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MCQOPTIONS
This section includes 378 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 201. |
In D.C. generators on no-load, the air gap flux distribution in space is |
| A. | Sinusoidal |
| B. | Triangular |
| C. | Pulsating |
| D. | Flat topped |
| Answer» E. | |
| 202. |
Magnetic field in a D.C. generator is produced by |
| A. | Electromagnets |
| B. | Permanent magnets |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» B. Permanent magnets | |
| 203. |
In a D.C. generator the ripples in the direct e.m.f. generated are reduced by |
| A. | Using conductor of annealed copper |
| B. | Using commutator with large number of segments |
| C. | Using carbon brushes of superior quality |
| D. | Using equalizer rings |
| Answer» D. Using equalizer rings | |
| 204. |
The armature core of a D.C. generator is usually made of |
| A. | Silicon steel |
| B. | Copper |
| C. | Nonferrous material |
| D. | Cast-iron |
| Answer» B. Copper | |
| 205. |
When two D.C. generators are running in parallel an equalizer bar is used |
| A. | To increase the series flux |
| B. | To increase the generated e.m.f. |
| C. | To reduce the combined effect of armature reaction of both the machines |
| D. | So that the two identical machines will pass approximately equal currents to the load |
| Answer» E. | |
| 206. |
For a D.C. machines laboratory following type of D.C. supply will be suitable |
| A. | Rotary converter |
| B. | Mercury are rectifier |
| C. | Induction motor D.C. generator set |
| D. | Synchronous motor D.C. generator set |
| Answer» D. Synchronous motor D.C. generator set | |
| 207. |
The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except |
| A. | Armature reaction |
| B. | Armature resistance drop |
| C. | Field weakening due to armature reaction and armature |
| D. | Commutation |
| Answer» E. | |
| 208. |
The main factor which leads to unstable parallel operation of flat and over compounded generators is |
| A. | their rising voltage characteristics |
| B. | unequal number of turns in their series field windings |
| C. | unequal speed regulation of their primemovers |
| D. | unequal series field resistances |
| Answer» B. unequal number of turns in their series field windings | |
| 209. |
To avoid formation of grooves in the commutator of a D.C. machine |
| A. | The brushes of opposite polarity should track each other |
| B. | The brushes of same polarity should track each other |
| C. | Brush position has no effect on the commutator grooving |
| D. | All of the above |
| Answer» B. The brushes of same polarity should track each other | |
| 210. |
The demagnetizing component of armature reaction in a D.C. generator |
| A. | Reduces generator e.m.f. |
| B. | Increases armature speed |
| C. | Reduces interpoles flux density |
| D. | Results in sparking trouble |
| Answer» B. Increases armature speed | |
| 211. |
Welding generator will have |
| A. | Lap winding |
| B. | Wave winding |
| C. | Delta winding |
| D. | Duplex wave winding |
| Answer» B. Wave winding | |
| 212. |
Eddy currents are induced in the pole shoes of a D.C. machine due to |
| A. | Oscillating magnetic field |
| B. | Pulsating magnetic flux |
| C. | Relative rotation between field and armature |
| D. | All above |
| Answer» D. All above | |
| 213. |
The number of brushes in a commutator depends on |
| A. | Speed of armature |
| B. | Type of winding |
| C. | Voltage |
| D. | Amount of current to be collected |
| Answer» E. | |
| 214. |
Which of the following generating machine will offer constant voltage on all loads? |
| A. | Self-excited generator |
| B. | Separately excited generator |
| C. | Level compounded generator |
| D. | All of the above |
| Answer» D. All of the above | |
| 215. |
In lap winding, the number of brushes is always |
| A. | Double the number of poles |
| B. | Same as the number of poles |
| C. | Half the number of poles |
| D. | Two |
| Answer» C. Half the number of poles | |
| 216. |
Open circuited armature coil of a D.C. machine is |
| A. | Identified by the scarring of the commutator segment to which open circuited coil is connected |
| B. | Indicated by a spark completely around the commutator |
| C. | Both (A) and (B) |
| D. | None of the above |
| Answer» D. None of the above | |
| 217. |
