Investigation on Thermal Aging of HVDC XLPE

摘要

HVDC XLPE cables were widely used in the transmission line for the excellent characteristics. The thermal aging properties of HVDC XLPE insulation were investigated in this work, based on different assessment techniques, such as IR Prestige-21 Infrared Spectrometer, Thermo-Gravimetric Analyzer, and X-Ray Diffractometer. It was found that, the molecular structure of XLPE cable insulation changed during the thermal aging process, carbonyl deposed as the increase of aging time and the increase of aging temperature. There was one fastest decomposition temperature for un-aged specimen and specimen aged at low temperature, while there were multiple decomposition temperatures for specimens aged at high temperature. Numerous new chemical bonds, whose activation energies differ from that of XLPE, arise during the high temperature aging. The XLPE crystallinity increased during low-temperature aging while decreased during high-temperature aging. Low-temperature is conducive to the transition of amorphous region into crystallization region, while high-temperature has damaging effect on the crystallization region.