IET Nanodielectrics最新文献

The suitability of corn oil nanofluid as an insulation material is studied herein by analysing the partial discharge characteristics. Experiments are conducted on nano-silica modified corn oil at 0.01, 0.05, and 0.1 wt.% mass fractions. Electrode configurations are used to generate partial discharge (PD) sources such as corona discharge, internal discharge, and surface discharge. Partial discharge inception voltage dependency on electrode geometry is studied. Phase-resolved partial discharge analysis (PRPD) at various test conditions is done to understand the influence of live element geometry that causes PD in real-time operations, Weibull statistical analysis of PD parameters like scale parameter, shape parameter, skewness, and repetition rate is evaluated to understand the influence of nanofiller mass fraction in corn oil. The results illustrate that the addition of silica nanoparticles to corn oil has a significant influence on PD characteristics. The PRPD pattern analysis reveals information about the PD dependency on electrode configuration of the test condition. The addition of nanofillers in optimal concentrations without agglomeration can influence the PD characteristics to a certain degree. The test results may be inferred to suggest corn oil-based silica nanofluids as an alternative biodegradable liquid insulation.

The trend of choosing insulating materials has changed in the past few decades, and a considerable shift has occurred from conventional ceramic to non-ceramic insulating materials. The addition of inorganic fillers has greatly improved the thermal conductivity, discharge resistance, hydrophobicity recovery, and vandalism-resistance properties of polymeric insulating materials. Since the beginning of the present century, the field of nanomaterial research has gained much attention. Several studies have been conducted to investigate and analyze polymer nanocomposites by adding nanoparticles of varying size and concentration as fillers. The aim is to improve the characteristics and reformation of thermal, electrical, and mechanical properties of existing polymeric insulation materials. However, certain inconsistencies are prevalent with results obtained for polymer nanocomposites. A comprehensive review is presented based on available literature focussing on the advancement from polymeric insulating materials to polymeric nanocomposites and its impact on partial discharge resistance, surface charging, and tracking and erosion resistance. It is observed that the weight percent and dispersion of nano- or micro-sized particles into the base polymer matrix governs the performance of polymer composites. At higher filler loading, resistance to partial discharge and tracking and erosion decreases as a result of the agglomeration of fillers, whereas resistance to surface charge accumulation increases at higher filler loading because the formation of shallow traps increases the charge decay rate. It is suggested that when both micro- and nanofillers are mixed in proper proportion, micro–nano hybrid composites provide better performance than composites filled with only nano- or microfillers.

Cross-linked polyethylene (XLPE) is commonly used as an insulation material in power cables. Due to the recent advancements in the field of high voltage power transmission and distribution, there is a need for novel cable insulation materials that have high performance, recyclability and high working temperature as alternatives for the conventional XPLE-based insulation materials. Polypropylene (PP) shows excellent properties and has drawn considerable attention as a potential high voltage direct current (HVDC) insulation material. Therefore, the development of PP-based HVDC cable insulation with improved electrical, thermal and mechanical properties is important in discovering a potentially recyclable cable insulation material. Due to the remarkable development in the field of nanodielectrics, nanotechnology can be a promising solution for enhancing the overall dielectric properties of PP-based insulation materials. This review presents the important aspects of PP-based nanocomposites for HVDC cable insulation with a special focus on understanding the effects of various parameters of nanofillers on the dielectric properties of PP-based HVDC cable insulation. Based on the gathered information, future perspectives for improving the dielectric properties of PP-based nanocomposites for HVDC cable are provided.

The state of the ampere-hour capacity of the battery depends on the condition of materials used in it. Large reduction of capacity ends with maintenance or replacement of the battery. Modern battery materials include application of nanomaterials and nanotechnology in various stages of production. This article attempts to monitor the capacity of battery used for vehicles which are made of different types of materials using switching transients. The analytical part was done using wavelet-based decompositions. Data sets of large number of coefficients have been developed for learning. Their statistical behaviour has been studied, and monitoring was initially carried out by some selective parameters. Then the artificial neural network-based algorithm was developed which includes all features of statistical variation for better monitoring. Case studies have been carried out followed by comparison. The study ends with a satisfactory monitoring.

Laser texturing has been carried out on the surface of the silicone nano-micro composites to achieve super hydrophobic properties, and water droplet-initiated Corona discharge studies were carried out. The Corona inception voltage (CIV) exhibits considerable enhancement with increase in the nano filler content under DC voltage compared with AC voltage. The corona inception voltage is high with the textured surface and is found to have direct correlation with contact angle of the composite specimen. The Corona inception voltage was measured using Ultra-high frequency (UHF) and fluorescent fibre techniques. It is observed that the fluorescent fibre technique is more sensitive in identifying discharges. Frequency domain analysis of UHF signal shows a dominant frequency at 1 GHz and for fluorescent signal, the spectral content is in the range of DC to 10 MHz. The rise time and pulse width of the UHF signal increases with the increase in the nano filler in composite material. The energy content of UHF/fluorescent signal due to discharges shows similar trend with its increase in energy with variation in its magnitude of the signal formed. The pulse width of fluorescent signal formed due to water droplet-initiated discharges under AC and DC voltage is almost the same, and with the textured specimen it is quite low than the non-textured material.

