300 Important Alternator MCQ Question and Answer | PDF Free Download
1.Alternator operates on the principles of
- AElectromagnetic induction
- BSelf-induction
- CMutual induction
- DSelf or mutual induction
2.In a synchronous machine, if the field flux axis is ahead of the armature field axis in the direction of rotation, the machine operating is
- ASynchronous motor
- BSynchronous generator
- CAsynchronous motor
- DAsynchronous generator
3.The armature of an alternator
- Ais a stationary member
- Bis a revolving member
- Cis the frame
- DConsists of the winding into which current is induced
4.In modern alternators, the rotating part is
- AField system
- BArmature
- CArmature as well as field system
- DNone of the above
5.The current from the stator of an alternator is taken output the external load circuit through
- ASlip rings
- BCommutator segments
- CSolid connections
- DCarbon brushes
6.What is the primary reason for placing field on rotor in an alternator?
- ASmall power in the filed circuit
- BInsulation of high voltage is made easy on stator than on rotor
- CLarge power in stator
- DLarge current in stator
7.Which type of alternator is used in hydroelectric power stations?
- ANon salient pole alternator
- BTurbo generator
- CSalient pole alternator
- DSteam turbine alternator
8.In a synchronous machine, the stator frame serves the purpose of
- AHolding the armature stampings in position and also in some cases for circulating cold water for cooling
- BInsulating the armature windings
- CProviding path to the magnetic flux
- DProtecting the whole machine
9.In a synchronous machine, the stator frame is made of
- AStainless steel
- BCRGOS
- CCast iron or welded steel plates
- DLaminated silicon steel
10.The stator core of a synchronous machine is built up of ___laminations.
- AStainless steel
- BSilicon steel
- CCast iron
- DCast steel
11.The stator core stampings also have opening which make____ ventilating ducts to provide efficient cooling.
- AAxial
- BRadial
- Cradial as well as radial
- DNone of the above
12.The open slots are commonly used in the stator of a synchronous machine as
- AThe inductance of the winding is less
- BThey permit the placement of form wound and insulated coils giving least expensive and more satisfactory
- CBoth (a) and (b)
- DNone of these
13.The field system of an alternator is usually excited at
- A250/ 250 V DC
- B110 / 220 V AC
- C3-phase, 50 Hz 400 V
- D230V AC
14.The slip rings employed in a 3 phase synchronous machines are insulated for
- AOutput rated voltage
- BLow voltage
- CVery low voltage
- DVery high voltage
15.Squirrel cage bars placed in the rotor pole faces of an alternator help reducing hunting
- AAbove synchronous speed only
- BBelow synchronous speed only
- CAbove and below synchronous speeds both
- DNone of the above
16.Hydro-generators are generally employed to run at ___rpm
- A500
- B1000
- C1500
- D3000
17.In case of turbo alternator, rotor is made of
- AForged steel
- BCast iron
- CStainless steel
- DLaminated silicon steel
18.The salient pole rotors have
- AA large number of projecting poles carrying the filed coils
- BThick steel laminations riveted together and fixed to the rotor by a dove tail joint
- CPole faces usually provided with slots for damper windings
- DAll of the above
19.In salient pole field structure, the pole shoes cover about ___of pole pitch.
- AOne third
- BOne half
- CTwo third
- DWhole
20.Larger diameter salient pole rotors have shorter axial length because
- Ait occupies much less space
- Bif saves lot of copper in stator winding
- Cit reduces weight of the rotor
- Dnumber of conductors held in large circumference of rotor is very large and so they need not long