Power system top questions

1➤ Which of the equipment/instrument is not used for controlling voltage in a Power system network?

Series inductorTap changing transformerShunt capacitorSeries capacitor

2➤ How can the steady state stability be increased?

Increasing the excitation of the generator only Reducing the reactance only Increasing the excitation of the motor only 1,2 and 3

3➤ Which of the following lines has highest steady state limit?

400 kV220 kV 132 kV66 kV

4➤ The equal area criterion of stability is applicable to-

Multi-machine system only Two machine system and infinite bus bars One machine system and infinite bus bars None of the above

5➤ Active Power is a function of _______ and reactive power is a function of _______.

Voltage phase angle, voltage phase angleVoltage magnitude, voltage magnitudeVoltage magnitude, voltage phase angleVoltage phase angle, voltage magnitude

6➤ The electrical power is not transmitted by D.C. due to its limitation like-

Can not be stepped up or down None of aboveGreater voltage drop in D.C. Skin effect in D.C

7➤ HVDC link between two power systems is used to

avoid transfer of effects of one system to otherimprove stabilitytransfer more power Only 1,2 and 3

8➤ For enhancing the power transmission in/along EHV transmission, the most preferred method is to connect a

series capacitive compensator in the lineshunt capacitive compensator at the sending endshunt inductive compensator at the receiving endseries inductive compensator in the line

9➤ Steady state stability of a power system is the ability of the power system to :

Maintain a spinning reserve margin at all timesMaintain synchronism between machines and on external tie linesMaintain frequency exactly at 50 Hzmaintain voltage at the rated voltage level

10➤ If the capacitance of transmission line is increased, the transmitted power will

decreaseremain same increasetend to be zero at receiving end

11➤ Harmonics in power system are not generated by :

Non linear switchesBalanced loading with a balanced sourceBalanced source and unbalanced loadUnbalanced source and balanced load

12➤ ________ is also known as average power factor tariff.

kVA Maximum demand tariff kW and kVAR tariffThree part tariff Sliding scale tariff

13➤ The function of Ball mill in thermal power plant is:

To supply feed waterTo create draughtTo prepare fine powdered coalTo generate electricity

14➤ Which of the following is NOT a part of coal based thermal power plant?

ChimneyBoilerControl rodsEconomiser

15➤ For high voltage DC transmission, state TRUE/FALSE for following statements:.A. It does not suffer from skin effect. B. The stability problem is severe and requires compensation.

True TrueTrue false False trueFalse false

16➤ In AC transmission system the load current is:

directly proportional to power factorindependent of power factorinversely proportional to power factorinversely proportional to square of power factor

17➤ What are the advantage of DC transmission system over AC transmission system?

Corona limits are negligible for DC circuit as compared to AC circuit DC system is economical for long lineThere is no skin effect in DC system All of the above

18➤ Regulation of a line is defined as percentage …….. in voltage with ............ sending end voltage when the load is thrown off at the receiving end voltage

Decrease-FixedDecrease-VariableIncrease - VariableIncrease-fixed

19➤ The characteristic impedance of a lossless transmission line necessarily is:

Purely realPurely imaginaryComplex NumberCan't say

20➤ Which of the following applications is incorrect for gas turbine plants for the purpose of power plant engineering?

To drive generators and supply peak load in steam, diesel or hydro plantsTo act as good part load efficiency power plantTo work as combination plants with conventional steam boilersTo supply mechanical drive of auxiliarie

21➤ The unique advantages of a hydropower plant are that it

Is located in hillsProduces no pollutionBurns no fuel Both B and C

22➤ The most appropriate operating speeds in rpm of generators used in thermal, nuclear and hydro power plants would be respectively-

3000, 300 and 15003000, 3000 and 3001500, 1500 and 30001000, 900 and 750

23➤ The hydel power plant of run-off river type should be provided with pondage so that the

Kinetic energy of the running water is fully utilized.Pressure inside the turbine casing remains constantOperating head is controlledFirm capacity of the plant is increased

24➤ The sudden change of pressure in penstock pipes due to sudden reduction of load is avoided using

water hammertail race spill waysurge tank

25➤ Which one of the following A.C.S.R. conductors is having lowest cross-sectional area?

ZebraDogPantherDeer

26➤ The power which is available under emergency conditions is

Spinning reserveFirm reserveHot reserveCold reserve

27➤ The shoft circuit kVA is maximum when the fault occurs .

Near the generatorIn between the middle and the end of the transmission line.At the middle of the transmission lineAt the end of the transmission line

28➤ The smaller the lagging reactive power drawn by the circuit,

The higher is the power factorThe smaller is the power factor. There is no change in the power factorThe higher is the active power

29➤ In order to improve the voltage profile of the line, compensation is resorted by providing.

Resistors at the receiving end.Insulators at the receiving endReactors at the receiving endCapacitors at the receiving end

30➤ Due to the effect of arc resistance, a relay tends to

UnderreachDownreachOverreachReach

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