300 Important Alternator MCQ Question and Answer | PDF Free Download
1.Which one of the following method gives more accurate result for determination of voltage regulation of an alternator?
- AMMF method
- BSynchronous impedance method
- CPotier triangle or ZPF method
- DAmerican institution standard method
2.Slip test is conducted on a synchronous generator to determine
- ASlip
- BDirect axis reactance and quadrature axis reactance
- CPositive sequence reactance and negative sequence reactance
- DSub transient reactance
3.For maximum current during slip test on a synchronous machine the armature mmf align along
- AD-axis
- BQ-axis
- C45 degree to d-axis
- D45 degree to q-axis
4. Reluctance power is developed in which of the following machine?
- ASalient pole alternator
- BNon salient pole alternator
- CSquirrel cage induction motor
- DTransformer
5.In salient pole synchronous machine, maximum power occurs at a load angle of
- A0 degree
- B45 degree
- C90 degree
- DLess than 90 degree
6.An alternator with higher value of SCR has
- APoor voltage regulation and lower stability limit
- BBetter voltage regulation and higher stability limit
- CPoor voltage regulation and higher stability limit
- DBetter voltage regulation and low stability limit
7.The maximum power developed in cylindrical synchronous machine is occurs at a load angle of
- A90 degree
- B0 degree
- CGreater than 90 degree
- DLess than 90 degree
8.If the excitation of a 3-phase alternator operating on infinite bus bars is changed, which one of the following shall alter?
- AActive power of machine
- BReactive power of machine
- CTerminal voltage of machine
- DFrequency of machine
9.A 3-phase synchronous generator with constant steam input supplied power to an infinite bus at a lagging power factor. If the excitation is increased
- ABoth power angle and power factor decrease
- BBoth power angle and power factor increase
- CThe power angle decreases while power factor increases
- DThe power angle increases while power factor decreases
10.A turbo alternator set feeds power to a 3-phase constant voltage constant frequency bus. If the steam supply to the set is cut off, then the set will
- AContinue to run at rated speed in the same direction
- BContinue to run at a reduced speed in the same direction
- CRun at rated speed in the reverse direction
- DCome to stop
11.The mmf produced by single phase winding is
- APulsating and rotating with constant speed
- BPulsating and stationary
- CConstant in amplitude and stationery
- DConstant in amplitude and rotating
12.A polyphase field is
- APulsating and stationary
- BPulsating and rotating
- CConstant in amplitude and rotating at synchronous speed
- DConstant in amplitude and stationary in space
13.A synchronous generator has its field winding on the rotor and armature winding on the stator. When running under steady state conditions its air gap field is
- AStationary with respect to stator
- BRotating at synchronous speed with respect to rotor
- CRotating at synchronous speed against the direction of rotor rotation
- DRotating at synchronous speed in the direction of rotor rotation
14.The alternators are operated in parallel because it
- AIncreases the reliability of supply
- BMakes the repairing economical and convenient
- CIs easy to install an additional unit as and when required
- DAll of the above
15.Which one of the following is not necessary condition to be satisfied for synchronizing an incoming alternator to an already operating alternator?
- ASame voltage magnitude
- BSame frequency
- CSame prime mover speed
- DSame phase sequence
16.Which of the following methods used for synchronizing of 3-phsae synchronous generator is considered best one?
- AThree dark lamp method
- BTwo bright and one dark lamp method
- CSynchroscope
- DNone of these
17.While synchronizing a 3-phase alternator to the bus-bar the paralleling switch should be closed
- AJust before the pointer reaches the vertical position when moving in the fast direction
- BJust after the pointer passes the vertical position when moving in the fast direction
- CWhen pointer indicates fast position
- DWhen pointer indicates slow position
18.The two bright and one dark lamp method is used for
- ADetermination of phase sequence
- BSynchronizing of 3 phase alternators
- CSynchronizing of single-phase alternators
- DTransfer of load.
19.Desirable feature for successful parallel operation of two alternators is that both should have
- ASame resistance
- BSame reactance
- CHigher reactance in comparison to resistance
- DLow reactance in comparison to resistance
20.Two alternators are operating in parallel. For taking one of the alternators out from the system
- ALoad shared by this alternator is transferred to the other by adjusted the power fed to the prime mover before opening OCB
- BPower fed to the prime-mover is stopped
- COCB is switched off
- DLoad connected to the bus-bar is reduced.