The commutator segments are connected to the armature conductors by means of |
| A. | Copper lugs |
| B. | Resistance wires |
| C. | Insulation pads |
| D. | Brazing |
| Answer» B. Resistance wires | |
| 218. |
Wave winding is composed of |
| A. | Any even number of conductors |
| B. | Any odd number of conductors |
| C. | That even number which is exact multiple of poles + 2 |
| D. | That even number which is exact multiple of poles |
| Answer» D. That even number which is exact multiple of poles | |
| 219. |
Lap winding is composed of |
| A. | Any even number of conductors |
| B. | Any odd number of conductors |
| C. | That even number which is exact multiple of poles + 2 |
| D. | That even number which is exact multiple of poles |
| Answer» B. Any odd number of conductors | |
| 220. |
Brushes of D.C. machines are made of |
| A. | Carbon |
| B. | Soft copper |
| C. | Hard copper |
| D. | All of above |
| Answer» B. Soft copper | |
| 221. |
A separately excited generator as compared to a self-excited generator |
| A. | Is amenable to better voltage control |
| B. | Is more stable |
| C. | Has exciting current independent of load current |
| D. | Has all above features |
| Answer» E. | |
| 222. |
With a D.C. generator which of the following regulation is preferred? |
| A. | 100% regulation |
| B. | Infinite regulation |
| C. | 50% regulation |
| D. | 1% regulation |
| Answer» E. | |
| 223. |
In a D.C. generator the magnetic neutral axis coincides with the geometrical neutral axis, when |
| A. | There is no load on the generator |
| B. | The generator runs on full load |
| C. | The generator runs on overload |
| D. | The generator runs on designed speed |
| Answer» B. The generator runs on full load | |
| 224. |
In D.C. generators, the brushes on commutator remain in contact with conductors which |
| A. | Lie under South Pole |
| B. | Lie under North Pole |
| C. | Lie under interpolar region |
| D. | Are farthest from the poles |
| Answer» D. Are farthest from the poles | |
| 225. |
Permeance is the reciprocal of |
| A. | Flux density |
| B. | Reluctance |
| C. | Ampere turns |
| D. | Resistance |
| Answer» C. Ampere turns | |
| 226. |
Shunt generators are most suited for stable parallel operation because of their |
| A. | rising voltage characteristics |
| B. | identical voltage characteristics |
| C. | drooping voltage characteristics |
| D. | linear voltage characteristics |
| Answer» D. linear voltage characteristics | |
| 227. |
The e.m.f. induced in the armature of a shunt generator is 600 V. The armature resistance is 0.1 ohm. If the armature current is 200 A, the terminal voltage will be |
| A. | 640 V |
| B. | 620 V |
| C. | 600 V |
| D. | 580 V |
| Answer» E. | |
| 228. |
In a commutator |
| A. | Copper is harder than mica |
| B. | Mica and copper are equally hard |
| C. | Mica is harder than copper |
| D. | None of the above |
| Answer» D. None of the above | |
| 229. |
In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when |
| A. | r.p.m. is more than 300 |
| B. | r.p.m. is less than 300 |
| C. | Number of poles is 4 |
| D. | Number of poles is 2 |
| Answer» E. | |
| 230. |
In D.C. generators, the cause of rapid brush wear may be |
| A. | Severe sparking |
| B. | Rough commutator surface |
| C. | Imperfect contact |
| D. | Any of the above |
| Answer» E. | |
| 231. |
In a D.C. generator the actual flux distribution depends upon |
| A. | size of air gap |
| B. | shape of the pole shoe |
| C. | clearance between tips of the adjacent pole shoes |
| D. | all of the above |
| Answer» E. | |
| 232. |
Following D.C. generator will be in a position to build up without any residual magnetism in the poles |
| A. | Series generator |
| B. | Shunt generator |
| C. | Compound generator |
| D. | Self-excited generator |
| Answer» E. | |
| 233. |
Which of the following statement about D.C. generators is false? |
| A. | Compensating winding in a D.C. machine helps in commutation |
| B. | In a D. C. generator interpoles winding is connected in series with the armature winding |
| C. | Back pitch and front pitch are both odd and approximately equal to the pole pitch |
| D. | Equalizing bus bars are used with parallel running of D.C. shunt generators |
| Answer» E. | |
| 234. |
Armature reaction in a generator results in |
| A. | Demagnetization of leading pole tip and magnetization of trailing pole tip |
