300 Important DC Generator MCQ Question and Answer | PDF Free Download
1.Poles of dc machine are often laminated to
- AReduce pulsation loss
- BReduce armature reaction
- CReduce iron weight
- DDissipate more heat
2.The ventilating ducts in most of the dc machines are
- ARadial
- BLongitudinal
- CRadial as well as longitudinal
- DNone of these
3.The armature core of a dc machine is usually made of
- AConducting material
- BInsulating material
- CNon ferrous material
- DSilicon steel
4.The armature of a dc machine is laminated
- ATo reduce the hysteresis loss
- BTo reduce eddy current loss
- CTo reduce the mass
- DTo reduce the inductance
5.Slot wedges in a dc machine are made up of
- AMild steel
- BSilicon steel
- CFiber
- DCast iron
6.The armature of a dc machine is made of silicon steel lamination to
- AReduce hysteresis loss only
- BReduce the eddy current loss only
- CIncrease the permeability
- DReduce both hysteresis and eddy current loss
7.The armature of a DC machine is always placed on the rotor to
- ASupport commutation
- BReduce losses
- CSave iron
- DDecrease armature reaction
8.The teeth in the armature of a dc machines are skewed to reduce
- AHysteresis loss
- BCopper loss
- CEddy current loss
- DVibrations
9.The commutator of a dc motor serves the purpose of
- AChanging friction
- BConverting dc into ac
- CReducing friction
- DAvoiding arc at the brushes
10.In a dc machine, the brushes are physically placed in the
- APolar axis and electrically connected to the coils lying in the interpolar axis
- BPolar axis electrically connected to the coils lying in the polar axis
- CInterpolar axis and electrically connected to the coils lying in polar axis
- DInterpolar axis and electrically connected to the coils lying in interpolar axis
11.The armature winding of a dc machine is placed on the rotor to
- AElectromechanical energy conversion
- BGeneration of voltage
- CSupport Commutation
- DDevelopment of torque
12.Wave winding is employed in a dc machine of
- AHigh current and low voltage rating
- BLow current and high voltage rating
- CHigh current and high voltage rating
- DLow current and low voltage rating
13.If two 8 ?pole dc machines of identical armatures are wound, one with lap winding and the other with wave winding, then
- AWave wound machine will have more rated current and more voltage
- BLap would machine will have more rated voltage and more current
- CLap wound machine will have more rated voltage and less current
- DWave wound machine will have more rated voltage and less current
14.In lap winding, the number of brushes is always _______the number of poles.
- ADouble
- BSame as
- CHalf
- DNone of these
15.A lap wound dc machine has 400 conductors and 8 poles. The voltage induced per conductor is 2V. The machine generates a voltage of
- A100 V
- B200 V
- C400 V
- D800 V
16.A 4-pole generator with 16 coils has a two-layer lap winding. The pole pitch is
- A32
- B16
- C8
- D4
17.Welding generator will have
- ALap winding
- BWave winding
- CEither lap or wave winding
- DNone of these
18.If in a 6-pole lap wound dc machine, the air gap under each pole is not the same, this is likely to result in
- AHigher terminal voltage
- BReduced eddy currents
- CUnequal currents in parallel paths
- DOne of the above
19.The number of parallel paths in the armature for a 4-pole duplex lap winding DC machine will be
- A2
- B4
- C6
- D8
20.Minimum number of coils of r400 V, 6-pole lap connected dc machine for a maximum voltage of 15V between adjacent commutator segments should be
- A80
- B160
- C200
- D400