300 Important DC Generator MCQ Question and Answer | PDF Free Download
1.The commutating flux produced by inter pole must be proportional to
- AArmature current
- BField current
- CBoth armature and field currents
- DNone of the above
2.The interpole air gap is ????that under the filed poles, in dc machines
- ASmaller than
- BLarger than
- CEqual to
- DNone of these
3.A dc machine is provided with both interpole and compensating windings. These two windings with respect to armature circuit will be in
- ASeries
- BParallel
- CFormer in series and the latter in parallel
- DFormer in parallel and the latter in series
4.The mmf necessary for establishment of flux in the magnetic circuit of a dc generator can be obtained by means of filed coils excited by
- ASome separate source
- BThe generator itself
- CEither of the above methods
- DNone of these
5.In a separately excited dc generator the field is connected
- AIn series with an armature
- BAcross the armature
- CTo an external supply source
- DNone of the above
6.Series field winding of a dc machine consists of
- AFew turns of thick wire
- BFew turns of thin wire
- CMany turns of thick wire
- DMany turns of thin wire
7.When the shunt field of a dc compound generator is connected across both the series filed and armature. This connection is called
- AShort shunt
- BLong shunt
- CCumulative compounding
- DDifferential compounding
8.The slight curvature at the lower end of the OCC of a self excited dc generator is due to
- AMagnetic inertia
- BResidual flux
- CHigh speed
- D High field resistance
9.The fall in speed of a dc generator due to increase in load can be corrected by
- ACooling the armature
- BIncreasing the excitation
- CReducing the load voltage
- DIncreasing the input to the prime mover
10.The magnetic field which initially induces emf in the armature in a self excited dc generator is because of
- APermanent magnets
- BArmature rotation
- CResidual magnetism
- DNone of the above
11.A generator may loose residual magnetism due to
- AHeating
- BVibration
- COver excitation
- DAny of these
12.In dc generators the residual magnetism is of the order of
- A2.5 %
- B10 %
- C15 %
- D25 %
13.A separately excited generator as compared to a self excited generator
- AIs more reliable
- BIs amenable to better voltage regulation
- CHas exciting current independent of load characteristic
- DHas all of the above features
14.The voltage at the terminals of a dc series generator running at rated rpm and no load will be
- AMore than the rated voltage
- BFull rated voltage
- CA very small voltage
- DZero
15.A dc series generator is provided with diverter and is delivering its rated current. If the diverter switch is opened, the terminal voltage will
- ARemain constant
- BDecrease
- CIncrease
- DNone of these
16.A 4 pole, 25 kW, 200 V wave wound dc shunt generator the current in each parallel path will be
- A62.5A
- B125 A
- C31.25A
- D250 A
17.A dc shunt generator is supplying load of 1.8 kW at 200 V. Its armature and filed resistances are 0.4 ohm and 200 ohm respectively. What is the generated emf?
- A190 V
- B196 V
- C204 V
- D210 V
18.If the field circuit resistance of a dc shunt generator exceeds its critical value, the generator
- AFails to build up voltage
- BBuild up a very light voltage
- CExceeds its current capacity
- DProduces power beyond its rating
19.A shunt generator has a critical field resistance of 200 ohm at a speed of 800 rpm. If the speed of the generator is increased to 1,000 rpm, what is the change in the critical filed resistance of the generator?
- ADecreases to 160 ohm
- BRemains the same at 200 ohm
- CIncreases to 250 ohm
- DIncreases to 312.5 ohm
20.The factor that is not responsible for drop in terminal voltage of a dc shunt generator on load is
- ACommutation
- BArmature reaction
- CArmature resistance drop
- DFiled weakening due to (b) and (c)