A base gel was prepared with bisphenol A epoxy resin E124 as the main resin, polymercaptan as the curing agent, and imidazole as the accelerator. A single component high thermal conductive structural adhesive was prepared by adding different proportions and sizes of spherical alumina and irregular alumina into the base gel. The effects of different filling content and different particle sizes of alumina on the thermal conductivity, bonding strength, viscosity, and thixotropy of the single component high thermal conductive structural adhesive were studied. The results show that when the mass ratio of base gel to the three different particle sizes of alumina is m(base gel)∶m(40 μm Al₂O₃)∶m(2 μm Al₂O₃)∶m(0.5 μm Al₂O₃) =15∶59.5∶25.5∶6, m(base gel)∶m(40 μm Al₂O₃)∶m(5 μm Al₂O₃)∶m(0.5 μm Al₂O₃) =15∶59.5∶25.5∶8, m(base gel)∶m(40 μm Al₂O₃)∶m(10 μm Al₂O₃)∶m(0.5 μm Al₂O₃)=15∶68∶17∶8, three kinds of high thermal conductive structural adhesives cured at 90℃ for 15 min can be obtained, their thermal conductivity is 2.73, 3.05, 2.85 W/(m·K), their bonding strength is 5.49, 5.55 and 5.31 MPa, and their viscosity is 145 000, 127 467 and 118467 mPa·s, respectively. The volume resistivity of the three kinds of high thermal conductive structural adhesives is above 10¹⁴ Ω·m, and the adhesive survival rate after high temperature and humidity, cold and thermal shock is more than 70% and 90%, respectively. The performance of the high thermal conductive structural adhesive meets the basic performance requirements of screen printing and heat dissipation materials for chip packaging.

In order to solve the prediction problem of water tree density of XLPE cable, an analysis method combining the macro detection data with the micro water tree profile of aged cable was proposed. Two new parameters (carbon and oxygen index and water content index) were proposed to quantitatively describe the changes of EDS and FTIR results in the water tree region. Firstly, the polarization and depolarization current method (PDC) was used to detect the water-tree ageing cables under different experimental conditions. A series of macroscopic parameters such as cable ageing factor, DC conductivity, and 0.1 Hz dielectric loss factor were obtained. Then, the micro parameters of water tree were obtained by microscopic observation of cable slice. The water tree growth model was established to calculate the water tree density of cable, and the correlation between the macroscopic parameters of cable and the microscopic water tree density was analyzed. The results show that the longer the ageing time, the greater the carbon oxygen index and water content index, and the faster the rate of increase. Based on the correlation coefficient, a new mathematical model for predicting the growth density of water tree inside XLPE cable is established, which realize the combination of microstructure of water tree inside cable and macro test parameters.

The thermal conductivity mechanism and common thermal conductive fillers of thermal conductive silicone composites for electronic packaging were presented, the preparation strategies and research progress of filled-type high thermal conductive silicone composites were reviewed, and the future research direction of thermal conductive silicone composites for electronic packaging was prospected.

A kind of epoxy resin matrix with high heat resistance was developed, and glass cloth laminates was prepared by high temperature hot-poressing technology using glass cloth as reinforce material. The properties of the matrix resin, cured resin, and the laminates were analyzed. The results show that this cured resin has high heat resistance and good mechanical properties, its glass transition temperature reaches up to 201℃, and the 5% weight loss temperature is 367℃; its tensile strength and flexural strength reaches to 76 MPa and 82 MPa, respectively. The glass cloth reinforced laminates show comprehensive performance, the tensile strength, compression strength, and impacting strength of the laminates is 411 MPa, 480 MPa, and 226 kJ/m², respectively. The flexural strength at room temperature and 180℃ is 633 MPa and 416 MPa, respectively. Moreover, the tracking index (CTI) of the laminates can reach to 550.

In order to study the influence of semi-conductive shielding materials on the charge transport behavior in insulation, we selected three different types of semi-conductive shielding materials made in and out of China to cooperate with the same insulation, and trial-produce a shield-insulation-shield sandwich structure sample by simulating the actual cable structure, and conducted high-field conductance tests and space charge measurements. The results show that the introduction of the shielding layer changes the conduction mode inside the insulation. Compared with the pure insulation sample, the charge injection of the insulation sample with shielding layer increases significantly. The insulation-shielding interface of the imported shielding material sample has a stronger ability to inhibit charge injection, and the charge injection degree is weaker. The measurement of the space charge of each sample shows the impact of charge injection on the degree of space charge accumulation inside the insulation, the space charge accumulation of the shielding material sample made in China is more serious, while that of the imported sample is lower. It is needed to concern the impedance mismatch problem caused by the particularity of the sample structure in the measurement of space charge.

