(Last Updated On: May 3, 2019)
This is the Multiples Choice Questions Part 4 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 field, 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 4 of the Series
Choose the letter of the best answer in each questions.
151. The friction and wind age losses in a dc motor depends upon
A. speed
B. armature current
C. flux
D. field and armature resistance
Answer: Option A
Solution:
152. If a transformer core has air gaps then
A. reluctance of magnetic path is decreased
B. hysteresis loss is decreased
C. magnetizing current is greatly increased
D. eddy current is increased
Answer: Option C
Solution:
153. The effect of leakage flux in a transformer is to
A. increase copper losses
B. decrease copper losses
C. cause voltage drop in the windings
D. reduce eddy current losses
Answer: Option C
Solution:
154. The iron losses in a dc motor depend upon
A. flux only
B. speed only
C. both flux and speed
D. temperature
Answer: Option C
Solution:
155. The greatest percentage of power loss in a dc motor is due to
A. wind age loss
B. core loss
C. copper loss
D. friction loss
Answer: Option C
Solution:
156. Excessive sparking at the brushes may caused due to
A. dirt on the commutator
B. misalignment of machine
C. loose coupling
D. worn bearings
Answer: Option A
Solution:
157. The temperature rise of a transformer is directly proportional to
A. apparent power
B. leakage reactance
C. reactive power
D. true power
Answer: Option A
Solution:
158. A graphical relation between the generated emf and the field current of a machine
A. current generation curve
B. voltage generation curve
C. voltage current curve
D. magnetization curve
Answer: Option D
Solution:
159. Majority of alternators in use have
A. revolving ac armature winding
B. stationary field type construction
C. revolving field type construction
D. stationary ac armature winding
Answer: Option C
Solution:
160. The stator of an alternator is identical to that of a
A. dc generator
B. 1 phase induction motor
C. 3 phase induction motor
D. Rosenberg generator
Answer: Option C
Solution:
161. Excessive motor vibration is caused by
A. too much brush tension
B. open armature coil
C. worn bearings
D. bent shaft
Answer: Option C
Solution:
162. Hot bearings of a dc motor may be caused by
A. poor ventilation
B. loose coupling
C. incorrect voltage
D. lack of dirty lubricant
Answer: Option D
Solution:
163. Intermittent sparking at the brushes of dc motor may be caused due to
A. an open armature coil
B. loose coupling
C. intermittent load
D. incorrect voltage
Answer: Option A
Solution:
164. When the load on a transformer is increased, the eddy current loss
A. is decreased
B. remains the same
C. is increased
D. becomes zero
Answer: Option B
Solution:
165. The yoke of a dc machine is made of
A. silicon steel
B. aluminum
C. soft iron
D. cast steel
Answer: Option A
Solution:
166. The armature of a dc machine is made of
A. silicon steel
B. cast steel
C. wrought iron
D. soft iron
Answer: Option C
Solution:
167. The voltage per turn of the primary of a transformer is _________ the voltage per turn of the secondary
A. more than
B. the same as
C. less than
D. twice
Answer: Option B
Solution:
168. The winding of the transformer with greater number of turns will be
A. high voltage winding
B. low voltage winding
C. either high or low voltage winding
D. high power
Answer: Option A
Solution:
169. The coupling field between electrical and the mechanical systems of a dc machine is
A. electric field
B. both electric and magnetic fields
C. magnetic field
D. electromagnetic field
Answer: Option C
Solution:
170. The real working Part of a dc machine is the
A. commutator
B. armature winding
C. field winding
D. stator
Answer: Option B
Solution:
171. Which DC machines are the most common?
A. 2 pole
B. 6 pole
C. 4 pole
D. 8 pole
Answer: Option C
Solution:
172. The core type transformer provides
A. much longer magnetic pattern
B. lesser average length per turn
C. shorter magnetic path
D. longer magnetic path
Answer: Option C
Solution:
173. A machine with field excitation by both shunt and series windings
A. complex machine
B. compound machine
C. universal machine
D. shunt/ series machine
Answer: Option B
Solution:
174. The armature winding of a dc machine is placed on the rotor to
A. save iron
B. facilitate commutation
C. reduce losses
D. reduce armature reaction
Answer: Option B
Solution:
175. The yoke of a dc machine carries _____ poke flux
A. one third of
B. two times of
C. one half of
D. one fourth of
Answer: Option C
Solution:
176. The greatest eddy current loss occurs in the __________ of a dc machine
A. field poles
B. commutating process
C. yoke
D. armature
Answer: Option D
Solution:
177. The commutator pitch for a simplex lap winding is equal to
A. number of poles of the machines
B. 1
C. poles pairs
D. 2
Answer: Option B
Solution:
178. In a simplex wave winding, the number of parallel paths is equal to
A. number of poles in the machine
B. 2
C. number of pair poles
D. 1
Answer: Option B
Solution:
