同标称值替代法与换位法在直流电阻测量中的应用

介绍了同标称值替代法和换位法校准直流电阻的原理,给出了各自的数学模型,从不确定度、测量结果两个方面对两种方法进行了分析、比较,并对其各自优缺点给出了评价.     

高准确度直流电阻仪整体检定方法探讨及不确定度评定

介绍了几种整体检定直流电阻仪器的检定方法 ,着重分析了用数字多用表整体检定高准确度直流电阻仪器的工作原理和检定方法 ,并进行了不确定度的计算。     

射频控制器1805B直流替代原理及校准

四线法是精确测量小电阻时最常用的一种方法。射频控制器1805B作为微波功率计自动校准装置中（系统ⅡA）的重要组成部分，它的直流替代电路是由三个臂的惠斯通电桥组成，其每四个臂可以用两个100Q的标准电阻等效代替。通过对标准电阻两端直流电压的准确测量，就可判断1805B在各档的直流替代功率是否满足要求，本文最后给出了直流替代功率所对应的直流电压范围。     

数字化智能有源直流电阻箱

文章介绍了采用有源电路代替电阻的一种方法，从而制作出数字化智能有源直流电阻箱。它可以和微机联机，构成智能检测系统，有着广泛的应用前景。     

大型电力设备直流电阻智能化测试仪的研究

介绍一种用于测量大型电力设备直流电阻的高准确度、实用性、智能化仪器的研制过程。采用MCS-51系列单片机作为数据处理，利用直流比较仪实现微小电阻快速而又准确地校验，并给出了产品的性能指标，具有准确度高，噪声低，功耗小，抗干扰能力强且操作简便，安全等优点。     

电线电缆产品质量检验中导体直流电阻测量不确定度评定

导体直流电阻是电线电缆生产企业及产品质量监督检验部门对电线电缆产品质量检验不可或缺的检验项目。因此,对电线电缆导体直流电阻的测量不仅要求测量准确,而且其检验报告也应该给出测量不确定度,以使客户了解测量结果的质量。本文介绍了电线电缆产品质量检验中导体直流电阻的测量不确定度评定。     

变压器直流电阻测量方法改进方案的探讨

电力变压器绕组具有大电感和小电阻的固有特点,测量直流电阻时充电时间常数很大,长期以来技术人员研究各种方法试图缩短测量时间。本文研究了电力变压器直流电阻快速测量的各种方法,分析了方法的优缺点,简介了变压器直流电阻测量改进方案。     

电线电缆产品质量检验中导体直流电阻测量不确定度评定

导体直流电阻是电线电缆生产企业及产品质量监督检验部门对电线电缆产品质量检验不可或缺的检验项目。因此，对电线电缆导体直流电阻的测量不仅要求测量准确，而且其检验报告也应该给出测量不确定度，以使客户了解测量结果的质量。本文介绍了电线电缆产品质量检验中导体直流电阻的测量不确定度评定。     

用QJ36电桥测量系统测量导体直流电阻不确定度分析

对使用QJ36电桥测量系统进行的导体直流电阻测试的测量不确定度进行了分析。基于这次软铜导体的测试数据对构成导体直流电阻测量不确定度的主要分量进行了较全面的评定,最终给出了本次测量的扩展不确定度。     

一种新型绝缘监测系统的设计

直流系统的绝缘性能直接影响直流回路的可靠性。针对监测电网直流系统的绝缘问题，提出了一种主-从式绝缘监测系统的设计方案，即用一个绝缘主模块来测量主回路的绝缘电阻，而用专门的支路模块来判断出现绝缘降低的那条支路，并利用不平衡电桥法给出了一个较为精确的，用于电网直流系统计算正负母线绝缘值都出现降低的情况下的正、负绝缘电阻的公式，在实际应用中取得了很好的效果，测量精度可达到5％。     

