378 + Mcqs in D.C. Generators Page 6 McqOptions

251.	In case of D.C. machines, mechanical losses are primary function of%!
A.	Current
B.	Voltage
C.	Speed
D.	None of above
Answer» D. None of above

Discussion

252.	In a D.C. generator in case the resistance of the field winding is increased, then output voltage will%!
A.	Increase
B.	Decrease
C.	Remain unaffected
D.	Fluctuate heavily
Answer» C. Remain unaffected

Discussion

253.	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

Discussion

254.	The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is%!
A.	2
B.	4
C.	6
D.	8
Answer» C. 6

Discussion

255.	Number of tapings for each equalizer ring is equal to%!
A.	Number of pole pairs
B.	Number of poles
C.	Number of parallel paths
D.	Number of commutator segments
Answer» B. Number of poles

Discussion

256.	*$_Permeance is the reciprocal of?
A.	Flux density
B.	Reluctance
C.	Ampere turns
D.	Resistance
Answer» C. Ampere turns

Discussion

257.	*$_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

Discussion

258.	*$_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.

Discussion

259.	*$_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.

Discussion

260.	*$_A D.C. welding generator has?
A.	Lap winding
B.	Wave moving
C.	Duplex winding
D.	Any of the above
Answer» B. Wave moving

Discussion

261.	*$_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.

Discussion

262.	/_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.

Discussion

263.	/_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

Discussion

264.	/_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

Discussion

265.	/_Which of the following could be lamina proximately the thickness of laminations of a D.C. machine??
A.	0.005 mm
B.	0.05 mm
C.	0.5 m
D.	5 m
Answer» D. 5 m

Discussion

266.	/_The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is?
A.	2
B.	4
C.	6
D.	8
Answer» C. 6

Discussion

267.	/_Number of tapings for each equalizer ring is equal to?
A.	Number of pole pairs
B.	Number of poles
C.	Number of parallel paths
D.	Number of commutator segments
Answer» B. Number of poles

Discussion

268.	/_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.

Discussion

269.	/_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

Discussion

270.	/_If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to?
A.	reverse the field connections
B.	increase the field resistance
C.	increase the speed of primemover
D.	check armature insulation resistance
Answer» B. increase the field resistance

Discussion

271.	/_In a D.C. generator the critical resistance refers to the resistance of?
A.	Brushes
B.	Field
C.	Armature
D.	Load
Answer» C. Armature

Discussion

272.	/_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

Discussion

273.	/_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

Discussion

274.	/_If a D.C. generator fails to build up the probable cause could not be?
A.	Imperfect brush contact
B.	Field resistance less than the critical resistance
C.	No residual magnetism in the generator
D.	Faulty shunt connections tending to reduce the residual magnetism
Answer» C. No residual magnetism in the generator

Discussion

275.	/_If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by?
A.	Blv
B.	Blv¬¨‚â§
C.	Bl¬¨‚â§v
D.	Bl¬¨‚â§v¬¨‚â§
Answer» B. Blv¬¨‚â§

Discussion

276.	/_Satisfactory commutation of D.C. machines requires?
A.	Brushes should be of proper grade and size
B.	Brushes should smoothly run in the holders
C.	Smooth, concentric commutator properly undercut
D.	All of the above
Answer» E.

Discussion

277.	/_A shunt generator can self-excite?
A.	Only if the resistance of the field circuit is less than critical value
B.	Only if the resistance of the field circuit is greater than critical value
C.	Irrespective of the value of the resistance in the field circuit
D.	None of the above
Answer» B. Only if the resistance of the field circuit is greater than critical value

Discussion

278.	/_Copper brushes in D.C. machine are used?
A.	Where low voltage and high currents are involved
B.	Where high voltage and small currents are involved
C.	In both of the above cases
D.	In none of the above cases
Answer» B. Where high voltage and small currents are involved

Discussion

279.	/_A D.C. generator works on the principle of?
A.	Lenz's law
B.	Ohm's law
C.	Faraday's law of electromagnetic induction
D.	None of the above
Answer» D. None of the above

Discussion

280.	/_Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be?
A.	270 V
B.	267.5 V
C.	265 V
D.	257.4 V
Answer» C. 265 V

Discussion

281.	_ 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

Discussion

282.	_ 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.

Discussion

283.	_ 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

Discussion

284.	_ 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

Discussion

285.	_ 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.

Discussion

286.	_ 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.

Discussion

287.	_ 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

Discussion

288.	_ 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.

Discussion

289.	_ 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

Discussion

290.	_ Inter-pole flux should be sufficient to$?
A.	Neutralize the commutating self induced e.m.f.
B.	Neutralize the armature reaction flux
C.	Neutralize both the armature reaction flux as well as commutating e.m.f. induced in the coil
D.	Perform none of the above functions
Answer» D. Perform none of the above functions

Discussion

291.	_ In a D.C. machine stray loss is the sum of$?
A.	Total copper loss and mechanical loss
B.	Armature copper loss and iron loss
C.	Shunt field copper loss and mechanical loss
D.	Iron loss and mechanical loss
Answer» E.

Discussion

292.	_ 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.

Discussion

293.	_ 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

Discussion

294.	_ The bearings used to support the rotor shafts are generally$?
A.	Ball bearings
B.	Bush bearings
C.	Magnetic bearings
D.	Needle bearings
Answer» B. Bush bearings

Discussion

295.	_ While applying Fleming's right-hand rule to and the direction of induced e.m.f., the thumb points towards$?
A.	Direction of induced e.m.f.
B.	Direction of flux
C.	Direction of motion of the conductor if forefinger points in the direction of generated e.m.f.
D.	Direction of motion of conductor, if forefinger points along the lines of flux
Answer» E.

