Title :
The role of microscopic defects in multistress aging phenomena of micaceous insulation
Author :
Kimura, K. ; Kaneda, Y.
Author_Institution :
Central Res. Lab., Mitsubishi Electr. Corp., Amagasaki, Japan
Abstract :
Multistress aging mechanism of mica/epoxy insulation is discussed based on both experimental breakdown data and microscopic observation of aged samples. The result of simultaneous multistress testing shows that thermal and mechanical stresses have a synergistic effect on electric life. A similar trend is also found in residual breakdown characteristics after thermal and mechanical agings in sequence. It is confirmed with SEM pictures of the aged insulation that thermal aging causes isolated delamination at mica/epoxy interfaces. Using a newly developed SEM apparatus with servomechanics, the development of delamination and cracks is observed in real time. A multistress aging model is proposed with the generation and development of microscopic defects
Keywords :
ageing; composite insulating materials; cracks; delamination; electric breakdown; electron microscopy; epoxy insulation; insulation testing; life testing; mica; scanning electron microscopy; stress effects; thermal stresses; SEM; cracks; delamination; electric life; mechanical aging; mechanical stresses; mica/epoxy interfaces; micaceous insulation; microscopic defects; multistress aging; real time observation; residual breakdown; servomechanics; synergistic effect; thermal aging; thermal stresses; Aging; Dielectrics and electrical insulation; Electric breakdown; Insulation testing; Laboratories; Life testing; Numerical analysis; Scanning electron microscopy; Strain measurement; Thermal stresses;
Conference_Titel :
Electrical Insulation, 1994., Conference Record of the 1994 IEEE International Symposium on
Conference_Location :
Pittsburgh, PA
Print_ISBN :
0-7803-1942-7
DOI :
10.1109/ELINSL.1994.401517
