Practical Precision Electrical Impedance Measurement for the 21st Century – EMPIR Project 17RPT04 VersICal

The core objective of EMPIR project 17RPT04 VersICaL is to improve the European measurement infrastructure for electrical impedance, with particular emphasis on the capabilities of developing NMIs and calibration centres. The project will seek to exploit the results of existing research on digital impedance bridges (DIBs) by designing, constructing and validating simple, affordable versions suitable to realise the impedance scale in the range 1 nF to 10 μF and 1 mH to 10 H with relative uncertainties in the range 10-5 to 10-6. The first results of the research project, including the bridge designs and details of a polyphase digitally synthesized multichannel source capable of providing voltage outputs of precise ratio and phase are presented.

Calibration and measurement capability (CMC) and customer technical qualification

In the context of metrological confirmation, calibration is an essential process in all quality assurance efforts. Several organizations choose to outsource this activity to accredited laboratories in accordance with the requirements set forth in ISO/IEC 17025: 2017. Companies understand that accredited laboratory has formal recognition of its technical competence to perform the services within its scope of accreditation. The document ILAC P14: 2013 sets out guidelines for the presentation of Calibration and Measurement Capability (CMC). However, when analysing the scope of accredited laboratories in some national calibration bodies, it is possible to observe that, for the same instrument and the same measuring range, different values are attributed to CMC. If the CMC should result from normal calibration operations on the best existing device, what causes this dispersion? How can the customer make effective use of the information contained in accreditation scopes? In order to further standardize the presentation of CMC in accreditation scopes, calibration methods adopted by laboratories should be required to meet the maximum permissible errors established by manufacturers or normative documents. Companies can outsource calibration activities. But the selection of service provider and the interpretation of the results remains a customer assignment. The paper presents an analysis of accreditation scopes of different national calibration bodies and discusses the qualification of those in charge of metrology management, regarding the knowledge and skills required for activity.

The role of magnetic sensors in the hybridisation and electrification of vehicles

Electrical currents need to be measured in a wide variety of different applications in the field of power electronics. However, the requirements for these measurement devices are becoming steadily more demanding regarding accuracy, size and especially bandwidth. In order to increase the power density of power electronics, as particularly important in the field of electromobility, there is a clear causal chain. Soft switching leads to higher efficiency and higher frequencies, which enable smaller dimensions for a given power output. Higher switching frequencies allow the size of magnetic components to be reduced significantly, resulting in more compact and lighter designs. This trend is now being reinforced by use of new wide bandgap semiconductor materials like silicon carbide (SiC) and gallium nitride (GaN), as their low on-resistances and low parasitic capacitances reduce switching losses. Conventional current sensor solutions, e.g. hallor shunt based sensors exhibit a limited bandwidth, typically less than 250 kHz. Other current sensors, like those based on the Rogowski-Coil, are capable of highly dynamic current measurement, but are significantly more expensive, larger and hence not suitable for large series applications. Furthermore, Rogowski-Coils are only capable of measuring alternating currents (AC), which prevents their use in applications where DC currents must also be measured. In order to meet the above mentioned requirements, magnetoresistive (MR) current sensors are ideally suited due to the fact that the bandwidth of the magnetoresistive effect extends up into the GHz-range. This paper describes the principle of operation and main performance characteristics of highly integrated MR current sensors and describes their benefits compared to other types of current sensor, in particular with regard to applications in the hybridisation and electrification of vehicles.

Precision of the Residual Stress determined by X-ray Diffraction: Summery and Limits

Today components specially for passenger cars are weight optimized. Often it is done by mechanical surface treatments. Therefore, the amount of compressive residual stress induced by the treatment must be known. The measurement is very often done by x-ray diffraction. But how precise can you determine (and not directly measured) the amount? A big question is the calibration of the equipment. A specimen must be designed and calibrated by round robin test, because no measurement standard is available.

