便携式数字压力校验仪的研制

本文介绍以微处理机为基础，采用电池供电的便携式数字压力校验仪表。其内部敏感元件采用扩散硅压力传感器采集压力信号，用单片机对误差进行分析处理。并安装有造压系统，工作介质为气体。可以非常方便的在现场或实验室中对压力仪表进行校验。     

扭簧表指针不平衡所引起的示值误差

本文主要阐述扭簧表指针不平衡所引起的示值误差变化，具体分析了由于仪表在使用中安装位置不同及指针所处刻度不同的示值误差变化，并对现行国家标准的有关规定提出了修改和补充意见。附图4幅、表1个     

消费指南

钟表走时超差算不算故障？不论机械神表还是石英钟表都有相应的质量标准，走时都自一定的误差。钟表走时难确是相对而言，绝对准确，一点不差的钟表是不可能的，但只要符合该钟表的走时质量标准就是合格的钟表。钟表出厂前都按规定校验合格，在销售时能校验的应再次校验，符合标准的出售，如个别超差的，调整校对好后再出售。钟表因使用人和使用条件不同，个别会在使用后出现超差（即快慢误差超过标准），这属使用中出现的正常现象，不算故障，经过调整可达到正常。但如走的快慢误差过大，又无法调整到正常标准，则属性能故障，需要进行项修…     

电动调节器闭环校验方法（二）

电动调节器闭环校验方法（二）大理卷烟厂黄文鑫（上接第１期）调给定钮，使给定刻度为１００％，拨手操拨盘使输出电流为１０ｍＡ。然后按上述方法校其它刻度。Ｃ．偏差表应指零（偏差表指针与固定指针同指一刻线）。输出电流应与给定刻度对应电备注：近期产品已无Ｗ２，...     

衡量法自校验常用移液器的程序与效果

移液器所标示的容积与其真实容积之间都存在误差,影响检测结果的可靠性。进行自校验既可保证检测结果的可靠又不影响检测工作的正常运作。采用衡量法对常用的移液器进行自校验,容量误差在国家规定的允差之内的才能用于样品检测,保证了检测结果的准确度和精密度。经过自校验,计量认证和实验室认可的未知样测定都能顺利通过,很多项目的校准曲线能达到相关系数R≥0．99999。     

一种新型限位百分表

一种新型限位百分表海红轴承厂（７２４２０４）白国华，李向明，李厚俊叙词：百分表，限位装置目前，在轴承行业使用的百分表，７般量程均为３～１０ｍｍ，虽然表上具有０．０１ｍｍ指针和１ｍｍ指针，但在测量时仪表本身无限位装置。操作者在对表时常因疏忽误将仪表多压...     

微机电表校验仪

一种用 Z80单板机控制的电表校验仪由无锡电表厂研制成功。该仪器有标准信号发生和误差检测两种工作方式,可用于交、直流电压表、电流表、频率表、单相及三相功率表、功率因数表的点盘与校验。自动化程度高,提高了校验设备的精度。     

智能变电站电能计量装置在线监测系统设计

现有的电能计量装置现场检测工作中所存在分布广、路途远、效率低等问题,对智能变电站中数字计量装置缺乏现场检测手段。对IEC61850-9-2LE中电子式互感器、数字电能表的输出规约及误差产生的原因进行了分析,设计了互感器、电能表的误差在线测试系统,并对实验数据进行分析,校验误差算法的准确度。此系统不需工作人员到达现场进行测试,实现了计量装置误差在线监测。     

数字气压表误差及测量结果不确定度的研讨

以3台数字气压计为研究对象,对其进行性能测试,并对其结果进行误差分析、不确定度评定及验证。通过对大量测试数据的分析和研究表明:数字气压计的误差来源主要为线性误差和回程误差;不确定度主要来源于测量数据的重复性、标准器的误差、被测表的分辨力。高温、低温、常温测试试验结果显示:该型号的气压计示值误差不大于0.17hPa,线性误差不大于0.07hPa,回程误差不大于0.03hPa,不确定度不超过0.06hPa。     

加磁车削细长轴实验研究

本文进行了加磁场方法车削细长轴的实验研究。研究表明：磁场能显著减小工件的鼓形误差，在一般工艺及切削条件下，对于长径比近４０的工件可限制其鼓形误差在０．０２ｍｍ；切削速度可提高３．５倍以上。此方法具有加工精度高、调整方便省时、易实现高速车削等特点。     

基于USB接口的高精度电荷校准仪

采用虚拟仪器技术、直接数字合成技术和计算机技术设计了电荷校准仪,其工作状态由计算机USB接口控制,能输出多种波形的电压和电荷信号,电路中采用双DAC结构实现了幅值的精确控制.计量检验结果表明设计的电荷校准仪精度高、性能稳定,能够满足高精度的压电测试系统和电荷放大器的校准需要.     

Development and evaluation of the calibration facility for high-pressure hydrogen gas flow meters

The calibration facility with the multi-nozzle calibrator was developed for the calibration of flow meters to be used with high-pressure, high-flow-rate hydrogen gas. The critical nozzles installed in the multi-nozzle calibrator were calibrated with traceability to the national standard. The relative standard uncertainty of the mass flow rates produced from the calibration facility is 0.09% when the flow rate is between 150 g/min and 550 g/min. In this study, the Coriolis flow meter was calibrated for a pressure range of 15–35 MPa. The relative standard uncertainty of the flow rates obtained from the Coriolis flow meter was 0.44% for the case of the worst fluctuations in the output of the flow meter; based on the calibration curve, this is 0.91%. The present result shows that there is a maximum 3% difference between the output of the Coriolis flow meter and the mass flow rates of the multi-nozzle calibrator, even though the Coriolis flow meter was calibrated using water. Therefore, for the development of a calibration facility that can calibrate a flow meter under the same conditions as those encountered in actual use, it will be important to develop a new flow meter.     

