RAJALAKSHMI ENGINEERING COLLEGE, CHENNAI

RAJALAKSHMI ENGINEERING COLLEGE, CHENNAIDepartment of Electrical and Electronics Engineering

EE1402 High Voltage Engineering

PART-A (2 marks)

1. Draw and define impulse voltage wave shape and mention its specification as per standards.

2. What are the causes of over voltages?

3. Mention the different kinds of over voltages.

4. What are temporary over voltage?

5. What is lightning phenomenon?

6. What is Isokeraunic level?

7. What are meant by switching surges? Mention the approximate magnitude of switching surges and their frequency.

8. State the different methods of protection against over voltages.

9. What is a surge diverter?

10. What is a ground wire or shielded wire?

11. Define tower footing resistance.

12. Define shielding angle.

13. Draw the V-I characteristics of non linear resistor lightning arrester.14. What are meant by ground rods and counter poise wires?

15. Compare switching surges and lightning

16. Write the expression for voltage developed during lightning.

17. Why a simple spark gap cannot offer full protection against over voltages.

18. Define uniform and non uniform fields and give example for each.19. What is meant by corona discharges?

20. Define the following as applied to disruptive discharges.(a) Flash over

(b) Spark over

21. What is meant by Townsends discharge? Explain its main features.22. Define Paschens Law.23. What are pure liquid dielectrics?24. Define Creepage Distance.

25. What do you mean by Disruptive Discharge Voltage?

26. What are the demerits of synthetic testing of circuit breakers?

27. What are the different tests done on insulators?

28. How radio frequency noise is measured?

29. What is insulation coordination?

30. Define 50 % and 100% flash over voltage.

31. Differentiate type test and routine test.

PART-B (16 marks)1. Discuss the mechanism of lightning strokes and over voltages on transmission lines. (16)

2. Discuss the different theories of charge formation of thunder clouds. (16)3. (a) Give the mathematical models for lightning discharges and explain them (8)

4. (b) Explain the different characteristics of the lightning strokes (8)

5. (a) Explain various methods to control switching over voltages. (10)6. (b) Give a brief note on protection of transmission lines using surge diverters. (6)

7. Write short notes on:

(a) Rod gaps used as protective devices (8)

(b) Ground wires for protection of overhead lines. (8)

8. State the criteria for sparking potential and hence obtain the relation between sparking

potential and (pd) values (Paschens Law).Discuss on the nature of variations of sparking

potential with (pd) values. (16)9. (a) Explain why electro negative gases have high breakdown stress. 6)

10. (b) Discuss meeks theory of breakdown in gases under non uniform fields. 10)

11. (a) Explain the Streamer Theory of breakdown in air at atmospheric pressure. (8)

12. (b) Explain about time lag in gas breakdown. (8)

(a) What electrical avalanche? How do avalanche give rise to an electrical breakdown in case of Townsends type of discharge. 12)13. (b) How vacuum breakdown occurs according to particle exchange mechanism? (4)

14. Discuss the various mechanisms of vacuum breakdown. (16)

15. Explain various theories which explains breakdown in commercial liquid dielectrics. (16)16. (a) Explain the Streamer Theory of breakdown in air at atmospheric pressure. (8)17. (b) Explain about time lag in gas breakdown. (8)a. Draw a neat diagram of high voltage Schering bridge and describe various features of the bridge.

b. Explain, with schematic diagram any one method of measuring RIV of transmission line.

18. Explain, with neat diagram the impulse testing of transformer. What is procedure adopted in location of fault?

a. What are the impulse tests done on insulators? Explain.

b. Explain the synthetic of circuit breaker.

19. What are the different tests conducted on cables.

20. Explain insulation coordination?21. What are the different tests conducted on surge diverter. Explain.

22. What are the different tests conducted on bushings. Explain.