Thermal ageing of a high temperature composite abstract

Results are presented of investigations into the thermal ageing behavior of a high temperature resin/nonwoven mat composite electrical insulation material. The clegree of ageing has been assessed by measuring the time rate of decrease of dielectric strength in the composite using a curved electrode fixture after ageing the composite in air for predetermined times as elevated temperatures, The composite was also evaluated as a component of an electrical insulation system that was subjected to thermal ageing in air followed by a sequence of exposures to vibration, cold shock, and humidity. Thermal endurance of the insulation system was determined by measuring the time to dielectric failure of a component in the system when subjected to a predetermined dielectric stress. The thermal ageing test results are reported as a time-temperature relationship using the logarithm of the test time to failure as a function of the reciprocal of the absolute ageing temperature in degrees Kelvin.