JNTU Previous question Papers-B-Tech-Ex-III-Year-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

1. Define the degree of uniformity of an electric field. Discuss the degree of uniformity

for simple electrode configurations. [16]


2. Write short notes on:

(a) Photo-ionization

(b) Secondary ionization. [8+8]


3. Explain in detail about the long-term breakdown in composite dielectrics. [16]


4. (a) Discuss about resonant transformers in detail.

(b) A Cockroft-Walton type voltage multiplier has eight stages with capacitances, all equal to 0.05 ?F. The supply transformer secondary voltage is 125KV at a frequency of 150Hz. If the load current to be supplied is 5mA, find

i. The percentage ripple

ii. The regulation

iii. The optimum numbers of stages for minimum regulation or voltage drop. [8+8]


5. Explain the principle and construction of an electro static voltmeter for very high

voltages. What are its merits and demerits for high voltage AC measurements? [16]


6. Explain the different aspects of insulation design and insulation co-ordination adopted

for EHV systems? [16]


7. Briefly explain the methods used for calibrating the partial discharge detectors[16]


8. (a) What are the significance of power factor tests and partial discharge tests on

bushings? How are they conducted in the laboratory?

(b) Explain the partial discharge tests on high voltage cables? [8+8]

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