The surface of basalt fibers was modified by nano alumina, and then modified basalt fiber/epoxy resin composite (BFRP) was prepared by lamination method, and the effect of nano-Al₂O₃ content on the insulation and mechanical properties of the modified composite was experimentally analyzed. The results show that when the mass fraction of nano-Al₂O₃ is 1.0%, the interface modification effect of BFRP is the best. Compared with untreated composites, the dielectric loss factor of 1.0K-BFRP reduces by 38.13%, the surface flashover voltage increases by 42.96%, and the breakdown voltage increases by 33.96%, demonstrating more superior insulation performance; the tensile strength, flexural strength, and interlaminar shear strength increases by 26.46%, 48.19%, and 66.06%, respectively, and the glass transition temperature increases by 4.49℃.

In order to obtain the location information of defects in buffer layer of HV cable, at first, according to the surface morphological characteristics of buffer layer, the buffer layer states were devided into dry state, damp state, corroded state, and corroded-ablative state, and the change law of volume resistivity and relative dielectric constant during the development of defects from dry state to corroded-ablative state of buffer layer was studied via thin slice samples. Then the computing formula of the distributed capacitance and distributed conductance in the network of HV cables transmission line was derived. The feasibility of applying the FDR method to locate defects in the buffer layer of HV cables was also evaluated. Finally, a long cable experimental platform was built in the laboratory to study the effectiveness of the FDR method in locating buffer layer defects. The results show that the development of buffer layer defect mainly affects the distributed capacitance, and impedance discontinuity points generate in the process. FDR can locate the moisture and defects of the buffer layer, but the further distinction between corrosion defects and ablation defects needs to be combined with other state detection methods.

In the study of damage mechanisms of composite materials, acoustic emission (AE), as a nondestructive testing technique, has gained excellent application results due to its high accuracy, real-time performance, insensitivity to geometry, and wide application prospects. In this paper, the analytical methods and application status of acoustic emission technology on damage mechanism of composite materials were summarized, the advantages and disadvantages of acoustic emission technology in the study of damage mechanism of composite materials were comprehensively elaborated, and the key technologies that need to be solved urgently were also explored, and the prospects of its application in the field of composite materials were envisioned.

In order to solve the problem of blank cracking in the pressing process of special-shaped nozzle, we designed a near-clean forming special-shaped nozzle pressing mold independently, and optimized the structure of the mold gradually. At the same time, the process parameters such as pressing pressure, pressing speed, and holding time were optimized based on the existing pressing process. The results show that, through the gradual optimization of the structure of the special-shaped pressing mold, the cracking problems of the arc transition area and the bottom of the V-shaped pad of the nozzle were solved. Through the optimization of the pressing process, the density consistency of each position of the nozzle blank is improved, the mechanical and electrical properties of the arc transition area have little difference with those of the two ends, and the raw material loss of the nozzle pressed by this process is reduced by about 30%.

At present, there is a lack of effective liquid repair materials for ablation defects in the buffer layer of high-voltage cables, resulting in the inability to timely and effectively eliminate the hidden dangers of ablation defects in high-voltage cable lines. In this paper, acrylic based buffer layer ablation defect liquid repair materials were prepared and repair experiments were conducted on actual ablation defects in cable buffer layer. The repair effect of carbon black content in repair solution on the electrical properties of the buffer layer was studied. The results show that when the mass fraction of carbon black in the repair solution coating is 20%, the volume resistivity of the repaired buffer layer decreases to the level of new buffer layer and basiclly remains unchange with temperature. Based on the characterization of micro morphology, it is analyzed that the repair solution forms a carbon black coating on the fiber surface of the buffer layer, covering the original uneven coating and non-conductive particles. At the same time, the continuous water blocking powder layer formed by ablation on the inner side of the non-woven fabric is repacked by the carbon black coating, rebuilding the electrical connection of the buffer layer, thus effectively repairs the erosion defects of the buffer layer.

