scholarly journals Pollution Flashover Characteristics of Composite Crossarm Insulator with a Large Diameter

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6491
Author(s):  
Jing Nan ◽  
Hua Li ◽  
Xiaodong Wan ◽  
Feng Huo ◽  
Fuchang Lin
Keyword(s):  
Silicone Rubber ◽  
Large Diameter ◽  
Surface Hydrophobicity ◽  
Voltage Gradient ◽  
Hydrophilic Surface ◽  
Core Diameter ◽  
Design And Optimization ◽  
The Core ◽  
Pollution Flashover ◽  
Flashover Voltage

The composite crossarm insulator differs greatly from the suspension insulator in structure and arrangement. This study aims to determine the pollution flashover characteristics of composite crossarm insulators under different voltage grades. Four types of AC composite crossarm insulators with diameters ranging from 100 mm to 450 mm are subjected to artificial pollution test, and then the effects of the surface hydrophobicity state of silicone rubber, core diameter, umbrella structure, arrangement, and insulation distance on the pollution flashover voltage of the composite crossarm insulators are analyzed. Under the pollution grade 0.2/1.0 mg/cm2 and voltage grade from 66 kV to 1000 kV, if the silicone rubber surface changes from HC5 to HC6, the pollution flashover voltage of the composite crossarm insulator will increase by 13.5% to 21.0% compared with the hydrophilic surface. If the core diameter changes from 100 mm to 300 mm, the pollution flashover voltage gradient decreases with the increase in core diameter; if the core diameter changes from 300 mm to 450 mm, the pollution flashover voltage gradient increases with core diameter. Under the same insulation height and core diameter, the umbrella structure will have a certain impact on pollution flashover voltage by up to 1.7% to 5.4%. Under the horizontal arrangement, the pollution flashover voltage can increase by 10.5% to 12.1% compared with that under the vertical arrangement. Under the hydrophilic surface and weak hydrophobicity state, the pollution flashover voltage has a linear relationship with the insulation distance. The above results can provide a reference for the structural design and optimization of the composite crossarm insulator.

scholarly journals Influence of Silicone Rubber Coating on the Characteristics of Surface Streamer Discharge

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3784
Author(s):  
Xiaobo Meng ◽  
Liming Wang ◽  
Hongwei Mei ◽  
Chuyan Zhang
Keyword(s):  
Silicone Rubber ◽  
Electrical Power ◽  
Electrical Power System ◽  
Streamer Discharge ◽  
Reliable Operation ◽  
Pollution Flashover ◽  
Flashover Voltage ◽  
Streamer Propagation ◽  
Rubber Coating ◽  
Rubber Coatings

A pollution flashover along an insulation surface—a catastrophic accident in electrical power system—threatens the safe and reliable operation of a power grid. Silicone rubber coatings are applied to the surfaces of other insulation materials in order to improve the pollution flashover voltage of the insulation structure. It is generally believed that the hydrophobicity of the silicone rubber coating is key to blocking the physical process of pollution flashover, which prevents the formation of continuously wet pollution areas. However, it is unclear whether silicone rubber coating can suppress the generation of pre-discharges such as corona discharge and streamer discharge. In this research, the influence of silicone rubber coating on the characteristics of surface streamer discharge was researched in-depth. The streamer ‘stability’ propagation fields of the polymer are lower than that of the polymer with silicone rubber coating. The velocities of the streamer propagation along the polymer are higher than those along the polymer with silicone rubber coating. This indicates that the surface properties of the polymer with the silicone rubber coating are less favorable for streamer propagation than those of the polymer.

