Title :
Investigating dc polyethylene threshold by space charge. Current and electroluminescence measurements
Author :
Augé, J.L. ; Laurent, C. ; Fabiani, D. ; Montanari, G.C.
Author_Institution :
Lab. de Genie Electr., Univ. Paul Sabatier, Toulouse, France
fDate :
12/1/2000 12:00:00 AM
Abstract :
It has been proposed recently that the lowest level of dc field, above which electrical degradation may occur, is associated with the formation of space charges in insulation. Therefore, inference of field levels above which space charge accumulates in a given material may provide fundamental information for material characterization and system design. Threshold field values were estimated through evidence of space charge accumulation derived from conduction current, space charge amplitude and electroluminescence (EL) counts vs, electrical field characteristics. Press-molded plates of polyethylene-based materials were used for this investigation. In order to be able to detect even by EL experiments the presence of the space charge accumulated at low fields, measurements were carried out during both polarization and short-circuit of specimens. It is shown that the threshold corresponding to the onset of EL upon grounding the specimen is close to the space charge accumulation threshold derived from space charge and conduction current measurements. This earlier value is considerably lower than the one previously detected from constant dc-voltage EL measurements, thus confirming that even at low fields and in the presence of voltage reversals or transients, space charges can trigger luminescence phenomena. The methodology developed in this paper enlarges the applicability of the EL technique to accommodate a wider electrical field range in view of insulation characterization
Keywords :
electroluminescence; insulation testing; polyethylene insulation; space charge; conduction current; current measurements; dc polyethylene threshold; electrical degradation; electroluminescence measurements; insulation; insulation characterization; polarization; press-molded plates; short-circuit; space charge; space charge accumulation; space charge amplitude; threshold; transients; voltage reversals; Amplitude estimation; Charge measurement; Conducting materials; Current measurement; Degradation; Dielectrics and electrical insulation; Electroluminescence; Optical polarization; Polyethylene; Space charge;
Journal_Title :
Dielectrics and Electrical Insulation, IEEE Transactions on