Dynamic mechanical analysis of degradation of rotating machine composite insulation

The long-term accelerated aging tests in laboratory environment has been conducted on the composite insulating materials (CIM) of actual rotating coils subjected combined stresses including thermal, electrical, mechanical and thermal cycling stresses. The dynamic mechanical experiments of CIM has been carried out in the different aging periods using dynamic mechanical analyzer (DMA) and the relationships between mechanical parameters and the aging time of CIM is also analyzed in this paper. Based on the Eyring absolute reaction speed theory, a method calculating the apparent activation energy of glass transition (AAEGT) is developed. By DMA, it has been suggested that the dynamic mechanical parameters, such as dynamic modulus, temperature of glass transition, dynamic mechanical loss peak value, width of half a peak value and apparent activation energy of glass transition can be used to characterize the aging properties of large generator stator composite insulating materials