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
1. Explain the applications of insulating materials in the construction of capacitors.
2. State and explain Pachen’s law. Derive the expressions for (pd)min and (Vb)min.
Assume A=12, B=365 and ?=0.02 for air. Determine the (pd)min and (Vb)min.
3. (a) What are the mechanisms that lead to intrinsic breakdown of a solid?
(b) Explain about the treeing in solid insulating materials. [8+8]
4. (a) Derive an expression for voltage efficiency of single stage impulse generator.
(b) An impulse current generator has total capacitance of 15 ?F, the charging voltage of 125 kV, the circuit inductance 2 mH and the dynamic resistance 1ohm. Find the peak current and wave shape of the wave. [8+8]
5. Discuss and compare the performance of
(b) Capacitance potential dividers for measurement of impulse voltages? [8+8]
6. Derive the expressions for the voltage and current waves on long transmission lines
and obtain the surge impedance of the line? 
7. What is non destructive testing of insulating materials? Give very briefly the characteristics of these methods. 
8. Mention the different electrical tests done on isolators and circuits breakers.