In the development of gas insulated switchgear (GIS) and gas insulated transmission lines (GIL) towards higher voltage and larger capacity, the insulation performance at the internal insulator's gas-solid interface is recognized as a critical factor affecting the operational safety of GIS/GIL equipment. To ensure the insulation safety of GIS/GIL equipment in engineering applications, it is imperative to elucidate the insulation failure mechanisms at the gas-solid interface and explore methods to enhance its insulation performance. In this paper, first, the research progress in the field of gas-solid interface insulation was reviewed, the mechanisms of dynamic charge behavior at the gas-solid interface and its influencing factors were analyzed, and methods for charge regulation at the gas-solid interface were introduced. Subsequently, the mechanism of insulation failure influenced by metal particles at the interface was discussed, and the motion characteristics of metal particles and their mitigation measures were summarized. Following this, the insulation characteristics at the gas-solid interface in environmental-friendly insulating gases were described, and the methods for electric field regulation and flashover voltage enhancement at the interface were summarized. Finally, the research directions for gas-solid interface insulation of insulator in GIS/GIL were outlined.

Mastering the distribution pattern of surface charges during DC pre-flashover is essential for clarifying the intrinsic mechanism of charge-induced flashover. This paper investigated the surface charge distribution characteristics of epoxy resin at DC pre-flashover moment and their influences on flashover voltage magnitude based on a plate-type insulation structure. Under two testing conditions—with and without pre-deposited charges on specimen surfaces—the dynamic distribution of surface charges was captured during the process of applied voltage escalation leading to flashover. By introducing SiC-epoxy composite coatings to modify specimen surface states, the dominant charge accumulation patterns during flashover triggering and the charge accumulation modes preceding flashover occurrence were comparatively analyzed. The results show that homopolar charge accumulation predominates on specimen surfaces during voltage escalation toward flashover. The charge accumulation mode exhibites a transition phenomenon shifting from the micro-charge zone to the charge surge zone during flashover triggering. Immediately before flashover, homopolar charges nearly coveres the entire specimen surface, while the pre-deposited charges primarily influence the flashover voltage magnitude by altering the homopolar charge accumulation quantity at the pre-flashover moment.

To investigate the application of anodization technology on improving the interface performance between epoxy resin and aluminum electrodes, aluminum alloys were electrolyzed for different durations to form anodized films on the substrate surface. The morphology, composition, structure, and electrical properties of the anodized films were characterized, and the effects of anodic oxide films on the adhesion and dielectric properties of the epoxy-aluminum interface were analyzed. The results show that after anodic oxidation, an amorphous anodized film with a nanoporous structure is formed. As the electrolysis time increases, the thickness of the anodized film increases linearly, while the internal defects also increase, which reduces the volume resistivity and electric strength. The film exhibits a high dielectric constant and dielectric loss factor, which remain stable at 25℃-125℃. Benefiting from the nanoporous structure and polar bonds, the adhesive shear strength between the aluminum substrate and epoxy resin increases from 6.76 MPa to 10.89 MPa, and the adhesive tensile strength increases from 6.89 MPa to 9.78 MPa after anodic oxidation. The impact toughness increases from 66.21 kJ/m² to 76.42 kJ/m², and the flexural strength increases from 147.65 MPa to 180.50 MPa. The anodized film improves the electric strength of the aluminum-epoxy composite, and the interface polarization makes the dielectric constant and dielectric loss factor of the aluminum-anodized film-epoxy composite structure slightly higher than those of the aluminum-epoxy structure. In HVDC electric fields, space charges mainly accumulate at the interface between the electrode and the dielectric, and the anodized film can inhibit the injection of charges into the dielectric. Therefore, as an effective interface modification method, anodic oxidation can enhance the mechanical and electrical properties of aluminum electrodes and epoxy resin.

The invasion of moisture at the insulation interface of cable accessories is the main cause of electrical breakdown and insulation failure. However, the effect mechanism of moisture on interface discharge and breakdown remained unclear. Therefore, this paper conducted experiments and simulations to analyze and study the causes of breakdown failure at the insulation interface of cable accessories under the influence of moisture. First, the discharge evolution characteristics during the breakdown process at dry and humid interfaces were described through experiments. Subsequently, by combining discharge products with electric field analysis, the effect mechanism of moisture on the breakdown development at the interface was explained. Finally, a field case was presented to confirm the validity of the proposed breakdown mechanism of the insulation interface under the influence of moisture. The results show that the discharge process during the interface breakdown of insulation interface develops in stages, accompanied by gas generation. The bubbles regions formed by the generated gases lead to severe electric field distortion, which reduces the electric strength of the interface. The dynamic motion of the bubbles also increases the randomness of interfacial discharge, causing the interfacial breakdown process to be accompanied by multiple discrete arc discharges along random path.

To investigate the effects of hydrophobic coatings on charge accumulation characteristics of silicone rubber, this study prepared hydrophobic coatings with hydrophobic fumed silica (SiO₂) particles as fillers. The surface charge distribution on silicone rubber surface coated with hydrophobic coatings containing different amounts of SiO₂ particles was measured under both positive and negative DC corona using an electrostatic capacitance probe. Additionally, the surface micromorphology, static contact angle, surface resistivity, and DC creepage flashover voltage of silicone rubber surface coated with hydrophobic coatings containing different amounts of SiO₂ were characterized. The results show that the static contact angle of silicone rubber surfaces increases with the increase of SiO₂ content in the hydrophobic coating. However, applying hydrophobic coatings on silicone rubber will exacerbate the surface charge accumulation. When the mass fractions of SiO₂ is 2%, 6%, and 10%, the maximum surface charge density accumulated on silicone rubber surface increases by 5.03%, 20.11%, and 24.06%, respectively, which will also decrease the surface resistivity and DC creepage flashover voltage of silicone rubber. Analysis suggests that the hydrophobic coating surface will generate more gaps and holes, thereby facilitating the capture and adsorption of charges, making it difficult for the charges to dissipate.

