基于非线性误差抑制算法的超高绝缘电阻测量

针对在超高绝缘电阻测量时,因存在衰减缓慢的时变非线性背景电流而难以快速准确测量的难题,提出一种基于非线性误差抑制算法的超高阻测量方法。首先分组交替改变测试电压极性,测量相应静电计输出信号,再根据非线性误差电流特点,采用n次多项式表示相邻n+2个分组的背景电流,构建连续n+2个分组测量的输出电压矩阵,最后通过误差抑制算法得到不含背景电流项的测量结果。实验结果表明,采用非线性误差电流抑制算法可将由固有衰减时间引起的测量过渡时间从长达数十分钟至数小时缩短到数分钟,同时提高了在10～0.1 pA极微电流条件下的超高阻测量精度,绝缘电阻测量量程可有效扩展到10¹⁶Ω量级。     

高压带电作业机器人绝缘系统的研究

研究了10kV配电线路高压带电作业机器人作业平台多级绝缘防护系统。介绍了高压带电作业机器人依靠绝缘斗臂车进行相对地绝缘;操作人员站在绝缘斗内,通过光纤通信远程遥控机械臂,解决了高压线对人的绝缘;钢结构支架缠绕环氧玻璃布,平台底面粘合环氧玻璃板,机械臂绝缘予支承,机械臂外包绝缘护套,边相加遮蔽罩进行相间绝缘。此外,通过绝缘斗臂车绝缘臂、整车,绝缘机械臂之间、绝缘机械臂与平台之间,绝缘平台进行了交流耐压试验、交流泄露电流试验,进一步说明所设计的绝缘系统安全、可靠。     

胶粉聚苯颗粒保温砂浆在既有建筑节能改造方面的经济效果分析

对目前既有的高能耗建筑进行节能改造,是实现节能战略目标必须要解决的问题。通过对胶粉聚苯颗粒保温砂浆的特性及造价分析,提出了用胶粉聚苯颗粒保温砂浆外墙外保温的方法对既有建筑进行节能改造。通过对这种保温体系的构造特性分析及保温造价的计算,论证了其技术经济上的合理性和可行性,经计算比较节能效益也相当明显。     

EPS板外墙外保温如何减少质量缺陷

EPS板外墙外保温是值得推广的一种节能体系,具有多项优点,但由于施工中的一些不当措施也会造成空鼓、裂缝、虚贴等问题。从基层处理、粘结胶浆的配制、苯板的切割与铺贴、网格布的铺贴及翻包网、加强网的设置这几个方面入手,在施工措施中加以注意,可以减少并有效控制这些易出现的质量缺陷。     

夏热冬冷地区混凝土保温砌块建筑研究与应用

对夏热冬冷地区混凝土复合保温砌块用于屋面和外围护墙中的保温隔热效果进行了分析,结果表明该复合保温砌块围护结构各项热工性能指标均符合地方节能标准,能有效提高室内舒适度,节能效果显著.     

Thermal Diffusivity Measurements on Insulation Materials with the Laser Flash Method

An iterative approach is adopted to determine the thermal diffusivity of the xonotlite-type calcium silicate insulation material with very low thermal conductivity. The measurements were performed with a conventional laser flash apparatus by rear-face detection of the temperature response of the three-layered sample, where the insulating material is sandwiched between two iron slices. In the evaluation of the thermal conductivity, the theoretical curve is fitted to the complete temperature–time curve, instead of just using the t _1/2 point. The theoretical model is based on the thermal quadrupole method. The nonlinear parameter estimation technique is used to estimate simultaneously the thermal diffusivity, heat transfer coefficient, and absorbed energy. Based on experimental results, the optimal thickness range of the insulation material in the sample is indicated as 1.6 to 1.9 mm. The effects of the uncertainties of the thicknesses, contact resistance, and thermophysical properties of the three layers on the measurement uncertainty are estimated, giving an overall uncertainty in the thermal conductivity of approximately 7.5%.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

Vacuum Insulation Panels – Exciting Thermal Properties and Most Challenging Applications

Vacuum insulation panels (VIPs) have a thermal resistance that is about a factor of 10 higher than that of equally thick conventional polystyrene boards. VIPs nowadays mostly consist of a load-bearing kernel of fumed silica. The kernel is evacuated to below 1 mbar and sealed in a high- barrier laminate, which consists of several layers of Al-coated polyethylene (PE) or polyethylene terephthalate (PET). The laminate is optimized for extremely low leakage rates for air and moisture and thus for a long service life, which is required especially for building applications. The evacuated kernel has a thermal conductivity of about 4 × 10⁻³ W · m⁻¹ · K⁻¹ at room temperature, which results mainly from solid thermal conduction along the tenuous silica backbone. A U-value of 0.2 W · m⁻² · K⁻¹ results from a thickness of 2 cm. Thus slim, yet highly insulating fa?ade constructions can be realized. As the kernel has nano-size pores, the gaseous thermal conductivity becomes noticeable only for pressures above 10 mbar. Only above 100 mbar the thermal conductivity doubles to about 8 × 10⁻³ W · m⁻¹ · K⁻¹, such a pressure could occur after several decades of usage in a middle European climate. These investigations revealed that the pressure increase is due to water vapor permeating the laminate itself, and to N₂ and O₂, which tend to penetrate the VIP via the sealed edges. An extremely important innovation is the integration of a thermo-sensor into the VIP to nondestructively measure the thermal performance in situ. A successful “self-trial” was the integration of about 100 hand-made VIPs into the new ZAE-building in Würzburg. Afterwards, several other buildings were super-insulated using VIPs within a large joint R&D project initiated and coordinated by ZAE Bayern and funded by the Bavarian Ministry of Economics in Munich. These VIPs were manufactured commercially and integrated into floorings, the gable fa?ade of an old building under protection, the roof and the facades of a terraced house as well as into an ultra-low-energy “passive house” and the slim balustrade of a hospital. The thermal reliability of these constructions was monitored using an infrared camera.Invited paper presented at the Seventh European Conference on Thermophysical Properties, September 5-8, 2005, Bratislava, Slovak Republic.     

表面含有半导电层的高压绝缘结构的电场的有限元分析

表面半导电层结构可以均匀电场和抑制表面电晕放电,因此被广泛应用于高压电力电缆接头和高压发电机定子线圈端部绝缘中。由于表面半导电层比主绝缘层薄得多,在应用有限元法进行分析时存在着分析区域难剖分的缺点。本文经过一个简单的分析实例,提出了表面含有半导电层的高压绝缘结构电场的有限元分析方法。     

氧化锌避雷器在线检测技术现场运用与结果分析

通过对氧化锌避雷器在线检测结果的分析，给出了不同型号氧化锌避雷器在运行电压下的全电流、阻性电流的经验值，指出影响测试结果的各种因素。     

Design of the winding–bushing interconnections in large power transformers

The paper presents the improvement in design of the conductor connecting the windings and bushings in oil power transformers. This is a sensitive part of large transformers and there is a need to optimise its manufacturing time and costs. The thermal problem of the heating of this conductor with increased insulation thickness on a part of it is treated using a non-linear two-dimensional thermal model. The experiments performed made determining of some problematic parameters (heat resistance of oil-paper insulation and the paper to oil convection heat transfer coefficient) of the thermal model feasible. The results obtained are of practical interest in the design practice of interconnections, but also affect the important parameters of heat transfer by devices with oil immersed paper insulation.