Spectrum change of electroluminescence with degradation in XLPE

Electroluminescence (EL) is precursory phenomenon of the electrical tree initiation. We consider that EL is caused by electron impact; namely, electrons injected from electrode are accelerated in micro cavity of sub-micron size and causes bond scission and excitation of luminescence center. But the detail of EL is still unclear. In this paper, we report spectrum change of EL with time of voltage application in XLPE. EL spectrum shifts to longer wavelength side after long time voltage application. The result suggests that degradation have a large influence on EL spectrum.