变压器绕组短路故障分析与处理

针对变压器绕组常见的短路故障,通过分析绕组发生短路故障原因,提出了检测变压器绕组短路故障方法、防止及处理此类故障的措施,以确保变压器能安全稳定运行。     

篁墩,北方移民的中转地

"程朱阙里"先后走出了众多中国史上著名人物的祖先,是因为篁墩是一个山环水复的"澳区"。     

双金属轧片管在发电厂空冷器中的应用

通过对绕簧管和双金属轧片管的性能分析比较,选取双金属轧片管对发电厂中的绕簧管空冷器进行合理设计改造,使其提高传热效率、降低流动阻力,达到节能降耗、提高效益目的。根据改造的结果以及在实际应用中看,采用双金属轧片管空冷器在发电机的空气冷却上各项参数均优于原绕簧管空冷器,达到了要求。证明双金属轧片管空冷器在发电厂中有很好的应用价值,在其它类似的场合中也值得应用推广。     

Analysis of a new 5-phase bearingless induction motor

This paper addresses the bearingless motor with a single set of multiphase windings. The interaction between M and M±1 pole-pair magnetic fields produces radial force. Based on this principle,a bearingless machine is obtained. Conventional bearingless machine has dual windings,levitation windings and torque windings,which produce the two magnetic fields. In the proposed bearingless motor,the two needed magnetic fields are produced by feeding two groups of currents to a single set of multiphase windings. Taking a 5-phase induction motor as example,the inductance matrices,considering air gap eccentricity,are calculated with the modified winding function method. The radial force analytical model is deduced by virtual displacement,and its results are validated by FEA. The mathematical model of the new bearingless machine is set up,and the simulation results verified the feasibility of this novel bearingless motor.     

三相异步电动机分数槽绕组排列表的绘制

本文讨论了如何确定三相异步电动机分数槽绕组排列表及用槽电势相量图检查的方法.     

从百家争鸣到独尊儒术

在中国学术发展史上,从先秦百家争鸣到汉武帝时的独尊儒术的转变,适应了社会发展的需要,有其深刻的历史必然性,是社会历史做出的合乎规律的选择。分析其发展轨迹和变化规律,能给我们以有益的启示,并对社会发展产生了深刻的影响。     

砂型温度场与烧损场的相关计算

通过试验和理论分析，建立了砂型中膨润土烧损的数学模型，揭示了膨润土烧损率与砂型所受热作用的温度和时间遵循指数关系．利用数值模拟方法对砂型温度场和烧损场进行了相关计算，能够对砂型中膨润土烧损量进行定量预测     

Analysis of Capacitive Parasitism in PWM Inverter—Fed Motor

The effects of parasitic capacitance in induction motor system are unnoticed when it is fed from the AC line,but they are obvious when supplied directly from a PWM inverter,Consequently,many parasitic problems occur.Such as motor-to-earth leakage current.Bearing current.incoming line current distortion and uneven distribution of electrical stresses along the winding.On the basis of the uniform transmission line principle.a complete equivalent circuit of the PWM inverter-fed motor system is presented,based on which all the capacitive parasitic problems mentioned obove are analyzed and simulated by means of PSPICE.All the results are consistent with the existing ones.     

低压排污用聚乙烯(PE)缠绕管断面结构优化设计思路

针对现有市政排水、建筑室外排水,农田低压输配水、工业排污等管网建设情况,本文在现有HDPE中空壁缠绕管结构的基础上,提出一种新型结构壁缠绕管的设计思路,利用此结构壁缠绕而成的产品可满足环刚度要求的同时,实现较少材料用量,使产品具有结构新颖、重量轻、高环刚度等优点.     

对磁感应强度相差1／12的讨论

讨论了线圈在球面上两种不同的均匀绕制方法，能使同一点产生的磁感应强度相差1／12的原因．