Title :
Microscopic characteristic and signal analysis of aging defects in epoxy/mica insulation bar under different stresses
Author :
Zhang, Xiaohong ; Hu, Chunxiu ; Gao, Junguo ; Hu, Qingjuan
Author_Institution :
Inst. of Electr. & Electron. Eng., Harbin Univ. of Sci. & Technol., China
Abstract :
In the present paper, the microscope detections are conducted on stator bars with epoxy/mica insulation subjected to electrical, thermal and mechanical stresses for 2000 h, respectively. It is observed that treeing defects appear in electrical aging samples, delamination is characteristic of thermal aging samples and crack in aging sample results from mechanical stress. The amplitude spectrum of acoustic signals obtained from various samples indicates that the defects in larger size lead to higher frequency components, such as the frequency components about 6 kHz are observed in thermal aging samples with delamination while the frequency components about 2 kHz are characteristics of the specimens subjected to electrical stress and mechanical stress. However joint time-frequency analysis (JTFA) of partial discharge (PD) pulse waveform exhibit that higher frequency components in dispersion appear in JTFA spectrum of electrical aging samples.
Keywords :
ageing; cracks; delamination; epoxy insulation; mica; microscopes; partial discharges; stators; time-frequency analysis; trees (electrical); acoustic signals; aging defects; crack; delamination; electrical aging; electrical stresses; epoxy insulation bar; joint time-frequency analysis; mechanical stresses; mica insulation bar; microscope detections; microscopic characteristic; partial discharge pulse waveform; signal analysis; stator bars; thermal aging; thermal stresses; treeing defects; Aging; Delamination; Dielectrics and electrical insulation; Frequency; Microscopy; Partial discharges; Signal analysis; Stator bars; Thermal conductivity; Thermal stresses;
Conference_Titel :
Electrical Insulating Materials, 2005. (ISEIM 2005). Proceedings of 2005 International Symposium on
Print_ISBN :
4-88686-063-X
DOI :
10.1109/ISEIM.2005.193469
