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Calculation of Dual Circle Closure Calibrations using Computer Spreadsheets Hy D. Tran
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721584
Publisher NCSL International | Published 3/1/2012 | Pages 30-36
Abstract: This technical note will detail a procedure for simultaneous calibration of two rotary devices by circle closure, along with the necessary calculations. These calculations can be implemented using numerical analysis software,
or with computer spreadsheets. We first detail an example procedure for a dual closure for two rotary tables with six sectors, and then provide a detailed derivation of the mathematics.
Economic Impact of Equivalence of Measurement Standards
Takashi Usuda, Andy Henson
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721588
Publisher NCSL International | Published 3/1/2012 | Pages 62-70
Abstract: This paper discusses a new method for estimating the economic impact of the equivalence of measurement standards. The method allows a quantitative calculation of the economic impact, based on a distribution function describing
the quality of the product and information about the agreement of measurement standards. In particular, the proposed method considers loss parameters (false positive, false negative, and loss function) due to the deviation of measurement standards.
The method can be applied to any industry, any market, and to users at any level of the calibration hierarchy. We illustrate the method with an example that demonstrates the economic impact of inconsistencies in a mass measurement standard due to
the quality distribution of weighing instruments. The example shows that the current system of assuring the equivalence of measurement standards is effective and delivers significant benefits. It also demonstrates the importance of information about
the agreement of measurement standards when assessing their economic impact.
Experimental Study and Computer Modeling of the Triple Point of Argon System
R. Ding, M.J. Zhao, T. Nielson, E. Nerdrum, D. Farley
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721587
Publisher NCSL International | Published 3/1/2012 | Pages 56-60
Abstract: The triple point of argon is a defined fixed point in ITS-90 for calibration of standard platinum resistance thermometers (SPRTs). A new triple point of argon system with multiple re-entrant wells was developed. This system
was tested to evaluate the duration and quality of the argon triple-point temperature plateau. The testing results showed that the plateau can be as long as 100 hours with the temperature change less than 0.05 mK. The re-entrant wells' uniformity
testing showed that the temperature is consistent among the multiple re-entrant wells. Uncertainty analysis shows that the combined uncertainty of the argon system is 0.26 mK (k = 2). In order to study the heat transfer process and the influence on
the thermal equilibrium of the argon system during the realization of the triple-point of argon plateau, finite element analysis (FEA) modeling was carried out to simulate the thermal conductivity, convection, and radiation inside the argon system.
The FEA simulation results are described and discussed in this paper.
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721585
Publisher NCSL International | Published 3/1/2012 | Pages 38-49
Abstract: Many strategies for risk mitigation are now practiced in calibration laboratories. This paper presents a modern look at these strategies in terms of compliance to ANSL/NCSLI and ISO standards. It distinguishes between “Bench
Level” and “Program Level” risk analysis techniques, which each answer different questions about risk mitigation. It investigates concepts including the test uncertainty ratio (TUR) and end of period reliability (EOPR) that are directly related to
risk, as well as the mathematical boundary conditions of false accept risk to gain a comprehensive understanding of practical, efficient risk mitigation. The paper presents practices and principals that can allow a calibration laboratory to meet the
demand of customers and manage risk for multifunction instrumentation, while complying with national and international standards.
Traceability and Quality Control in a Radiation Thermometry Laboratory
Tom Kolat, Frank Liebmann
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721589
Publisher NCSL International | Published 3/1/2012 | Pages 72-77
Abstract: In radiation thermometry, a number of steps have been taken to improve calibration quality at temperatures below 1000 °C. These steps involve work done by national metrology institutes and standards bodies. The Fluke Infrared
Calibration Laboratory in American Fork, Utah has benefitted from this progress and has established its own radiation thermometry program. The calibration range of this laboratory is −15 °C to 500 °C. This program involves calibrating radiometric
transfer standards (with pyroelectric detectors) that, in turn, are used to calibrate flat-plate radiation sources, sometimes referred to as blackbodies. The transfer standards are calibrated by a sequence of blackbody cavity radiation sources that
cover the entire temperature range of the laboratory. The radiometric transfer takes place between the cavity sources and the flat-plate sources. The intended use of the flat-plate sources is infrared thermometer calibration. Both the transfer standard
calibrations and the flat-plate calibrations are accredited by the National Voluntary Accreditation Program (NVLAP). This paper discusses the traceability involved in this radiometric calibration program. It also discusses numerous quality control
measures that have been taken to improve and assure measurement accuracy for both calibrations.
