Vol.3 No.3 2010

Research paper : National electrical standards supporting international competition of Japanese manufacturing industries (Y. Nakamura et al.)−215−Synthesiology - English edition Vol.3 No.3 (2010) electronic parts. We hope to contribute in strengthening the international competition power of the industries.2 Scenario2.1 Establishment of the development goal of the national standardIn developing a new national standard, it is necessary to establish the goal of the development, such as “What level of uncertainty (precision) should the national standard for the newly developed capacitance target?” and “What is the expected secondary measurement standard that will be the subject of calibration?” At the time we started the development, the mainly used secondary measurement standard capacitors, which were calibrated from the national standard (primary measurement standard), were air capacitors or mica capacitors. These were used because the temperature coefficients were small or the devices themselves were small and easy to handle. They were used widely in the corporate standard labs, but the expected uncertainly was of 1 ppm (1 F/F) level. The electronic parts companies or the capacitance measuring instrument manufacturers that demanded high-precision capacitance standard owned the fused-silica capacitor that had higher precision and stability than the air capacitor, and wanted standard for this type of capacitors. The fused-silica capacitors were capable of achieving uncertainty of 0.1 ppm level. Therefore, we set the fused-silica capacitor as the subject of calibration and developed the national standard for capacitance.The developed capacitance standard was compared with the standards of the national metrology institutes (NMI) of other countries to check its equivalency, and then to establish the international compatibility. Surveying the uncertainties of the capacitance standards realized at the NMIs of countries that realized the world’s top-level capacitance standard, specifically, the National Institute of Science and Technology (NIST, USA), Physikalisch-Technische Bundesanstalt (PTB, Germany), National Measurement Institute of Australia (NMIA, Australia), and Laboratoire National de Métrologie et d’Essais (LNE, France), it was found that these NMIs have established the standard of uncertainly of 0.1 ppm or less[2]-[5]. We decided that the world’s top-level standard must be achieved in assuming a highly precise and stable fused-silica capacitor as a calibration subject (secondary measurement standard), and to support the global competition of the Japanese industries. Therefore, we set the development goal: “the establishment of a national standard with standard uncertainty of 0.1 ppm or less”.2.2 Scenario for the dissemination of standard to industrial sitesTo disseminate the capacitance standard to the manufacturers’ production site and to build the metrological traceability system, we believe the role of the private calibration laboratories is mandatory. Currently, many NMIs around the world develop and organize standards required by industry and provide wide-ranging calibration services. (For example, the NIST and PTB provide about 330 types of electrical standards, while Standards and Calibration Laboratory [SCL, Hong Kong] provides about 200 calibration services[6].) However, it is not necessarily the best policy for AIST to organize and provide the standards for all ranges to meet the demands of industries. This is because there are several highly capable calibration labs and precision machine manufacturers in Japan compared to other countries. In building the metrological traceability system, if it is possible to maximize the calibration abilities of the cooperating laboratories in Japan, it will be possible to realize the stable dissemination of standards to the far corners of the industrial sites. At the same time, it will enable AIST to slim down its function and to allocate the resources efficiently. With this background, a standard provision system was considered for the capacitance standard and is shown in Fig. 1.In this system, AIST develops and establishes the national standard for the basic range and provides this to the Japanese calibration labs. The calibration labs expand the calibration range based on the disseminated basic range standard, and then disseminate them to the industrial sites. In this case, the role of AIST is limited to regularly disseminating the highly precise basic range standard to the upper-tier calibration labs, and this enables simplifying its calibration work. Also, by limiting the range of the standards provided, the AIST resources can be focused and concentrated, and this in turn enables achieving higher precision and efficiency of the calibration devices. The method for disseminating Fig. 1 Scenario for the system of capacitance standard provisionAISTNational standard of capacitanceReference standard(for technical exam)・Dissemination of reference standard・Technology transferCalibration labIndustrial siteElectronic parts (capacitors)Parts provisionElectrical appliance, communication device, automobile (manufacturing industries)


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