一种大电阻值的测量方法

介绍了一种利用两个低值电阻实测对高值电阻的简例测量方法，提出了选用低值电阻的条件，并分析了此测量方法的误差。     

减小ESR测量误差的方法

随着电容器和电感器的等效串联电阻(ESR)持续得到改善,低值ESR的测量变得越来越困难.造成ESR测量误差的原因有二:ESR(或ESR的绝对值)太小或复合信号矢量的相位太小.了解测量方法的局限性与频率的依赖关系和夹具误差修正可以用适当方法来获得最佳的测量结果.     

变压器线圈绝缘电阻与交流电阻的测量,判断标准及其故障分析

本文全面论述了变压器绝缘电阻与线圈直流电阻测量方法，注意事项。标准要求及有关故障分析。     

开关电器触头接触电阻测量方法的比较

触头接触电阻的的测量方法甚多,本文所述的是工厂对产品的出厂试验和型式试验所用的测量方法的比较。文中介绍了触头接触电阻的特点、触头接触电阻与开关电器工作状况的关系及三种接触电阻测量方法的比较。     

运行状态下变电站的接地电阻及其接地电位的测量方法

在测量变电站接地装置的接地电阻及其接地电位时，为了避免由于主变压器中性点或站用变压器中性点直接接地的不平衡电流的干扰，通常要求将变电站停电后再测量该变电的接地电阻及其接地电位，这就是传统的测量方法的主要缺点，此文介绍了一种可以变电站运行状态下测量接地电阻及接地电位的方法，这种测量方法对运行状态下的发电厂的接地电阻及其接地电位的测量了是适用的。     

城市配电网中性点电阻接地方式的特点及应用

介绍了城市配电网中性点经电阻接地方式的优点及其分类方法。阐述了高值电阻接地、中值电阻接地、低值电阻接地等3种电阻接地方式的使用范围、特点、接地电阻的选择等有关问题,叙述了中值电阻接地方式在南京配电网的应用情况。     

一种高精度电阻频率变换法

本文在简述了对负荷传感器常用的测量方法之后，提出了一种新的测量方法－电阻频率变换法，并对其技术指标如精度、灵敏度和分辨率进行了分析。     

钳形接地电阻测试仪在电力系统的应用

介绍了钳形接地电阻测试仪的基本原理和主要特点,详细探讨了钳形接地电阻测试仪在电力系统中的测量方法和与其他测量方法对比的优势,并指出了钳形接地电阻测试仪在使用时的注意事项.通过与传统测试方法的对比,作者认为钳形接地电阻测试仪非常适用于电力系统接地电阻的测量.     

半导电层电阻测量的研究

实验研究了电力电缆半导电层电阻的测量方法，发现ＩＥＣ ８４０附录Ｂ规定的测量方法不够合理及产生的原因并提出了改进意见。     

输电线路杆塔接地电阻测量方法的研究

输电线路杆塔接地电阻的合格程度与线路的耐雷水平密切相关。由于接地电阻测量方法不正确,测量出的结果不能正确反映实际值,使不合格的杆塔接地不能得到及时有效的改造,杆塔极易受雷电的侵害,直接威胁到电网的安全运行。文中通过对池州电网山区不同地形杆塔接地电阻测量方法的研究和实践,总结并制定了规范的测量方法和步骤,提高了杆塔接地电阻测量的准确性,为接地电阻改造提供了科学依据。     

On the realization of gyrators by nullors and resistors

It is proved that for the realization of a gyrator by nullors and resistors, at least two nullors and at least two resistors are needed. A generalization is the result that any n-port network possessing both an impedance and an admittance matrix and consisting of nullors and resistors must contain at least n resistors. It is conjectured that a realization of a gyrator with only two nullors requires four resistors and a realization of a gyrator with only two resistors requires three nullors.     

On the minimal realization of the gyrator by means of nullors and resistors

This paper is a second step in the proof of the conjecture that it is impossible to synthesize a gyrator by means of nullors and linear resistors with fewer than four resistors if only two nullors are permitted, or with fewer than three nullors if only two resistors are permitted. It is proved that a gyrator cannot be realized with only two nullors and two resistors. In a forthcoming paper (third step) it will be proved that a two-nullor, three-resistor gyrator realization cannot be obtained. The proofs are presented in such a way that at the same time a synthesis procedure for minimal nullor-resistor networks is demonstrated.     

