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MCQOPTIONS
This section includes 354 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
The electrical power output of an alternator will be maximum, if the power angle is equal to |
| A. | 0 degree |
| B. | 45 degree |
| C. | 90 degree |
| D. | 180 degree |
| Answer» D. 180 degree | |
| 102. |
The electrical power output in case of synchronous machine is |
| A. | Directly proportional to the power angle |
| B. | Inversely proportional to the power angle |
| C. | Directly proportional to the square of power angle |
| D. | None of these |
| Answer» B. Inversely proportional to the power angle | |
| 103. |
The effect of armature flux in an alternator depends on |
| A. | Magnitude of current flowing through the armature winding |
| B. | Nature of power factor of the load connected to the alternator |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 104. |
The disadvantages of scherbius system used for speed controlling in 3 phase induction motor is |
| A. | It cannot be used for slip ring induction motors |
| B. | It cannot be used for squirrel cage induction motors |
| C. | It can be used for large induction motors |
| D. | None of these |
| Answer» C. It can be used for large induction motors | |
| 105. |
“The direction of induced current in the rotor is so as to oppose the cause producing it”. This is given by |
| A. | Faraday’s law |
| B. | Lenz’s law |
| C. | Electromagnetic law |
| D. | Ampere’s law |
| Answer» C. Electromagnetic law | |
| 106. |
The direct method for finding the voltage regulation of an alternator is/are |
| A. | E.M.F method |
| B. | M.M.F. method |
| C. | Z.P.F method |
| D. | None of these |
| Answer» E. | |
| 107. |
The difference between field test and regenerative test is that |
| A. | Field test requires two identical machines while regenerative test requires only one machine |
| B. | In field test iron losses can be separated while in regenerative test it cannot |
| C. | In field test generator output is not fed back to the motor while in regenerative test generator output is fed back to the motor |
| D. | All of these |
| Answer» D. All of these | |
| 108. |
The diameter and axial length of rotors of smooth cylindrical type rotors are |
| A. | Small diameter, small axial length |
| B. | Large diameter, large axial length |
| C. | Large diameter, small axial length |
| D. | Small diameter, large axial length |
| Answer» E. | |
| 109. |
The curve obtained by plotting torque against slip from s = 1 to s = 0 is called torque slip characteristics. The nature of the graph in the low slip region and in the high slip region is |
| A. | Rising exponential, decaying exponential |
| B. | Both will be straight line |
| C. | Straight line, rectangular parabola |
| D. | Straight line, decaying exponential |
| Answer» D. Straight line, decaying exponential | |
| 110. |
The crawling and cogging is not predominant in |
| A. | Slip ring induction motor |
| B. | Squirrel cage induction motor |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Squirrel cage induction motor | |
| 111. |
The constant current transformer are mainly used for |
| A. | Supplying series connected street light |
| B. | Personal computers |
| C. | Arc welding |
| D. | Electric toys |
| Answer» B. Personal computers | |
| 112. |
The consequent pole method used for controlling the number of poles can be used for |
| A. | Only squirrel cage type motors |
| B. | Only slip ring induction motor |
| C. | For both squirrel cage and slip ring induction motor |
| D. | None of these |
| Answer» B. Only slip ring induction motor | |
| 113. |
The conductors which will cause distortion in the main field flux of d.c. machine are |
| A. | Demagnetizing armature conductors |
| B. | Cross magnetizing armature conductors |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 114. |
The compensating windings are used to neutralize the armature reaction in d.c. machines. These windings are connected |
| A. | Across armature |
| B. | In series with armature |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 115. |
The circle diagram can be used to |
| A. | Predict the performance of an induction motor under various load condition |
| B. | Find losses in an induction motor |
| C. | Efficiency of an induction motor |
| D. | All of these |
| Answer» E. | |
| 116. |
The cheapest starter for induction motor is |
| A. | Stator resistance starter |
| B. | Autotransformer starter |
| C. | Star-delta starter |
| D. | Rotor resistance starter |
| Answer» D. Rotor resistance starter | |
| 117. |
The change in excitation of the two alternators operating in parallel causes |
