利用直流数字电压表检定直流电位差计的示值基本误差

本文以7081DVM为例,分析了用数字电压表可检何种电位差计,并介绍了相应的检定方法。     

利用直流数字电压表测量直流比较仪式电位差计的绝缘电阻

由检定规程ＪＪＧ５０５－８７的表１可知,绝缘电阻是直流比较仪式电位差计的周期检定项目之一。ＪＪＧ５０５－８７第１０条指出,０－０００１级直流比较仪式电位差计的绝缘电阻应分别不低于１ＧΩ、２ＧΩ。规程规定测量上述绝缘电阻用直流电压１００～２５０Ｖ的绝缘电阻测量仪或高阻电桥,测量误差不大于２０％。但是这样的绝缘电阻测量仪或高阻电桥,很多计量技术机构不具备,而准确度较高的数字多用表（ＤＭＭ）或直流数字电压表（ＤＶＭ）比较多见,可利用ＤＭＭ的直流电压功能（或ＤＶＭ）测量上述绝缘电阻。现以用７０８１ＤＭＭ…     

用数字电压表检定携带式直流电位差计的示值误差测量不确定的评定

本文主要阐述用数字电压表检定携带式电位差计的原理，分析示值误差测量不确定度的来源并对其测量结果进行不确定度的评定。     

利用数字电压表检定便携式直流电位差计示值基本误差

本文主要介绍利用数字电压表检定便携式直流电位差计示值基本误差的工作原理 ,技术要求 ,误差分析及装置不确定度的计算     

数字电压表法检定直流电位差计及其测量结果的不确定度分析

本文描述了用数字电压表作为标准器检定直流电位差计的工作原理,并就数字电压表法检定直流电位差计的测量结果不确定度进行了分析。实验结果表明,数字电压表法检定低精度直流电位差计具有方便、快捷、可靠等优点。     

直流电位差计自动检定系统

本提出了一种自动检定直流电位差计（以下简称电位差计）的检定系统，利用纳伏表和微型计算机实现对电位差计各测量盘示值的基本误差，变差，温度补偿盘误差和零电势的自动检定及数据处理，可按计量检定规程的要求以检定证书格式打印出检定结果并判断被检电位差计是否合格。     

用数字电压表检定便携式直流电位差计示值误差的测量不确定度

笔者在检定实践中依据JJG123-2004《直流电位差计》检定规程中用数字电压表检定电位差计的方法要求,摸索出一个简便易行的、用直流数字电压表检定便携式直流电位差计示值误差的方法,现对其不确定度进行分析。     

应用1281型数字多用表检定高准确度直流电位差计

本文主要论述用1281型数字多用表检定0.002级高准确度电阻型直流电位差计的检定原理,着重进行了测量不确定度分析.     

检定热电偶如何选择直流电位差计

<正>直流电位差计是温度计量不可缺少的标准器,它采用补偿测量法,主要用于测量0.1μv至75mV之间的微小电势。利用直流电位差计检定热电偶时,应遵循以下原则选     

直流数字电压表示值误差测量值的不确定度评定

本文详细介绍了直流数字电压表示值误差测量值的不确定度评定方法。     

Pulsewidth Modulation DC Potentiometer

This instrument uses pulsewidth modulation techniques in which a crystal oscillator, frequency divider, and preset counter replace the resistive divider to form a precision potentiometer. The smoothing of the time-division intervals to a steady-state direct current without introducing prohibitive time constants is solved by a "sectional average" integrating circuit. This utilizes a short time-constant integrator combined with a switched unity-gain buffer amplifier in the feedback to integrator input. This switch, integrate, and sample-and-hold circuit provides output within ±0.1 percent of the eventual steady-state value in less than 400 ms after a step change and within ±0.001 percent in 600 ms. The system provides digital compatibility with tape, cards, digital voltmeters, etc. An engineering prototype has 7 decade dials covering a 0-100.0000-volt range with ±(0.1 ppm + 5?V) voltage-ratio accuracy and, ±0.05 ppm/50°C temperature coefficient and ±0.05 ppm/ 10-week long-term stability, and it is expected that this may be improved.     

用数字电压表检定携带式直流电位差计的示值误差测量不确定度的评定

本文主要阐述用数字电压表检定携带式电位差计的原理,分析示值误差测量不确定度的来源并对其测量结果进行不确定度的评定.     

A Comparatorless Dual-Slope Digital Voltmeter

This paper discusses the design and operation of a digital voltmeter employing a new technique in the analog-to-time converter. The circuit is based on dual-slope integration, which eliminates the necessity of a highly stable clock. Any long term drift in the clock is canceled, so that a simple two-transistor multivibrator clock is used. With the aid of a special diode circuit, the ramp-generating integrator also serves as an accurate comparator, so that no separate comparator is needed for analog-to-digital conversion. Finally, the new circuit requires only a single up counter, and no special polarity switching circuits for automatic polarity indication are needed. The new voltmeter, developed for the University of Arizona's new Locust Computer, has full-scale ranges of ±1 volt and ±10 volts. Tests on the instruments have shown its accuracy to be ±0.02 percent of half-scale. The sampling rate can be varied from 80 ms to 1 second, and the input impedance is 2 MU on the 10-volt range.     

An RMS Digital Voltmeter/Calibrator for Very-Low Frequencies

A portable rms digital voltmeter (DVM) has been developed at NBS to support vibration measurements over the ranges of 0.1 to 50 Hz and 2 mV to 10V. A self-contained calibrator provides for self-calibration and may be used for calibrating other VLF voltmeters. The calibrator basically consists of a Kelvin-Varley divider fed by a reference voltage (either dc or sinewave generated by a ROM-DAC combination) A multijunction thermal converter (MJTC) was selected as the sensing device in the rms/dc converter of the DVM since its low ac/dc difference facilitates calibration of the ac calibrator. Factors affecting accuracy and response time are analyzed. The DVM response time is 40 s for the lowest input frequency. Its accuracy (percent of reading) is 0.1 percent above 0.5 Hz and 5 mV and 0.2 percent below these values. The ac calibrator accuracy is 0.02 percent. Measurement accuracy improves by a factor of about 4 for transfer measurements (comparing input voltages with ac calibrator voltages) Means for extending this accuracy to 0.01 percent are discussed.     

数字电位器在测阻上的应用

介绍了数字电位器的使用原理,详细介绍了利用数字电位器的阻值变化,调整放大电路的倍率进行阻值测试的设计过程。     

数字电位器在电源上的应用

本文分析了集成稳压电路与数字电位器的使用原理,并通过利用数字电位器的阻值变化,来达到调整电源输出电压大小的目的,为数字电位器在电源上的应用提供了设计思路。     

无独立线路标准化电位差计的自检

无独立线路标准化电位差计按单个电阻进行元件检定不方便、时间长、过程复杂。采用ｊ＋１盘的１０／Σ１Ｕｉ＾ｊ＋１示值检定ｊ盘每个步进值的电压比较法，可缩短时间，方便易行。提高了检定精度，并推导出系列计算公式和应用实例。     

高位数表直流电压示值误差测量结果的不确定度评定

介绍了高位数表直流电压示值误差测量结果的不确定度评定并给出结果。