Preparation and Performance of RTV Coating for Anti-Pollution Flashover with Superhydrophobicity by Filling CaCO3/SiO2 Composite Particles into Silicone Rubber

2011 ◽  
Vol 328-330 ◽  
pp. 1263-1267 ◽  
Author(s):  
Jing Hai ◽  
Jin Xin Yang ◽  
Jiang Cheng ◽  
Zhuo Ru Yang
Keyword(s):  
Silicone Rubber ◽  
Spray Coating ◽  
Composite Particles ◽  
Coating Film ◽  
Water Contact ◽  
Pollution Flashover ◽  
Flashover Voltage ◽  
Strong Adhesion ◽  
Rubber Coating ◽  
And Performance

Room temperature vulcanizing (RTV) silicone rubber coating with superhydrophobicity for anti-pollution flashover is prepared by filling silica-encapsulated calcium carbonate particles (CaCO3/SiO2 composite particles) into polydimethylsiloxane (PDMS) rubber. Two-step spraying technology is applied for fabricating the superhydrophobic RTV coating film on outdoor insulators. The primary spray coating provides basically the strong adhesion and certain hydrophobicity, and the second one produces the appropriate roughness structure and further enhances the superhydrophobicity. The water contact angle on the prepared RTV coating film is 165°and the sliding (rolling) angle of water droplet is about 5°, allowing water droplets to move easily on the coating surface and give self-cleaning function of the RTV coated insulator surface. The flashover voltage of insulators with superhydrophobic RTV coating is 29.95 kV, quite higher than that of insulators with common RTV coating (23.29) and that without RTV coating (11.34 kV).

Magnetic Properties of Fe3O4/CoFe2O4 Composite Nanoparticles with Core/Shell Architecture

2020 ◽  
Vol 65 (10) ◽  
pp. 904
Author(s):  
V. O. Zamorskyi ◽  
Ya. M. Lytvynenko ◽  
A. M. Pogorily ◽  
A. I. Tovstolytkin ◽  
S. O. Solopan ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Spinel Ferrite ◽  
Composite Nanoparticles ◽  
Core Shell ◽  
Cofe2o4 Nanoparticles ◽  
Core Diameter ◽  
The Core ◽  
Shell Particles ◽  
Interface Parameters ◽  
Shell Composite

Magnetic properties of the sets of Fe3O4(core)/CoFe2O4(shell) composite nanoparticles with a core diameter of about 6.3 nm and various shell thicknesses (0, 1.0, and 2.5 nm), as well as the mixtures of Fe3O4 and CoFe2O4 nanoparticles taken in the ratios corresponding to the core/shell material contents in the former case, have been studied. The results of magnetic research showed that the coating of magnetic nanoparticles with a shell gives rise to the appearance of two simultaneous effects: the modification of the core/shell interface parameters and the parameter change in both the nanoparticle’s core and shell themselves. As a result, the core/shell particles acquire new characteristics that are inherent neither to Fe3O4 nor to CoFe2O4. The obtained results open the way to the optimization and adaptation of the parameters of the core/shell spinel-ferrite-based nanoparticles for their application in various technological and biomedical domains.

scholarly journals Geometrical Scaling of Antiresonant Hollow-Core Fibers for Mid-Infrared Beam Delivery

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 420
Author(s):  
Ang Deng ◽  
Wonkeun Chang
Keyword(s):  
Structural Parameters ◽  
Transmission Band ◽  
Confinement Loss ◽  
Hollow Core ◽  
Core Size ◽  
Core Diameter ◽  
Mid Infrared ◽  
The Core ◽  
Tubular Type ◽  
Beam Delivery

We numerically investigate the effect of scaling two key structural parameters in antiresonant hollow-core fibers—dielectric wall thickness of the cladding elements and core size—in view of low-loss mid-infrared beam delivery. We demonstrate that there exists an additional resonance-like loss peak in the long-wavelength limit of the first transmission band in antiresonant hollow-core fibers. We also find that the confinement loss in tubular-type hollow-core fibers depends strongly on the core size, where the degree of the dependence varies with the cladding tube size. The loss scales with the core diameter to the power of approximately −5.4 for commonly used tubular-type hollow-core fiber designs.

