Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Electrical Engineering


The drastic increase in the ratings of power apparatus in recent years, as a, result of rapidly increased power needs, has brought about dramatic developments in electrical insulation. As voltage and power ratings increased, while size reduction and higher efficiencies were sought, temperatures which insulations must withstand without losing their characteristics also increased. In an effort to produce insulations with higher thermal and electrical properties, insulation manufacturers began producing electrical insulations utilizing synthetic high polymers, phenolic, and other thermosetting resins and silicones. The result has been a series of advanced insulation systems which the has been so rapid that a complete knowledge of the properties of some of these materials is still incomplete. During a series of discussions with Professor M.L. Manning, the author became aware of the existing need for an accurate evaluation of the impulse characteristics of a group of synthetic electrical insulating materials with temperature ratings of 155°c to 220°c. A number of these insulations are based on DuPont’s patented Nomex, whose impulse characteristics have not yet been determined despite its widespread use. Others incorporate mica for corona suppression and asbestos for improved thermal properties, while still others are combinations of purely synthetic components (refer to Appendix I). An examination of the existing research on impulse testing showed that this was also an opportunity for applying some of the newly developed computer-generated techniques for impulse wave standardization and their subsequent evaluation and improvement. The ASTM and IEEE Standard Procedures for Impulse Testing exist in a constant state of flux as a result of continuing improvement, therefore, testing the material in accordance with these procedures facilitates a working knowledge of their limitations, which may become of importance to subsequent researchers. Finally, since all insulating materials considered in this thesis are tested ill the same laboratory, under the same carefully controlled conditions, and by the same calibrated equipment, it is believed that a meaningful means of comparison would be available to the apparatus designer using the material, as well as to the researcher who is attempting to improve the performance of the material.

Library of Congress Subject Headings

Electric insulators and insulation



Number of Pages



South Dakota State University