High Voltage Engineering | MSc Electrical Engineering (POWER) Sample Paper 2021

High Voltage Engineering | MSc Electrical Engineering (POWER) Sample Paper 2021

100%  Correct answer highline will be Red option 

1.  A good dielectric should have all the following properties EXCEPT

Select one:

a. freedom from gaseous inclusions.

b. high dielectric loss 

c. high mechanical strength

d. high resistance to thermal deterioration

2. A Tesla coil is a

Select one:

a. cascade transformer

B. high frequency resonant transformer

C. coreless transformer

D. low impedance transformer.

3. All of the following are the preferred properties of a dielectric gas EXCEPT

Select one:

a. high dielectric strength

b. physiological inertness

c. good heat transfer.

d. low atomic number

4. All of the following are the preferred properties of a dielectric gas EXCEPT

Select one:

A. low atomic number 

B. high dielectric strength

C. physiological inertness

5. All of the following are the preferred properties of a dielectric gas EXCEPT

Select one:

a. high dielectric strength

b. physiological inertness

c. good heat transfer.

d. low atomic number

6. All of the following dielectric materials are preferred for high frequency applications EXCEPT

Select one:

a. Butyl rubber 

b. Polyethylene

c. Teflon

d. Polystyrene.

7. Alternating current power is transmitted at high voltage

Select one:

a. to reduce cost of generation

b. to make the system reliable.

c. to minimize transmission losses 

d. to safeguard against pilferage

8. As compared to air the relative dielectric strength of Sulphur hexafluoride is nearly

Select one:

a. 1.5 times

b. 5.0 times.

c. 4.0 times

d. 2.5 times

9. At unvarying temperature breakdown voltage in a uniform field is a function of the product of gas pressure and distance between the electrodes. The above statement is known as

Select one:

a. Breakdown voltage law.

b. Thermal stability principle

c. Panchen's law 

d. Electron avalanche

10. Corona effect can be identified by

Select one:

a. bushy sparks

b. red light

c. faint violet glow 

d. arcing between conductors and earth

11. Corona results in

Select one:

a. improvement in power factor

b. increased capacitive reactance of transmission lines

c. radio interference 

d. better regulation.

12. Dielectric strength in case of mica can be expected to be more than

Select one:

a. 3500 kV/mm.

b. 1500 kV/mm

c. 500 kV/mm 

d. 2500 kV/mm

13. Electro-mechanical breakdown of solid insulating materials occurs due to

Select one:

a. vibrations

b. magnetic bum

c. electrical stresses produced by the voltage fluctuations.

d. mechanical stresses produced by the electrical field

14. Electro-mechanical breakdown of solid insulating materials occurs due to

Select one:

a. magnetic bum

b. vibrations

c. mechanical stresses produced by the electrical field

d. electrical stresses produced by the voltage fluctuations.

15. Impulse testing of transformers is done to determine the ability of

Select one:

a. windings to withstand voltage fluctuations

b. insulation to withstand transient voltages 

c. bushings to withstand vibrations

d. all of the above.

16. Impulse voltages are characterized by

Select one:

a. all of the above. 

b. peak value

c. time of half the peak value

d. polarity

17. In 'plasma' state a gas

Select one:

a. loses electrical conductivity

b. becomes perfect insulator

c. attracts moisture.

d. conducts electricity

18. In high voltage transmission lines the top most conductor is

Select one:

a. B-phase conductor

b. Y- phase conductor

c. Earth conductor. 

d. R-phase conductor

19. In sphere gaps, the sphere are made of

Select one:

a. bronze

b. any of the above. 

c. brass

d. aluminum

20. In Van de Graaff generators output voltage is controlled by

Select one:

a. controlling the lower spray point

b. controlling the belt speed

c. any of the above.

d. controlling the corona source voltage

21. Insulators for high voltage applications are tested for

Select one:

a. power frequency tests

b. impulse tests

c. none of the above.

d. both A. and B. above

22. Large capacity generators are manufactured to generate power at

Select one:

a. 400 kV.

b. 132 kV to 220 kV

c. 6.3 to 10.5 kV 

d. 440 V

23. Liquids are generally used as insulating materials up to voltage stresses of about

Select one:

a. 500 V/cm.

