
130. The number of cycles generated in a 6 pole alternator in one revolution is
A. 3
B. 5
C. 6
D. 2
View Answer:
Answer: Option A
Solution:
131. If the lagging load power factor of an alternator is decreased, the demagnetizing effect of the armature
reaction
A. remains the same
B. is increased
C. is decreased
D. becomes infinite
View Answer:
Answer: Option B
Solution:
132. In a very large dc motor with severe heavy duty, armature reaction effects are corrected by
A. using interpole only
B. using compensatory windings in addition to interpoles
C. shifting the brush position
D. fixing the brush position
View Answer:
Answer: Option B
Solution:
133. The amount of copper in the primary is _________ that of the secondary
A. about the same as
B. smaller than
C. greater than
D. twice
View Answer:
Answer: Option A
Solution:
134. The open circuit test on a transformer gives
A. copper losses
B. iron losses
C. friction losses
D. total losses
View Answer:
Answer: Option B
Solution:
135. The speed of a __________ motor is practically constant
A. commutatively compounded
B. differentially compounded
C. series
D. shunt
View Answer:
Answer: Option D
Solution:
136. The running speed of a dc series motor is basically determined by
A. field excitation
B. armature resistance
C. load
D. applied voltage
View Answer:
Answer: Option C
Solution:
137. If the excitation of an alternator operating in parallel with other alternators is decreased, its
A. power factor becomes more leading
B. output kW will change
C. power factor becomes more lagging
D. power factor becomes unity
View Answer:
Answer: Option A
Solution:
138. The distribution of load between two alternators operating in parallel can be changed by changing
A. phase sequence
B. field excitation of alternators
C. driving torques of prime movers
D. current direction
View Answer:
Answer: Option C
Solution:
139. After a shunt motor is up to speed the speed may be increased considerably by
A. increasing field circuit resistance
B. decreasing field circuit resistance
C. increasing the armature circuit resistance
D. reducing the load
View Answer:
Answer: Option B
Solution:
140. When the secondary of a transformer is short circuited, the primary inductance
A. is decreased
B. remains the same
C. is increased
D. becomes zero
View Answer:
Answer: Option A
Solution:
141. For the same rating __________ motor has the least starting torque
A. commulatively compounded
B. shunt
C. series
D. differentially compounded
View Answer:
Answer: Option B
Solution:
142. The deciding factor in the selection of a dc motor for a particular application is its _____ characteristics
A. speed torque
B. torque armature current
C. speed armature current
D. speed
View Answer:
Answer: Option A
Solution:
143. The rotor of a turbo alternator is made cylindrical in order to reduce
A. eddy current loss
B. wind age loss
C. hysteresis loss
D. copper loss
View Answer:
Answer: Option B
Solution:
144. The disadvantage of a short pitched coil is that
A. harmonics are introduced
B. waveform becomes non-sinusoidal
C. voltage round the coil is reduced
D. voltage round coil is increases
View Answer:
Answer: Option C
Solution:
145. The demand for a large increase in torque of a dc shunt motor is met by a
A. large decreased in speed
B. large increased in current
C. large increased in speed
D. small increased in current
View Answer:
Answer: Option B
Solution:
146. For 20% increase in current, the motor that will give the greatest increase in torque is _________ motor
A. shunt
B. series
C. differentially compounded
D. commulatively compounded
View Answer:
Answer: Option B
Solution:
147. What cell is used to detect infrared radiation, either its generated voltage or its change of résistance may be
used as a measure of the intensity of the radiation?
A. lead sulfide cell
B. Faure storage cell
C. infrared cell
D. Leclanche cell
View Answer:
Answer: Option A
Solution:
148. A galvanic cell resulting from difference in potential between adjacent on the surface of a metal immersed in
an electrolyte
A. NiCd cell
B. lead acid cell
C. local cell
D. lithium cell
View Answer:
Answer: Option C
Solution:
149. Which motor is used to start heavy loads?
A. series
B. differentially compounded
C. shunt
D. commulatively compounded
View Answer:
Answer: Option A
Solution:
150. When load is removed, the motor that will run at the highest speed is the _________ motor
A. shunt
B. commulatively compounded
C. series
D. differentially compounded
View Answer:
Answer: Option C
Solution:
Questions and Answers in Power Generators, Sources, Principles, Applications
Following is the list of practice exam test questions in this brand new series:
MCQ in in Power Generators, Sources, Principles, Applications
PART 1: MCQs from Number 1 – 50 Answer key: PART 1
PART 2: MCQs from Number 51 – 100 Answer key: PART 2
PART 3: MCQs from Number 101 – 150 Answer key: PART 3
PART 4: MCQs from Number 151 – 200 Answer key: PART 4
PART 5: MCQs from Number 201 – 250 Answer key: included
PART 6: MCQs from Number 251 – 300 Answer key: included
PART 7: MCQs from Number 301 – 350 Answer key: included
PART 8: MCQs from Number 351 – 400 Answer key: included
MORE ON: MCQ in Power Generators, Sources, Principles, Applications Series
Complete List of MCQs in Electronics Engineering per topic
Series of Multiple Choice Questions in Electronics Engineering
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