Wattmeter Calibration for Use in Standby Power Testing to IEC 62301
Ilya Budovsky
NCSLI Measure | Vol. 7 No. 1 (2012) | 10.1080/19315775.2012.11721586
Publisher NCSL International | Published 3/1/2012 | Pages 50-55
Abstract: A growing number of household appliances include a standby mode, in which the appliance consumes a small amount of electrical power. Standard 62301 of the International Electrotechnical Commission (IEC) describes the measurement
of standby power and the requirements for wideband wattmeters used for this purpose. These requirements include the ability to measure power with uncertainty of less than 0.01 W for current waveforms having crest factors up to 10. The National Measurement
Institute, Australia, has developed a system for the calibration of wideband wattmeters used in the measurement of standby electrical power in accordance with IEC 62301. The system has uncertainties significantly lower than those required by the standard
and has been tested with current waveforms having crest factors up to 20.
A Multi-Sensor Approach for Complex and Large-Area Applications in Micro and Nanometrology
Tino Hausotte, Gerd Jäger, Eberhard Manske
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721597
Publisher NCSL International | Published 6/1/2012 | Pages 44-50
Abstract: In micro and nanotechnology, the metrological demands are increasing. The structures to be measured are becoming more complex with smaller structure widths, increasingly larger surface regions, and thousands of inspection features.
In order to solve the problems, it has become desirable and even necessary to combine multi-sensor technology with high precision nanopositioning and nanomeasuring technology. The Nanopositioning and Nanomeasuring Machine NMM-1 with a measuring range
of 25 mm × 25 mm × 5 mm and sub-nanometer resolution allows the application of several optical, tactile and atomic force probes. The combination of several sensor technologies in a multi-sensor approach for application with the NMM-1 is demonstrated.
Establishing Traceability for Quantities Derived from Multiple Traceable Quantities
Jian Liu, Alberto Campillo
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721595
Publisher NCSL International | Published 6/1/2012 | Pages 30-34
Abstract: Some quantities are traceable to a single quantity with the same unit but a lower uncertainty. For instance, a weight of 50 g ± 1 g might be calibrated with a reference weight of 50 g ± 0.1 g. Meanwhile, other quantities are
calibrated by using multiple quantities with different units as references. A simple example would be measuring DC current with a volt meter and a standard resistor. In this case, the current measurement is derived from DC voltage and resistance.
A more complicated example of a derived quantity is phase noise. The question is: how do we establish traceability for such derived quantities? This paper discusses the International System of Units (SI), base and derived quantities, and traceability;
and presents a general approach for establishing traceability for a quantity that is derived from multiple traceable quantities. The traceability of phase noise measurements is then considered as an example, based upon two common measurement techniques
that utilize a spectrum analyzer and a phase detector.
High Level Humidity Generator for Nitrogen-Water Mixtures
Peter Huang, Wyatt W. Miller, Gregory Strouse
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721600
Publisher NCSL International | Published 6/1/2012 | Pages 72-77
Abstract: A high level humidity generator has been developed at the National Institute of Standards and Technology (NIST). This device provides the capability for research, testing and calibration at high levels of water vapor content
in such gases as hydrogen, nitrogen, and ambient air for applications such as hydrogen-powered fuel cells, standard reference materials and food processing. The generator produces a gas stream of nitrogen-water vapor mixture having mixing ratios from
0.16 g to 1.47 g of water vapor per gram of dry nitrogen (g H2O/g dry N2). This is equivalent to dew point temperatures of 60 °C to 90 °C at standard atmospheric pressure and to water vapor pressures of 19 948 Pa to 70 182 Pa. The generated gas can
be fed to a test chamber with independent temperature control from 25 °C to 200 °C and pressure control from 0.1 MPa to 1.5 MPa, for the calibration of hygrometers. Inter-comparisons with a NIST reference standard dew point hygrometer gave results
that in all cases agreed to within 0.014 g H2O/g dry N2.
Proficiency Testing Program for U.S. State Weights and Measures Laboratories
Elizabeth Gentry, Georgia Harris, Val Miller
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721599
Publisher NCSL International | Published 6/1/2012 | Pages 60-70
Abstract: The National Institute of Standards and Technology (NIST) Office of Weights and Measures (OWM) manages a State Laboratory Program for weights and measures laboratories that includes: 1) Laboratory recognition using ISO/IEC 17025:2005
and sponsorship of accreditation through the National Voluntary Laboratory Accreditation Program (NVLAP); 2) Hands-on training courses held at NIST, regional measurement assurance program (RMAPs) training held annually throughout the United States,
and a number of web-based short courses; and 3) Formal proficiency testing and interlaboratory comparisons (PT/ILC). The main objective of the State Laboratory Program is to ensure nationally consistent measurement results, acceptable accuracy and
metrological traceability, and the credibility and acceptance of state laboratory measurements. This paper presents the key features of the PT/ILC program: measures of success; collaboration challenges; the use of template tools; and continual improvement
efforts. Note that while most interlaboratory comparisons are also proficiency tests, some are not. For simplicity, however, this paper will refer to the PT/ILC effort as the PT program.
