Anna University of Technology Tirunelveli 2011 B.E Electrical and Electronics Engineering /b.tech s, /e- - Question Paper

B.E/B.TECH DEGREE exams MAY/JUNE-2011
REGULATIONS 2008
SIXTH SEMESTER
EE 63- HIGH VOLTAGE ENGINEERING
ELECTRICAL AND ELECTRONICS ENGINEERING
TIME: 3 hours Maximum:100 marks

ans ALL ques.
PART-A(10*2=20 marks)

1. State the various kinds of over voltages occurring in power system and mention their magnitude
2. describe indirect stroke
3. What is composite dielectric?
4. describe uniform and non uniform fields and provide example for every
5. Mention the specification of impulse voltage as per Indian standards
6. What is the need for generating impulse currents
7. Why are capacitance voltage dividers preferred for high a.c voltage measurements?
8. elaborate the factor influencing the measurement using sphere gap?
9. Classify the kinds of tests to be conducted for electrical apparatus
10. provide the Indian standard reference atmosphere is conditions for high voltage testing.


PART-B(5*16=80 marks)

11(a)(i) provide the mathematical model of lightning discharges and discuss them.(8)
(ii) explain the causes of power frequency over voltage in transmission line(8)

or

(b) discuss the characteristics of switching surges with typical wave shapes clearly(16)

12(a) discuss the streamer theory of breakdown in air at atmospheric pressure. Derive the criterion for breakdown in electronegative gases (16)

or
(b)(i) discuss the phenomenon of thermal breakdown in solid dielectrics(8)
(ii) explain Meek's theory of breakdown in gases under non uniform fields(8)

13(a)(i) discuss the need for generating high DC voltages(6)
(ii) Draw the circuit of n-stage cockroft walton circuit for generating very high DC voltages and explaining its operation also derive the expression for the ripple content in the output wave form.(10)

or

(b)(i) discuss tripping of impulse generators(6)
(ii) Starting from the basic "MARX" circuit develop the circuit of a modern multistage impulse generator and discuss its operation. explain on the significance of different parameter.(10)

14(a) With a neat sketch discuss the principle operation of an electrostatic voltmeter for HVAC measurement. elaborate the merits and demerits?(16)

or

(b)Tabulate the high voltage and high current measurements techniques for various kinds of voltages and currents.(16)

15(a) explain with circuit arrangement, the detailed procedure for conducting impulse voltage withstand test on the 33kV porcelain insulator(16)

or

(b)(i) elaborate the needs for high voltage testing of electrical apparatus?(8)
(ii) discuss the need for recording supplementary oscillagrams during impulse testing of transformer.(8)

Earning:   Approval pending.