Most common MCQ machine+P.S

1➤ Superheater is employed to: 1. remove moisture from the vapours 2. increase the temperature of vapours 3. heat the feed water Which of the given statements is incorrect?

3 1 and 2 2 and 31

2➤ Air pollution due to smoke around a thermal power plant can be reduced by installing

EconomizerSuper heaterElectrostatic PrecipitatorID fan

3➤ The average load factor of thermal power plants in India is

35 – 45 %80 – 95 %100%50 – 60 %

4➤ In which of the following given faults, all the sequence currents are equal?

LGLLLLGLLL

5➤ In a superheater

pressure rises and temperature remains the sametemperature rises and pressure dropspressure rises and temperature dropstemperature rises and pressure remains unchanged

6➤ Which of the following device is suitable for removal of gaseous pollutants ? .

Fabric filterElectrostatic PrecipitatorWet collector (Scrubber)Cyclone separator

7➤ Block rate tariff, where energy charge decreases with the increase in energy consumption,

Encourages the consumers to improve the power factor.Encourages the consumers to restrict their demandEncourages the consumers for more consumptionDiscourages the consumers for more consumption

8➤ Which of the following methods of voltage control in a power system is INCORRECT?

Shunt capacitorSeries resistorInduction regulatorExcitation control at generating station

9➤ Which of the following options is correct for a single- phase induction motor? I. Its output is only 50 % of the three-phase motor for a given frame size and temperature rise. II. It is more expensive than three phase motor of the same output.

Only II is correctBoth I and II are correctOnly I is correct Both I and II are incorrect

10➤ In a biased differential relay the bias is defined as a ratio of

fault current and operating coil currentfault current and restraining coil currentnumber of turns of restraining and operating coil operating coil current and restraining coil current

11➤ The volume of copper required for an a.c. transmission line is inversely proportional to

VoltageCurrentVoltage and power factorPower factor

12➤ Lighting in restaurants and malls is an example of _______.

commercial loadagriculture loadAll of thesedomestic load

13➤ A DC generator delivers a 30-A current to a load at 120 V by consuming 4500 J/s of mechanical energy. Determine the efficiency of the generator.

85%80%90%75%

14➤ In a steam power plant, the value of the reheat factor is of the order of:

2.1 to 3.01.1 to 1.50.5 to 1.0 1.6 to 2.0

15➤ Which of the following effects is resulted because of the size of the conductor, frequency and the specific resistance of the conducting material?

Proximity effectCorona effectThomson effectSkin effect

16➤ Which of the following statements about magnetostriction and its ill effects is INCORRECT?

Using a low value of flux density core is one of the reasons for humming sound in a transformer.This effect causes losses which produce heat in ferromagnetic coresThe applied magnetic field changes the magnetostrictive strain until reaching its saturation valueThe transformer buzzing noise is caused by a phenomenon of magnetostriction.

17➤ The thickness of lamination (which reduces eddy current loss) in electrical machine varies from: (Select the closest range)

0.5 to 5 mm0.1 to 2 mm0.5 to 2 mm 0.1 to 1 mm

18➤ At what value of load angle (δ) does the maximum power transfer in power system?

δ = 90°δ < 90° δ = 180° δ > 90°

19➤ Which of the following statements about the nature of speed control required by different industrial drives is INCORRECT?

In some cases, speed is needed for adjusting the work on a driven machine only for a few revolutions per minute; such a speed is known as creeping speed.Some drives require only two or three fixed speeds over a region; such drives are called multi-speed drivesSome drives require continuously variable speed over the range from zero to full speed; such drives are called variable speed drives.Some drives require only one fixed speed over a region; such drives are called mono-speed drives

20➤ Which of the following is NOT the advantage of bundled conductors? A. B. C. D.

Reduced clearance requirements at structuresReduced corona loss due to larger cross- sectional area Reduced interferences with communication circuitsImproved voltage regulation

21➤ According to the latest practice, the approximate land required for a 220 kV substation is:

70 acres10 acres25 acres50 acres

22➤ The clearance above ground for EHV lines shall NOT be less than:

5.2 m5.4 m6.3 m4.6 m

23➤ Torques are associated with synchronous motor; which of the following torques is also known as breakaway torque?

Pull out torqueRunning torquePull in torqueStarting torque

24➤ When there is no ferromagnetic material but only air present in between the coils, such a transformer is called

Dry type transformerWet type transformer Steel-core type transformer Iron-core type transformer

25➤ Which one of the following is the element exhibiting antiferromagnetism at room temperature? .

ChromiumNickelCobaltIron

26➤ What is a capacitor voltage transformer?

It is a transformer used in power systems to step down extra high voltage signals an provide low voltageIt is a transformer used in power systems to step up low voltage signals and provide extra high voltage It is a transformer used in power systems to step up high voltage signals and provide extra high voltageNone of these

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