B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.
Electrical and Electronics Engineering
EE 2353 — HIGH VOLTAGE ENGINEERING
Time : Three hours
Maximum : 100 marks
Answer ALL questions.
PART A — (10 × 2 = 20 marks)
1. What are the causes of over voltages in power system?
2. What is counter poise wire? Give its use.
3. Write the Paschen’s law.
4. What are two main reasons for long term break down in composite dielectrics?
5. Give the specifications for standard impulse wave.
6. What are the advantages of cascaded transformer method?
7. What is Rogowski coil? Give its limitations.
8. What are the limitations of series resistance micro ammeter method?
9. What are the tests conducted on surge arrester?
10. What is insulation coordination?
PART B — (5 × 16 = 80 marks)
11. (a) (i) Give the origin and characteristics of switching surges and explain the causes of over voltage due to switching surges in EHV and UHV system. (10)
(ii) Explain the control measures for over voltage due to switching surge. (6)
(b) Elaborate the discussion on protection of power system equipments using protective devices.
12. (a) Explain in detail the breakdown mechanism in non-uniform fields and phenomenon of Corona. (16)
(b) (i) Describe the ageing and breakdown in composite dielectrics due to partial discharge. (8)
(ii) Describe the thermal breakdown mechanism of solid dielectrics. (8)
13. (a) (i) Explain the operation of simple voltage doubler circuit. (4)
(ii) Discuss the principle of operation of vande graff generator with neat sketch. (12)
(b) (i) How the impulse current is generated using capacitor bank. Explain in detail. (8) (ii) Write a brief note on resonant transformer method. (8)
14. (a) Tabulate and explain the methods used for the measurement of high voltages and high currents. (16)
(b) With neat sketch explain the sphere gap arrangement method of high voltage measurement and give the factors influencing the measurement. (16)
15. (a) Explain the power frequency and impulse voltage test conducted on bushings.
(b) Discuss the dielectric power factor test and partial discharge test conducted on high voltage cables. (16)