以水玻璃为源常压制备高保温二氧化硅气凝胶

以低成本工业级水玻璃为硅源,水为反应物及溶剂,在无需复杂的树脂交换和水洗条件下,分别采用HF一步快速催化法和HNO3-NaOH酸碱两步催化法,通过溶胶-凝胶技术制备出二氧化硅水凝胶.采用三甲基氯硅烷(TMCS)和六甲基二硅醚(HMDSO)作为表面修饰剂,在常压条件下制备了低热导率(0.03W/(m·K))、比表面积在200～500m2/g之间的低密度、疏水特性可调,具有高效保温性能的纳米多孔二氧化硅.对该材料的制备过程、形成的结构以及反应机理、保温原理进行了讨论.     

Effects of temperature on creepage discharge characteristics in oil-impregnated pressboard insulation under combined AC–DC voltage

Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard (OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70°C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge (LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge (HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after discharging. The ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.     

气吹弧装置仿真与试验研究

并联间隙雷击闪络后能快速疏导电弧保护绝缘子,但无法有效切除后续工频续流。因此,基于“气吹弧”思想研究设计了一种应用于高压输电线路的气吹弧装置。该装置与绝缘子串并联安装,当雷击线路时利用绝缘配合先于绝缘子击穿闪络泄放雷电流入地,并同时利用雷电脉冲信号触发灭弧气丸产生高速气流,能够在继电保护装置最快响应动作前熄灭电弧。通过仿真在理想状态下得出该装置能够在4 ms内将20 kA的工频续流熄灭;通过试验得出该装置能够在2.6 ms内将5.1 kA的续流电弧熄灭。仿真与试验结果基本一致,共同验证了所设计气吹弧装置具有良好的灭弧效果。     

便携式电缆测试仪的设计

为了实现部队某型导弹电缆的自动测试维护,针对部队维护使用特点,研制了一种小型、便携、实用的电缆测试仪;该产品采用嵌入式计算机技术,硬件电路模块化设计技术,便于测量通道扩展,实现了导弹电缆的导通测试和绝缘测试;文中阐述了该系统的工作原理、设计方案和硬件、软件实现方法;试用结果表明,该测试仪能够对各种型号设备和电缆的导通电阻、绝缘电阻等电气性能参数进行自动测量,能及时快速地检测设备电缆存在的故障隐患,缩短检测时间,提高检测效率。     

变压器用绝缘纸胶带的研制

为了适应变压器绝缘新工艺的技术发展要求，研究开发了绝缘纸胶带；以环氧树脂、酸酐、咪唑等为主要原料并添加改性剂，配制了一种能在中温下快速固化的胶粘剂；经过工艺试验，找出了制备绝缘纸胶带的较佳工艺条件；样品性能测试结果表明：固化剂、促进剂、改性剂的组份含量对胶化时间、剥离强度、击穿电压、储存期等均有影响，所制绝缘纸胶带达到预期指标的要求。     

Suppressing the effect of lightning-induced overvoltages by the combined use of surge arresters and overhead ground wires

Lightning voltage induced by nearby strokes is one of the causes of major overvoltages which threaten the insulation of power distribution lines. Surge arresters as well as an overhead ground wire usually are employed for the protection of equipment and line insulation on overhead power distribution lines. The fundamental mechanism of suppressing effects of overvoltages induced by nearby strokes has been demonstrated independently by one of the present authors for surge arresters and for an overhead ground wire. In this paper, the protective effect of the combination of surge arresters and overhead ground wire is analyzed. As a result, it is found that the effect of surge arresters used together with an overhead ground wire is almost the same as that of surge arresters alone.     

高效太阳热反射涂料降低油品蒸发损耗的研究

分析了高效太阳热反射涂料的隔热原理和油罐受太阳辐射热的传热特点。初步应用表明:高效太阳热反射涂料可大幅度降低油罐表面温度,改善罐内受热情况,其隔热效果明显好于"凉凉胶",可取代喷淋水降温,从而降低油品蒸发损耗。     

多片BCD拨码盘与单片机接口电路

本文主要讲述多片BCD拨码盘在与MCS－51单片机接口时的一种简单而有效的隔离方法及相应的软件设计。     

H级Nomex~纸绝缘干式变压器

介绍了35kV级OVDT式H级Nomex纸绝缘干式变压器的主要特点。     

真空多层绝热软管的设计与计算

介绍了软管的结构及其设计计算，研究了允许漏放气速率指标的确定。使用表明，按设计要求制造软管的绝热性能优良。