Title :
Dielectric polarization and relaxation behaviour of AC aged polyethylene with liquid electrodes
Author :
Svatik, A. ; Scarpa, P.C.N. ; Das-Gupta, D.K. ; Cooper, D.E. ; Rackowski, C.
Author_Institution :
Sch. of Electron. Eng. & Comput. Syst., Univ. of Wales, Bangor, UK
Abstract :
Thermally stimulated discharge current (TSDC) measurement and dielectric spectroscopy of low-density polyethylene (LDPE) aged with an AC field and liquid electrodes are reported. The dielectric response of aged sample after DC poling at 70°C shows two parallel relaxation processes. At low frequencies an LFD (low-frequency dispersion) process with a constant ε"/ε\´ ratio is dominant, possibly due to the presence of ionic species in LDPE. At higher frequencies an additional dipolelike relaxation occurs as a result of charge injection and trapping enhanced by electrical ageing. Without DC poling at high temperature only the LFD is evident. The unaged sample does not show any fundamental changes in the dielectric response after additional DC poling, thus indicating the absence of a significant trap density
Keywords :
ageing; dielectric polarisation; dielectric relaxation; polyethylene insulation; thermally stimulated currents; 70 degC; AC aged polyethylene; AC field; DC poling; LDPE; ageing; charge injection; dielectric polarization; dielectric response; dielectric spectroscopy; dipolelike relaxation; electrical ageing; high temperature; ionic species; liquid electrodes; low frequencies; low-density polyethylene; low-frequency dispersion; relaxation behaviour; relaxation processes; thermally stimulated discharge current; trap density; Aging; Current measurement; Dielectric liquids; Dielectric measurements; Electrochemical impedance spectroscopy; Electrodes; Frequency; Polarization; Polyethylene; Temperature;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena, 1993. Annual Report., Conference on
Conference_Location :
Pocono Manor, PA
Print_ISBN :
0-7803-0966-9
DOI :
10.1109/CEIDP.1993.378898
