Principles are given for the development of test procedures to evaluate the thermal endurance of solid electrical insulating materials and simple combinations of such materials. The results of accelerated thermal endurance tests, which are conducted according to prescribed procedures, may be used to establish temperature indexes for insulating materials. The test procedures apply to materials before they are fabricated into insulating structures identified with specific parts of electric equipment. Tests for specific insulating materials are not covered. The procedures may or may not apply to the aging characteristics of dielectric fluids or of porous materials impregnated with dielectric fluids.

This standard gives principles for the development of test procedures to evaluate the thermal endurance of solid electrical insulating materials and simple combinations of such materials. The results of accelerated thermal endurance tests, which are conducted according to prescribed procedures, may be used to establish temperature indexes for insulating materials. Thermal endurance tests and temperature indexes can be used to provide relative comparisons between the thermal capability of new materials and older, more accepted materials. Temperature indexes, while giving guidance on materials, should not in themselves be taken to predict the relationship between temperature and life of an insulation material or system in service. Thermal endurance tests provide a means for determining the rate at which important properties of insulating materials deteriorate irreversibly as a function of temperature and time. Such tests and the temperature indexes derived from them can aid in selecting ...