In order to solve the problem that the current national standard can not fully meet the actual needs due to the imperfection and indeterminacy of the test method and judgment standard of partial discharge test of the electrical penetration assembly for reactor, on the basis of comprehensive consideration of various index requirements, we set a test scheme for partial discharge characteristics of electrical penetration assembly of medium voltage by pulse current method, and validation tests were carried out. The results show that it is reasonable to set the low value of partial discharge pulse parameter amplitude corresponding to the extinction voltage of the medium voltage electrical penetration as 15 pC, and partial discharge mainly occurs in the air gap between the multi-layer heat shrinkable tubes of its conductor components.

Aiming at the high risk factor of manual fault detection of strut insulators, this paper proposes a real-time fault diagnosis of strut insulators based on thermal imaging technology. The binarized segmentation of the infrared image of the strut insulator was taken as the feature extraction, and the grayscale median filter was introduced for preprocessing, then a Gaussian kernel support vector machine classification architecture was built. At last, the fault diagnosis of the strut insulator was realized. The results show that the diagnosis method can not only complete the fault monitoring of the strut insulator, but also improve the efficiency and accuracy.

Epoxy resin is used as the main material for insulated packaging of electronic device and motors, it is urgent to improve its thermal conductivity to meet more demanding use requirements. In this research, epoxy resin was modified by filling irregular alumina (i-Al₂O₃), and the effects of irregular i-Al₂O₃ with different volume fraction on the thermal conductivity and other properties of EP were studied. The results show that with the increase of the mass fraction of i-Al₂O₃, the viscosity of the composite mixing system gradually increases, the tensile strength increases at first and then decreases, the thermal stability and thermal conductivity gradually increase. When the volume fraction of i-Al₂O₃ is 45%, the epoxy composite material shows good the overall performance, its thermal conductivity coefficient reaches to 1.44 W/(m·K), which is 585.7% higher than that of pure epoxy resin with the thermal conductivity of 0.21 W/(m·K), at the same time, the volume resistance of the composite remains at the 10¹⁴ Ω·cm quantitative level.

The existing detection and evaluation technology for composite insulator mainly relies on offline methods, which is difficult to assess the ageing degree of insulators in large-scale operation quickly and conveniently. This article proposes a rapid detection and rating method for surface ageing degree of composite insulators based on hyperspectral technology. At first, the Fourier infrared spectral absorption peaks of Si-O-Si and Si-CH₃ between the umbrella skirt and the substrate of aged composite insulator were compared, and then the ageing degree of insulator was rated. At last, the aging degree of insulator was classificated combining hyperspectral data with SVM algorithm models. The results show that the accuracy of the three classifications including slight, moderate, and severe is 71.8%, while the accuracy of the two classifications including sligh and severe is 97.3%. By using intensity threshold segmentation method, it is possible to remove contaminated areas from composite insulator images, and extract ageing areas.

When flashover and other accidents occur on the composite insulator in operation, the temperature rises steeply. Combined with the synergistic effect of electric field, the silicone rubber used for composite insulator will crack and destroy rapidly. In this paper, molecular model of silicone rubber was established, and then the mechanism and characteristics of electrothermal cracking of silicone rubber under steep temperature rise were studied based on the reactive force field simulation, in order to compensate for some limitations of macroscopic tests. The results show that in the flashover development stage, temperature and electric field have different mechanisms of action on the cracking of silicone rubber, temperature plays a dominant role, and electric field decreases the cracking temperature and accelerates the deterioration of material. The cracking process is triggered by the breakage of Si-C bonds, with CH₄, H₂, C₂H₄, C₂H₂, and H₂O as the main products at different stages. The number of Si-CH₃ bonds decreases by about 40% with a large number of methyl groups shed from the main chain of silicone rubber. With the further destruction of the main chain structure and the formation cross-linked structure, the number ratio of Si-O-Si bond to Si-C bond and the carbon hydrogen ratio increase continuously, the maximum is 2.93 times and 1.87 times higher than that of the pre-cracking level, respectively. The diffusion of impurity gas products dominated by H₂ generates voids in the material, leads to the structural reorganization, results in the insulation failure eventually.