Insulation system evaluation for rotating machines

In the last decade the electrical industry has become increasingly conscious of temperature classification of insulation. AIEE #1 "General Principles Upon Which Temperature Limits are Based in the Rating of Electrical Equipment" has recognized in recent revisions that temperature classification by chemical composition is inadequate. Therefore, AIEE #1 provides that insulation may be classified thermally, not only by chemical composition, but also by experience and by accepted tests. Also recognized are the differences between insulating materials and insulation systems as applied to equipment. It is with these accepted tests on insulation systems that this paper is concerned.