Power Transmission and Distribution MCQ Part-2

June 30, 2021

1. Capacitors having large capacitance in small size use a dielectric of

A paper

B nylon

C mica

D ceramic

Answer: D ceramic

2.Transmission efficiency increases as

A voltage and power Factor both increase

B voltage and power factor both decrease

C voltage increases but power factor decreases

D voltage decreases but power factor increases

Answer: A voltage and power Factor both increase

3.Skin efect depends on

A size of the conductor

B frequency of current

C resistivity of conductor material

D all of the above

Answer: D all of the above

4.In over head transmission lines the effct of capacitance can be neglected when the length of the line is less than

A 200 km

B 160 km

C 100 km

D 80 km

Answer: D 80 km

5. The surge impedance for over head line is taken as

A 10 to 20 ohm

B 50 to 60 ohm

C 100 to 200 ohm

D 1000 to 2000 ohm

Answer: C 100 to 200 ohm

6. Pin insulators are used upto voltage of about

A 100 KV

B 66 kV

C 33 kV

D 25 kV

Answer: C 33 kV

7. Corona effect can be detected by

A hissing sound

B joint bluish colour of illumination

C presence of ozone detected by odour

D all of the above

Answer: D all of the above

8. The effect of wind pressure is more predominant on

A transmission lines

B netural wires

C insulators

D supporting tower

Answer: D supporting tower

9. Which of the following regulation is considered to be the best

A 0.02

B 0.1

C 0.2

D 0.3

Answer: A 0.02

10. Transposition of tranmission lines is adopted to make uniform throughout the line

A reactance

B zero reactance

C capacitance

D none of these

Answer: A reactance

11. Skin effct is proportional to

A Frequency

B square of frequency

C independent of frequency

D none of these

Answer: A Frequency

12. Ring main system is usually used for

A urban areas

B rural areas

C both [a] and [b]

D none of these

Answer: D none of these

13. Per unit impedance of transformer referred to primary is that of secondary winding.

A less than

B greater than

C equal to

D may be less than or greater than

Answer: C equal to

14. Which of the following is not transmission voltage level used in india?

A 132 kV

B 220 kV

C 350 kV

D 400 kV

Answer: C 350 kV

15. Corona produces ozone gas that is

A useful

B causing corrosion of conductor

C causing hissing noise

D causing radio interference

Answer: B causing corrosion of conductor

16. Bundle conductors are used to

A increase power transfer

B reduce corona loss

C decrease line reactance

D all of these

Answer: D all of these

17. Skin effect result into

A increase in conductor diameter

B increase in conductor resistance

C increase in sag

D increase in frequency

Answer: B increase in conductor resistance

18. Which conductors are generally used for high voltage power transmission?

A iron conductors

B copper conductors

С carbon conductors

D ACSR

Answer: D ACSR

19. In distribution system the permissible voltage variation in

A + - 1

B + - 10

C + - 20

D + - 30

Answer: B + - 10

As per IE Rule, In the case of low or medium voltage, by more than 6%

As per IS 12640:1988, Supply variation will become 230 V + 10 percent with effect from 31 December 2009.

Earlier it was 6 percent in the case of low or medium voltage

20. As the spacing between conductors increase, the line inductance

A increases

B decreases

C remains unaffected

D first increases and then decreases

Answer: A increases

21. The ratio of GMR to actual radius for a stranded conductor is

A equal to 1

B equal to 0.7788

C greater than 0.7788

D less than 0.7788

Answer: D less than 0.7788

22. In which type of transmission line the effect of shunt capacitance can be neglected?

A long

B medium

C short

D all of these

Answer: C short

Different text books have different opinion about short, medium and long transmission line.

Short line: < 50 km & < 20 kV, capacitance neglected Medium transmission line: >50 & < 150 km, >20 kV and < 100 kV, line parameter considered as lumped long line: > 150 km & > 100 kV, line parameter

considered as distributed.

23. The surge impedance of overhead transmission line that of underground cables.

A is less than

B is greater than

C is equal to

D may be less than or greater than

Answer: B is greater than

24. When receiving end voltage of transmission system under light load condition becomes more than that of sending end side, this phenomenon is called

A Ferranti effect

B Proximity effect

C Missioner effect

D Thompson effect

Answer: A Ferranti effect

Ferranti effect: When receiving end voltage of transmission system under light load condition becomes more than that of sending end side

Skin Effect: The tendency of alternating current to concentrate near the surface of a conductor

Promity: eneven current distribution due to other conductor placed in proximity.

25. Which are the factors, out of following, affects the sag of transmission line?

A temperature

B length of span

C weight of conductors