环氧浇注干式变压器的长期耐热性

环氧浇注干式变压器是以固体绝缘为特征的电气产品，本文对有机固体绝缘结构的短时耐热性和长期耐热性方面作出阐述，给出整体变压器的长期耐热性试验评估，论证了环氧树脂浇注干式变压器具有长寿命和高可靠的性能优势。     

防止污氮电加热器接线腔过热和潮湿的技术探讨

污氮气体是一种氮气占绝对比重,氧气、氩气、氦气、氖气等气体占比极小的空气分离工艺所需气体。污氮电加热器是一种常见的加热污氮气体的空分设备,在进口处污氮气体温度很高的工况下,接线腔内温度更高,对电缆等零部件的寿命影响较大;在潮湿恶劣环境下,接线腔内铜排、电加热管等导电零部件易凝结露水,影响绝缘性能。鉴于此,创新设计了一种能够防止过热和潮湿的污氮电加热器接线腔,并对其技术方案进行了简要介绍。     

新AL—UNDER水平浸渍型铝液保温炉

日本株式会社东热生产的新AL—UNDER水平浸渍型铝液保温炉用于压力铸造、重力铸造、低压铸造等领域。该保温炉首先采用了对提高保温寿命有关键作用的精细陶瓷加热器保护管，大大延长了保温炉寿命，从而使性能得到了显著的提高。加热器从侧面插入就是所谓的水平浸渍型。不仅解决了以前反射型及垂直浸渍型的所有缺点，并日．把浸渍型炉本来的优点完全发挥出来。     

长寿烙铁头电镀工艺

一、概述紫铜具有良好的导热性及浸润性,有较好的焊接工作性能,所以烙铁头大都采用紫铜材料。但是紫铜烙铁头存在下列缺点:1.由于烙铁头必须长期在高温情况下工作,紫铜表面很容易氧化发黑,影响焊接性能。2.在工作过程中,长期在高温下的焊料、焊剂对烙铁头有侵蚀作用,使焊接点焊料的含铜量升高,影响焊点的质量。3.经过较长时间使用后,烙铁头和烙铁加热器很容易烧结在一起,往往使更换烙铁头较困难,有时甚至会损坏加热器。4.由于氧化、腐蚀及需经常修锉,所以紫铜制成的烙铁头寿命很短。因此,对紫铜烙铁头的延寿课题都很重视。现将我们取得较好使用效果的试验     

BF-1分相绝缘器

BF-1分相绝缘器,主要用于交流电气化铁道不同相之间做相间绝缘及机械联接。该分相绝缘器采用圆截面式双绝缘滑道,两侧具有双开式引弧角隙结构,此分相器具有单位长度重量轻、引弧及消弧能力强、受电弓过渡平滑、局部可调整负驰度等特点,基本上解决了现有分相器各方面的缺点,并可满足高速铁路运行的要求。此分相器质量稳定,正常运营寿命可达10年以上,大大提高了分相器的使用寿命。     

焊前预热、焊后消除内应力的新颖电加热器

在焊接时,正确地应用预热,后热的焊后热处理工艺,有助于焊接质量的提高。过去在这方面大都采用的是传统的、耗能大的工频加热、火焰加热或花较大投资制造的大型加热炉进行焊前预热和焊后热处理。现介绍一种新颖的电加热器,该电加热器共有三种型式,现分别简介如下。 JL 型履带式加热器:JL型履带式加热器是由耐高温优质镍铬电阻丝和高级陶瓷绝缘器件,按特殊工艺要求编结而成(见图1),这是一种在     

液压油加温方法的改进

液压油加温目前国内基本采用两种方法:1、蒸气加温;2、电热加温。后者由于使用方便等原因,被普遍采用,其基本结构如图1 在使用中通常使加热器工作在额定状态,这样加热的外表面的温度可达700～800℃。由图1可知,加热器外表面的油温也在700～800℃,所以常常可看到处于加热器外表面周围的液压油冒青烟。在如此高的温度下,液压油的性能早已破坏殆尽。这样不仅使液压油提     

片弹簧贮存中性能和结构变化分析

采用周期性作业法和线性回归分析方法分析了片弹簧在不同变形量贮存过程中弹性性能和残余变形随时间的变化规律和趋势,并对产品的贮存寿命进行了评估；分析了片弹簧在强化变形量条件下贮存后的组织结构变化情况.结果表明,该片弹簧在一定变形量条件下贮存3293h后,其性能依然满足设计要求,在工作负荷下预期贮存寿命可达20年.     