| A. | Only the kVAR sharing of two alternators without disturbing kW sharing of the two machines |
| B. | Only the kW sharing of two alternators without disturbing kVAR sharing of the two machines |
| C. | Both the kVAR sharing and kW sharing of two alternators |
| D. | None of the above |
| Answer» B. Only the kW sharing of two alternators without disturbing kVAR sharing of the two machines | |
| 118. |
The capacitor connected permanently in capacitor run motor |
| A. | Improves power factor |
| B. | Lowers power factor |
| C. | Does not affect power factor |
| Answer» B. Lowers power factor | |
| 119. |
The brush contact losses in a d.c. Machine is |
| A. | Inversely proportional to the square of current |
| B. | Directly proportional to the square of current |
| C. | Inversely proportional to the current |
| D. | Directly proportional to the current |
| Answer» E. | |
| 120. |
The best suited method for smooth speed control by controlling number of poles is |
| A. | Consequent poles method |
| B. | Multiple stator winding method |
| C. | Pole amplitude modulation method |
| D. | None of these |
| Answer» D. None of these | |
| 121. |
The basic difference between three point starter and four point starter is |
| A. | No volt coil is connected in series with the field winding in three point starter while connected independently across the supply in four point starte |
| B. | No volt coil is connected across supply in three point starter while in series with field winding in four point starter. |
| C. | No volt coil is connected across field winding in three point starter while connected across supply in four point starter. |
| D. | None of these |
| Answer» B. No volt coil is connected across supply in three point starter while in series with field winding in four point starter. | |
| 122. |
The back to back test is best suited for |
| A. | Small machines |
| B. | Medium size machines |
| C. | Large machines |
| D. | All of these |
| Answer» D. All of these | |
| 123. |
The average power factor at which V-V bank is operating is less than that with the load. The power factor is |
| A. | 57.7% of the balanced load power factor |
| B. | 66.7% of the balanced load power factor |
| C. | 86.6% of the balanced load power factor |
| D. | None of theses |
| Answer» D. None of theses | |
| 124. |
The armature reaction in d.c. machine causes distortion in the main field flux. This effect of armature reaction can be reduced by |
| A. | Increasing the length of air gap |
| B. | Decreasing the length of air gap |
| C. | Increasing the number of poles |
| D. | Decreasing the number of poles |
| Answer» B. Decreasing the length of air gap | |
| 125. |
The armature reaction effect in d.c. machines can be completely neutralized by using |
| A. | Only compensating winding |
| B. | Only interpoles |
| C. | Both compensating winding and interpoles |
| D. | None of these |
| Answer» D. None of these | |
| 126. |
The armature in d.c. machines are always placed on rotor |
| A. | Otherwise commutation will not be possible |
| B. | Otherwise there will not be any induced emf |
| C. | Otherwise current will not flow |
| D. | All of these |
| Answer» B. Otherwise there will not be any induced emf | |
| 127. |
The approximate value of torque angle at which maximum pull out torque will occur under practical circumstances is |
| A. | 90 degree |
| B. | 75 degree |
| C. | 60 degree |
| D. | 30 degree |
| Answer» C. 60 degree | |
| 128. |
The air gap in a salient pole machine is |
| A. | Maximum at the center of poles |
| B. | Least at the center of poles and increases while moving away from the center |
| C. | Maximum at the center and decreases while moving away from the center |
| D. | Equally distributed |
| Answer» C. Maximum at the center and decreases while moving away from the center | |
| 129. |
The air gap flux of induction motor does not contain |
| A. | 2nd harmonics |
| B. | 3rd harmonics |
| C. | 5th harmonics |
| D. | 7th harmonics |
| Answer» C. 5th harmonics | |
| 130. |
The advantages of star-delta starter over other types of starter is |
| A. | Cheapest of all |
| B. | Maintenance free |
| C. | Both (a) & (b) |
| D. | None of these |
| Answer» D. None of these | |
| 131. |
Scott connection is used for the conversion of |
| A. | Single phase to three phase |
| B. | Three phase to single phase |
| C. | Single phase to two phase |
| D. | All of these |
| Answer» D. All of these | |
| 132. |
Salient pole type rotors are generally used for the range of 125 rpm to 500 rpm. The limiting factor for the size of the rotor is the |
| A. | Rotating field type construction |
| B. | Rotating armature type construction |
