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Tsutsumi S.,Japan Electrical Meters Inspection Corporation
Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) | Year: 2014

Inductive voltage dividers (IVDs) are widely used in the field of ac measurements, such as impedance measurements at audio frequencies. The two-stage guarded IVD was developed by D.N. Homan and T.L. Zapf about 40 years ago. However, it is not easy to construct a two-stage guarded IVD. Therefore, we have developed a two-stage IVD using a special winding method without guarding by magnetic and electrical shields. To reduce the admittances of the winding wires, corrugated polypropylene board is used for the new two-stage IVD. In addition, the ratio winding and excitation winding are wound toroidally around two FINEMET ring cores using PEW flat cable 0.7 mm in diameter. As a result, the in-phase ratio errors are within ±6.1×10-8 of the input at frequencies of 1 kHz or below. In this report, the winding methods and measurement results of the new two-stage IVD are described. © 2014 Wiley Periodicals, Inc. Source

Sato H.,Japan Electrical Meters Inspection Corporation
AIP Conference Proceedings | Year: 2013

According to the IEC standard 60751 Ed.2 (2008), the stability of the resistance value of platinum resistance thermometers (Pt100) should be less than the declared tolerance value after a minimum of 672 hours maintained at the upper temperature limit. However, the most important requirement for thermometers to use as a working standard is whether the resistance value will be stabilized or not after 672 hours annealing. We carried out stability tests of 15 thermometers at 450 °C over 1000 hours to confirm that these products are capable to use as temperature standards in our laboratory. And the result of additional experiments show that pre-annealing process before fabrication of a thermometer is able to improve stability. © 2013 AIP Publishing LLC. Source

Goto T.,Japan Electrical Meters Inspection Corporation
20th IMEKO World Congress 2012 | Year: 2012

In the case of calibration of direct acting indicating analogue electrical measuring instruments (hereinafter called the "analogue instruments"), uncertainty budget largely depends on dispersion of readings for scales through a needle. This paper describes experimental results for three levels of voltage (10 V, 6 V, and 3 V) of analogue instruments. In the experiments, two way layout nested design was introduced for each voltage level. From the results of present experiments, it was revealed that expanded uncertainties obtained were about 1/3 for the specification that obtained from the past experience. Source

Sato H.,Japan Electrical Meters Inspection Corporation
Proceedings of the SICE Annual Conference | Year: 2012

Industrial Platinum Resistance Thermometer (IPRT) is a temperature sensor makes use of relationship between resistances of a platinum sensing element and temperatures. IPRT is widely used in industry, research and developing fields due to its high reliability. In precision measurements, AC bridges or high resolution digital instruments which can reverse the polarity of measurement current are used to eliminate parasitic electromagnetic-force (EMF) produced at somewhere in a metal-sheath of IPRT. On the other hand, low-cost digital instruments which cannot reverse the polarity are using in some applications. It should be noted that the readout temperatures from such instruments may be affected by parasitic EMF depending on measurement conditions. In some cases, the magnitude of temperature affected by parasitic EMF may be beyond calibration uncertainty. This problem has not been focused in the past. The results of measurements using 10 IPRTs are reported. © 2012 SICE. Source

Kodaira K.,Japan Electrical Meters Inspection Corporation
IEEJ Transactions on Fundamentals and Materials | Year: 2012

An evaluation method of platinum resistance thermometers (PRTs) used in the stationary air was considered. A comparison measurement apparatus to evaluate PRTs was developed by using a commercially available temperature bath and the performance of the apparatus was evaluated. The apparatus has high temperature stability and good temperature distribution although the thermal medium is the air. The uncertainty of the apparatus is less than 1 mK. A PRT was evaluated for a trial with this apparatus at 23 °C. First, a PRT that was set in the water was measured with a Standard Platinum Resistance Thermometer (SPRT) in the temperature bath. Next, the identical PRT was set in the air chamber of the developed apparatus and measured with the SPRT. And, each result was compared. As a result, it was possible to distinguish the difference of behavior of the PRT at different environment by a proposed method in this study. And, it was confirmed that the cause of different behavior was the self-heating of the PRT. © 2012 The Institute of Electrical Engineers of Japan. Source

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