Sensors for Optical 3D Measurements of Micro Geometries
Holger Bremer, Ulrich Neuschaefer-Rube, Thomas Birth
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721598
Publisher NCSL International | Published 6/1/2012 | Pages 52-58
Abstract: This paper provides an overview of some of the optical measurement techniques for dimensional measurements of surface topographies. These techniques are used in laboratories, as well as close to the production line. The principles
of white light interferometry, focus variation, fringe projection, confocal microscopy, and image processing will be addressed. Examples of typical applications will be given and some of their benefits and limitations discussed.
Testing and Calibration of Phasor Measurement Units
Richard Pirret
NCSLI Measure | Vol. 7 No. 2 (2012) | 10.1080/19315775.2012.11721596
Publisher NCSL International | Published 6/1/2012 | Pages 36-42
Abstract: In the evolving Smart Grid, time-variant sources and loads introduce disturbances that can threaten the stability of the grid. Sophisticated protection and control systems are required to preserve reliability. These systems
rely on accurate, synchronous measurements of voltage, current and frequency made by Phasor Measurement Units (PMUs). Although PMUs first appeared in 1988, their recent deployment has exposed inconsistent measurements and poor interoperability across
brands and models. However, several recent developments promise to enhance the accuracy and consistency of PMU measurements. IEEE C37.118.1:2011, “Standard for Synchrophasor Measurements for Power Systems”, established new performance limits for PMU
test and calibration. The revised standard more clearly defines existing concepts, and enhanced and added material to the sections on steady state and dynamic tests. The emergence of automated systems supports the consistent execution of standard
tests during PMU calibrations, and the observance of sound traceability practices for PMU ensures the accuracy of those calibrations. This paper describes the fundamentals of phasor measurements, the recent revisions to the IEEE C37.118.1 standard,
a new automated PMU calibration system developed at Fluke, and the establishment of traceability for PMU calibrations.
A Sub-Sampling Digital PM/AM Noise Measurement System
David Howe, Craig Nelson
NCSLI Measure | Vol. 7 No. 3 (2012) | 10.1080/19315775.2012.11721610
Publisher NCSL International | Published 9/1/2012 | Pages 70-73
Abstract: A digital phase/amplitude modulation (PM/AM) noise measurement system (DNMS) implementing field programmable gate array (FPGA) based digital down converters (DDCs), and 250 MHz analog to digital converters (ADCs) is reported.
Measurements in the first, baseband Nyquist region shows white phase noise floors of less than −180 dBc/Hz. With proper prefiltering of the input signals to prevent undesired aliasing, high bandwidth track and hold amplifiers (THA) extend the operating
range of the DNMS to microwave frequencies. Preliminary testing with an 18 GHz THA shows residual white phase noise floors at 10 GHz of less than −160 dBc/Hz.
Measurement Techniques for Evaluating Current Range Extenders from 1 Ampere to 3000 Amperes
Marlin Kraft
NCSLI Measure | Vol. 7 No. 3 (2012) | 10.1080/19315775.2012.11721606
Publisher NCSL International | Published 9/1/2012 | Pages 32-36
Abstract: When measuring standard resistors at different ratios with a direct current comparator (DCC) incorporating current range extenders (CREs), it can be difficult to determine if the measurements are correct and to evaluate measurement
uncertainty. This technical note discusses techniques developed at the National Institute of Standards and Technology (NIST) for measuring a set of low value resistors at the same current using different ratios. The design of modern automated DCCs
allows measurement currents up to about 150 mA and DCCs can operate at 1:10 ratios with uncertainties well below one part in 106. Higher currents require CREs with ratios from 1:10 to 1:100,000 or more. The techniques described here allow low uncertainties
to be obtained by measuring high quality medium current resistors at different power levels, so that they can be used as standards when measuring high current resistors. These techniques also allow you to determine if your CRE is functioning properly.
