Practice MCQ machine+p.s

1➤ The commonly used material of condenser tube is

Admiralty brassMild steelCast ironAluminium

2➤ In an induction motor what is the ratio of rotor copper- loss and rotor input (A) (B) (C) (D)

S/(1-S)S1/S(1-S)

3➤ The pressure at the furnace is minimum in case of

Natural draught systemInduced draught system Balanced draught systemForce draught system

4➤ What are the conditions to be satisfied for alternators to be synchronized with an incoming supply? 1. Equal voltage 2. Equal frequency 3. Same power rating 4. Same phase sequence Select the correct answers using the code given below

1, 2 and 43 and 42, 3 and 41, 2 and 3

5➤ How can reactive power delivered by a synchronous generator be controlled?

By hanging the prime moves speedBy changing the direction of rotationBy changing the prime moves inputBy changing the excitation

6➤ In hard-tool applications which one of the following single-phase motors is used?

Capacitor run motorAC series motorCapacitor start motorShaded pole motor

7➤ What is the angle between the induced voltage and supply voltage of a synchronous motor under running generation?

Between 90° and 180° >180Greater than zero but =< 90°Zero

8➤ When does a synchronous motor operate with leading power factor current?

While it is heavily loadedWhile it is over excitedWhile it is critically excited While it is under excited

9➤ The crawling in the induction motor Is caused by

Harmonics developed in motorHigh loadsLow voltage supplyImproper design of stator lamination

10➤ Which of the following motors is most suitable for signaling devices and many kinds of timers

Inductance motord.c series motorReluctance motord.c shunt motor

11➤ According to Fleming’s right hand rule for finding the direction induced emf, when induced finger points in the direction of induced emf, forefinger will point the direction of

Motion of conductorLines of forceEither of the aboveNone of the above

12➤ Reheat factors in steam turbine depends on

Initial pressure and temperature onlyExit pressure onlyStage efficiency onlyAll of these

13➤ For the same maximum demand if load factors are decreased, the cost of generation will

IncreaseDecreaseRemain unchangedNone of these

14➤ Bundle conductors in a transmission line

None of theseNo effectIncreases radio interferenceReduce radio interference

15➤ For cooling of large size generators hydrogen is used because

All of theseIt has high thermal conductivity It offers reduced fire riskIt is light

16➤ A negative sequence relay is commonly used to protect

A transmission lineA bus bar A transformerAn alternator

17➤ Which part of a motor needs maximum attention for maintenance

Stator windingRotor windingBearingFrame

18➤ Which of the following is the advantages of electric breaking (A) (B) (C) (D)

More heat is generated during breakingIt avoids wear of track It is instantaneousAll of the above

19➤ The dc series motors are preferred for traction applications because

Torque and speed are inversely proportional to armature currenThe torque is proportional to square of armature Current and the speed is inversely proportional to the torqueThe torque is proportional to the square root of armature currentThe torque is proportional armature current

20➤ Sparking at the commutators of a dc motor may result in

Increased power consumptionDamage to the commutator’s insulationDamage to the commutator’s segmentsAll of the above

21➤ The flash point of transformers oil should be higher than

104°C80°C60°C40°C

22➤ A large value of short-circuit indicator

A poor power factorZero power factorA good power factorNone of the above

23➤ Which type of connection is employed for current transformers for the protection of star-delta connected 3-phase transformer

star-delta delta-starstar-stardelta-delta

24➤ Francis turbine is usually used for

For all headsHigh installation above 180mLow head installation up to 30mMedium head installation from 30m to 180m

25➤ Which of the following is not a source of power?

ThermocouplePhoto electric cellPhotovoltaic cell Solar cell

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