The merits and abuses of the present methods for thermal classifications of insulating materials and systems

As predicted, the revision of AIEE No. 1 "General Principles Upon Which Temperature Limits Are Based In The Rating Of Electric Equipment" by AIEE Co-ordinating Committee No. 4 has resulted in certain abuses for thermal rating of insulating materials, systems, and equipment. These abuses are, in my judgment, not deliberate, but rather result from insufficient basic knowledge of the chemical, physical, and electrical considerations involved in the uprating of organic materials to higher temperature of operation and/or the complexities of the physical and electrical structure of insulating systems.