10-nF capacitance transfer standard

New dielectric capacitance standards with a nominal value of 10 nF, suitable to be employed in the reproduction of the farad unit starting from the quantum Hall resistance, have been constructed. The standards are based on commercial chip capacitance components encased in a thermostat, and are defined as four terminal-pair impedance standards. The capacitance value is within 50/spl middot/10/sup -6/ relative to nominal; dissipation factor is about 8 /spl middot/ 10/sup -5/ at 1 kHz. The relative temperature coefficient of the capacitance value versus external ambient temperature is expected to be /spl ap/1/spl middot/10/sup -8/ K/sup -1/ near 23 /spl deg/C.     

Both active and reactive power and energy transfer standard

A thermal converter to DC voltage, with 10-ppm accuracy and a frequency range of 0-200 kHz, which can be used for active power measurements, has been developed using an infrared thermal converter. Moreover, a proposal for implementing, with lower accuracy, the converter for energy and reactive power is also illustrated     

毫瓦级超声功率传递标准的研制

针对各类毫瓦级超声功率计的量值溯源问题,选用压电陶瓷材料,根据其压电效应原理,设计为厚度伸缩振动模式,采用能陷技术及真空镀膜等技术工艺,制作了一系列1MHz、3MHz、5MHz的园片形单元超声换能器,并研制与之配套的阻抗匹配器,与功率信号源等,组成一套毫瓦级超声功率传递标准。该套标准经济实用、性能可靠稳定,重复性好,有效地解决了毫瓦级超声功率计的量值溯源问题。     

Calibration of a low-voltage AC-DC transfer standard

The paper describes improvements in the determination of the ac-dc transfer difference of an electronic low-voltage transfer standard (LVTS). Expanded calibration uncertainty in the 10 Hz-1 MHz frequency range and 2 mV-100 mV voltage range has been estimated to be less than 100 μV/V. Improvements have been achieved by modification of the step-down procedure that does not require loading error corrections and careful examination of the error sources     

Tests on the IEN electrometric AC-DC transfer standard

Tests on the electrometric AC-DC transfer standard built at IEN have been performed. The instrument was shown to work correctly, and comparison with thermal converters showed a short-term repeatability (1σ) of about 2 parts in 10⁶. Mechanical effects such as deformations and vibrations have been analyzed, both theoretically and experimentally. Direct determinations of the transfer difference made using thermal converters have shown results almost comparable with those obtained by the step-up procedure. The long-term stability of the instrument has also been investigated     

Evaluation of ADC testing systems using ADC transfer standard

A transportable high-stability reference AD device was designed and built to compare the systems for testing the dynamic quality of analog-to-digital converters (ADCs) or analog-to-digital (AD) modules. Three different input modules can be used in the frequency range up to 5 MHz. First, this paper refers to the results of an AD device application in the frequency range of the testing signal up to 100 kHz, where four ADC testing systems were compared in different laboratories, and a short time amplitude and/or frequency instability of testing signal generators was evaluated. Second, it describes the first experience of its application in the frequency range from 100-5 MHz.     

Development of a new transfer standard for high UV irradiances

Source-based radiometry requires reliable transfer standards which are easy to handle. For low irradiances in the UV spectral range, 30 W deuterium lamps are commonly used. However, for the growing field of high UV irradiance applications, new high power standards are required. Here we report on a Xe-Hg lamp system which has been characterised and improved to match the high requirements of a working standard. For this purpose, several parameters of the system such as lamp stability, re-ignition reproducibility, irradiance uniformity and usability have been investigated. Components for the customised light guide-based output optics have been selected with the help of extensive characterisations. The resulting lamp system can be used for a high-grade instrument calibration at high UV irradiance levels.     

