Surface charge accumulation on the spacers is one of key issues restraining development HVDC GIS/GIL. The precise measurement surface properties provides basis for further study transport mechanism as well charge-induced flashover under DC voltage. In this study, authors discuss their perspective current status, needs and potential developing orientation characterisation techniques. Different methods inversion algorithms are reviewed regarding previous studies future research needs....

The usability of any material hinges upon its stability over time. One the major concerns, focusing on polymeric materials, is degradation they face during their service life. mechanisms are deeply influenced by aging temperature to which subjected. In this paper, low-density polyethylene (LDPE) flat specimens were thermally aged under two different temperatures (90 °C and 110 °C) analyzed. Specimens characterized through both most common mechanical chemical measurements techniques (e.g.,...

This paper investigates the changes in electrical and physico-chemical properties of low-voltage power cables for nuclear application when subjected to combined effects gamma radiation temperature. Electrical response is evaluated by means dielectric spectroscopy, while are analyzed at different structural scales through five complementary techniques (OIT measurements, FTIR swelling DSC analysis micro-indentation). The spectroscopy first two chemical shown be appropriate evaluating...

The accuracy of instrument transformers (ITs) is vital for the accurate measurement electrical quantities. However, their performance influenced by various factors during operation, including environmental conditions such as temperature, pressure, and humidity, well other like positioning, electromagnetic fields, geometry. Given that IT challenging to verify once installed in field, it essential thoroughly understand its beforehand. This paper investigates how variations resin properties...

This paper deals with the study of a non-destructive technique to detect aging state cable insulation used in nuclear environment subjected radiation and temperature aging. Cable samples were aged under dose rates ranging from 0.42 1.06 kGy/h at 55 85 °C. The imaginary part permittivity 100 kHz is found correlate well mechanical properties, such as elongation break, which typically diagnose insulation, but it destructive property cannot be on field. It has been demonstrated also that...

This paper presents a comprehensive study on the impact of antioxidants (AOs) aging process insulating polymeric materials, specifically complex permittivity, conductivity, and AC breakdown voltage. Accelerated was achieved through high temperatures (up to 130°C) in air crosslinked polyethylene (XLPE) both with without AOs. In addition electrical tests, chemical analyses were performed better understand role AOs during thermal aging. The results indicate that effectively inhibit oxidation,...

This article presents the development and application of a modelling approach based on quantities obtained from mechanical electrical tests to assess aging low voltage cable insulation for nuclear applications. In order obtain experimental data needed establishing models, accelerated is performed coaxial cables. The first part this paper focuses predictive properties; allows evaluation Dose Equivalent Damage (DED) as function stress (dose rate). However, use assessment some problems, being...

The radio-thermal ageing of silane-crosslinked polyethylene (Si-XLPE) was studied in air under different γ dose rates (6.0, 8.5, 77.8, and 400 Gy·h−1) at temperatures (21, 47, 86 °C). changes the physico-chemical electrical properties Si-XLPE throughout its exposure were determined using Fourier transform infrared spectroscopy coupled with chemical gas derivatization, hydrostatic weighing, differential scanning calorimetry, dielectric current measurements an applied electric field. From a...

In this article, the aging behavior of nuclear-grade low voltage cables, characterized by different geometries and insulation compositions, is investigated. Cables were subjected to radio-chemical at dose rates (7 Gy/h, 66 Gy/h 400 Gy/h), in order simulate typical environments inside nuclear plants. The changes properties due are investigated scales, aiming highlighting possible correlations between molecular-scale global macroscopic material (e.g., mechanical electrical ones). Microscale...

Surface flashover of spacers is a key factor limiting the application HVDC GIS/GIL, while charge accumulation on surface spacer could have potential adverse effect voltage.This paper discusses laws regarding distribution patterns charges and related mechanism.The fielddependent property discussed in detail to comprehensively illustrate transport mechanism explain research differences different obtained by previous researchers.In addition, main control methods for epoxy resin are summarized...

To investigate the effect of fluorination on surface electrical performance ethylene propylene rubber (EPR), four pieces EPR specimens are prepared and fluorinated for different duration ranging from 120 min to 480 min. The morphology element compositions experimental tested. potential decay complex permittivity measured. tracking discharge property erosion properties after test investigated. charge transport tailoring mechanism discussed. results show that when is 360 min, gradually becomes...