新型升降式绝缘验电器搭载平台的研制

介绍一种适用于750kv特高电压的新型升降式绝缘验电器搭载平台,该平台伸展高度可达20米以上,升降机构采用鱼竿式伸缩结构,便于操作,重量轻,安全绝缘,经济实用。     

BF-1型分相绝缘器

ＢＦ 1型分相绝缘器 ,主要用于交流电气化铁道不同相之间做相间绝缘及机构联接。该发相器采用圆截面式双绝缘滑道 ,两侧具有双开式引弧角隙结构 ,此分相器具有单位长度重量轻、引弧及消弧能力强、受电弓过渡平滑、局部可调整负驰度等特点 ,基本上解决了现有分相器诸多方面的缺点、并可满足高速铁路运行的要求。此分相器质量稳定 ,正常运行寿命可达 1 0年以上 ,大大提高了分相器的使用寿命。主要技术性能 :1 标准雷电冲击耐受电压 :≥ 3 0 0ＫＶ2 工频干耐受电压 :≥ 2 40ＫＶ3 工频湿耐受电压 :≥ 2 40ＫＶ4 工频污耐受电压 :≥ 45ＫＶ (…     

A Vacuum High-Temperature Electric Furnace for Investigating Thermal Properties of Materials

A vacuum electric furnace for investigating thermal properties of materials at temperatures of up to 2500°C was developed and tested. The furnace allows experimental studies of the heat conduction of both liquid and solid materials and measurements of the temperature and heat of phase transitions. It can be used to smelt and cake metals and alloys in vacuum or in an inert-gas medium. The heater is made of a graphite tube with special slots for increasing its resistance. The electric power is supplied from an ОСУ-40 step-down transformer. The temperature in the heated zone is controlled and monitored with an РТЭ-4.1 digital temperature controller connected to a computer. The power consumed by the furnace is no higher than 20 kW, and the volume of the working chamber is 0.3 L. The time for reaching the maximum temperature is at most 30 min.     

DIFFERENTIAL 3ω METHOD FOR THERMAL MEASUREMENTS

The 3ω technique has been applied to measure thermal properties of thin films and suspended wires. In this article, we report the implementation and technical design of a 3ω system to measure the thermal conductivity in small dimension structures. Alternating current is applied to a line heater that dissipates power and varies its resistance. The 3ω voltage drop across the heater provides information that determines the thermal properties of the heater or of the adjacent material. A differential bridge is used to subtract the first harmonic voltage and systematic noise. We introduce the use of a synchronous detector associated with the differential bridge to obtain the in-phase and out-of-phase components of the third harmonic signal. The combination improves the bridge method for a broad range of frequency analysis that permits either thermal conductivity and/or heat capacity measurements.     

空调冷热源选择能耗分析

分析了常用空调冷／热源（电制冷／热泵、溴化锂机组、燃气机机组和燃气锅炉）和生活热水（燃气和电热水器）的一次能源利用率，认为可在电力有保障的情况下优先考虑使用电动机组作为空调的冷热源；对电网峰谷差比较大而燃气充足的地区可采用燃气机组作为空调的冷热源；而单效溴化锂机组仅用于有余热利用的场所；生活热水应使用燃气热水器；不提倡使用电锅炉作空调的热源或电热水器提供生活热水。     

Cutting performance of Si<Subscript>3</Subscript>N<Subscript>4</Subscript> based SiC ceramic cutting tools

Composites of Si₃N₄-SiC containing up to 30 wt% of dispersed SiC particles were fabricated via hot-pressing with an oxynitride glass. To determine the effect of sintering time and SiC content on the mechanical properties and the cutting performance, the composites with fixed 8 hr-sintering time and 20 wt% SiC content were fabricated and tested. Fracture toughness of the composites increased with increasing sintering time, while the hardness increased as the SiC content increased up to 20 wt%. The hardness of the composites was relatively independent of the grain size and the sintered density. For machining heat-treated AISI4140, the insert with 20 wt% SiC sintered for 8 hr showed the longest tool life while the insert with 20 wt% SiC sintered for 12 hr showed the longest tool life for machining gray cast iron. An effort was made to relate the mechanical properties, such as hardness, fracture toughness and wear resistance coefficient with the tool life. However, no apparent relationship was found between them. It may be stated that tool life is affected by not only the mechanical properties but also other properties such as surface roughness, density, grian size and the number of the inherent defects in the inserts.     

