In this paper, epoxy resin bulk molding compound (EP-BMC) was prepared by mixing short cut glass fibers and calcium sulfate whiskers with epoxy resin matrix. After molding and curing, the influence of glass fiber filler ratio on the wear resistance, mechanical properties, and dimensional stability of EP-BMC material was researched. The results show that with the increase of glass fiber filler ratio, the wear resistance and the linear expansion coefficient of EP-BMC material after thermal ageing decrease continuously, while the tensile strength and bending strength increase at first and then decrease. When the mass ratio of glass fiber to filler is 30∶40, the EP-BMC material shows optimal comprehensive performance. After thermal ageing, the volume wear is 1.00 mm³, the tensile strength and bending strength is 56 MPa and 145 MPa, respectively, the linear expansion coefficient is 24.94 μm·m^-1·℃^-1, and the volume resistance reaches 2.0×10¹³ Ω.

This paper reviewed the research progress on active esters for epoxy curing at home and abroad in recent years, with a focus on the structures of different active esters. By classifying active esters according to raw material sources and ester bond positions, the characteristics and differences of active esters with different structures in epoxy resin curing agents were explored. Finally, the development trend and application prospects of active esters for epoxy curing were discussed.

In order to solve the problem of significant decrease of insulation performance caused by condensation on the surface of switchgear insulation components in high temperature and high humidity environments, in this paper, E51 epoxy resin was modified by adding different mass fractions of nano-alumina, and the electrical properties of the modified samples were tested. The results show that the resistivity and dielectric loss factor of the modified epoxy resin decrease slightly. In the condensation environment formed under different temperature difference, the flashover voltage of the modified epoxy resin clean sample with nano-alumina mass fraction of 1%, 3%, and 5% is 56.7%, 84.5%, and 66.7% higher than that of unmodified sample, respectively. With nano-alumina mass fraction of 1%, 3%, and 5%, the flashover voltage of the contaminated sample is 10.8%, 17.3% and 14.9% higher than that of unmodified sample, respectively, and the effective value of the leakage current is 40.3%, 46.6% and 45.8% lower than that of unmodified sample, respectively. In summary, the electrical properties of modified epoxy resin samples containing 3% nano-alumina are improved significantly.

In order to investigate the influence of copper and insulating paper on the properties of alkylbenzene insulating oil inside oil-filled high-voltage cables, alkylbenzene insulating oil was placed in four different environments and subjected to a thermal ageing experiment at 120℃ for 50 days. Ageing characteristic parameters of oil sample such as acid value, dielectric loss factor, interfacial tension, and water content were measured during the ageing process, and the correlation between the four indicators was studied using regression analysis. The results show that as the ageing time increases, the ageing degree of oil sample intensifies, copper accelerats the ageing of alkylbenzene insulating oil, while insulating paper has no significant effect on the ageing of the oil. The dielectric loss factor of insulating oil is positively correlated with its acid value and water content, and negatively correlated with interfacial tension, both of which are exponential functions. The regression fitting equation is y=A₁·exp(±x/t₁)+y₀, and the goodness of fit is greater than 0.94. In the results of multiple linear regression, there is a common constraint relationship between the dielectric loss factor, acid value, interfacial tension, and water content.

In order to reduce the use of greenhouse gas SF₆ in switchgear, we designed a 126 kV environmental friendly GIS by an insulating scheme using "vacuum disconnect + clean air", and focused on researching the insulation performance of its isolated grounding switch. Firstly, the breakdown characteristics of clean air insulation medium under different working pressure conditions were researched based on verification test of SF₆ busbar insulation, and the allowable design field strength value of clean air insulation medium was determined based on this characteristic. Then, the working pressure of environmentally friendly GIS (0.65 MPa) was determined by utilizing the allowable field strength value and equipment size. Finally, taking the allowable design field strength requirement of clean air at 0.65 MPa as the constraint condition, a simulation model was constructed to research the influence of the structural design of the isolated grounding switch on its internal electric field distribution characteristics. The results show that the chamfer position at the edge of the isolated contact and the three-phase junction of the air, conductor, and epoxy material of the basin insulator are the weak links in insulation. Combined with the verification test of the GIS prototype, the insulation performance of the environmental friendly GIS isolated grounding switch designed in this paper meets the design requirements, and the method for determining the allowable field strength of the clean air insulation medium is reasonable and sufficient.