In this article, the impact of two different antioxidants (Irganox® 1076 and PS802) on electrical properties a cross-linked polyethylene (XLPE) matrix is investigated discussed. Materials were tested by means dielectric spectroscopy, thermally stimulated depolarization currents (TSDC) DC conductivity measurements to provide comprehensive analysis for their applications under AC electric fields. Results reveal that are notably modified introduction additives amplitude variation somehow...

This paper deals with the effect of a long storage time after thermal and radiation aging on electrical mechanical properties insulating materials used in nuclear power plant cables. Strong post-irradiation effects were found XLPE cable insulation years irradiation. In particular, dramatic reduction was observed, suggesting crosslinking and/or oxidation, as well an increase imaginary permittivity values, particularly low frequency range where interfacial phenomena are active. latter could be...

A theoretical model considering the dynamic change of surface charge accumulation in transient and steady states is proposed.The under are simulated using three spacers with different volume conductivities.The results show that on convex a spacer, when conductivity lower than 2 × 10 -18 S/m, hetero-polarity accumulated spacer dominant, while homo-polarity dominant higher 6 -17 S/m.The density non-uniformly distributed, time duration process at positions different, due to distribution...

This paper investigates the evolution of electrical properties with aging for two XLPE based materials having different chemical compositions. It is shown that and material composition can significantly affect response, suggesting suitability dielectric spectroscopy polymer diagnostics. Furthermore, response correlated mechanical properties, in particular elongation at break (EaB), order to evaluate possible scaling-up current cable qualification standard.

Investigation of thermal degradation low-density polyethylene (LDPE) has been carried out in this paper. LDPE plaques made directly from commercial pellets thermally stressed at high temperature (110°C) and characterized through both chemical electrical measurements. In particular, oxidation morphological changes contributions inside polymer have correlated to modification the imaginary part dielectric constant. This comparison could put basis developing specific nondestructive techniques...

This paper deals with realization of multifunctional composite materials, having piezoelectric effect. First all polymeric mats electrospun nanofibers were realized different geometries. Such effect has been maximized by designing properly the electrospinning apparatus in order to enhance electric field interelectrodic space which polarize dipolar moments. The are then integrated a silicon rubber matrix and measurements electromechanical response materials thus manufactured performed. A good...

This article deals with the modification on electric behavior of crosslinked polyethylene (XLPE) for nuclear applications due to effect additives and fillers. Material responses were investigated through dielectric spectroscopy which appeared be very sensitive change in filler composition. It is shown that addition antioxidants fire-retardant fillers provides a imaginary real parts permittivity spectra respect base material. Furthermore, influence degassing treatment resulting crosslinking...

Space charge can affect significantly the reliability of DC cross-linked polyethylene (XLPE) power cables. For limiting injection and accumulation space charge, specimens with graphene coating applied on a sandwich composed XLPE semiconductive layer were made. distribution was measured at 10 40 kV/mm. The measuring results show that when is coated side, negative accumulates in XLPE, quantity positive injected from anode reduced. When graphene, little into near interface electrode, which...

This work presents an innovative model for the derivation of permittivity evolution polyethylene (PE)-based materials with aging. First, microscale contributions to real methylene unit [constitutive repetitive (CRU) PE] and its oxidation products, that is, ketones hydroperoxides, in solid state is presented. Then, a chemical kinetic recalled predicting concentration, under proper hypotheses, oxidized species created during polymer The proposed combines concentrations products respective...

This work presents the development, validation, and sensitivity analyses of a portable device capable performing high-frequency dielectric spectroscopy tests on site. After brief introduction operation principle description impact frequency spectroscopy, article results reference samples confirming good agreement with expected values. The region in which operates, 1–200 kHz, was chosen because its correlation oxidative species polymeric compound. were performed measuring response low voltage...

DC cross-linked polyethylene (XLPE) power cables are being used recently for HV/EHV applications, the reliability of which is claimed to be significantly affected by space charge accumulation in insulating material. Many methods have been provided limiting injection and charge. In paper, three kinds specimens with graphene coating applied on a sandwich composed XLPE semiconductive layer were made. Space distribution was measured at 10 kV/mm 40 under room temperature 60 °C. The measurement...

During operation of high voltage (HV) motors, different types discharges, e.g. surface discharge, corona discharge and bar-to-bar can occur at the same time, increasing difficulty partial (PD) sources determination PDs pattern identification. In this study, end-winding a 10 kV motor coil was artificially aged related PD measured. The initiation variation under multi-factor stresses were studied. localised fingerprints coexisting with multiple identified analysed. results confirm that process...