b. 100 MV/cm

c. 50 kV/cm 

d. 50 MV/cm

24. Stranded conductors arc used

Select one:

a. ease-in handling 

b. increased tensile strength

c. low cost.

d. better wind resistance

25. Moles bridge is used to measure

Select one:

a. modulation ratio frequencies.

b. properties of dielectric at dc

c. high frequency high voltages

d. dispersion in insulation

26. Panchen's law is associated with

Select one:

a. none of the above.

b. ionization

c. breakdown voltage 

d. thermal radiations

27. Polar dielectrics are normally used for

Select one:

a. none of the above.

b. dc and power frequencies 

c. high frequencies

d. microwaves

28. Surge diverters are

Select one:

a. shunt reactors to limit the voltage rise due to Ferranti effect

b. over-voltages of power frequency harmonics.

c. arc quenching devices

d. non-linear resistors in series with spark gaps which act as fast switches

29. Surge voltage originate in power systems due to

Select one:

a. any of the above. 

b. lightning

c. switching operations

d. faults

30. Surge voltage originate in power systems due to

Select one:

a. lightning

b. switching operations

c. faults

d. any of the above.

31. Switching surge is

Select one:

a. high voltage dc

b. short duration transient voltage

c. hyperbolically dying voltage.

d. high voltage ac

32. The breakdown voltage in gases depends on

Select one:

a. humidity

b. relative air density

c. distance between the electrodes

d. all of the above.

33. The electrical breakdown strength of insulating materials depends on

Select one:

a. nature of applied voltage

b. pressure, temperature and humidity

c. all of the above. 

d. imperfections in dielectric material

34. The essential condition for the Paschen's law to be valid is that

Select one:

a. voltage must be ac

b. humidity must be low.

c. temperature must be constant 

d. voltage must be dc

35. The impurity in liquid dielectric which has significant effect in reducing the breakdown strength, is

Select one:

a. ionic impurities.

b. moisture 

c. dissolved gases

d. dust

36. The phenomenon of corona is generally accompanied by

Select one:

a. a hissing sound 

b. a bang

c. all of the above.

d. magnetic hum

37. The relationship between the breakdown voltage V and gap d is normally given as

Select one:

a. v = kdn. 

b. d = kV2

c. V = kd

d. d=kV3

38. The variety of paper used for insulation purpose is

Select one:

a. blotting paper

b. rice paper

c. craft paper 

d. mill-board.

39. Transformers contribute to radio interference due to

Select one:

a. sparking

b. any of the above. 

c. internal or partial discharges in insulation

d. corona discharges in air

40. Vacuum insulation is used in all of the following EXCEPT

Select one:

a. Field emission tubes

b. X-rays.

c. Particle accelerators

d. EHT of color TV

41. Van de Graaff generators are useful for

Select one:

a. Very high voltage and high current applications

b. High voltage pulses only.

c. Very high voltage and low current applications 

d. Constant high voltage and current applications

42. Which of the following gas has been used as insulating medium in electrical appliances ?

Select one:

a. Freon.

b. Sulphur hexafluoride 

c. Carbon dioxide

d. Nitrogen

43. Which of the following gas has been used as insulating medium in electrical appliances?

Select one:

a. Carbon dioxide

b. Nitrogen

c. Freon.

d. Sulphur hexafluoride

44. Which of the following is a non-polar dielectric ?

Select one:

a. Plasticized cellulose acetate

b. Phenolic plastics

c. Castor oil.

d. Polystyrene

45. Which of the following is a polar dielectric ?

Select one:

a. Nylon 

b. Quartz

c. Polyethylene.

d. Teflon

46. Which of the following statement about corona is incorrect?

Select one:

a. Corona results in loss of power in transmission

b. Corona is always accompanied by a hissing noise.

c. Corona discharge can be observed as red luminescence 

d. Corona gives rise to radio interference

47. Which soil has the least specific resistance?

Select one:

a. Clay

b. Loamy soil

c. Peat. 

d. Land

48. Which soil has the maximum specific resistance?

Select one:

a. Black cotton soil

b. Sand 

c. Peat

d. Loamy soil.

49. Which variety of mica is hard and brittle ?

Select one:

a. Phlogopite

b. Fibiolite

c. Lipidolite 

d. Muscovite

50. Polar dielectrics are normally used for

Select one;

a. high frequencies

b. microwaves

c. dc and power frequencies

d. none of the above.