An ANF/mica composite insulating paper was prepared by vacuum assisted filtration and hot pressing technology taking aramide nanofiber (ANF) as matrix and natural mica (mica) as filler. The microscopic morphology, tensile strength, electrical insulation properties, and temperature resistance of the composite insulating paper were studied systematically. The results show that the mica and ANF are superimposed in order during vacuum filtration process, and the mica fragments fill the gaps in paper effectively, creating a dense "brick-and-mortar structure", which significantly enhances the electric strength and insulating properties of the composite insulating paper. Furthermore, the glass transition temperatures of pure ANF insulating paper and ANF/mica-10 composite insulating paper are higher than 300℃, exhibiting excellent thermal stability. Although the addition of mica slightly reduces the tensile properties of pure ANF insulating paper, its insulation strength and tensile performance remain superior to traditional mica paper.

To address the issues of inadequate high-temperature insulation performance and thermal stability of wires, a high-temperature resistant ceramic coating was prepared using the nano alumina and a small quantity of nano silica as the primary raw materials by nanoparticle surface modification technology, then the ceramic coating was coated on quartz fiber braided layer to prepare a high-temperature composite insulating material. The structure, composition, and thermal stability of the coating were analyzed by X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), and thermogravimetric-differential scanning calorimetry (TG-DSC). The morphology, volume resistivity, and electric strength of the high-temperature resistant ceramic coating-quartz fiber composite insulation layer before and after calcination were analyzed by scanning electron microscopy (SEM), high insulation resistance tester, and automatic voltage tester. The results show that the ceramic coating forms a ceramic protective layer on the quartz fiber braided layer after high temperature calcination, which can enhance the temperature resistance rating of the quartz fiber and improve its insulation performance. When the temperature exceeds 800℃, the insulation resistivity of the high-temperature resistant composite insulation layer still exceeds 2×10⁶ Ω·m, and the average electric strength at room temperature is as high as 400 kV/m, which has certain application prospects in the wires on specialized equipments such as aerospace engines, excitation coils, transformers.

Algae is a special kind of biofouling, its attachment on the insulator surface of electrical equipment will significantly reduce the fouling flash resistance of insulator , which poses a threat to the safe and stable operation of power grids. In this paper, a semantic segmentation algorithm of insulating algae integrated multi-scale convolution attention mechanism was proposed. Firstly, a model for insulating algae class semantic segmentation was constructed on the basic U-Net network model, and VGG16 was used as the backbone feature extraction network. The model adopts a U-shaped structure, and the left side is the feature extraction part of the VGG16 backbone, which can effectively extract the informations of five feature layers. The right side was the enhanced feature extraction part. CBAM module was selected for attention module, and the multi-scale convolution was introduced based on CBAM module. Then the CABM convolutional attention module was added to the encoder and the decoder of U-Net network before up-sampling and down-sampling. Finally, the model was compared with Deeplabv3+ and Transfuse network on the self-constructed algae-covered insulator image dataset. The results show that compared with the basic U-Net model, the mIoU value of this model improves by 0.28, mPA value improves by 0.27, Dice coefficient improves by 0.06, Hausdorff distance reduces by 11.77, and the RVE value reduces by 0.06. The visualization results of the segmentation process demonstrates that the model in this paper can pay more attention to the algal coverage region, and locate the boundary of the algal coverage region more accurately, which reduces the segmentation error effectively.

The main insulation of large motor will produce many kinds of insulation defects during its operation process, and only used the phase resolved partial discharge (PRPD) pattern cannot reflect the characteristics of the defects fully. In this paper, four typical insulation defects such as internal air gap, coil wear in slot, overlapping part fault of end semiconductor coating and anti corona layer, and surface contamination were simulated in laboratory, their partial discharge (PD) information were collected in the electromagnetic shielding chamber, and the PRPD patterns and PSA patterns were drawn respectively. Combined with the characteristics of PRPD and PSA patterns under different voltage levels, the discharge characteristics of the typical insulation defects were analyzed. The results show that considering the symmetry, discharge amplitude, spectrum envelope shape of PRPD pattern and the discharge cluster number, discharge cluster distribution position, discharge cluster shape of PSA pattern, the four typical insulation defects can be identified accurately.

High temperature vulcanized (HTV) silicone rubber insulators and liquid silicone rubber (LSR) insulators are widely used in power system transmission lines. In order to compare the performance differences of HTV silicone rubber and LSR material for external insulation under typical formulas, the mechanical properties, electrical properties, and hydrophobicity of the two materials were tested. The results show that LSR has better mechanical and electrical properties than HTV silicone rubber. The initial hydrophobicity characteristics of HTV silicone rubber and LSR are similar. The crystallization temperature of LSR is lower than that of HTV silicone rubber, and the thermal stability is higher than that of HTV silicone rubber, which indicates that LSR is more suitable for operation in low temperature or high temperature outdoor environment.