11-06-2013, 12:49 PM
SEMESTER EXAMINATIONS FOR HIGH VOLTAGE TESTING TECHNIQUES
HIGH VOLTAGE.pdf (Size: 23.66 KB / Downloads: 16)
Answer any five questions
All questions carry equal marks
1.a) Explain the performance of transformer ratio arm bridge in high voltage and high current applications.
b) Discuss briefly the importance of measuring DC resistivity.
2.a) What is the need of testing standards? Explain various testing standards available for porcelain/glass insulators.
b) Discuss various types of tests specified for cap and pin of Porcelain and Glass insulators.
3. Discuss in detail over voltage tests on insulators and circuit Breakers.
4.a) What are the different types of contaminants? How these are affecting the performance of insulators? Classify the contamination based on the severity.
b) Discuss about the artificial contamination test on high voltage insulators.
5. Describe the impulse testing of surge diverters.
6.a) Derive an expression for discharge magnitude and discharge energy due to a single discharge in a void present in an insulating medium.
b) A specimen of solid insulating material 1 cm thickness has a cylindrical air void 0.5 cm thick. Calculate the voltage to be applied to the specimen to start discharge in the void, given that the dielectric constant of the material is 4. Also calculate the ratio between the apparent and actual charges.
7. Explain the different arrangements for measuring RI and RIV. What are the limitations?
8.a) Discuss about the various types of cleaning methods of insulators to remove the contaminations on the insulator surfaces.
b) Discuss about the methods for detecting the defective porcelain and non ceramic insulators.