Oxidation and Water Tree Formation in Service-Aged XLPE Cable Insulation

Garton, A.; Bamji, S.S.; Bulinski, A.T.; Densley, J.

doi:10.1109/tei.1987.298900

Cited by 72 publications

(13 citation statements)

References 6 publications

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“…The FTIR difference spectrum of the treed vs. nontreed region for purified LDPE in Figure 16 shows a very distinct carbonyl peak and thus confirms the observations of other authors that water treeing phenomenon is frequently associated with oxidation [17,18]. Initially, binary LPE blends did not reveal any excess oxidation (Figure 16), owing to the high crystallinity of this material as compared with LDPE.…”

supporting

confidence: 84%

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Water treeing in binary linear polyethylene blends: the mechanical aspect

Bulinski

Bamji

Densley

et al. 1994

IEEE Trans. Dielect. Electr. Insul.

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Water treeing t e s t s were performed on low density polyethylene (LDPE) and four different binary blends of sharp linear polyethylene (LPE) fractions (M, = 2500 and 76000), which were e i t h e r quenched in air from the melt or isothermally crystallized at 123'C. Although the morphology and initial mechanical properties of the materials tested were significantly different, the v e n t e d tree g r o w t h characteristics were similar for all of them. This is in disagreement w i t h the electromechanical models of w a t e r treeing, which correlate w a t e r tree g r o w t h w i t h the f r a c t u r e toughness of the material. Time to breakdown distributions were also similar for both LDPE and the b i n a r y LPE blends, which indicates that, regardless of the initial material morphology and the a c t u a l s t r u c t u r e of w a t e r trees, the length of w a t e r trees is one of the controlling factors in insulation failure. The visible light image of w a t e r trees in LPE blends did not disappear upon drying a s it usually does in LDPE and crosslinked polyethylene insulation.

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confidence: 84%

“…The FTIR spectra obtained for the dried, water treed regions of LPE blends also did not show any presence of water. Thus, the visible water trees in binary LPE blends were not due to chemically bound water as, for example, in some cases of XLPE insulation [17]. Aging lime (h) Figure 15.…”

mentioning

confidence: 97%

Water treeing in binary linear polyethylene blends: the mechanical aspect

Bulinski

Bamji

Densley

et al. 1994

IEEE Trans. Dielect. Electr. Insul.

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“…Polyethylene leads to an increase of conductivity through the formation of chemical compounds such as carbonyl groups which contribute to the hopping sites to the dielectric, i.e. traps of relatively shallow depth [9]. The transport mechanism refers to both the electric field and elevated temperature, which will cause Cu ++ ions from electrode surface to drift along electric field into polymer, at positive polarization of the copper electrode.…”

Section: Resultsmentioning

confidence: 99%

Migration effects at conductor / XLPE interface subjected to partial discharges at different electrical stresses

Florkowski

Florkowska

Roehrich

et al. 2013

2013 Annual Report Conference on Electrical Insulation and Dielectric Phenomena

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Migration effects occurring at conductor/XLPE interface are presented in the paper. The phenomenon was studied under various electrical stresses: direct current (DC), pulse-width modulated (PWM) and sinusoidal (SIN). The comparison of aging effects on specimens subjected to the stimuli was presented. The electrical stress results in partial discharges, both around the electrode in the form of surface discharges and directly at the micro air gap interface between conductor and polymeric material. In order to isolate the impact of interface discharges, the surface effects were suppressed, eliminated and compared with results containing both forms of discharges. The electrical and thermal mechanism was investigated in the paper and assessment was performed by means of time to breakdown and both micro morphological and elemental analysis. Migration of the conductor, where metallic particles are transferred to the insulating medium, was observed. Primarily, attention was afforded to the migration of copper and aluminum electrode atoms in two zones; one zone being the direct contact area at the interface and the second zone incorporating the area surrounding the electrode which is enhanced by surface discharges. A novel aspect relates to the investigation of the migration depth profile and the concentration intensity at different voltage stresses. The transport phenomena were analyzed with respect to both electrical and thermal mechanisms.

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“…Nevertheless, by using FTIR spectroscopy. Garton et al [5] have observed that the Figure 3. Cross-cut bow-tie tree (bush-type) observed at 1.2 mm from the conductor shield in cable RI6.…”

Section: Resultsmentioning

confidence: 99%

Field-aged cable material diagnosis by thermally stimulated currents

Amyot¹,

Pélissou²

Proceedings of Conference on Electrical Insulation and Dielectric Phenomena - CEIDP '96

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The Thermally Stimulated Currents (TSC) technique has been studied as a method for detecting dry state water trees in field-aged cables. Measurements were taken on medium voltage extruded cable samples of crosslinked polyethylene (XLPE). Samples were peeled-off from several well characterized field-aged and one unaged cables. Insulating material has been characterized with regard to water-tree density. TSC peaks were observed around -3OOC (p) and 1 10°C (a)for field-aged and unaged insulation. Lowtemperature peak intensity variations throughout cable radii have been observed and assumed to be related to the cable insulation characteristics. No correlation has been observed between the total integrated charge from p peak integration and the dry state water-tree surface density of the samples. In addition, TSC and TSPC (Thermally Stimulated Polarization Currents) measurements on treed and untreed regions of the same cable at the same radius have been carried out in order to compare samples having the same characteristics . except for the presence of dry state water trees. Variations in a peak intensity was related to the lower water-tree resistivity even in the dry state.

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Oxidation and Water Tree Formation in Service-Aged XLPE Cable Insulation

Cited by 72 publications

References 6 publications

Water treeing in binary linear polyethylene blends: the mechanical aspect

Water treeing in binary linear polyethylene blends: the mechanical aspect

Migration effects at conductor / XLPE interface subjected to partial discharges at different electrical stresses

Field-aged cable material diagnosis by thermally stimulated currents

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