Characteristics of nanosecond pulse dielectric surface flashover in high pressure SF<sub>6</sub>

Sun, Chuyu; Zhou, Hui; Chen, Weiqing; Li, Junna; Xie, Lizhe; Wang, Haiyang; Zhang, Guowei; He, Xiaoping

doi:10.1109/tdei.2018.006759

Cited by 7 publications

(2 citation statements)

References 15 publications

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“…It indicates that charge transport is easier in the gas than that in the solid and that surface flashover finally occurs in the gas phase. Interestingly, when the gas pressure of SF 6 reaches 1 MPa [109], the corresponding breakdown strength is ∼89 kV/mm, which is higher than that of epoxy resin. The DC surface flashover voltage barely changes with the gas pressure.…”

Section: Competing Mechanisms Of Charge Transport In Surface Flashovermentioning

confidence: 99%

Surface flashover in 50 years: Theoretical models and competing mechanisms

Liu

Ohki

et al. 2023

High Voltage

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Surface flashover is a devastating electronic avalanche along the gas–solid interface when a high electric field is applied, which is a potential issue that threatens the safe operations of advanced power electronic, electrical, and spacecraft applications. However, the underlying physical mechanisms for surface flashover development are still under investigation owing to the complex charge transport processes through the gas phase, solid phase, and gas–solid interface. In this study, the history of surface flashover theory in the last 50 years is introduced, and several key questions are reviewed from the perspective of the competing mechanisms of charge transport: the role of each phase in a surface flashover, the origin of surface charging, and effects of traps in solid on surface flashover. Then, some suggestions involve charge transport processes in each phase, and their correlations are put forward, and a predictable ‘charge transport competitive flashover model’ is proposed by clarifying the competing mechanisms of charge transport processes through multiple phases. This study summarises the history and hot topics of physical mechanisms of surface flashover proposed based on classic and recent progress and offers promising routes for developing a more precise surface flashover theory and improving surface flashover performances.

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Section: Competing Mechanisms Of Charge Transport In Surface Flashovermentioning

confidence: 99%

Surface flashover in 50 years: Theoretical models and competing mechanisms

Liu

Ohki

et al. 2023

High Voltage

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“…The main parameters that govern the flashover process in the dry conditions used in this paper are the Characterising the effect of the introduction of modifications to spacer surfaces, whether achieved by simple roughening of the surface using sandpaper in 1980, [1], or via a more intricate PIII processing system in 2020, [2], has been an engineering challenge for many years, with designers attempting to increase the hold-off voltages of their insulation systems by means other than simply increasing the length of the spacer. Another common method of increasing the hold-off voltage is to modify the insulator geometry, to increase the path length that the discharge channel must traverse during the flashover process [3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Flashover of Smooth and Knurled Dielectric Surfaces in Dry Air

Macpherson,

Wilson,

Timoshkin

et al. 2024

IEEE Trans. Dielect. Electr. Insul.

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In pulsed power engineering, solid spacers are used to insulate high voltage parts from extraneous metal parts, providing electrical insulation as well as mechanical support. The breakdown/flashover voltage, at which a discharge process initiates across the solid/air interface, is important in the design process, as it informs designers of specific threshold 'failure' voltages of the insulation system. In this paper, a method to potentially increase the failure voltage, tested under multiple environmental conditions, without increasing the length of the solid spacer, was investigated. Three dielectric materials: HDPE (high-density polyethylene), Ultem (polyetherimide) and Delrin (polyoxymethylene), were tested under a 100/700 ns impulse voltage. Cylindrical spacers made of these materials were located in the centre of a plane-parallel electrode arrangement in air, which provided a quasi-uniform electric field distribution. Breakdown tests were performed in a sealed container at air pressures of −0.5, 0 and 0.5 bar gauge, with a relative humidity (RH) level of <10%. The materials were tested under both, negative and positive polarity impulses. The surfaces of a set of solid spacers were subjected to a 'knurled' finish, where ~0.5 mm indentations are added to the surface of the materials, prior to testing, to allow comparison with the breakdown voltages for samples with 'smooth' (machined) surface finishes. The results show that the flashover voltage can be increased by the addition of a spacer with a knurled surface, by up to 60 kV under certain conditions, in comparison to a 'smooth' (machined) surface finish.

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Analysis and Experimental Verification of the Peaking Capacitor’s Flashover Process in an EMP Simulator

et al. 2022

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The flashover process of the peaking capacitor in the electromagnetic pulse (EMP) simulator is studied based on theoretical analyses and experimental verification in this paper. There are deeper and denser ablation spots on the film surface near the inner core of the destroyed peaking capacitor, while the damage of the outer film is relatively slight, which indicates that the flashover current along the inner film is larger. Besides, the circuit simulation analyses show that the earlier the flashover occurs on the film of the peaking capacitor, the smaller the flashover current. The electric field on the non-conical surface of the capacitor is mainly occupied with normal component. Differently, for the conical surface, the electric field on the outer layer is dominated by the normal component and the parallel component is the main part on the inner layer. It is considered that the flashover on the conical surface originates from outer layers and develops gradually to the inner until the flashover penetrates through all layers. Furthermore, the images of flashover show that the flashover firstly occurs on the outermost layers and develops to the inner layers with the increase of the voltage. For such special structure of the peaking capacitor, the parallel component of electric field is more likely to facilitate the flashover under nanosecond pulse. These results may exhibit specific reference implication in the design of insulation for the peaking capacitor used in EMP simulator.

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Characteristics of nanosecond pulse dielectric surface flashover in high pressure SF₆

Cited by 7 publications

References 15 publications

Surface flashover in 50 years: Theoretical models and competing mechanisms

Surface flashover in 50 years: Theoretical models and competing mechanisms

Flashover of Smooth and Knurled Dielectric Surfaces in Dry Air

Analysis and Experimental Verification of the Peaking Capacitor’s Flashover Process in an EMP Simulator

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Characteristics of nanosecond pulse dielectric surface flashover in high pressure SF6

Cited by 7 publications

References 15 publications

Surface flashover in 50 years: Theoretical models and competing mechanisms

Surface flashover in 50 years: Theoretical models and competing mechanisms

Flashover of Smooth and Knurled Dielectric Surfaces in Dry Air

Analysis and Experimental Verification of the Peaking Capacitor’s Flashover Process in an EMP Simulator

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Product

Resources

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Characteristics of nanosecond pulse dielectric surface flashover in high pressure SF₆