Date of Award

1-1-2019

Document Type

Dissertation

Degree Name

Ph.D.

Department

Computer Science and Engineering

First Advisor

Maciej Kumosa, Ph.D.

Keywords

Ballistics, Coatings, High velocity impact, Low velocity impact, Power grid, Transformer bushing

Abstract

This dissertation contributes unique approaches to improve the fundamental understanding of the impact behavior of porcelain high-voltage (HV) transformer bushings under high-velocity impact, with a focus on their protection with feasible methods which could be quickly applied in service to prevent vandalism and other undesirable impact situations. The bushings are brittle and pressurized; prone to explosive damage when hit by a high-velocity projectile. Damaged bushings can destroy transformers and entire substations in complex fashions. This can put the power grid at risk for cascading failures and electrical blackouts, affecting consumers. Therefore, suggesting practical approaches which could be used to protect the bushings against impact is of paramount importance.

Testing of impact protection concepts on a full-scale bushing without exploratory study is expensive. Therefore, this research focused heavily on the development of new laboratory based experimental and numerical approaches for pressurized borosilicate glass cylinders and flat plates using both ballistic and low-velocity impact techniques, to best represent a bushing under high-velocity impact. The laboratory-based testing approaches were further verified by full-scale impact tests with a .308 caliber Winchester rifle cartridge. It was discovered from the laboratory and full-scale tests that an unprotected bushing would display an explosive symmetrical distribution of fragments, potentially destroying transformers, other neighboring equipment, and personnel. It was also demonstrated for the first time that a protective elastomeric coating can be used on the surface of a bushing to absorb an explosive blast from a combined effect of high-velocity impact and internal pressure. Nature was used as a guide to select an appropriate polymer coating for blast mitigation. It turned out that small amounts of Line-X XS-100 applied on the surface of the cylinders, plates, and bushings dramatically changed their failure modes from brittle to ductile. Most importantly, Line-X XS-100 successfully confined fragments on pressurized borosilicate cylinders and full-scale transformer bushings.

This research successfully used an extensive combination of engineering and scientific approaches to recommend a solution to a potentially serious engineering problem created by an explosion of an unprotected bushing in the middle of a HV substation.

Publication Statement

Copyright is held by the author. User is responsible for all copyright compliance.

Provenance

Received from ProQuest

Rights holder

Christine Nichole Henderson

File size

267 p.

File format

application/pdf

Language

en

Discipline

Engineering

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