The Contribution of the Metrological Management in the Moroccan Establishments of Blood Donation (Experiment of the regional center of blood transfusion in Oujda Morocco)

Metrological verification consists of proving by calibration measurements that specified requirements are met. The result of an audit is a compliance decision followed by re-commissioning or non-compliance followed by an adjustment, repair, decommissioning, or device reform. At the regional blood transfusion center of Oujda, from 2010 to 2018 the number of metrological qualification has increased from 88 to 152 acts with compliance going from 92% to 97%, thus the number of visit for preventive and curative maintenance of the share of external companies has also increased since 2010 to 2018 from 10 annual visits to 43 annual visits, which indicates a strong progressive metrological activity and an important place of the metrological process in the continuity of guaranteeing a safety of the result obtained from the operations carried out for the practitioners and for donor and recipient patients of the blood product. An action plan was implemented to correct the anomalies identified such as the acquisition of new metrology equipment, to predict the change of climatic chambers and non-adapted devices, the acquisition of more sophisticated machines and the establishment of a continuous recording system of the cold chain.

Traceability Features of the Electric Power Unit in Ukraine

The paper describes some aspects concerning the realization of the electric power unit traceability in Ukraine in the CIPM MRA understanding through participation in Key and Supplementary Comparisons of national standards and in the ILAC MRA understanding through participation in inter-laboratory comparisons. The authors have demonstrated comparative analysis of EURAMET.EM-K5.1, COOMET.EM-S2, COOMET.EM-K5 comparisons results and practically realized the procedure for realisation traceability of the electric power unit in Ukraine.

Improvement of INRiM static expansion system as vacuum primary standard between 10-4 Pa and 1000 Pa.

The INRiM static expansion system has been recently modified in order to improve its performance and extend the working range down to 5.10-4 Pa. A new characterization of the system has been performed and a preliminary estimate of the uncertainty has been evaluated.

Influence of storage time of pulp and paper industry wastewaters in AOX determination

The feasibility of storing wastewater samples from pulp and paper industry during more than 5 days (time recommend by ISO 5667-3:2018) for AOX determination was addresses in this study. Samples were collected before and after the aerobic biological treatment of a Portuguese industry. Experimental protocol included AOX measurements at days 4, 5, 6, 8, 11, 13, 15, 18 and 20 after sampling. Results obtained indicate that storage time is not matrix-dependent and it can be extended up to 20 days, which clearly improves management of laboratory activities concerning AOX determination.

Achieving precision measurements under non-standard environmental conditions

Geometric measurements should be made at standard temperature 20°C, otherwise errors due to thermal expansion of workpieces and scales will occur. If measurements in serial production have to be made at different temperatures, DIN EN ISO 15530-3 describes a technique to correct the measurement error by referring to a calibrated reference workpiece. We have investigated this approach theoretically and experimentally and present some results.

Determination of the coefficient of expansion of a carbon tube and its assembly for thermal compensation of metrological structures

Composite materials are increasingly used in 3D metrology devices. Their use is justified by their interesting mechanical properties including their low density and good rigidity but especially their low coefficient of thermal expansion. In fact, in order to improve production efficiency, companies nowadays integrate more and more control equipment directly in situ. These are then subject to thermal variations. The use of composite materials is an interesting approach. However, in some cases, the lack of knowledge of their coefficient of thermal expansion and their behavior might increase measurement uncertainties. The objective is to study the thermal behavior of a carbon tube alone and the same tube with aluminium fixing elements at its extremities, in order to determine the coefficients of expansion of the carbon alone and to quantify the influence of the fixation with aluminium elements. This experiment makes it possible to directly compensate the dimensional variations of the metrological structure depending on the temperature variations and thus to limit measurement uncertainties. The thermal expansion coefficients of the carbon tube and its assembly are determined by measuring relative variations in height with a ZERODUR® reference bar. The whole is positioned in a climatic chamber. *