数字功率表示值误差测量结果的不确定度评定

数字式功率表不仅具有以前功率表计的作用,而且具有多参数示值显示功能,并具有与PC机接口的直流输出端口。在重要的监视场合它要求表计本身示值与到PC机的显示示值有较小的允差范围,否则无法根据示值来调节负荷,造成不必要的双方争执,所以在这里对表计自身示值与到PC机的延展示值的不确定度评定显得尤为重要。文中根据JJF1059-1999《测量不确定度评定与表示》标准中对不确定度的定义和评定要求,对电测量仪表检定装置的不确定度进行了分析,并以实例说明了数字功率表在作这种用途时示值误差测量结果的不确定度评定。     

An automatic calibrator for wattmeters with harmonic analysis capability

This paper deals with a three-phase phantom-power generator, which is designed for calibrating digital wattmeters with harmonic analysis capability. The calibration of such instruments is a critical task due to the lack of suitable calibrators. Fortunately, the calibration procedure can be limited to the first harmonic components when digital wattmeters are employed to characterise electrical machines, so that also simple calibrator design can be adopted. This paper describes a three-phase calibrator arrangement which is able to generate an arbitrary spectrum up to 5 kHz and a phantom power variable up to 3 kVA per phase. The uncertainty on the power associated to the first harmonic components is of about 0.1% in nonsinusoidal conditions. The calibrator employs a Direct Digital Synthesis technique, so that a frequency change of the output signal can be obtained without modifying the sampling frequency. Such a technique also permits to generate the frequency modulated signals that are often encountered at the output of static power converters that feed electrical machines.     

一种直流数字化电能表的量值溯源方案

直流数字化电能表在电能计量中应用日益广泛,但缺乏专门针对直流数字化电能表量值溯源方案的研究。针对我国缺乏对直流数字电能表量值溯源方案的研究现状,以及现有的交流数字电能表量值溯源方案中存在标准电能计算准确度受采样频率限制、量传误差环节多等问题,提出了一种基于直流数字化标准功率源的直流数字电能表量值溯源方案。该方案在交流数字电能表量值溯源方案的基础上,利用标准数字功率源内置DSP的数字波形拟合与抽取,替代交流溯源方案中的A/D转换;利用DSP高频数字采样积分,替代交流溯源方案中的标准数字电能表。简化了交流数字表的溯源方案,减少量传误差,提高了直流标准电能计算精度,实现了直流数字化电能表的量值溯源,是直流数字化电能表量值溯源的一种新方案。     

基于LabView的多功能声级计设计

在常规的噪声测量中普遍采用声级计,传统的声级计一般是利用硬件计权网络实现对噪声信号的计权,利用硬件的滤波网络实现噪声的倍频程分析以及给出平均声级等。设计了一种基于LabView的虚拟式声级计,介绍了该虚拟声级计的硬件结构、软件设计流程、频率计权和统计分析模块。采用TES-1356音压校准器对所设计的系统进行了校准,通过和TES-1357精密声级计的比较实验,验证了所设计声级计的正确性,性能达到了Ⅰ型声级计指标。所开发的多功能虚拟声级计程序模块化、灵活,很容易和其它设备集成,可应用于工业过程需要噪声或声级测量的众多场合。     

Evaluation of discrete displacement transducer by spectral analysis of surface roughness

A discrete displacement transducer using an optical technique and attached to a commonly used stylus instrument is described. The proposed transducer plays an important role in generating a digital output of surface profile from the viewpoint of sampling error. The working accuracy is discussed with reference to the spectral analysis of surface roughness.     

Autonomous algorithm for relative error of generalized flow meters in tree topology

This paper treats electricity meters or water meters on-site as a cluster of generalized flow meters constructing a tree topology. Providing flow conservation, it is demonstrated that every meter’s relative error can be calculated according to a group of readings of the meter cluster if the relative error of any meter in the cluster is given. The autonomous algorithm obtains relative errors without usage of external standard instrument. By the same algorithm, providing the accuracy class of any meter rather than the relative error exact, the range of relative errors of rest meters in the cluster can be worked out. With the aid of remote automatic reading system, the algorithm can reduce the maintenance cost of meters on site, and contributes to forecast the meters’ service lives.     

Plant accuracy- who needs it

Accurate instrument calibration is the most often overlooked item in the continuing search for improving plant performance.

The best techniques used by highly trained technicians cannot compensate for test equipment that is not as accurate as the instruments being calibrated.

Calibrator specifications should be as carefully considered as those of plant instrumentation. A 3:1 ratio of calibrator accuracy to instrument accuracy should become the acceptable standard.     

Automatic, tracking, peak timer

We have designed an inexpensive instrument for automatically measuring time of flight for repetitive signals. It is stable in the presence of noise resembling the real signal. Specific peaks in a multipeak signal can be timed to an accuracy of about 10 ns with the present design. The output is either a digital word or an analog voltage. Computer control is simple and would make it possible to time several signals with the same instrument.