Study the Performance of the AC/DC Resistors During Their DC and AC Measurements

Some of traceability chains for the AC resistance measurements are based on AC/DC resistors. In this paper, performance of two types of them with different values has been investigated for their optimum utilization. Tinsley and Cambridge AC/DC resistors have been measured as DC resistors using different measurement methods and as AC resistors at various frequencies. DC direct method using digital reference multimeter is more accurate for the resistance values 1, 10, 100 Ω, and 1 kΩ. For the values 10 and 100 kΩ; measurement results are very near by using the DC direct and ratio methods. At 100 kΩ; representation of the resistance as an equivalent series resistance is not suitable at frequencies above 10 kHz, while for 100 mΩ and 1 Ω; the equivalent parallel representation is not suitable above the same frequency. The uncertainty analysis is also studied for all the obtained results.     

便携式直流电阻电桥QJ23A检定量程系数比方法探讨

想探讨关于检定便携式直流电阻电桥QJ23A量程系数比M的方法,根据《直流电桥》检定规程所说测量便携式直流电阻电桥的量程系数比要用整体检定法,接入电阻箱进行测量。由于QJ23A的量程倍率为七个固定的比率分别为×0.001,×0.01,×0.1,×1,×10,×100,×1000,均是10的整数次幂由此突发奇想,想用准确度更高的,年稳定性0.0003%的一等标准电阻作为被测接入电桥中测量电桥的量程系数比看看是否可行,将从测量原理,实验方法,及两种实验各种因素所引进的不确定度进行分析,探讨两种方法的区别,最终选择电阻箱法测量。     

直流电阻箱半自动检定系统

简要介绍了直流电阻箱半自动检定系统的构成、工作原理、测量方法及软件设计,并对该系统的可行性进行了验证.     

直流大电流比较仪谐波影响问题的研究

本提出了在谐波影响下直流大电流比较仪的等效电路模型及计算方法,通过仿真给出了该模型的频率特性,通过试验数据与仿真结果的比较证实了电路模型的可行性,对研究直流大电流比较仪和电流互感器的谐波影响具有指导意义。     

高准确度直流电阻分压箱的校准

分析了直流电阻分压箱的技术指标和校准水平，提出了等分测量的校准方法，进行了不确定度分析，给出了验证方法。结果表明：用该方法校准的分压箱，比率误差为１０＾－７量级。     

Research on resistance characteristics of YBCO tape under short-time DC large current impact

Research of the resistance characteristics of YBCO tape under short-time DC large current impact is the foundation of the developing DC superconducting fault current limiter (SFCL) for voltage source converter-based high voltage direct current system (VSC-HVDC), which is one of the valid approaches to solve the problems of renewable energy integration. SFCL can limit DC short-circuit and enhance the interrupting capabilities of DC circuit breakers. In this paper, under short-time DC large current impacts, the resistance features of naked tape of YBCO tape are studied to find the resistance – temperature change rule and the maximum impact current. The influence of insulation for the resistance – temperature characteristics of YBCO tape is studied by comparison tests with naked tape and insulating tape in 77 K. The influence of operating temperature on the tape is also studied under subcooled liquid nitrogen condition. For the current impact security of YBCO tape, the critical current degradation and top temperature are analyzed and worked as judgment standards. The testing results is helpful for in developing SFCL in VSC-HVDC.     

Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

Cu–Al₂O₃ nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.     

Microstructure and characterization of Ni-Co/Al2O3 composite coatings by pulse reversal electrodeposit

Ni-Co/Al₂O₃ composite coatings were obtained by pulse reversal electrodeposit (PRC) and direct current electrodeposit (DC). The microstructure of the coatings was characterized by means of SEM, XRD and TEM. Hardness, wear resistance and macro residual stress of coatings were also investigated. The results showed that the microstructure and performance of the coatings were significantly affected by the electrodeposit methods and the Al₂O₃ particles content. The PRC composite coatings exhibited compact surface, high hardness and excellent wear resistance. The macro residual stress of PRC composite coatings was lower than that of DC ones. With the increasing of Al₂O₃ particles content, the hardness and wear resistance of the composite coatings increased.