Discussion

296.	_ Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be$?
A.	270 V
B.	267.5 V
C.	265 V
D.	257.4 V
Answer» C. 265 V

Discussion

297.	_ Welding generator will have$?
A.	Lap winding
B.	Wave winding
C.	Delta winding
D.	Duplex wave winding
Answer» B. Wave winding

Discussion

298.	_ In a separately excited generator supplying rated load the armature reaction:$?
A.	Is always present
B.	Is always absent
C.	May be sometimes present
D.	None of the above
Answer» B. Is always absent

Discussion

299.	_ A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be$?
A.	Zero
B.	About 2 V
C.	About 50 V
D.	220 V
Answer» C. About 50 V

Discussion

300.	_ Armature coil is short circuited by brushes when it lies$?
A.	Along neutral axis
B.	Along field axis
C.	In any of the above positions
D.	In none of the above positions
Answer» B. Along field axis

Discussion

Explore topic-wise MCQs in Electrical Engineering.

In case of D.C. machines, mechanical losses are primary function of%!

In a D.C. generator in case the resistance of the field winding is increased, then output voltage will%!

Which of the following generators will be preferred if they are required to be run in parallel?%!

The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is%!

Number of tapings for each equalizer ring is equal to%!

*$_Permeance is the reciprocal of?

*$_In a commutator?

*$_Following D.C. generator will be in a position to build up without any residual magnetism in the poles?

*$_Which of the following D.C. generators will be in a position to build up without any residual magnetism in the poles ??

*$_A D.C. welding generator has?

*$_For the parallel operation of two or more D.C. compound generators, we should ensure that?

*/*_The number of brushes in a commutator depends on?

*/*_For a D.C. machines laboratory following type of D.C. supply will be suitable?

*/*_Magnetic field in a D.C. generator is produced by?

*/*_Which of the following could be lamina proximately the thickness of laminations of a D.C. machine??

*/*_The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is?

*/*_Number of tapings for each equalizer ring is equal to?

*/*_A separately excited generator as compared to a self-excited generator?

*/*_The commutator segments are connected to the armature conductors by means of?

*/*_If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to?

*/*_In a D.C. generator the critical resistance refers to the resistance of?

*/*_Which of the following generators will be preferred if they are required to be run in parallel??

*/*_The demagnetizing component of armature reaction in a D.C. generator?

*/*_If a D.C. generator fails to build up the probable cause could not be?

*/*_If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by?

*/*_Satisfactory commutation of D.C. machines requires?

*/*_A shunt generator can self-excite?

*/*_Copper brushes in D.C. machine are used?

*/*_A D.C. generator works on the principle of?

*/*_Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be?

_ Shunt generators are most suited for stable parallel operation because of their$?

_ The resistance of armature winding depends on$?

_ D.C. series generator is used$?

_ In case of a 4 pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be$?

_ Which of the following statement about D.C. generators is false?$?

_ In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when$?

_ Which of the following generating machine will offer constant voltage on all loads?$?

_ The terminal voltage of a D.C. shunt generator drops on load because of all of the following reasons except$?

_ In a D.C. generator the ripples in the direct e.m.f. generated are reduced by$?

_ Inter-pole flux should be sufficient to$?

_ In a D.C. machine stray loss is the sum of$?

_ With a D.C. generator which of the following regulation is preferred?$?

_ Wave winding is composed of$?

_ The bearings used to support the rotor shafts are generally$?

_ While applying Fleming's right-hand rule to and the direction of induced e.m.f., the thumb points towards$?

_ Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be$?

_ Welding generator will have$?

_ In a separately excited generator supplying rated load the armature reaction:$?

_ A 220 V D.C. generator is run at full speed without any excitation. The open circuit voltage will be$?

_ Armature coil is short circuited by brushes when it lies$?

/_The number of brushes in a commutator depends on?

/_For a D.C. machines laboratory following type of D.C. supply will be suitable?

/_Magnetic field in a D.C. generator is produced by?

/_Which of the following could be lamina proximately the thickness of laminations of a D.C. machine??

/_The number of armature parallel paths in a two-pole D.C. generator having duplex lap winding is?

/_Number of tapings for each equalizer ring is equal to?

/_A separately excited generator as compared to a self-excited generator?

/_The commutator segments are connected to the armature conductors by means of?

/_If a self excited D.C. generator after being installed, fails to build up on its first trial run, the first thing to do is to?

/_In a D.C. generator the critical resistance refers to the resistance of?

/_Which of the following generators will be preferred if they are required to be run in parallel??

/_The demagnetizing component of armature reaction in a D.C. generator?

/_If a D.C. generator fails to build up the probable cause could not be?

/_If B is the flux density, I the length of conductor and v the velocity of conductor, then induced e.m.f. is given by?

/_Satisfactory commutation of D.C. machines requires?

/_A shunt generator can self-excite?

/_Copper brushes in D.C. machine are used?

/_A D.C. generator works on the principle of?

/_Two D.C. shunt generators, each with armature resistance of 0.02 ohm and field resistance of 50 ohm run in parallel and supply a total current of 1000 amperes to the load circuit. If their e.m.fs. are 270 V and 265 V, their bus bar voltage will be?