| C. | Centrifugal force acting on the rotating member |
| D. | All of these |
| Answer» D. All of these | |
| 133. |
Salient pole alternators are best suitable for the application of |
| A. | Hydro electric power plant |
| B. | Thermal power plant |
| C. | Tidal power plant |
| D. | Nuclear power plant |
| Answer» B. Thermal power plant | |
| 134. |
Pulse transformers are small in size. The leakage inductance and permeability of alloy used is |
| A. | Low, high |
| B. | Low, low |
| C. | High, low |
| D. | High, high |
| Answer» B. Low, low | |
| 135. |
Practically in d.c. machines, it may happen that the emf induced in different parallel paths may not be same. This will cause inequality in brush arm currents and will give rise to copper losses. These effects can be avoided by using |
| A. | Compensating windings |
| B. | Interpoles |
| C. | Equalizer rings |
| D. | All of these |
| Answer» D. All of these | |
| 136. |
Practically, most of the alternators prefer which type of construction? |
| A. | Rotating field type |
| B. | Rotating armature type |
| C. | Both are equally important |
| D. | None of these |
| Answer» B. Rotating armature type | |
| 137. |
Practically in a synchronous motor, the pull-out torque will occur when the torque angle is nearly equal to |
| A. | 30° electrical |
| B. | 45 ° electrical |
| C. | 60 ° electrical |
| D. | 75 ° electrical |
| Answer» E. | |
| 138. |
Permanent magnet d.c. motors are extensively used in |
| A. | Automobiles |
| B. | Heaters |
| C. | Air conditioners |
| D. | All of these |
| Answer» E. | |
| 139. |
Out of two alternators which are sharing an inductive load equally, if excitation of one alternator is increased then |
| A. | Other alternator will deliver less current |
| B. | Other alternator will deliver more current |
| C. | Both will deliver equal current |
| D. | None of these |
| Answer» B. Other alternator will deliver more current | |
| 140. |
Out of electrical, mechanical and magnetic losses, the losses which is minimum is |
| A. | All are equal |
| B. | Electrical losses |
| C. | Magnetic losses |
| D. | Mechanical losses |
| Answer» E. | |
| 141. |
Out of different methods available for testing of d. c. motors, Swinburne’s test and Hopkinson’s test are commonly used in practice on |
| A. | Shunt generators |
| B. | Series motors |
| C. | Shunt motors |
| D. | All of these |
| Answer» D. All of these | |
| 142. |
Oscillations of the rotor about its new equilibrium position, due to sudden application or removal of load in synchronous motor is called |
| A. | Hunting |
| B. | Galloping |
| C. | Swinging |
| D. | Both (a) and (c) |
| E. | None of the above |
| Answer» E. None of the above | |
| 143. |
On unity power factor, the terminal voltage of an alternator is |
| A. | Always less than induced emf |
| B. | Always greater than induced emf |
| C. | Same as induced emf |
| D. | None of these |
| Answer» B. Always greater than induced emf | |
| 144. |
Neglecting saturation, if the current drawn from by a d.c. series motor is increased from 15 A to 18 A, then the increase in the torque expressed as percentage of initial torque will be |
| A. | 22 % |
| B. | 33% |
| C. | 44% |
| D. | 56.78% |
| Answer» D. 56.78% | |
| 145. |
Nature of the rotor power factor in running condition is always |
| A. | Leading |
| B. | Lagging |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 146. |
Most familiar application of zig - zag transformer is as |
| A. | Ground reference on an ungrounded system |
| B. | Converting single phase to two phase |
| C. | Reducing harmonics |
| D. | All of these |
| Answer» B. Converting single phase to two phase | |
| 147. |
Mechanical power developed in armature of a d.c. motor is given by |
| A. | Electrical power input to motor – copper losses |
| B. | Motor output + iron and friction losses |
| C. | Both (a) & (b) |
| D. | None of these |
| Answer» D. None of these | |
| 148. |
Low value of SCR in an alternator indicates |
| A. | High stability limit |
| B. | Low stability limit |
| C. | None of these |
| Answer» C. None of these | |
| 149. |
Laminations and varnish are used to reduce the eddy current losses. The laminations and varnish tends to present a |
| A. | High resistance path to eddy current |
| B. | Low resistance path to eddy current |
| C. | Low reluctance magnetic path |
| D. | High reluctance magnetic path |
| Answer» B. Low resistance path to eddy current | |
| 150. |
Kramer system for controlling the speed of 3 phase induction motor is mostly used for motors of |
| A. | Above 4000 kW |
| B. | Below 4000 kW |
| C. | Below 3000 kW |
| D. | None of these |
| Answer» B. Below 4000 kW | |