JNTU B.Tech II Semester Examinations, HIGH VOLTAGE ENGINEERING, Apr/May 2008

JNTU B.Tech II Semester Examinations, HIGH VOLTAGE ENGINEERING, Apr/May 2008

(Electrical & Electronic Engineering)

Time: 3 hours Max Marks: 80

Answer any FIVE Questions

All Questions carry equal marks

SET-IV

1. Discuss about surge voltage and their distribution and control in high voltage power

apparatus. [16]

 

2. (a) Explain in detail ionization by collision with neat diagrams.

(b) Explain the difference between photo-ionization and photo electric emission. [8+8]

 

3. Explain thermal breakdown in solid dielectrics. How this mechanism is more significant than the other mechanisms. [16]

 

4. (a) Explain with diagrams, different types of rectifier circuits for producing high DC voltages.

(b) Determine the ripple voltage and regulation of a 10 stage Cockroft-Walton type DC voltage Multiplier circuit having a stage capacitance = 0.01 ?F, supply voltage = 100 kV at a frequency of 400 Hz and load Current = 10 mA.

[8+8]

 

5. What are the problems associated with measuring very high impulse voltages?

Explain how these can be taken care during measurments. [16]

 

6. (a) Explain the different theories of charge formation in clouds?

(b) What are the mechanisms by which lightning strokes develop and induce over

voltages on overhead power lines? [8+8]

 

7. Explain the concept of apparent charge in partial discharge measurements. Describe

a simple experiment technique to measure partial discharge [16]

 

8. Mention the different electrical tests done on isolators and circuits breakers. [16]

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