On the minimal realization of the gyrator by means of nullors and resistors. II

It is proved that it is impossible to synthesize a gyrator with only two nullors and three resistors. Combining the results obtained in References 1 and 2 and in this paper, we obtain the following necessary and sufficient conditions: a nullor-resistor gyrator realization is minimal if and only if it consists of either two nullors and four resistors or three nullors and two resistors.     

500 kV输电线路断路器合闸电阻配置原则

通过对某500 kV输电线路断路器取消合闸电阻的投切试验、断路器事故进行分析,并对此进行电磁暂态仿真计算,讨论了500 kV输电线路断路器取消合闸电阻的原则,与线路操作过电压幅值、线路两端高压并联电抗器配置情况的关系。研究结果表明,500 kV输电线路断路器合闸电阻配置时,需要考虑线路高压并联电抗器的配置情况,这将直接影响断路器断开的成功与否。     

On a class of pseudo‐logarithmic amplifiers suitable for use with digitally switched resistors

This paper describes three circuits that implement pseudo‐logarithmic functions, which are simple and easy to implement. The circuits can be realized using operational amplifiers or current feedback amplifiers. Tuning can be achieved using switched resistors, or active resistors, or tunable transconductors, but are best suited for use with digitally switched resistors. Frequency response and stability considerations for two of the circuits are thoroughly discussed and PSPICE results confirming the theoretical results are presented alongside measured results. Copyright © 2007 John Wiley & Sons, Ltd.     

Current mode CCII oscillators using grounded capacitors and resistors

New realizations of grounded C, grounded R current mode oscillators using the current conveyor (CCII) are given. The proposed oscillators are classified into two classes depending on the number of feedback loops. In class I, there is a single current feedback loop, whereas in class II, there are two current feedback loops. Class I includes two types and it employs two CCIIs, three capacitors and three or four resistors. Class II employs two CCIIs having two-outputs each, two capacitors and three resistors and has independent control on the condition of oscillation and on the frequency of oscillation by varying two alternative resistors. PSpice simulations are included. Exact analysis based on the parasitic elements of the CCII is carried out indicating that class I has a third order characteristic equation. Class II has the advantage that the effects of the parasitic elements of the CCIIs can be absorbed in the circuit components. © 1998 John Wiley & Sons, Ltd.     

A generalized theorem of Reichert for biquadratic minimum functions

This paper is concerned with a generalized theorem of Reichert for biquadratic minimum functions, which states that any biquadratic minimum function realizable as the impedance of networks with n reactive elements and an arbitrary number of resistors can be realized with n reactive elements and two resistors. First, a series of constraints on networks realizing minimum functions are presented. Furthermore, by discussing the possible resistor edges incident with vertices of the reactive‐element graphs, it is proved that any minimum function realizable as the impedance of networks with three reactive elements and an arbitrary number of resistors can be realized with three reactive elements and two resistors, from which the validity of the case of n = 3 follows. Similarly, the validity of the case of n = 4 is proved. Together with the Bott–Duffin realizations, the generalized theorem of Reichert for biquadratic minimum functions is finally proved. The results of this paper are motivated by passive mechanical control. Copyright © 2016 John Wiley & Sons, Ltd.     

An improved pseudo-exponential, pseudo-logarithmic circuit

In this paper a useful pseudo-exponential and pseudo-logarithmic circuit is proposed that offers improved performance compared to a current-conveyorbased design. The circuit employs two operational amplifiers and several resistors and mimics the exponential and logarithmic functions over predefined ranges. Control of the pseudo-functions is achieved by a single resistance, which may be digitally switched or implemented by tunable transconductors. Measured results using digitally switched resistors and commercially available components demonstrate the versatility of the circuit for audio/video applications.     

On the geometry of parallel impedances

A geometrical construction for the equivalent (sinusoidal) impedance of two impedances connected in parallel is presented. The special case of two resistors connected in parallel is reviewed     

合金材料中性点接地电阻器的研制

对各种合金材料接地电阻器在模拟接地故障状态下的通流过程及相关的力场及热场特性进行了研究,分析、比较并优选了部分合金材料;根据接地电阻器在短时故障状态下发热与散热的特点,构建了接地电阻器热分析仿真模型,并提出了不同材料、结构的中性点接地电阻器的设计方案。根据仿真结果可对设计方案进行优化,旨在为实现接地电阻器的国产化提供参考。