A study of humidification in the thermal life determination of motorette insulation systems

The moisture conditioning cycle is recognized as probably the most critical factor in the functional evaluation of rotating machinery insulation systems. An analysis is made of some of the humidity problems currently existing, particularly in respect to the use of the now proposed IEEE 117 Test Procedure and the NRL designed condensation chamber. A time dependence ratio of surface to bulk absorption has been discovered which varies with the degree of thermal aging. This is explored. Cautionary measures are given for use of the condensation chamber with recommendations as to temperature differentials and exposure time durations needed to insure stable test conditions.