连城电厂2号主变压器绝缘油总烃量突然升高的原因分析及处理

变压器绝缘油的色谱分析是判断变压器内部故障的重要手段，通过分析连城电厂2号主变压器绝缘油总烃量突然升高的原因，找出了影响2号主变压器安全运行的隐患，并加以解决。     

±500 kV换流变压器交流耐压试验放电超标分析

金中直流工程YY5换流变压器出厂试验的外施交流耐压及局部放电检测试验中,发现换流变压器本体内部发生放电超标现象。采用绝缘油色谱分析验证内部放电现象的存在,通过超声探测确定了放电点的位置,并通过换流变的解体检查最终查找到故障源头,对故障的原因进行了分析,给出了处理意见和后续产品的整改建议。     

330kV变压器局放试验异常的分析和处理

为了找出某330kV 变电站变压器局部放电试验过程中发现的变压器高压侧 B相局部放电量数据异常的原因,进行变压器绝缘油色谱分析、超声波定位和多次加压分析,排除外在干扰,发现该变压器 B相高压引出线绝缘纸 包扎部位有明显放电痕迹,为包扎脱节现象.该缺陷不常见,在变压器绝缘油色谱分析合格,现场并无理想的试验室环境下发现该缺陷并不容易.这表明在电气试验中局部放电试验是发现变压器内部缺陷的有效手段之一,但发现变压器的缺陷位置并解决问题需要采取多种手段.     

大型变压器内部故障的分析及处理

文中介绍芜湖供电公司师专变电站1号主变压器运行中绝缘油中特征气体含量超标,根据色谱分析判断为低能量放电故障,曾做过现场处理,但未能彻底消除故障;经返厂解体消缺,消除内部放电和过热故障后,投运至今情况良好。     

变压器内部过热故障分析及检修处理

分析了变压器绝缘油中溶解气体的含量能提前预测设备的内部故障，可防止设备损坏和由于设备损坏而导致的电网大面积停电事故发生。因此，利用绝缘油中溶解气体的色谱分析方法和油色谱在线监测装置，并结合其他试验手段可以随时监视设备的运行状况，对保障设备乃至电网的安全运行可起到积极作用。文章以甘肃金昌供电局利用绝缘油中溶解气体的色谱分析方法和油色谱在线监测装置，结合其他试验手段成功捕捉并处理330kV变压器内部过热故障为例，对其应用电气设备状态监测与故障诊断技术进行了分析总结，并对应用绝缘油中溶解气体的色谱分析方法和油色谱在线监测装置提出了建议。     

变压器过热性缺陷与绝缘油中气体色谱的关系

变压器过热性缺陷与绝缘油中气体色谱的关系华北电力科学研究院（北京１０００４５）孙维本定期进行变压器油中气体的色谱分析，是发现变压器内部过热、放电性故障非常有效的方法。该法近几年来越来越受到重视。一般来讲，变压器导电、导磁回路存在缺陷，便会引起变压器油...     

一起750kV变压器放电故障的定位与分析

一台750kV变压器在油色谱分析中检出乙炔,并呈增长趋势,为了分析该变压器故障原因,对该变压器进行了带电测试,结合绝缘油试验进行了综合分析,明确了故障原因,找到了放电位置,避免了事故的发生。     

变压器绝缘油色谱单氢气增长探讨及案例分析

绝缘油色谱检测对于发现变压器内部潜伏性故障有着至关重要的作用.在变压器故障中,氢气含量的变化 较为敏感.变压器受潮、局部放电,火花放电、电弧放电时,氢气含量都会增长,另外绝缘材料、金属材料中析出氢 气,绝缘漆、绝缘油种类等都会影响氢气含量变化.     

一台新投运500kV变压器油色谱异常的缺陷诊断和处理

变压器油色谱分析是发现变压器内部早期潜伏性故障的重要手段,笔者针对某500 kV变压器在投运初期发生的油色谱异常情况,结合变压器局部放电带电检测和故障定位,综合分析判断了缺陷性质和部位,为随后变压器的内部检查和消缺处理提供了有力的指导意见。内部检查结果与色谱分析、局放定位结果相吻合,充分验证了故障诊断方法的有效性和正确性,为大型变压器油色谱异常后的故障诊断和缺陷处理提供了经验。     

某500 kV主变压器故障的分析及处理

对某500kV主变压器进行油色谱分析时发现变压器本体绝缘油中乙炔的体积分数上升，停运后运用脉冲电流法、放电图谱测量、超声波定位、油色谱试验等试验技术进行检查，判断该变压器内部存在电弧放电，经返厂维修后恢复正常运行。     

On a wing and a prayer

The article talks about recent Defense Research Projects Agency (DARPA) presolicitation notice in the area of hybrid insect micro-electromechanical systems (MEMs). DARPA's goal is to fund promising interdisciplinary research that will permit the creation of "insect-cyborgs"     

利用光伏电池给蓄电池充电

磷酸锂铁（LiFePO4）电池对比钻基德Li离子/聚合物电池,具有安全性性高、浮充电压小、自放电率低、使用寿命长等一系列优点。本文所述LT36521C为可实现太阳能跟踪、单块式补偿蓄电池充电的集成电路。当LT3652由单块太阳能电池板供电时,其输入调节回路能确保在最大输出功率下工作,充分体现出这一新型太阳能充电器的优越特性。     

Making a Case for a New Connector

The emergence of quick lock connectors, particularly quick lock versions of the SMA and N connectors (QMA and QN, respectively), was an inevitable development in the RF connector industry and is of significant importance in that nearly 50% of all practical applications for RF connectors are currently supported by either SMA or N. Once QMA and QN can achieve similarity in cost and performance to the present SMA and N connectors, they will take the place of their predecessors in most applications, creating a huge new market. Our RF team has long been dedicated to research and development of these two connector types in the hopes of creating an optimal design. In this article, we will show some of the results of our research.     

