Decomposition Characteristics of SF6 under Flashover Discharge on the Epoxy Resin Surface

Wen, Hao; Zhang, Xiaoxing; Xia, Rong; Hu, Guoxiong; Wu, Yunjian

doi:10.3390/ma12091408

Cited by 7 publications

(3 citation statements)

References 29 publications

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“…A reduction of glass transition temperature means the polymer can be softened at a lower temperature and the effect of reduced thermal stability and yield strain or stress may promote electrical tree growth. It was reported that gas by-products such as SOF2, CF4, SO2, CO2, SO2F2, CS2 and H2S were generated in flashover tests with epoxy resin in SF6 [10]. Simulation of decomposition in epoxy resin in ReaxFF program shows that H2O, H2, CO2, CH2O CO and CH4 are the major by-products at 1300 K. Gas by-products such as SOF2 and SF4 can react with H2O and form hydrogen fluoride (HF) [11].…”

Section: Discussionmentioning

confidence: 99%

Effect of Insulating Gases on Electrical Treeing in Epoxy Resin

Han

Iddrissu

Chen

et al. 2021

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

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Electrical trees initiated from defects in solid insulation are one of the main causes of cable insulation failure. Both the initiation and propagation of electrical trees are linked to PD activity in the free volume and interfaces between electrode, gaseous and solid dielectrics. This work investigates the potential of suppressing partial discharge (PD) during tree propagation by displacing air with a higher electron affinity gas. Epoxy resin samples with pre-existing trees were energized under 7 kVrms in atmospheric air and SF6 under 2 bar absolute for 3 hours. PD measurements indicate that the permeation of SF6 into the epoxy sample could significantly reduce the discharge energy and lead to a reduced number of discharges. However, the tree length growth was comparable for both gases. This is attributed to offsetting of reduced PD energy by SF6 within the tree channels and subsequent reaction between gas by-products and the epoxy.

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Section: Discussionmentioning

confidence: 99%

Effect of Insulating Gases on Electrical Treeing in Epoxy Resin

Han

Iddrissu

Chen

et al. 2021

2021 IEEE Conference on Electrical Insulation and Dielectric Phenomena (CEIDP)

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“…Finally, the chamber was filled with fresh SF 6 to reach the desired pressure value, making sure that most of the water vapor and air were removed. Thus, the purity of the SF 6 used during the experiments could be guaranteed [ 15 ].…”

Section: Methodsmentioning

confidence: 99%

Dielectric Surface Flashover under Long-Term Repetitive Microsecond Pulses in Compressed Gas Environment

Lin

Zhang

et al. 2021

Materials

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As a key component of a high-power microwave (HPM) system, a multi-gap gas switch (MGS) has recently developed insulation failure due to surface flashover. Although design criteria for surface insulation have been put forward, it is still not clear how the insulation in this case deteriorated under long-term repetitive microsecond pulses (RMPs). In this paper, flashover experiments under RMPs were carried out on various dielectric surfaces between parallel-plane electrodes in SF6 and air atmospheres, respectively. Based on tests of the surface insulation lifetime (SIL), an empirical formula for SIL prediction is proposed with variations of insulator work coefficient λ, which is a more suitable parameter to characterize SIL under RMPs. Due of the accumulation effect, the relationship between E/p and ptdelay varies with the pulse repetitive frequency (PRF) and SIL recovery capability decreases with an increase in PRF and surface deterioration is exacerbated during successive flashovers. It is concluded that the flashover path plays a crucial role in surface insulation performance under RMPs due to the photoemission induced by ultraviolet (UV) radiation, signifying the necessity of reducing surface paths in future designs as well as the improvement of surface insulation.

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“…Yang et al found that when there are particles attached to the epoxy surface, the discharge of the particles will destroy the covalent bonds on the surface during the long-term degradation process, resulting in a decrease in the trap energy level [10]. Wen et al carried out the effect of degradation on the microstructure of materials due to AC discharge, and their proposed epoxy cleavage products include H 2 O and CH 4 , and their formation mechanisms include reactions involving free radicals, demethylation reactions, etc [11]. However, the degradation mechanism due to discharge differs from that due to the electric field and heat.…”

Section: Introductionmentioning

confidence: 99%

Influence mechanisms of epoxy degradation on surface traps and charge accumulation under DC electrical–thermal stress

Zhang

Yang

et al. 2023

J. Phys. D: Appl. Phys.

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As trapping sites for surface charges, the surface trap is an important factor affecting the insulation performance of the epoxy-SF6 interface, which is closely related to the microstructure and its evolution. However, existing studies often ignore the effect of the degradation of the epoxy surface on the surface traps and charge accumulation during the long-term service of the insulation system. In this study, the surface physicochemical evolution and its influence on surface traps of a typical epoxy-SF6 insulation structure were researched under a DC-temperature gradient condition, and an evolution mechanism of surface traps was proposed. The results show that the free radicals introduced during the material degradation process increase the density and depth of both positive and negative charge traps on the epoxy surface. The effect of free radicals formed by the cleavage of epoxy molecules on the electronic orbital and molecular electrostatic potential of epoxy molecules is the intrinsic reason for the evolution of surface trap evolution. This work may help to understand the long-term evolution mechanisms of the physicochemical characteristics of the epoxy-SF6 interface in DC field and may provide a theoretical basis for the long-term failure mechanism revealing and the insulation performance enhancement.

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Decomposition Characteristics of SF6 under Flashover Discharge on the Epoxy Resin Surface

Cited by 7 publications

References 29 publications

Effect of Insulating Gases on Electrical Treeing in Epoxy Resin

Effect of Insulating Gases on Electrical Treeing in Epoxy Resin

Dielectric Surface Flashover under Long-Term Repetitive Microsecond Pulses in Compressed Gas Environment

Influence mechanisms of epoxy degradation on surface traps and charge accumulation under DC electrical–thermal stress

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