1,721,032 research outputs found
Effects of Loss of Coolant Accidents (LOCAs) on dielectric properties of nuclear LV cables
No full textQuantitative investigation and modelling of the electrical response of XLPE insulation with different filler content
Full text linkIn this article, electrical properties of XLPE-based materials with different additives are reported. In particular, it is shown that additives can deeply influence, among others, the complex permittivity of the analyzed material, putting the basis for a modelling approach which correlates the variation of the dielectric properties with the additive concentrations and characteristics
Life modeling analysis of Silane crosslinked polyethylene cables for nuclear applications
Full text linkIn this article, the evolution of the electrical and
mechanical properties of short XLPE cables subjected to radiochemical
aging is reported. From these results, an initial multiphysics
life modelling approach is presented. In particular, the
proposed modelling of the electrical properties (here complex
permittivity) showed to successfully assess of the health of the
cables through non-destructive techniques putting the basis of a
diagnostic method for cable management on site
Additive effect on dielectric spectrum of crosslinked polyethylene (XLPE) used in nuclear power plant cables
Full text linkThis article deals with the modification on electric behavior of crosslinked polyethylene (XLPE) for nuclear applications due to the effect of additives and fillers.
Material responses were investigated through dielectric spectroscopy which appeared to be very sensitive to the change in filler composition. It is shown that the addition of antioxidants and
fire-retardant fillers provides a modification on the imaginary and real parts of permittivity spectra with respect to the base material. Furthermore, the influence of degassing treatment and the
resulting crosslinking by-products removal on dielectric spectra are here investigated
A technique for defect investigation in pulse-controlled motors through partial discharge measurements
No full textThis paper presents a procedure for the investigation of partial discharge (PD) sources in PWM-controlled motors, based on off-line measurements under bipolar squarewaves. PD measurements were carried out on three-phase motors with open-star windings and different configurations, e.g., one phase supplied while the other two were grounded, two phases connected in series, grounding the motor frame. The voltage waveforms generated by a power supply and applied to motor windings was recorded at the winding terminals, for each test configuration. These measurements allowed to highlight winding positions where insulation can be overstressed by uneven voltage distribution, as occurs on motors in service. By comparing partial discharge measurement patterns along windings and under different test configurations, a qualitative evaluation of the location of partial discharge sources inside the tested motors was carried ou
Investigation of Si3N4 Nanoparticles Effect on the Electrical Properties of Polyimide for Power Electronics Applications
No full textIn this article, the electrical characterization of nanostructured polyimide (PI) films is presented. The addition of silicon nitride (Si3 N4) as nanoparticles ensures an enhanced thermal conductivity and high temperature endurance of PIs, without worsening their electrical performances. The effect of different concentrations of nanoparticles on the base PI is investigated by means of broadband dielectric spectroscopy and thermally stimulated depolarization currents (TSDC)
Investigation of Thermal Degradation of LDPE-Based Materials Through Electrical Measurements
Full text linkChemical and electrical characterization of XLPE cables exposed to radio-thermal aging
Full text linkThe aging of twisted pair cables with silane cross-linked polyethylene insulation has been examined by means of both chemical and electrical techniques. Radio-chemical aging has been performed through three different dose rates in order to evaluate the contribution of the dose rate on the changing of the analyzed properties with aging. Correlation between the different techniques has been performed and the antioxidant contents has been successfully linked to the variation of the dielectric properties
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