179. In a practical transformer, copper losses account for how many percent of the total losses?
A. 75%
B. 25%
C. 85%
D. 95%
Answer: Option C
Solution:
180. By laminating the core of a transformer, __________ decreases
A. leakage reactance
B. eddy current loss
C. hysteresis loss
D. copper loss
Answer: Option B
Solution:
181. The number of parallel paths in a simplex lap winding is equal to
A. 2
B. number of poles
C. number of pair poles
D. 1
Answer: Option B
Solution:
182. In a dc machine the number of commutator segments is equal to
A. number of conductors
B. number of coils
C. twice the number of poles
D. twice the number of coils
Answer: Option B
Solution:
183. A dc compound generator having full load terminal voltage equal to the no load generator voltage is called __________ generator
A. under compounded
B. flat compounded
C. over compounded
D. un compounded
Answer: Option B
Solution:
184. The terminal voltage of a __________ generator vary widely with changes in load current
A. series
B. flat compounded
C. shunt
D. over compounded
Answer: Option A
Solution:
185. The nature of armature winding of a dc machine is decided by
A. front pitch
B. back pitch
C. commutator path
D. number of coils
Answer: Option C
Solution:
186. The voltage regulation of an alternator is larger than of a dc generator because of
A. large armature resistance
B. large leakage reactance
C. complex effects of armature reaction
D. small armature resistance
Answer: Option C
Solution:
187. High voltage dc machines use what winding?
A. Lap
B. wave
C. either lap or wave
D. open circuit
Answer: Option B
Solution:
188. In a lap winding, the number of the brushes required is equal to
A. number of poles
B. commutator pitch
C. number of pairs of poles
D. number of coils
Answer: Option A
Solution:
189. What is the approximate efficiency of large transformer?
A. 65%
B. 80%
C. 50%
D. 95%
Answer: Option D
Solution:
190. In a wave winding, the commutator pitch is approximately equal to
A. pole pitch
B. thrice the pole pitch
C. twice the pole pitch
D. half the pole pitch
Answer: Option C
Solution:
191. A triplex wave winding will have _________ parallel paths
A. 6
B. 4
C. 2
D. 8
Answer: Option A
Solution:
192. For a given dc generator, the generated voltage depends upon
A. flux only
B. both speed and flux
C. speed only
D. armature rotation
Answer: Option B
Solution:
193. For the same rating, a dc machine has _________ an ac machine
A. the same weight as
B. less weight than
C. more weight than
D. half the weight than
Answer: Option C
Solution:
194. Difference between the speed of a rotating magnetic field and the associated rotor
A. split
B. salient pole
C. slip
D. pull out torque
Answer: Option C
Solution:
195. The field winding of a dc shunt machine usually carries ___________ of the rated current of the machine
A. 2% to 5%
B. more than 20%
C. 15% to 20%
D. less than 0.5%
Answer: Option A
Solution:
196. A separately excited dc generator is not used because
A. it is costly
B. a separate dc source is required for field circuit
C. voltage drops considerably with load
D. it is bulky
Answer: Option B
Solution:
197. The effect of armature reaction is to
A. decreased the total flux
B. make the air gap flux uniform
C. increase the total flux
D. make the flux constant
Answer: Option A
Solution:
198. In a dc generator armature reaction __________ pole tip
A. weakens the flux at the trailing
B. weakens the flux at the leading
C. strengthens the flux at the leading
D. strengthens the flux at the trailing
Answer: Option B
Solution:
199. The greatest percentage of the heat loss in a dc machine is due to
A. eddy current loss
B. copper loss
C. hysteresis loss
D. frictional loss
Answer: Option B
Solution:
200. The size of a dc generator can be reduced by using
A. lap winding
B. high resistance winding material
C. iron commutator
D. magnetic material of high permeability
Answer: Option D
Solution:
Questions and Answers in Power Generators, Sources, Principles, Applications
Following is the list of practice exam test questions in this brand new series:
Complete List of MCQ in Electronics Engineering per topic
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