Improved DC flashover performance of epoxy insulators in SF6 gas by direct fluorination

Que, Longkai; An, Zhenlian; Ma, Yong; Xie, Danli; Zheng, Feihu; Zhang, Yewen

doi:10.1109/tdei.2017.006112

Cited by 75 publications

(39 citation statements)

References 21 publications

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“…Surface modification has been proven as a potential method for optimizing the surface properties without changing the mechanical and electrical behaviors of the entire dielectric [10,11]. Direct fluorination is an effective method of polymer surface modification, which regulates the surface’s mechanical and chemical properties by replacing the active hydrogen atoms with fluorine atoms, and is usually achieved in a gas mixture composited of F 2 with N 2 or O 2 [12]. Du et al investigated the effects of direct fluorination on the electrical properties of both outdoor and indoor insulators, and revealed that surface fluorination could reduce the accumulation of surface charges and improve the flashover voltage [13,14].…”

Section: Introductionmentioning

confidence: 99%

Surface Layer Fluorination-Modulated Space Charge Behaviors in HVDC Cable Accessory

et al. 2018

Polymers

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Space charges tend to accumulate on the surface and at the interface of ethylene–propylene–diene terpolymer (EPDM), serving as high voltage direct current (HVDC) cable accessory insulation, which likely induces electrical field distortion and dielectric breakdown. Direct fluorination is an effective method to modify the surface characteristics of the EPDM without altering the bulk properties too much. In this paper, the surface morphology, hydrophobic properties, relative permittivity, and DC conductivity of the EPDM before and after fluorination treatment were tested. Furthermore, the surface and interface charge behaviors in the HVDC cable accessory were investigated by the pulsed electroacoustic (PEA) method, and explained from the point of view of trap distribution. The results show that fluorination helps the EPDM polymer obtain lower surface energy and relative permittivity, which is beneficial to the interface match in composite insulation systems. The lowest degree of space charge accumulation occurs in EPDM with 30 min of fluorination. After analyzing the results of the 3D potentials and the density of states (DOS) behaviors in EPDM before and after fluorination, it can be found that fluorination treatment introduces shallower electron traps, and the special electrostatic potential after fluorination can significantly suppress the space charge accumulation at the interface in the HVDC cable accessory.

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Section: Introductionmentioning

confidence: 99%

Surface Layer Fluorination-Modulated Space Charge Behaviors in HVDC Cable Accessory

et al. 2018

Polymers

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“…It is widely accepted that the dynamic processes of surface charge accumulation and dissipation are dependent on surface trap states and electrical conductivity that can be modulated by many interface tailoring techniques. Using interface tailoring methods such as fluorination [14,15], plasma treatment [21][22][23][24] and non-linear surface coating [33][34][35], shallow traps can be introduced on the spacer to effectively accelerate charge dissipation and improve flashover strength. From another perspective, deep traps can be formed by elaborate regulation of the types and concentrations of nanofillers in the surface coating to capture injected charges and lead to homo-charge accumulation, thus reducing the electric field in the vicinity of electrodes [36,37].…”

Section: Potential Application Scenarios Of Interface Tailoringmentioning

confidence: 99%

Review of interface tailoring techniques and applications to improve insulation performance

et al. 2021

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Interfaces between different materials, for instance, electrode-dielectrics and vacuum/ air/SF 6 -insulators and oilpaper, are universal in high-voltage insulation systems. Targeted tailoring of the interfacial properties, e.g. chemical structures, micro-/nanoscale morphology, the charge injection barrier, trap states, and surface conductivity, is thought to be an effective approach to improve insulation properties such as breakdown and flashover strength, corona/tracking resistance, and wettability. In this article, the authors review recent progress in interface tailoring methods and their application to improve various insulation properties. The potential application scenarios of interface tailoring in different facilities are first summarised, and the desired insulation properties of various applications are highlighted. Interface tailoring methods are classified as physical/ chemical surface modification and surface coating (inorganic, organic and composite), and the features of different techniques are described in detail. The structure-property relationships between interfacial states and various microscopic parameters such as charge injection barrier, trap distribution and surface conductivity are discussed together with the tailoring mechanisms for different insulation properties. Finally, the future development prospects of interface tailoring methods and their applications, e.g. multifunctional coating and stimuli-response smart coating, are presented.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.

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“…Studies have shown that the higher the conductivity, the more conducive to speed up the migration of surface charge along the surface of the medium, to achieve the purpose of promoting the rapid dissipation of surface charge . [31][32][33] As can be seen from the figure, the surface conductivity of samples treated by plasma jet increases to some extent, and Ar/CF 4 plasma jet treatment has a more obvious effect, which can increase the surface conductivity of samples to 4.6 Â 10-16 S, about two orders of magnitude higher than that of untreated samples. After 30 days of storage, the surface conductivity of the untreated sample was basically unchanged, while the sample treated with Ar plasma jet decreased by about 0.45 orders of magnitude, and the sample treated with Ar/CF 4 plasma jet decreased slightly.…”

Section: Surface Conductivity and Surface Potentialmentioning

confidence: 99%

Study on the ageing effect of alumina/epoxy composites modified by atmospheric plasma jet

et al. 2021

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Alumina/epoxy resin (Al 2 O 3 /EP) composite material is widely used in the manufacture of insulators. However, the operation environment of long-term high-voltage direct current will destroy Al 2 O 3 /EP surface insulating performance. In this article, Al 2 O 3 /EP was modified by atmospheric pressure Ar and Ar/CF 4 plasma jet, and its aging effect was studied by investigating the physicochemical characteristics and the electrical performances of the sample 0 $ 100 days after modification. The experimental results show that after plasma treatment the surface roughness of the material increases; the O/C ratio on the surface of the material increases after Ar treatment, and the F element is grafted on the surface after Ar/CF 4 treatment. These changes lead to the increase of surface energy and hydrophilicity, and the improvement of electrical performance. The surface properties change within 100 days owing to the oxidation reactions and the variability of recombination chemical bonds and molecular chains after high-energy plasma treatment. The surface O/C ratio of the materials treated by Ar plasma is obviously reduced, the hydrophobicity is restored to some extent, and the electrical properties are also obviously weakened. In comparison, the properties of Ar/CF 4 plasma-modified materials do not change significantly.

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Improved DC flashover performance of epoxy insulators in SF6 gas by direct fluorination

Cited by 75 publications

References 21 publications

Surface Layer Fluorination-Modulated Space Charge Behaviors in HVDC Cable Accessory

Surface Layer Fluorination-Modulated Space Charge Behaviors in HVDC Cable Accessory

Review of interface tailoring techniques and applications to improve insulation performance

Study on the ageing effect of alumina/epoxy composites modified by atmospheric plasma jet

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