Electroluminescence properties of water-treed XLPE under long time voltage application

Electroluminescence (EL) occurs in initiation phase of electrical tree and is considered to be a probe of the degradation of polymer insulating materials. 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. Under existence of water, water treeing takes place when subjected to a high electric field. Water tree provides a starting point of electrical tree, and therefore is responsible for the final breakdown of power cables with polymeric insulation. But the relation between EL and degradation in water-treed region is still unclear. We studied the EL properties of cross-linked polyethylene (XLPE) with a water-treed region after drying process. Wepsilall discuss the relation between EL properties and progress of material degradation in water treed region.