Document Type

Thesis

Date of Award

5-31-1987

Degree Name

Master of Science in Electrical Engineering - (M.S.)

Department

Electrical Engineering

First Advisor

S. Pandey

Second Advisor

Raj Pratap Misra

Third Advisor

W. H. Warren Ball

Abstract

The main objective of this thesis was to find correlation between the electrical noise generated within the body of the solid dielectric material with the failure (puncture), under simultaneously applied thermal and electrical stresses.

The term 'Corona' is commonly used to describe any partial discharges occurring in voids (defects) in the material. Precisely corona is a flow of electrons and ions which occur in a void in air or other gasses. This event emits acoustic, optical and radio frequency energy, and can be detected by measuring any of these radiations. In the present thesis, Radio Interference Voltage (RIV) technique was used for detecting the electrical noise.

The tests were carried out on varnished fiber glass cloth gifted by Westinghouse Electric Corporation. Three hundred samples were tested for their noise level and classified in two groups (28 samples each) one group consisting of the most noisy samples and the other of least noisy ones. These sets were put to life test at a temperature of 80°C and electrical stress of 0.15 Kv/nil. It was found that within a week's time the noisy units failed (punctured) at much higher rate than the less noisy units. In another experiment we decided to put two specimen together without trying to remove the entrapped air and compared the results with single sheet specimen. It was found that the failure rate was double compared to single sheet specimen in the first four hours.

These results are indicative that by monitoring electrical noise a screening method could be deviced to reduce the cost of equipment failure.

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