Effects of surface “micro-holes” on the flashover properties of a disk-type ceramic-vacuum insulator

Xiao, Sun; Zhong, Hui-Huang; Xun, Tao; Zhang, Jun

doi:10.1016/j.vacuum.2017.03.036

Cited by 9 publications

(6 citation statements)

References 28 publications

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“…Previous studies have demonstrated that surface roughness is an important factor affecting surface electrical performance. , The 3D morphology and root mean squared roughness R a of pristine and coated PI were measured using high-precision AFM, as illustrated in Figure . Interestingly, despite the surface morphology differences shown in Figure , the roughness R a of the hybrid PI remained within the same order of magnitude as the pristine PI, which is in the nano-scale range.…”

Section: Resultsmentioning

confidence: 99%

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Yang,

Sun,

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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High-voltage and high-power devices are indispensable in spacecraft for outer space explorations, whose operations require aerospace materials with adequate vacuum surface insulation performance. Despite persistent attempts to fabricate such materials, current efforts are restricted to trial-and-error methods and a universal design guideline is missing. The present work proposes to improve the vacuum surface insulation by tailoring the surface trap state density and energy level of the metal oxides with varied bandgaps, using coating on a polyimide (PI) substrate, aiming for a more systematical workflow for the insulation material design. First-principle calculations and trap diagnostics are employed to evaluate the material properties and reveal the interplay between trap states and the flashover threshold, supported by dedicated analyses of the flashover voltage, secondary electron emission (SEE) from insulators, and surface charging behaviors. Experimental results suggest that the coated PI (i.e., CuO@PI, SrO@PI, MgO@PI, and Al2O3@PI) can effectively increase the trap density and alter the trap energy levels. Elevated trap density is demonstrated to always yield lower SEE. In addition, increasing shallow trap density accelerates surface charge dissipation, which is favorable for improving surface insulation. CuO@PI exhibits the most remarkable increase in shallow trap density, and accordingly, the highest flashover voltage is 42.5% higher than that of pristine PI. This study reveals the critical role played by surface trap states in flashover mitigation and offers a novel strategy to optimize the surface insulation of materials.

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Section: Resultsmentioning

confidence: 99%

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Yang,

Sun,

Guo

et al. 2023

ACS Appl. Mater. Interfaces

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“…According to a previous research study, the interface between different materials is prone to generate deep traps [10]. Therefore, when the Al 2 O 3 nanoparticles are initially added, the interface area between different media increases rapidly, leading to a large number of deep traps [28]. However, a large number of shallow traps are formed between the same medium when adding excessive Al 2 O 3 nanoparticles.…”

Section: Resultsmentioning

confidence: 99%

“…When a very small amount of CNTs was added, deep traps would generate at the interfaces. When appropriate CNTs were added, they could improve the surface charge characteristics, accelerate the surface charge dissipation of the composite, and inhibit the accumulation of free charges near the electrodes, thereby increasing the flashover voltage [10,28]. Nevertheless, the CNTs would overlap each other to form a local or continuous bridge network when excessive CNTs were added, which will cause the surface flashover voltage of the material to drop rapidly (Figure 6d).…”

Section: Dissipation and Trap Distributionmentioning

confidence: 99%

The synergistic effect of micro structure/nanofiller/superhydrophobicity on the surface flashover

Xie

Wang

et al. 2022

High Voltage

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The surface flashover is affected by many factors, such as surface roughness, nanofillers and chemical functional groups. In this research study, polyamide mesh was utilised as a scaffold to systematically study the synergistic effect of micro structure/nanofiller/ superhydrophobicity on the surface flashover. Based on the dissolution and resolidification method, nanofillers were partially embedded into the mesh fabrics. Here, Al 2 O 3 nanoparticles were used as a typical non-conductive nanofiller, and carbon nanotubes were used as a typical conductive nanofiller. Moreover, the micro structure was determined by altering the mesh size, and chemical fluorination was utilised to change the surface chemical group. It was found that the polyamide mesh with 300# demonstrated best anti-flashover properties. Chemical fluorination could effectively improve the flashover voltage. By further adjusting the ratio of Al 2 O 3 to carbon nanotubes, the flashover voltage can be increased by up to 30%.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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“…The statistics of the number of flashover faults and damaged parts are processed and the detection rate is calculated, as described by Equation (6). Finally, the efficient detection rate can be calculated, as expressed by Equation (7).…”

Section: Real-time Performance Assessmentmentioning

confidence: 99%

“…Currently, the available solutions and analysis of insulator flashover fault are mainly focused on the area of flashover mechanism and discharge detection, and few studies have been carried out for insulator flashover detection based on visual aerial images. In [6][7][8][9], the feature extraction of the discharge area using ultraviolet images and the corona ultraviolet image segmentation were exploited. However, this solution was observed with an unsatisfactory performance under certain conditions due to a limited hardware processing capability.…”

Section: Introductionmentioning

confidence: 99%

Multi-Saliency Aggregation-Based Approach for Insulator Flashover Fault Detection Using Aerial Images

et al. 2018

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Accurate and timely detection of insulator flashover on power transmission lines is of paramount importance to power utilities. Most available solutions mainly focus on the exploitation of the flashover mechanism or the discharge area detection, rather than the identification of a damaged area due to flashovers using captured aerial images. To this end, this paper proposes a multi-saliency aggregation-based porcelain insulator flashover fault detection approach. The target area of the insulator is determined using the Faster-Pixelwise Image Saliency by Aggregating (F-PISA) algorithm based on the color and structural features. The color model can be established based on the color feature of the damaged areas on the insulator surface, and hence the damaged area can be identified. Based on the information obtained above, the contour information can be extracted. With the preceding process, the fault location can be confirmed with a good accuracy. The performance of the proposed detection approach is assessed through a comparative study with other available solutions. The numerical result demonstrates that the suggested solution can detect the insulator flashover with improved performance in terms of the average detection rate and average efficient detection rate. Additional analysis is carried out to evaluate its robustness and real-time performance, which confirms its deployment feasibility in practice.

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Effects of surface “micro-holes” on the flashover properties of a disk-type ceramic-vacuum insulator

Cited by 9 publications

References 28 publications

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

Tailoring Organic/Inorganic Interface Trap States of Metal Oxide/Polyimide toward Improved Vacuum Surface Insulation

The synergistic effect of micro structure/nanofiller/superhydrophobicity on the surface flashover

Multi-Saliency Aggregation-Based Approach for Insulator Flashover Fault Detection Using Aerial Images

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