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Project of a digital cryogenic current comparator bridge for high precision dc resistance measurements
No full textThe argument of the thesis is the project of a digital CCC bridge for accurate measurement of resistance ratios. The thesis is divided in two parts. The first two chapters are dedicated to the resistance standards technology and the normal Direct Current Comparator bridge. Then a chapter describes the electronic circuit of the bridge. The next describes the cryogenic parts of the bridge: the flux detector, the CCC with its probe and the shields system
Realizzazione di un partitore di tensione 1:10 per la taratura di sorgenti di tensione allo stato solido
No full textTraceable Technique to calibrate Clamp Meters in AC Current From 100 to 1500 A
No full textA measurement technique to calibrate current clamp
meters in ac current in the measurement range from 100 to 1500 A
at 50 Hz has been developed at the National Institute of Metrological
Research (INRIM) in addition to the primary reference
measurement systems for ac current calibrations at INRIM. This
technique is traceable to the national standards of dc resistance,
dc voltage, and ac current ratio. It is based on a standard current
transformer (CT), on a 50-mΩ standard shunt, and on a
61/2-digit digital voltmeter (DVM) that measures the voltage on
the standard shunt inserted in a conductor, to which also the clamp
meter is applied, whose current is supplied by a CT that can
generate currents up to 1500 A. The CT is controlled by a variable
transformer. The clamp meter is applied to a copper wire and
placed on a tilting support simulating the actual operating mode of
the meter. This measurement technique is applicable in industrial
metrological laboratories and is an alternative to measurement
practices of accredited secondary laboratories1 involving digital
calibrators and turn current coils. This measurement technique
was also tested utilizing an 81/2-digit high-accuracy DVM. The results
of the evaluation are presented and discussed. The expanded
(k = 2) uncertainties of the technique span from 1.0 × 10−2 at
100 A to 2.0 × 10−3 at 1500 A
Generatore multifunzione per lo studio delle caratteristiche di dispositivi superconduttori
No full textAnalysis of a national inter-laboratory comparison of high dc resistance at 10 MΩ and 1 GΩ level
No full textControllo automatico di un sistema di commutazione per misure di precisione di resistori campione basato su un microprocessore
No full textRealisation at IEN of a new automatic instrument for calibration of high value resistors
No full text1 AND 10 k HIGH PRECISION TRANSPORTABLE SETUP TO CALIBRATE MULTIFUNCTION ELECTRICAL INSTRUMENTS
Full text linkA temperature controlled 1 {Omega}-10 k{Omega} standard Resistors transportable setup was developed at National Institute of Metrological Research, (INRIM) for the calibration and adjustment of multifunction electrical instruments. The two Standards consist respectively of two 10 {Omega} and 100 k{Omega} parallel connected resistors nets inserted in a temperature controlled aluminium box. Novelty of the realization is the oil insertion of the 1 {Omega} net with its internal connectors lowering the thermo-electromotive forces (emfs) effects. Short and mid-term stabilities of the setup Standards resulted on the order and in some cases better than other top level 1 {Omega} and 10 k{Omega} commercial Standards. The transport effect turning off the setup temperature control did not cause appreciable measurement deviations on the two Standards. The Standards uncertainties meet those requested by DMMs and MFCs manufacturers to calibrate and adjust these instruments. A test to adjust a multifunction calibrator gave satisfactory results.A temperature controlled 1 and 10 kΩ transportable setup was developed at National Institute of Metrological Research (INRIM) for the calibration and adjustment of multifunction electrical instruments as digital multimeters (DMMs) and multifunction calibrators (MFCs). The two standards are made of two 10 and 100 k resistor nets connected in parallel and inserted in a temperature controlled aluminium structure. Novelties of the realization are the oil insertion of the 1 net with the internal side of the connectors lowering the thermo-electromotive forces (EMFs) effects, and the possibility to know instantly the temperatures of the environment, of the internal of the structure and the last calibration values of the 1 and10 kΩ standards. Short- and mid-term stabilities of the setup standards resulted on the order and in some cases better than other metrology-grade 1 and 10 kΩ commercial items. The transport of the setup even turning off its temperature control did not cause appreciable measurement variations on the two standards. The standards uncertainties meet those requested by DMMs and MFCs manufacturers to calibrate and adjust these instruments. A test to adjust a MFC gave satisfactory results
A temperature, humidity and pressure independent 1 GΩ standard resistor: realization and preliminary results
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