Space charge and associated electroluminescence processes in XLPEcable peelings

摘要

The intent of this paper is to cross-correlate the informationobtained by space charge profile analysis and electroluminescence (EL)detection in cross-linked polyethylene samples submitted to dc fields,with the objective to make a link between space charge phenomena andenergy release as revealed by detection of visible photons. Space chargemeasurements carried out at different electrical fields by the pulsedelectro-acoustic method show the presence of a low-field threshold,close to 15 to 20 kV/mm, above which space charge begins to accumulateconsiderably in the insulation. Charges are seen to cross the insulationthickness through a packet-like behavior at higher fields, starting atabout 60 to 70 kV/mm. EL measurements show the existence of two distinctthresholds, one related to the permanent excitation of EL under voltage,the other being transient EL detected upon specimen short-circuit. Theformer occurs at values of field corresponding to space charge packetformation, and the latter to the onset of space charge accumulation. Thetwo techniques give therefore consistent information on space chargephenomena and associated energy release in the optical EM spectrum