1,775 research outputs found
Advanced electro-thermal life and reliability model for high voltage cable systems including accessories
No full textA novel model for estimating life and reliability of high voltage cable systems, including cable length, joints, and terminations, is proposed
Comparing frequency-dependent and distributed parameter with lumped losses power cable line models for cable insulation coordination against overvoltages
No full textSimulations of transients are an obliged step for the insulation coordination of cable lines. Although a frequencydependent power cable line model better takes into account real conditions since resistive and inductive parameters vary with frequency, a distributed parameter with lumped losses power cable models can be useful to simplify and give higher flexibility to the insulation coordination study. In such a case, a dilemma rises up when a frequency shall be selected for the determination of the cable parameters. In this study, a comparative analysis between the two models has been performed considering a typical configuration layout, i.e. an overvoltage coming from an overhead line and stressing the cable line terminated on a transformer. The overvoltages stressing both cable insulation wall and cable thermoplastic jacket are evaluated using the same system configuration with both frequency-dependent and distributed parameter with lumped losses power cable line models, in the latter case sweeping different frequency values for the determination of the cable parameters. A frequency range that minimise the differences between the overvoltage estimation using the two models is suggested
The feasibility of cable sheath fault detection by monitoring sheath-to-ground currents at the ends of cross-bonding sections
No full textThis paper aims at checking the possibility that cable sheath faults in unipolar three-phase HV and extra HV cables with sheath cross-bonding systems can be detected by monitoring sheath-to-ground currents at the solid bonding ends of major cross-bonding sections. This goal is achieved by calculating such currents for some reference case studies of faults of the outer thermoplastic jacket in unipolar three-phase land cables for power transmission in flat formation. The case studies differ as to cable voltage ratings, resistance and location of the fault, symmetry of minor sections, and number of major sections. The results show that the aforementioned possibility does exist, particularly for some fault types and for sufficiently high cable load
Impulsive strength of power cables with different XLPE compounds
No full textStandard lightning impulsive dielectric strength tests were performed on cable model samples manufactured with the same technology and the same materials used for high voltage cable application. In particular four different commercial XLPE compounds are considered. Tests were carried out with the aim to investigate the impulsive strength behaviour at room and 90°C of the compounds when they are subjected to both positive and negative testing wave polarities. The results have been compared in terms of Weibull scale and shape parameters. ©2006 IEEE
Influenza della lunghezza di posa dei cavi di media e alta tensione sulla distribuzione statistica delle tensioni di scarica
No full textDiagnosis and location of faults in submarine power cables
No full textNowadays, when compared with overhead lines, power cables are becoming increasingly attractive for the delivery of electrical power. Their reduced environmental impact complies with the public concern on the compatibility of electrical infrastructures in residential areas. The lower fault rate of high voltage DC (HVDC) cables matches the need of transmission and distribution system operators for high reliability in power delivery [1], [2], and sometimes they are the only solution, e.g., submarine links. In general, the growing demand and dependency on offshore produced renewable energy makes submarine cables essential, and they have become critical infrastructures for the reliable delivery of electrical power [1]-[3]
EPR lifetime under impulsive voltage stress
No full textAccelerated lifetime tests on EPR specimens were performed with the aim to investigate the endurance under impulsive electric stress at room and 90°C temperature. The results outline that relationship of the electric field on the number of applied pulses, at 63% of probability of breakdown, can be described by the well-known inverse power model
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