In order to investigate the application of laser-induced breakdown spectroscopy (LIBS) technology in rapid quantitative detection of insulator contamination, and improve the accuracy and speed of insulator contamination detection, a detection platform based on LIBS technology was established to test artificial and natural contamination samples. The artificial contamination samples were formulated by mixing NaCl, CaSO₄, CaCO₃, and kaolin, while the natural contamination samples were taken from silicone rubber insulators which had been in operation for two and four years in a regional power grid in southern China. The rapid quantitative detection of insulator contamination was carried out by means of the calibration-free LIBS method. The results show that there are 9 kinds of elements with different proportions in the two artificially contaminated samples, while the two naturally contaminated samples contain 9 and 11 distinct elements, respectively. After self-absorption correction, the contaminant elements of the insulators are presented as neatly arranged distribution points on the Boltzmann plot, with consistent regression line slopes, and high fitting degrees, and the spectral line intensities of each element enhances significantly. This effectively mitigates the impact of self-absorption on rapid quantitative detection of insulator contamination, and improves the detection accuracy.

In order to investigate the ageing characteristics of the FRP/RPUF interface of composite insulation cross-arm under the effect of water intrusion, FRP/RPUF interface specimens were prepared, and water intrusion and destruction process in the FRP/RPUF interface was accelerated by hygrothermal ageing method. According to the test results of water absorption, shear strength, and leakage current, the ageing characteristics of the FRP/RPUF interface under water intrusion were obtained by combining with SEM, FTIR, and TGA. The results show that water intrusion can cause moisture plasticisation of the interface, reduce the shear strength and increase the leakage current, while that destructive effects decrease with the dissipation of water; hydrolytic reaction of FRP/RPUF interface material undergoes under the effect of water, leading to the generation of local defects and the increase of impurity ions, which further destroys the mechanical and electrical properties of the interface.

In order to improve the toughness and oil absorption of wet-processed insulating parts such as insulation molding parts and angle rings, strengthen the process operability in the assembly process, and thus improve the operation reliability of transformer, the performance of the cotton pulp composite insulating paper with different raw material ratio was studied. The cotton pulp ratio of the cotton pulp composite insulating paper was determined, and then the finished product was processed and their performance was tested. The results show that the comprehensive performance of the cotton pulp composite insulating paper with 25% volume fraction of cotton pulp is the best, and the corner ring and insulating parts produced by the cotton pulp composite insulating paper have better flexibility and oil absorption.

Vegetable insulating oil is easy to age in electrical equipment and produce polar small molecule substances such as formic acid, acetic acid, and formaldehyde, which reduces the physicochemical properties and electrical properties of insulating oil and affects the safety operation of equipment. In order to solve the quality deterioration problem of insulating oil, the aged vegetable insulating oil can be purifed by adsorption technology to reduce the polar small molecule impurities generated during ageing. In this paper, a 2-methylimidazole zinc salt (ZIF-8) and alumina (Al₂O₃) composite material was prepared, the ZIF-8/Al₂O₃ composite material was used to adsorb and purify the aged vegetable insulating oi, and the physicochemical properties and electrical properties of the vegetable insulating oil after adsorption and purification were tested. The results show that after adsorption and purification by ZIF-8/Al₂O₃ composite material, the acid value and dielectric loss factor of the vegetable insulating oil decrease significantly, the volume resistivity and initial oxidation temperature increase significantly, and the quality is improved significantly. In addition, the molecular simulation results also show that the adsorption capacity of ZIF-8/Al₂O₃ composite material for polar small molecules in vegetable insulating oil is better than that of Al₂O₃.

The epoxy resin for casting in saturated reactors is prone to ageing and cracking when subjected to electrical stress and mechanical vibration, it is necessary to improve its mechanical and thermal properties on the basis of maintaining its excellent insulating properties and corrosion resistance. In this paper, taking the functional optimization design as principle, a silicon dioxide dielectric layer was formed on the surface of silicon carbide whiskers (SiCw) by heat treatment to obtain SiCw@SiO₂. Then a SiCw@SiO₂/EP composite dielectric was prepared by doping modification, and its dielectric properties, mechanical properties, and thermal properties were tested. The results show that the SiCw@SiO₂/EP composite dielectric has both high dielectric constant and low dielectric loss, and its toughness is also improved. Due to the continuous thermal conductivity network formed by the contact of SiCw, the thermal conductivity of the SiCw@SiO₂/EP composite dielectric increases by 117% than that of pure epoxy resin.