Standardisation of pressure measurement using pressure balance as transfer standard

This paper describes the results of the interlaboratory comparison for pressure measurements of 9 laboratories that are accredited by the National Accreditation Board for Testing and Calibration of Laboratories (NABL). The artifact used for the comparison was a pressure balance covering the pressure range (7 to 70) MPa. The primary objective of this comparison was to assess the laboratory’s technical competence to perform measurements and also to assess the compatibility of the results submitted by the laboratories. The comparison began during March 2008 and ended during April 2010. For assigning the reference values, the pilot laboratory (NPLI) carried out 3 calibrations of the transfer standard; the first one at the beginning, the second at the middle and the last one at the end of the programme. The comparison was carried out at 10 pressure points i.e. (7, 10, 15, 20, 25, 30, 40, 50, 60 and 70) MPa throughout the entire pressure range of (7 to 70) MPa. The measurements were carried out by each laboratory with their own resources (personnel, calibration systems, environmental conditions in their installations). The deviations for each laboratory were compared against the reference values and the compatibility of the results was calculated using the normalized error value method. Out of the total 87 measurement results reported, 68 (78.2%) results are found in good agreement with the results of the reference laboratory. The normalized error (E_n) values of 5 laboratories out of the total 9 were found well within ± 1 over the entire pressure range. However, 2 other laboratories had shown good agreement with the reference values except one pressure point each. The E_n values of one of the participating laboratory were found beyond acceptable limits at all measurements points. Another laboratory had acceptable results only at 3 pressure points. The laboratories with unacceptable results have been advised to review their pressure measurement process. The deviations between laboratory values and of the reference values were found well within the uncertainty band of the reference values for 37% measurement results. The relative deviations for 82 measurement results were found well within 0.05%.     

Hysteresis and Related Error Mechanisms in the NIST Watt Balance Experiment

The NIST watt balance experiment is being completely rebuilt after its 1998 determination of the Planck constant. That measurement yielded a result with an approximately 1×10⁻⁷ relative standard uncertainty. Because the goal of the new incarnation of the experiment is a ten-fold decrease in uncertainty, it has been necessary to reexamine many sources of systematic error. Hysteresis effects account for a substantial portion of the projected uncertainty budget. They arise from mechanical, magnetic, and thermal sources. The new experiment incorporates several improvements in the apparatus to address these issues, including stiffer components for transferring the mass standard on and off the balance, better servo control of the balance, better pivot materials, and the incorporation of erasing techniques into the mass transfer servo system. We have carried out a series of tests of hysteresis sources on a separate system, and apply their results to the watt apparatus. The studies presented here suggest that our improvements can be expected to reduce hysteresis signals by at least a factor of 10—perhaps as much as a factor of 50—over the 1998 experiment.     

A calorimeter for μW level optical power transfer standard

A calorimeter which can measure microwatt-level optical power has been developed for an optical power transfer standard. It can measure the optical power of a light beam and can be used with optical fiber simply by attaching an adapter. This calorimeter sensor uses a compensative absorber to reduce the influence of pressure fluctuation and temperature variation in the measurement room and an ultra-low-noise preamplifier. With this calorimeter, the standard deviation of the measured value is in the range of 0.02-0.4% in 20-mW to 10-μW optical power measurements. An error evaluation for an optical power level of 10 μW yielded a two-sigma (two standard deviation) total uncertainty of 0.9%     

浅析智能电能表检定接线方式的改进

本文涉及电能表计量检定领域,提出了一种用于智能电能表快速检定的接线器,属于电力系统的计量范畴.目的是为改变智能电能表上下表手工接线的操作方式,且设计结构简单.该接线器的信号传递针为可拆卸,长度可伸缩且具有弹性,使智能电能表检定装置上下表操作方便、稳定可靠,能有效节省检定智能表过程中的接线耗时,提高了智能电能表的检定工作效率,满足电能表计量检定人员的使用需求.     

