热流量传感器在冰箱设计中的应用探讨

热负荷是冰箱设计中重要的基础数据之一,目前通常采用理论计算或反向热泄漏的方式测算冰箱热负荷。本文以热流量传感器在冰箱反向热泄漏测试中的应用为例,介绍一种定量分析冰箱保温层热流量分布的方法。     

油流放电和绝缘降低缺陷的原因分析及处理对策

分析了220kV变电站主变压器内部油流放电和绝缘降低故障的原因,提出了处理办法和预防措施.     

Simulation of the insulation properties of a HVDC transformer using a hybrid discretization based on finite elements and harmonic functions

During the development of technical devices, numerical simulations are widely used to avoid costly experiments. Here, the insulation properties of a single-phase transformer are calculated using a discretization scheme which accounts for cylindrically symmetric parts by local sub-grids. The size of the numerical model is therefore reduced significantly while a high accuracy is maintained. For the optimal insulation configuration the field intensity is decreased significantly.     

Partial discharge study in transformer oil due to particle movement under DC voltage using the UHF technique

Converter transformers are one of the key components in high voltage DC power networks. The insulation of these transformers is stressed by both AC and DC voltages. Therefore, AC and DC voltage tests are routinely applied during factory tests to verify the performance of the insulation structure. Partial discharges in an insulation system are incipient discharges that can damage materials and may eventually lead to complete failure of the insulation system during operation. Recently it has been shown that monitoring such discharges formed under AC stress is feasible using Ultra High Frequency (UHF) measurement technique and that there is a reasonable correlation between the partial discharge magnitude and the amplitude of the UHF signal generated by partial discharges. However, the partial discharge activity under DC voltages is not fully understood. This paper describes a study using the UHF technique to improve our understanding of particle-induced partial discharge activity under DC voltages in mineral oil insulation. UHF signals generated due to conducting particle contamination in transformer oil under AC and DC voltages are compared and analyzed. A method for distinguishing particle discharges in regions of high or low electric field stress is proposed based on frequency-domain analysis of the measured UHF signal.     

发电机端部线圈及汽轮机汽封的质量事故及其防范

结合两例发电机线圈故障,指出了新设备的薄弱环节和新机组投入运行后的维护要点,提出对发电机运行振动模态试验的重要性,防范发电机组端部线圈质量事故的发生。     

分接开关绝缘故障及其诊断

阐明了分接开关绝缘故障的产生原因、故障特征和绝缘故障的诊断方法,并通过实例的分析,探讨了防止分接开关绝缘故障的措施.     

Powder sintering and gel casting methods in making glass foam using waste glass: A review on parameters,performance, and challenges

The application of insulation materials in buildings and energy storage facilities is gaining global attention to reduce energy consumption, heat loss, and CO₂ emissions. Given the high insulation performance, glass foam is gaining popularity replacing combustible, high energy-consuming, and costly conventional insulation materials. The industrial process of glass foam manufacturing is an energy-consuming and non-ecofriendly process which requires the annealing of glass around its melting temperature. Therefore, researchers have developed powder sintering and gel casting methods to sinter glass foam mix at a temperature slightly above its glass transition point. However, research findings on these two methods are scattered because of the different parameters being used by researchers. The properties and performances of glass foam depend on the processing parameters, especially on the materials design and sintering conditions. Therefore, this study aimed to provide a comprehensive review on the key parameters for material selection and sintering of glass foams and provide necessary guidelines for the best practice and a direction for future research. Moreover, this review covers the current strategies and challenges associated with the powder sintering and gel casting methods including their sustainability and environmental performance.     

Influence of substrate temperature on the microstructure of YSZ films and their application as the insulating layer of thin film sensors for harsh temperature environments

Thin film sensors are employed to monitor the health of hot-section components of aeroengine intelligence (for instance, blades), and electrical insulating layers are needed between the metal components and thin film sensors. For this purpose, the electrical insulation characteristics of an yttria-stabilized zirconia (YSZ)/Al₂O₃ multilayer insulating structure were investigated. First, YSZ thin films were deposited by DC reactive sputtering at various substrate temperatures, and the microstructural features were investigated by scanning electron microscopy and X-ray diffraction. The results indicate that the micromorphology of the YSZ thin film gradually became denser with increasing substrate temperature, and no new phases appeared. The compact and uniform topography of the YSZ thin film improved the insulation properties of the multilayer insulating structure and enhanced the adhesion of the thin film sensors. In addition, the electrical insulation properties of the YSZ/Al₂O₃ multilayer insulating structure were evaluated via insulation resistance tests from 25 to 800 °C, in which the YSZ thin film was deposited at 550 °C. The results show that the insulation resistance of the multilayer structure increased by an order of magnitude compared with that of the conventional Al₂O₃ insulating layer, reaching 135 kΩ (5.1 × 10^?6 S/m) at 800 °C. Notably, the insulation resistance was still greater than 75 kΩ after annealing at 800 °C for 5 h. Finally, the shunt effect of the YSZ/Al₂O₃ multilayer insulating structure was estimated using a PdCr thin film strain gauge. The relative resistance error was 0.24%, which demonstrates that the YSZ/Al₂O₃ multilayer insulating structure is suitable for thin film sensors.     

便携式绝缘参数在线测试仪的研制

本文对便携式绝缘参数在线测试仪的研制进行了说明,叙述了测试原理及电路的组成,对软件的设计也进行了简述并给出了测试仪的主要参数。     

在循环轴向机械力作用下大型变压器绕组绝缘层累积破损效应研究

为了研究大型变压器在开闸合闸或电流突变时绕组绝缘层的累积破损效应,借助于液压伺服疲劳试验机,进行了模拟多次电磁涌流作用下绕组与绝缘垫块间相互接触的疲劳试验,并对试验结果进行了分析。