Early interactions, adhesion, and establishment of the infection court by Erysiphe graminis

1995 ◽  
Vol 73 (S1) ◽  
pp. 609-615 ◽  
Author(s):  
Ralph L. Nicholson ◽  
Hitoshi Kunoh
Keyword(s):  
Hydrophobic Surface ◽  
Surface Hydrophobicity ◽  
Infection Process ◽  
Erysiphe Graminis ◽  
Hydrophilic Surface ◽  
Colletotrichum Graminicola ◽  
Appressorium Formation ◽  
Barley Leaf ◽  
Powdery Mildew Pathogen ◽  
Suitable Substratum

The establishment of a fungal pathogen on the surface of its host is essential to the success of the infection process. For many fungi, establishment on the host is an active process that may depend on recognition of the host surface through chemical or topographic signals. Events that allow for establishment may be considered to represent the "preparation of the infection court" by the pathogen. This sometimes involves the adhesion of the pathogen to the host and possibly the alteration of the host's surface topography or chemistry. Adhesion is often presumed to be a single, chemically mediated event associated with germ tube or appressorium formation. However, adhesion of ungerminated propagules may also occur, and evidence suggests that it is mediated by the release of adhesive materials directly from the propagule upon contact with a suitable substratum. Fungi may require either a hydrophobic or a hydrophilic surface to initiate the infection process. The barley powdery mildew pathogen, Erysiphe graminis, requires a hydrophilic surface for appressorium formation, yet the barley leaf is extremely hydrophobic. The problem is resolved by the release of an exudate from conidia that makes the hydrophobic leaf surface hydrophilic. In contrast, Colletotrichum graminicola requires a hydrophobic surface for the initiation of its infection process. Ungerminated conidia of this fungus release materials that allow for the rapid adhesion of conidia, which ensures that germination and appressorium formation occur, initiating the infection process. For both fungi, these events happen well in advance of germination and establish the pathogen at the site of the infection court. Key words: adhesion, cuticle, cutinase, surface hydrophobicity, infection process.

Determination of all Dimensions of CdSe Seeded CdS Nanorods Solely via their UV/Vis Spectra

2017 ◽  
Vol 231 (1) ◽  
Author(s):  
Patrick Adel ◽  
Julian Bloh ◽  
Dominik Hinrichs ◽  
Torben Kodanek ◽  
Dirk Dorfs
Keyword(s):  
Absorption Spectra ◽  
Extinction Coefficient ◽  
Core Diameter ◽  
The Core ◽  
Extinction Spectra ◽  
Cds Nanorods ◽  
Fast Route ◽  
Characteristic Points ◽  
Electron Microscopical

AbstractIn the present manuscript we develop a method to determine all characteristic dimensions of CdSe seeded CdS nanorods solely via their extinction spectra without the need for electron microscopical investigations. In detail, the core diameter as well as the overall diameter and length and the molar extinction coefficient can all be derived from characteristic points in the absorption spectra. We carefully investigate in which size regime our assumptions are valid and give an estimation of the expected error, making it possible for the reader to decide whether this method is sufficiently accurate for their respective system. Our method displays a comfortable and fast route to analyze these nowadays often used nanorods.

Design and Optimization of Core Balancing Fixture in Vibration Sorting Rig (VSR)

2016 ◽  
Vol 852 ◽  
pp. 568-574
Author(s):  
Karumanchi Vinay Prakash ◽  
R. Bakthavachalam ◽  
M. Senthil Kumar
Keyword(s):  
Work Piece ◽  
Fixture Design ◽  
Cfd Analysis ◽  
Turbine Wheel ◽  
Compressor Wheel ◽  
Rotating Speed ◽  
Design And Optimization ◽  
The Core ◽  
Turbo Charger

This work studies the design of a fixture used in vibration sorting rig which is used for core balancing in turbo charger. The main objective of this paper is to design and optimize the fixture for holding the turbo chargers. To balance the core of turbo charger, turbine wheel and compressor wheel should balance which is turbine wheel is placed into the fixture. This paper analyzes the existing fixture and proposed new design. The fixture runs at higher speeds which is why we have to put the more concentration on the fixture design. The small issue in the fixture design results more problems due to high rotating speed of the turbine wheel of turbo charger. Many of the parts rejects due to poor fixture design. New fixture design is based on several aspects like design of work piece, rotating speed etc. The CFD analysis on the existing and proposed design is carried out. The results obtained were compared with existing fixture design.

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