A Time-Domain Sub-Micro Watt Temperature Sensor With Digital Set-Point Programming

To realize the on-chip temperature monitoring of VLSI circuits, an accurate time-domain low-power CMOS thermostat based on delay lines is proposed. Contrary to the voltage-domain predecessors, the proposed circuit can benefit from the performance enhancement due to the scaling down of fabrication processes. By replacing R-string voltage division and voltage comparator with delay line time division and time comparator, only little static power is consumed. The power consumption and chip size can be reduced substantially. Without any bipolar transistor, the temperature sensor composed of a delay line is utilized to generate the delay time proportional to the measured temperature. Instead of a conventional voltage/current DAC or an external resistor, a succeeding multiplexer (MUX) along with a reference delay line is used to program the set-point. The test chips with mixed-mode design were fabricated in a TSMC CMOS 0.35-mum 2P4M digital process. The chip area is merely 0.4 mm². The effective resolution is around 0.5degC with a 256-to-1 multiplexer and -40degC ~ 80degC nominal temperature range. The achieved measurement error is within plusmn0.8degC for a total of 20 packaged chips over the temperature operation range of commercial ICs. The power consumption is 0.45 muW per conversion and a measurement rate as high as 1 MHz is feasible when necessary.     

检定电能表的测量不确定度分析与计算

本文简要介绍了电能表检定装置的不确定度来源和组成,并对0．1级三相电能表检定装置的测量不确定度进行分析计算。     

三表检定的不确定度评定

采用交直流标准源作为主标准器来检定模拟指示式电流表、电压表和功率表(简称三表)是目前三表检定的主要方法。本文分析了检定过程中的不确定度并给出了交直流电流、电压、功率的不确定度评定方法。     

机电式电能表误差调整的方法

本文介绍了机电式电能表误差调整的一些实践经验和方法。     

Details of the 1998 Watt Balance Experiment Determining the Planck Constant

The National Institute of Standards and Technology (NIST) watt balance experiment completed a determination of Planck constant in 1998 with a relative standard uncertainty of 87 × 10⁻⁹ (k = 1), concurrently with an upper limit on the drift rate of the SI kilogram mass standard. A number of other fundamental physical constants with uncertainties dominated by this result are also calculated. This paper focuses on the details of the balance apparatus, the measurement and control procedures, and the reference calibrations. The alignment procedures are also described, as is a novel mutual inductance measurement procedure. The analysis summary discusses the data noise sources and estimates for the Type B uncertainty contributions to the uncertainty budget. Much of this detail, some historical progression, and a few recent findings have not been included in previous papers reporting the results of this experiment.     

无超调不限阶数的M型次多容惯性标准传递函数

提出一种通用的多容惯性标准传递函数,具有无超调和不限系统阶数的特点。论证所提出的多容惯性标准传递函数的型次为M,分析多容惯性标准传递函数系统的阶跃响应和斜坡响应特性,并讨论应用多容惯性标准传递函数设计控制器的方法问题。     

A dynamic analysis of the LO noise transfer mechanism in a Rb-cell frequency standard

Frequency noise of the local oscillator at even harmonics of the modulation frequency is known to contribute to the short-term instability of passive frequency standards. The mechanism by which this noise transfer takes place in Rb-cell standards is described here in a comprehensive approach that includes both signal theory methods and a time-dependent quantum mechanical analysis. The resulting calculated transfer coefficients for the various even harmonics are discussed in relationship with measured coefficients in an actual experiment.     

电能表试验中奇次谐波和次谐波的频谱分析

对于电能表电流线路中存在的畸变形波、引起误差的情况,为在电能表试验中实现该影响试验项目提出了一种新的方法。该法对试验项目中所施加的试验电流波形进行了频谱分析,为通过试验装置的计算机软件进行检定提供了理论基础。     

论电子式直流电能表实行强制检定的必要性

由直流电流(或代表直流电流的电压)和直流电压作用于固态(电子)元件而产生与被测电能成正比输出的仪表,称为电子式直流电能表。通过对电子式直流电能表的计量检定,加强了直流电能、直流功率测量技术和测量方法的研究,推动了整体质量的不断提升。