North American 100 Ampere Interlaboratory Comparison
Jay Klevens
NCSLI Measure | Vol. 7 No. 3 (2012) | 10.1080/19315775.2012.11721607
Publisher NCSL International | Published 9/1/2012 | Pages 38-47
Abstract: The base SI unit for electricity is the ampere. At present, there is no intrinsic standard for the ampere, so in practice it is disseminated by measuring voltage across a resistor, using Ohm's Law (I = E /R). Higher current
is measured with a shunt, which is a high power resistor. Accurate electrical current measurement is critical to the power and electrical test industries. In cooperation with the National Institute of Standards and Technology (NIST) and the NCSLI
Utilities Committee, Ohm-Labs performed a North American 100 ampere interlaboratory comparison (ILC). Many measurements did not meet claimed uncertainties, revealing errors in measurement and uncertainty estimation. Two rounds of measurements were
performed, and the results of both rounds are presented in this paper.
Precise Blackbody Sources Developed at VNIIOFI for Radiometry and Radiation Thermometry
Svetlana Morozova, Victor Sapritsky, Mikhail Samoylov, Boris Lisiansky, Boris Khlevnoy, Sergey Ogarev
NCSLI Measure | Vol. 7 No. 3 (2012) | 10.1080/19315775.2012.11721609
Publisher NCSL International | Published 9/1/2012 | Pages 56-68
Abstract: This paper reviews a wide list of precise blackbody (BB) sources developed at the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI). These radiometric, photometric and radiation thermometry standards
are for the entire UV-visible-IR spectrum, and cover the temperature range from 80 K to 3500 K [1, 2, 3]. Low temperature blackbodies with temperatures from cryogenic to 450 K were developed for space borne instruments calibration [4, 5, 6]. We present
models of variable-temperature BBs, as well as those based on fixed-points of Ga, In and binary metal-metal eutectic alloys. BBs are characterized with high temperature uniformity and stability. For example, for the BB100-V1 model, these parameters
account for 0.05 K to 0.1 K, and 0.1 % for the 1.5 μm to 15 μm wavelength region under cryo-vacuum conditions of medium background environment emulating the orbital working environment. Copper and aluminum alloys are used as the radiation cavity materials
for the low-temperature and cryogenic BBs. Recent advances in high-temperature technology and a novel design made it possible to develop the Planckian sources with temperatures as high as 3500 K, high uniformity, and stable radiation characteristics
[7, 8, 9]. These large-area blackbodies allow the creation of a new generation of radiometric and radiance temperature standards with low uncertainties. High-temperature, large aperture blackbodies of the BB3500 series allow the realization of projects
requiring high-temperature fixed points based on metal-carbon eutectic and peritectic alloys.
Software Tools for Evaluation of Measurement Models for Complex-valued Quantities in Accordance with Supplement 2 to the GUM
Hing-wah Li, Aaron Y.K. Yan, Cho-man Tsui
NCSLI Measure | Vol. 7 No. 3 (2012) | 10.1080/19315775.2012.11721608
Publisher NCSL International | Published 9/1/2012 | Pages 48-54
Abstract: In October 2011, a new guidance document “Evaluation of measurement data – Supplement 2 to the ‘Guide to the expression of uncertainty in measurement’ – Extension to any number of output quantities” was released. It deals with
measurement models that have more than one output quantity. These models are common in electrical metrology where the measurands can be complex-valued quantities, such as S-parameters. The guidance document described a generalized GUM Uncertainty
Framework (GUF) and a Monte Carlo Method (MCM) to estimate the output quantities, their standard uncertainties, the covariances between them, and the coverage region. The GUF has more limitations. The MCM has a broader domain of validity but requires
software tools for its computation. The Standards and Calibration Laboratory (SCL) in Hong Kong has developed software tools for evaluation of complex-valued measurement models using both GUF and MCM. The software tools were written in Visual C++
and Visual Basic, with Microsoft Excel as a front-end user interface, but could be adapted to other programming languages. The user is only required to encode the measurement model as a Visual Basic subroutine and to enter the information of the uncertainty
components in a table. The software tool includes two parts that can be used separately, with the first part as a standalone simulator and the second part as an Excel user-defined function.
Army Primary Standards Laboratory Uncertainty Analysis for a 50 GPM Positive Displacement Piston Prover
Wesley England
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721621
Publisher NCSL International | Published 12/1/2012 | Pages 62-76
Abstract: This paper is a detailed uncertainty analysis for a 50 gallon per minute (gpm) positive displacement piston prover operated by the Liquid Flow Laboratory of the Army Primary Standards Laboratory (APSL). This uncertainty analysis
encompasses all known contributors included in the APSL estimation of liquid flow piston prover uncertainty, including connecting volume and viscosity. This uncertainty analysis is intended as an aid to those who work in the field of liquid flow metrology.
