Characterization of failed solid-dielectric cables: Phase 2, Final report
Eight field-aged cross-linked polyethylene (XLPE)-insulated 15 kV cables, consisting of two groups of four cables differing in age and wall thickness, were excavated and provided for testing by the utilities participating in this study. Each group covered a range of operating electrical stress. Degradation in these cables was determined by measurements of ac breakdown strength. Insulation specimens removed from the cables were studied in the laboratory to characterize the presence or absence of antioxidants, peroxide decomposition products, other volatiles as could be identified, and morphological features. Most of the field-aged cables contained high levels of volatiles that has coalesced in some cases to produce a halo in freshly exposed cross sections. The volatile contents of the insulations and their ac breakdown strengths were found to be inversely correlated by a power-law relationship. Significantly, ac breakdown strength for insulations containing halos were found to correlate inversely with operating electrical stress; no correlation was found for the cables not containing halos or for the complete population of eight cables. The combined influence of age and thinner insulation wall appeared to lead to lower breakdown strength, although the effect was small as compared to that of residual volatile content. 12 refs., 1 fig., 2 tabs.
- Research Organization:
- Battelle Columbus Labs., OH (USA); Electric Power Research Inst., Palo Alto, CA (USA)
- OSTI ID:
- 6146814
- Report Number(s):
- EPRI-EL-5387; ON: TI88920001
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
POWER TRANSMISSION LINES
BREAKDOWN
TESTING
UNDERGROUND POWER TRANSMISSION
ELECTRIC CABLES
ELECTRICAL INSULATION
POLYETHYLENES
SERVICE LIFE
CABLES
CONDUCTOR DEVICES
ELECTRICAL EQUIPMENT
EQUIPMENT
ORGANIC COMPOUNDS
ORGANIC POLYMERS
POLYMERS
POLYOLEFINS
POWER TRANSMISSION
200301* - Power Transmission & Distribution- AC Systems
EHV & UHV- (-1989)
360604 - Materials- Corrosion
Erosion
& Degradation