| B. | Demagnetization of trailing pole tip and magnetization of leading pole tip |
| C. | Demagnetizing the center of all poles |
| D. | Magnetizing the center of all poles |
| Answer» B. Demagnetization of trailing pole tip and magnetization of leading pole tip | |
| 235. |
In the case of lap winding resultant pitch is |
| A. | Multiplication of front and back pitches |
| B. | Division of front pitch by back pitch |
| C. | Sum of front and back pitches |
| D. | Difference of front and back pitches |
| Answer» E. | |
| 236. |
Which of the following D.C. generators will be in a position to build up without any residual magnetism in the poles ? |
| A. | Series generator |
| B. | Shunt generator |
| C. | Compound generator |
| D. | None of the above |
| Answer» E. | |
| 237. |
D.C. series generator is used |
| A. | To supply traction load |
| B. | To supply industrial load at constant voltage |
| C. | Voltage at the toad end of the feeder |
| D. | For none of the above purpose |
| Answer» D. For none of the above purpose | |
| 238. |
The series field of a short-shunt D.C. generator is excited by |
| A. | external current |
| B. | armature current |
| C. | shunt current |
| D. | load current |
| Answer» E. | |
| 239. |
In a shunt generator the voltage build up is generally restricted by |
| A. | speed limitation |
| B. | armature heating |
| C. | insulation restrictions |
| D. | saturation of iron |
| Answer» E. | |
| 240. |
A D.C. welding generator has |
| A. | Lap winding |
| B. | Wave moving |
| C. | Duplex winding |
| D. | Any of the above |
| Answer» B. Wave moving | |
| 241. |
The resistance of armature winding depends on |
| A. | Length of conductor |
| B. | Cross-sectional area of the conductor |
| C. | Number of conductors |
| D. | All of the above |
| Answer» E. | |
| 242. |
In any rotating machine that part which houses the conductors and in which e.m.f. induced is to be utilized is called |
| A. | Rotor |
| B. | Stator |
| C. | Field |
| D. | Armature |
| Answer» E. | |
| 243. |
For the parallel operation of two or more D.C. compound generators, we should ensure that |
| A. | Voltage of the incoming generator should be same as that of bus bar |
| B. | Polarity of incoming generator should be same as that of bus bar |
| C. | All the series fields should be run in parallel by means of equalizer connection |
| D. | Series fields of all generators should be either on positive side or negative side of the armature |
| Answer» E. | |
| 244. |
In case of a 4 pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be |
| A. | 4 |
| B. | 8 |
| C. | 16 |
| D. | 32 |
| Answer» C. 16 | |
| 245. |
The function of pole shoes in the case of D.C. machine is |
| A. | To reduce the reluctance of the magnetic path |
| B. | To spread out the flux to achieve uniform flux density |
| C. | To support the field coil |
| D. | To discharge all the above functions |
| Answer» E. | |
| 246. |
Which of the following generators will be preferred if they are required to be run in parallel? |
| A. | Shunt generators |
| B. | Series generators |
| C. | Compound generators |
| D. | None of the above |
| Answer» B. Series generators | |
| 247. |
If brushes of a D.C. generator are moved in order to bring these brushes in magnetic neutral axis, there will be |
| A. | Demagnetization only |
| B. | Cross magnetization as well as magnetization |
| C. | Cross-magnetization as well as demagnetizing |
| D. | Cross magnetization only |
| Answer» D. Cross magnetization only | |
| 248. |
In over compounded generator, full load terminal voltage is%! |
| A. | Almost zero |
| B. | Less than no load terminal voltage |
| C. | More than no load terminal voltage |
| D. | Equal to no-load terminal voltage |
| Answer» D. Equal to no-load terminal voltage | |
| 249. |
To achieve sparkless commutation brushes of a D.C. generator are rockedm ahead so as to bring them%! |
| A. | just ahead of magnetic neutral axis |
| B. | in magnetic neutral axis |
| C. | just behind the magnetic neutral axis |
| Answer» B. in magnetic neutral axis | |
| 250. |
Which of the following generator will have negligible terminal voltage while running on no-load?%! |
| A. | Series generator |
| B. | Shunt generator |
| C. | Compound generator |
| D. | Separately excited generator |
| Answer» B. Shunt generator | |