Chaos in a series circuit with a nonlinear capacitor and a nonlinear inductor

This paper proposes a nonlinear circuit that generates chaotic oscillations. The proposed nonlinear circuit includes a nonlinear capacitor and a nonlinear inductor by using Generalized Impedance Converters. Both computational experiments and experiments on real circuits show that the region for chaotic oscillation is very wide, demonstrating that the proposed circuit is effective as a chaos generator. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(2): 35–42, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10361     

Electric potential near a tip of a local discharge on a conductive film

To develop a propagation model of a local discharge on a wet polluted insulator, the authors have examined characteristics of the local discharge on an electrolytic solution simulating the wet polluted insulator surface. The local discharge was propagated on the solution under the impulse voltage. A shape of a contacting surface between the local discharge and the solution has been already obtained by the authors. By using the contacting surface, an electric potential near a tip of the local discharge on a conductive film of 1 mm in thickness was calculated. Furthermore, the potential was measured with a probe. The calculated values and the measured values of the electric potential agreed well regardless of the propagation length of the local discharge, the width of the conductive film, the resistivity of the conductive film, the peak value of the applied voltage and the applied voltage waveform.     

Power losses in a conducting ring enclosing a conductor with a transient current

Contents In the paper Joule power losses are calculated in a conducting ring enclosing a conductor with a transient current having an alternating component.—Theoretical calculation and numerical computation are worked out basing on a link Bubnov-Galerkin method in its numerical version using the finite elements for the conductor with the Time-Stepping algorithm for the time discretization.—On the basis of numerical computation, graphs of the relative power losses are plotted as a time function.

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Leistungsverluste in einem leitenden Ring, der einen Leiter mit einem instationären Strom umschließt

Übersicht In diesem Beitrag werden die Joulschen Leistungsverluste in einem leitenden Ring berechnet, der einen Leiter umschließt, in dem ein instationärer Strom mit Wechselanteil fließt. Die theoretischen Betrachtungen und numerischen Berechnungen hat man in Anlehnung an die Bubnov-Galerkin-Methode (in ihrer numerischen Variante, die von einen Leiter unter Verwendung der Methode der finiten Elemente realisiert wird) in Verbindung mit einem Schritt-Algorithmus mit der diskretisierten Zeit ausgeführt. Auf der Grundlage numerischer Berechnungen sind Diagramme für die relative Leistung in Abhängigkeit von der Zeit dargestellt.

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List of symbols Symbol Unit Physical parameter - B Wb/m² magnetic induction vector - H A/m magnetic field intensity vector - H, H A/m -component of the magnetic field vector - E V/m electrical field vector - E _r ,E _z V/m components of the electric field - f s^–1 frequency - I A current intensity (r.m.s. value) - L H inductance - P W power losses - P ₀ W power losses for d.c. - R resistance - t sec time - ^–1 m_–1 electric conductivity of the conductor - Hm^–1 magnetic permeability - _ijk m² finite element area - basis function - rad s^–1 pulsation - N _i ,N _j ,N _k function of finite element shape - 3.141593... - region - ² Laplace's operator - r, ,z cylindrical coordinates - ^h region approximating the region - ^e finite element region - M number of discretization points of the region - V number of finite elements - (N–1) number of steps - i, j, k indices of vertices of triangular finite element     

Extension of a driving-point and a transfer function to a positive real two-port matrix

A solution is presented to the problem, which arises in two-port modelling, of determining a second driving-point function from a given driving-point function and a transfer function. the given functions must have a common denominator and satisfy the necessary positive real (PR) matrix conditions: the driving-point function must be PR and on the imaginary axis the real part of the transfer function must be zero whenever the real part of the driving-point function is zero. By using a partial fraction expansion and determining a required first-order polynomial, a unique second (minimum) driving-point function is obtained. Examples to illustrate the method are worked out.     

When a feature detector becomes a feature generator

The neural network approach is reviewed in the context of studies in the animal and human visual systems. An attempt is made to explain perception, memory, and learning as a feedback loop similar to the one used in the ALOPEX optimization concept. Applications in pattern recognition and image processing are discussed. Experiments using visual evoked potentials in humans are described.     

Development of a deceleration control system for a winding machine based on a microcontroller

The development of an automatic deceleration system for a winding machine in a siderurgy factory is presented in this paper. The proposed system controls the speed of a winding machine in order to obtain the optimum stop point in terms of security and fast production. The system is based on a microcontroller and an extremely simple hardware. The system has been tested for two years and results evince a very good mean time between failures.