Compact electron-beam source for formation of neutral beams of very low vapor pressure materials

An electron-beam heater and associated power supply have been developed for use in formation of metal vapors for neutral beam studies. The device is small with relatively low power (250 W). It is easily constructed and designed such that the target surface is normal to the direction of propagation of the neutral beam. Beams of tantalum atoms and carbon particles have been formed using the device.     

回路电阻测试仪的使用与维护

介绍了回路电阻测试仪的工作原理和检测方法。由于其具有测量电阻小、工作电流大、持续时间短等特点,对它进行检测比较困难,因为缺乏允许流过100A以上电流的标准电阻。XC2003型直流大功率有源标准电阻器具有体积小、重量轻、量程宽、功耗低,准确度高等特点,可以专门用来检测回路电阻测试仪。     

焦化加热炉炉管的红外热象检测与剩余寿命在线评估

利用红外热成象技术，在金属材料剩余寿命预测理论研究的基础上，研制一套在线剩余寿命评估系统，实现了焦化加热炉炉管方便而快捷的在线检测与评估。研究结果在某厂焦化加热炉的改造中得到成功应用，在运行状况下进行炉管表面温度场的红外热象测试和剩余寿命预测，可为厂方决策提供科学依据。     

Numerical and experimental study of a thermal probe for measuring groundwater velocity

A thermal method for a rapid measurement of groundwater velocity, particularly in aquifers with preferential flow where groundwater velocities over tenths of (m/d) are expected, was studied. Some instruments for measuring groundwater velocity are based on the application of heat. Those consisting of a central heater surrounded by several thermistors seem adequate for the above purpose, but their measuring range lies below 30 md (meters per day) and there are few works about their theory. Based on the diffusion-convection-dispersion equation, an electrical model is proposed for representing this type of instruments and a theoretical study is presented in an attempt to extend their measuring range. The model can be excited with any shape of power or temperature signals, allows the signals to be feedbacked for controlling the heater's excitation, and includes the thermal features of the heater and thermistors. The model was validated through laboratory tests with velocities of up to 100 md and extrapolated up to 1000 md. Numerical results suggest that exciting the heater with constant temperature allows the measuring range of these probes to be extended.     

Development and characterization of flexible heating fabric based on conductive filaments

Active heating garments will be a promising product for improving life quality of rheumatisants and old people in the future. This paper presented an improved fabrication method of flexible heating fabrics (FHFs) which were developed by weaving intermittently silver filaments (SFs) or coated silver yarns (CSYs) into plain fabrics, this method can control more easily density of conductive filaments and rated power of FHFs in terms of requirements. Resistance thermostability and utmost load current of several kinds of conductive materials were utilized to determine an appropriate conductive material of FHFs. Subsequently, performances of FHF with SFs were characterized by a temperature controlling and power measuring device that was developed in our laboratory. Experimental results show SF can load over 0.3 A current, but the CSY and coated silver knitted fabric (CSKF) can load less than 0.1 A current. However, resistance variation ratios (RVRs) of SF are less than etc. 1.66%, but the RVRs of CSY and CSKF exceed 10% and 20%, when environment temperature increases from room temperature to 80 and 100 °C. Furthermore, strong positive linear correlations are between rated power and utmost ascending temperature of FHFs and between power consumption and presetting equilibrium temperatures of FHFs. In general, measurement data and analysis results can provide help for the design and prediction of physical properties of FHFs.     

等顶隙收缩齿锥齿轮传动设计

齿轮传动具有传动平稳,传动比精确,工作可靠,效率高,寿命长,使用的功率、速度和尺寸范围大等特点。等顶隙收缩齿与普通齿轮和不等顶隙收缩齿相比,可以增大小端的齿根圆角半径,减小应力集中,提高齿根强度;同时可增大刀具的圆刀尖圆角,提高刀具的寿命;还可减小小端齿顶过薄和因错位而"咬死"的可能性。重点研究了一种斜齿变位锥齿轮传动的参数设计方法,提出了等顶隙收缩齿的设计特点和优点,进而提高了整个产品的性能。