电气火灾中铝导线短路熔珠凝固后高温火烧对金相组织的影响

研究气体火灾中铝导线短路熔珠凝固后高温火烧对金相组织的影响。选用航空导线FVL与民用导线BV作为实验材料,对铝导线短路熔珠进行制备,对电气火灾中铝导线短路熔珠凝固后的温度进行模拟。结果:在高温、中温、低温环境下熔珠中共晶体含量大致一样,不同温度状态下均有部分熔珠内无共晶体存在,温度越低,无共晶体析出的熔珠数量越多。将凝固后的铝导线短路熔珠在1 000℃环境下加热10 min后,其金相组织主要是纤细的晶体状,熔珠中有部分细小等轴晶,有气孔现象出现;加热25 min和40 min后,其金相组织显示晶体已经变成粗大柱状晶体,其中含有少量气孔;加热55 min和70 min后,金相组织为粗大柱状晶和粗大等轴晶并存,晶界很明显,没有气孔现象。将凝固后的铝导线短路熔珠在500℃环境下加热20 min后的金相组织主要为等轴晶,其直径较小,分布均匀,晶界显著,有部分气孔存在;在800℃环境下加热20 min后的金相组织以等轴晶为主,晶粒直径不大同时较为均匀,晶界显著,形状相似;在1 000℃环境下加热20 min后的金相组织主要是等轴晶,晶粒直径较大,晶界显著,分布均匀,晶粒明显大于500℃和800℃的加热环境。高温环境下的铝导线短路熔珠密度明显高于中温和低温环境。结论:电气火灾中铝导线短路熔珠凝固后高温火烧能够使金相组织中晶粒变大,令熔珠中的气孔消失。     

Combined effects of fretting and pollutant particles on the contact resistance of the electrical connectors

Usually, when electrical connectors operate in vibration environments, fretting will be produced at the contact interfaces. In addition, serious environmental pollution particles will affect contact resistance of the connectors. The fretting will worsen the reliability of connectors with the pollutant particles. The combined effects of fretting and quartz particles on the contact resistance of the gold plating connectors are studied with a fretting test system. The results show that the frequencies have obvious effect on the contact resistance. The higher the frequency, the higher the contact resistance is. The quartz particles cause serious wear of gold plating, which make the nickel and copper layer exposed quickly to increase the contact resistance. Especially in high humidity environments, water supply certain adhesion function and make quartz particles easy to insert or cover the contact surfaces, and even cause opening resistance.     

基于专家系统的电厂电气设备缺陷诊断

在分析人工智能缺陷诊断必要的基础上,开发了一个基于知识的电厂电气设备缺陷诊断专家系统,并依次对系统的知识库、推理机和人机接口进行详尽阐述,最后通过实例验证系统的智能性和有效性。     

变电所电气系统可靠性分析

变电所运行的稳定性和可靠性对我国电力系统的安全有着重要的意义。变电所内的电气系统和电气元件的可靠性和稳定性是整个变电所安全运行的关键。纵观国内外的研究文献多是从如何提高变电所电气系统的可靠性及相关可靠性分析方法的角度进行研究,本文认为从分析变电所电气系统实效的原因入手,并针对这些原因对其可靠性进行评估和计算,进而提出提高变电所电气系统可靠性的方法,可以有效的提高我国电力系统安全运营的水准。     

Minor-alloyed Cu-Ni-Si alloys with high hardness and electric conductivity designed by a cluster formula approach

Cu-Ni-Si alloys are widely used due to their good electrical conductivities in combination with high strength and hardness. In the present work, minor-alloying with M =(Cr, Fe, Mo, Zr) was conducted for the objective of further improving their hardness while maintaining their conductivity level. A cluster-plus-glue-atom model was introduced to design the compositions of M-alloyed Cu-Ni-Si alloys, in which an ideal composition formula[(Ni,Si,M)-Cu_(12)]Cu_3(molar proportion) was proposed. To guarantee the complete precipitation of solute elements in fine δ-Ni_2 Si precipitates, the atomic ratio of(Ni,M)/Si was set as 2/1. Thus the designed alloy series of Cu_(93.75)(Ni/Zr)_(3.75)Si_(2.08)(Cr/Fe/Mo)_(0.42)(at%) were arc-melted into ingots under argon atmosphere, and solidsolutioned at 950 ℃ for 1 h plus water quenching and then aged at 450 ℃ for different hours. The experimental results showed that these designed alloys exhibit high hardness(HV 1.7 GPa) and good electrical conductivities(≥ 35% IACS). Specifically, the quinary Cu_(93.75)Ni_(3.54)Si_(2.08)(Cr/Fe)_(0.42)Zr_(0.21) alloys(Cu-3.32 Ni-0.93 Si-0.37(Cr/Fe)-0.30 Zr wt%) possess both a high hardness with HV = 2.5-2.7 GPa, comparable to the highstrength KLFA85 alloy(Cu-3.2 Ni-0.7 Si-1.1 Zn wt%,HV= 2.548 GPa),and a good electrical conductivity(35-36% IACS).     

AHP在矿井提升机电控系统改造中的应用

以提升机电控系统为研究对象,对传统的电控系统进行了描述,指出了其存在的弊端.利用层次分析法(AHP)建立了提升机设备改造模型,通过数据的分析与计算,得出了以计算机控制技术和PLC控制器对传统的电控系统进行改造为最佳方案.结果证明采用该方案大大降低了提升机的故障率,提高了系统的可靠性,保证矿井安全运行.     

稀土元素铈对Cu—Fe—P合金导电性和力学性能的影响

在Cu-Fe—P合金中添加稀土元素Ce,研究不同含量Ce对Cu—Fe-P合金的导电性、硬度、抗拉强度等性能的影响。结果表明,稀土元素Ce能起到基体净化和晶粒细化的作用,从综合性能考虑,添加0．1％稀土元素Ce能够提高材料的导电性、硬度及抗拉强度。     

铜系电子浆料的制备及其稳定性研究

以低温固化类电子浆料作为研究对象,研究了在表面镀银后的铜粉,再包覆一层有机保护膜的抗氧化效果,通过SEM、XRD、测量电阻方法及加速老化实验等手段对其进行了表征和分析,实验结果表明,制备得到的电子浆料在经过1000h室温放置、200h 100℃下及48h 120℃,80％湿度的加速失效实验后,仍具有较好稳定性及导电性质。     

Development of Simulated Testbed for Electrical Power Subsystem of a Certain Kind of Satellite

1.IWTaODUCTIONAfaultdiagnosticexpertsystem(FDES)isusedtoensurethespacecraftsafetyeffectively.Theexpertsystemmustrunreliablyandavailablytoanadequateextelltinordertoprovidethehighestpossiblelevelofservice.Ingeneral,beforetheFDESisputilltopractice,itshouldbeveriliedasfarasitsdiagnosticvalidityanditsoperationalmethodsareconcerned.Accordingtotheoperationalprincipleoftheelectricalpowersubsystemofacertainkindofsatellite,atestbedsystemwasdevelopedtosimulatethenormalstatesandfailuremodesofthesa…     

CCD信号分析及MTFi

本文对电子摄像式杂质测量仪的电耦合摄像器件进行了信号分析；确定了图象信号与视频信号之间的联系；推导了上述器件的光积分调制传递函数ＭＴＦｉ。