Characterization of Triangulation-Based 3D Imaging Systems Using Certified Artifacts
Jean-Angelo Beraldin, Luc Cournoyer, David MacKinnon, Benjamin Carrier
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721620
Publisher NCSL International | Published 12/1/2012 | Pages 50-60
Abstract: A set of test procedures and certified artifacts to characterize the capability of short-range triangulation-based three-dimensional (3D) imaging systems are presented. The approach consists of scanning metallic and coated-glass
certified artifacts in which the uncertainties in the associated characteristic reference values are smaller than the measurement uncertainties produced by the system under test (SUT). The artifacts were grouped on the same plate for portability.
To define a set of test procedures that is practical, simple to perform and easy to understand, we utilized a terminology that is well-known in the manufacturing field, i.e., geometric dimensioning and tolerancing (GD&T). The National Research
Council Portable Characterization Target (NRC-PCT) is specifically designed for the characterization of systems with depths of field from 50 mm to 500 mm. Tests were performed to validate the capability of the NRC-PCT. This paper presents these results,
along with some basic information on 3D imaging systems.
Circuits for the Calibration of Quartz and Mechanical Watch Testers
Hon-man Chan, Cho-man Tsui
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721616
Publisher NCSL International | Published 12/1/2012 | Pages 26-27
Abstract: Watch testers offer a fast and accurate way to calibrate stopwatches using the time base method. Watch testers usually include microphone sensors that pick up either the ultrasound from quartz oscillators or the acoustic vibration
from balance wheels, and instrumentation that measures the accuracy of these frequencies. As a laboratory instrument, the watch tester itself requires calibration. Two simple circuits have been developed to generate the acoustic signals for the calibration
of quartz and mechanical watch testers, respectively. The reference frequency is obtained from a signal generator phase locked to the laboratory frequency standard. It is assumed that the laboratory frequency standard has been calibrated, has a known
measurement uncertainty, and that metrological traceability to the International System (SI) second has been established.
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721618
Publisher NCSL International | Published 12/1/2012 | Pages 34-40
Abstract: Compact metal-foil standard resistors with four terminals have been developed. The main DC characteristics of the developed 100 Ω resistors are a drift rate of <0.1 (μΩ/Ω)/year, a temperature coefficient of <0.1 (μΩ/Ω)/°C
at 23 °C, changes in resistance due to humidity that are negligible or lower than 0.01 (μΩ/Ω) in the 35 % RH to 80 % RH range, and changes in resistance versus the pressure variation that are negligible or lower than 0.025 (μΩ/Ω)/(250 hPa) in the
700 hPa to 1200 hPa range. The power coefficient is negligible based on the quantized Hall resistance when the applied current is lower than 5 mA. The AC performance was also characterized: the frequency dependence is negligible below 2 kHz, and the
time constant is 3.7 ns. These excellent characteristics have been achieved by careful optimization of the composition, annealing conditions, and surface treatment of the element materials, and also by a strain-free supporting technique for the resistor
elements. The development of the 100 Ω resistors has been completed, and 1 Ω to 10 kΩ resistors are now being developed. Preliminary results for the 10 Ω resistors show a drift rate similar to that of the 100 Ω resistors.
High Accuracy Measurements Using a Scanning System with a Single Point Triangulation Sensor
Eric Stanfield, Wei Ren, Christopher Blackburn, Bala Muralikrishnan, Ted Dorian
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721617
Publisher NCSL International | Published 12/1/2012 | Pages 28-33
Abstract: The capabilities of non-contact laser spot triangulation sensors for high accuracy measurements have slowly increased over the past decade, and now have usable resolution below 0.1 μm. The Dimensional Metrology Group at the
National Institute of Standards and Technology (NIST) has developed a simple scanning system to work with these sensors, and presents the system details and data from a variety of geometries. The features measured include screw threads, fuel cell
channels, and computer tomographic (CT) scanner phantoms.
Spectrum Analyzer CW Power Measurements and the Effects of Noise
Francis Small
NCSLI Measure | Vol. 7 No. 4 (2012) | 10.1080/19315775.2012.11721619
Publisher NCSL International | Published 12/1/2012 | Pages 42-49
Abstract: Spectrum analyzers are used in various applications to measure the power of an electrical signal, their frequency discrimination capability making them a key component in the electronic test and measurement industry. Although
they do not have the same inherent amplitude accuracy as other measurement devices such as broadband power sensors [1], they have superior dynamic range that can extend in some cases to the environmental thermal noise limit. Previous work has described
the theoretical model of spectrum analyzer power measurements in the presence of noise, but practical guidelines for actual measurements are less forthcoming. This paper examines how to configure a spectrum analyzer to measure a low-power continuous
wave (CW) signal so that the trade-off between measurement time and accuracy is optimized. It presents equations describing both the bias and the variance of spectrum analyzer measurements due to noise.