To investigate the rejuvenation effect and enhancement mechanism of the voltage stabilizer-containing rejuvenation fluid on moisture-affected XLPE/SiR interface, XLPE was sanded by sandpapers with different granularities to prepare XLPE/SiR interface samples. At first, the surface roughness of the samples was measured using a profilometer, and interfacial breakdown tests were conducted. Then, the samples were subjected to moisture tests. After that, the antioxidant 300 and ferrocene were selected as voltage stabilizers, and five rejuvenation fluids with different stabilizer content were prepared to rejuvenate the moisture-affected interfaces. The interface samples before and after rejuvenation were further analyzed by surface profilometry, Fourier transform infrared spectroscopy (FTIR), polarization-depolarization current (PDC), and interface breakdown tests. The results show that the interfacial breakdown voltage decreases with the increase of surface roughness, while the moisture exposure elevates the interfacial DC conductivity and dielectric loss factor and decreases the interfacial breakdown voltage. After the rejuvenation, the interface roughness, DC conductivity, and dielectric loss factor of the samples decrease, and the rejuvenated product can homogenize the electric field distribution between the cavity and the solid dielectrics, and significantly increase the interfacial breakdown voltage. Moreover, the addition of antioxidant 300 and ferrocene can enhance the interfacial breakdown voltage, and ferrocene has a better improvement effect on the insulation performance of the moisture-exposed interface.

In this paper, different types of polyurethane potting materials were developed successfully by taking propylene epoxide-tetrahydrofuran polyether or polytetrahydrofurane glycol as polymer polyols, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and 3,3′-dimethyl-4,4′-biphenyl diisocyanate (TODI) as curing agents, and adding an appropriate amount of silica aerogel. The mechanical property, proccessability, low temperature resisitance, high temperature resistance, resistance to high and low temperature shock, and insulting property of the polyurethane potting materials were analyzed systematically. The results show that the polyurethane potting material formulated with propylene oxide-tetrahydrofuran copolymer and TODI as primary components, supplemented with silica aerogel with the mass fraction of 0.5%, exhibits outstanding processability, mechanical strength, and electrical insulation. It also demonstrates exceptional tolerance to extreme temperature fluctuations. This material achieves a glass transition temperature as low as -69.3°C and maintains a compression cold resistance coefficient of 0.54 at -60°C. Its 5% weight loss temperature reaches 302.3°C. After enduring 20 cycles of thermal shock between -65°C and 125°C, the material retains 93.5% of its tensile strength with a dimensional change rate of merely -0.6%, while preserving excellent insulation properties: volume resistivity of 4.2×10¹² Ω·cm and dielectric strength of 25 kV/mm.

Thick-film heating has become a key thermal-management solution for new-energy vehicles. To meet the relevant application demands, it is necessary to develop dielectric slurries for aluminum-based thick-film heating elements. This study utilized the built-in machine learning model of the Inorganic Glass Engineer System for property prediction to assist in the development of dielectric insulating glass formulations for aluminum-based thick-film heating elements, and conducted experimental verification. The results show that the insulating glass prepared by the optimal formula can be sintered at 580℃, with a thermal expansion coefficient of 18.8×10^-⁶℃^-1. When the dielectric-layer thickness exceeds 110 μm, it has a breakdown voltage over 1.29 kV and a leakage current less than 0.21 mA, which can meet the usage requirements of the medium layer of aluminum-based thick-film heating elements.

The interfacial characteristic between the shielding layer and insulation layer is a key factor determining the service life and operational reliability of the high-voltage cables. This study focused on the regulation of the dispersion of conductive carbon black (CB), and investigated the impact of interfacial characteristics between the shielding layer and cross-linked polyethylene (XLPE) insulation layer. The semi-conductive shielding materials with two different formulations were prepared, and an imported semi-conductive shielding material was selected as a comparison sample, then the mechanical, thermal, and electrical compatibility between the shielding materials and insulation layer were comprehensively evaluated. The results show that the introduction of polymer dispersant polyvinylpyrrolidone (PVP) into the matrix resin significantly improves the dispersibility of CB. The mechanical compatibility between the shielding layer and insulation layer is predominantly influenced by crosslinking, and an optimal crosslinking compatibility can enhance the interfacial adhesion and prevent delamination. The PVP-modified shielding layers exhibit better thermal compatibility with the insulation layer in terms of the coefficient of thermal expansion, and show superior thermal conductivity compared to the imported shielding material. Furthermore, the improved CB dispersion optimizes electrical compatibility between shielding layer and insulation layer, elevating the AC electrical strength at the shield-insulation interface.

To solve the ageing problem of transformer insulation oil after the long-term operation, three composite materials, including glucose attapulgite (GLU-APT), starch attapulgite (AL-APT), and polydopamine attapulgite (PDA-APT), were designed and prepared. The structures of the composite materials were characterized by X-ray diffractor, field emission scanning electron microscopy, Raman spectrometer, Fourier transform infrared spectrometer, and N₂ adsorption-desorption test. The results show that the decolorization and acid value reduction effects of the three composite materials on retired oil improves significantly compared to APT, among which the GLU-APT shows the best regeneration effect to retired oil. When the mass ratio of GLU-APT adsorbent and retired transformer oil is 1:2, the adsorption time is 2 h, and the adsorption temperature is 90℃, the decolorization rate of regenerated oil can reach 88.2%, and the acid value is reduced to 0.010 mgKOH/g, the adsorption efficiency can maintain 90% after 5 cycles of regeneration.