Here, the nano-sized dielectrics in biosystems and their functions are reviewed. For a variety of electromagnetic phenomena observed in biosystems, from a generation of weak electrical pulses in all kinds of neural systems to generation of high-power electrical pulses for sensing and attacking preys in electric eels, nano-dielectrics, such as lipid membrane, always play an important role. The electromagnetic pulses in neural systems are created by transmembrane ionic fluxes through a cluster of ion channels embedded in a lipid membrane, but the high-power pulses released by electric eels are simultaneously generated by billions of ion channels. An overlooked function of the nano-dielectrics is that they build up a network serving as the major transmitting paths for electromagnetic pulses in dendrites and axons, and even in ordinary cell membranes. Many fundamental questions in the working mechanisms of nano-dielectrics in nature biosystems remain open and answers to these questions may lead to novel, high-efficiency manmade power supplies and a better understanding of brain functions.

The authors demonstrate how a simple step of loading an electrochromically active Prussian blue (PB; an ionic solid) electrode with Li⁺ ions can help in achieving a more efficient viologen based solid state hybrid electrochromic device. To accomplish this, two different devices, with and without Li⁺ ion loaded PB electrodes, have been fabricated. These devices have been compared in terms of their current-voltage response, bias dependent optical modulation and corresponding colour switching to establish the role of Li⁺ ion in charge transport and charge balancing involved during bias induced redox mediated colour switching of the two devices. The Li⁺ containing PB electrode device exhibits a superior performance with twice (40%) the value of colour contrast (20%), quick response switching (1.3 s), excellent stability (8400 s) and better power efficiency as compared to the device containing as-synthesised PB electrode. A mechanism has been proposed to explain the role of the Li⁺ ion which is later substantiated using bias-dependent in situ Raman spectroscopic evidences.

Dielectric materials with high-energy-density and low-energy-loss have received lot of attention in terms of renewable energy storage and application. PVDF-based polymer/ceramics composite dielectrics are considered as one of the most promising materials due to their high dielectric constant. However, the high remnant polarisation (P_r) of ferroelectric polymer matrix and ceramics fillers generates a lot of energy loss and residual heat during charge-discharge cycles, which limits their practical applications. Compared with ferroelectrics, relaxor ferroelectric and antiferroelectric dielectrics may have high energy efficiency due to their lower P_r. Here, the relaxor ferroelectric matrix and antiferroelectric filler coated by the polydopamine layer were prepared by chemical grafting and solid-state method, respectively. Afterwards, the P(VDF-TrFE-CTFE)-g-PMMA/PLZST nanocomposite was prepared via solution casting. Experimental results show that the energy loss of the optimised nanocomposites was significantly reduced, leading to an enhanced charge-discharge efficiency (η) of 78% at 450 MV/m, which is 267% of the pure P(VDF-TrFE-CTFE) matrix and superior to those of most polymer/ferroelectric filler nanocomposites. It is encouraging that the breakdown strength and energy storage density of the P(VDF-TrFE-CTFE)-g-PMMA/PLZST nanocomposites with 6 wt% filler fractions reach the values of 458 MV/m and 10.3 J/cm³. This study establishes a simple and effective strategy for preparing capacitors with high energy efficiency.

A nanostructured film of NiCo₂O₄ has been prepared using a hydrothermal technique by simply using separate precursors to obtain nanoneedle-like architecture for electrochromic applications. A homogeneous film consisting of packed nanoneedles with moderate density, appearing translucent white in colour, has been obtained and characterized using XRD and Raman spectroscopy techniques for confirming the composition and structure. Electrochemical analysis of the film reveals that the film shows good electrochromic properties under the anodic scan of potential with strong stability. The mechanism of the electrode under the transformation from natural white to opaque dark brown colour has been understood with the help of an in situ optical absorption spectroscopy technique. The electrode is found electrochromically active with a bias of up to 2 V and shows 50% optical contrast which makes it a good candidate for application in a solid state electrochromic device.

This work presents a new approach for the design of an FMF with a Gaussian core and a trench in the cladding. For the proposed few-mode fibre (FMF), Fused Silica (SiO₂) is considered as a host-material, whereas Germanium Oxide(GeO₂) and Fluorine(F)are taken as the dopant for large data transmission. The mole percentages of the dopant material along with the fibre profile parameters are varied to achieve 10 linearly polarized (LP) modes through the proposed FMF. The proposed FMF structure is tested and verified through simulated experiments. The results indicate the proposed FMF structure with the mole percentage 11.5% of GeO₂, 2% of F, and the normalized full-width-half-maximum (FWHM) of the core in the range of 4 to 10 supports 10 LP modes in the order of LP₀₁, LP₁₁, LP₂₁, LP₀₂, LP₃₁, LP₁₂, LP₄₁, LP₂₂, LP₀₃, and LP₅₁. The effective index difference (Δn_eff) between the adjacent LP modes is maintained greater than $��1�\times �{10}^{�-�3�}�$ and a weakly coupled 10x10 Gbps SDM transmission link is established through intensity-modulation and direct-detection (IM/DD) using the proposed Gaussian core-FMF. The link performance is analysed, verified and an acceptable bit-error-rate (BER) of 10⁻²⁰ is achieved over 50 km without amplifiers.