9762 papers found
A transformer bridge to study low-loss dielectrics at the frequency 1 MHz is developed. The main components of the bridge: a ratio transformer and variable measuring standards of capacitance and conductance are made in the form of removable modules. The bridge measurement range by loss angle tangent D is 10 -6 - 10 -3 with the capacitance 1-1000 pF. Measurement uncertainty D is ± (2-3) &itimes; 10 -6 , k = 2.
Surface plates are used in the industry and measurement laboratories for performing measurements of length, angles and deviations of form and position of measured subjects, for checking and control of measurement bars and rulers. Our aim is to perform a calibration of the surface plate without involving either interferometric system or autocollimator, which would be too expensive, therefore using only electronic levels. And even when the appropriate device for calibration is chosen, the decision between many different types of algorithms has to be made. On top of all, traceability of...
The method and the results of the international comparison of AC current ratio standards 50 Hz frequency are introduced in this article. The national metrological laboratories of Hungary (OMH), Austria (BEV) and the Czech Republic (CMI) have taken part in this comparison realized as the project DUNAMET D7. The pilot laboratory was the national metrological laboratory OMH Budapest.
Following the Guide to the Expression of Uncertainty in Measurement (GUM) and other recent documents on uncertainty, we analyse typical measurement situations met in a set of Measurement Systems: measurement modelling and comparison, calibration and traceability of measuring devices, dissemination model and interlaboratory comparison, test of measurement compatibility, evaluation of dissemi-nation processes, improved evaluation methods of interlaboratory comparisons.
Calibration of measuring instruments is one of the fundamental metrological activities. Calibration is a specific art of measurement, which requires a lot of theoretical knowledge on the measurement, technical and metrological parameters of the instrument under Calibration, as well as the other ability to make the calibration procedure in a suitable and right way. Without the properly calibrated measuring instrument no measurement could be declared as correct and traceable to the national or international standard. In this paper, we will explain the basic requirements and practical...
The authors’ laboratory is accredited for calibration by comparison of contact thermometers and calibration baths and furnaces in the range from -55 °C to 1250 °C. The accreditation was granted to the laboratory in January 1997 as the first temperature calibration laboratory in Slovenia. It also became a holder of national standards for thermodynamic temperature thus providing the traceability of temperature in Slovenia. There are many thermometers and relative humidity sensors made combined as thermo-hygrographs. These applications serve mainly for monitoring environmental conditions at...
A method for calibrating multi-decade inductive voltage dividers has been developed which makes it possible to determine both the inphase and the quadrature error for ratios of i /11, i = 1, 2,..., 10 in the frequency range from 400 Hz to 5 kHz. Calibration is made by comparing the divider under test against a reference two-stage divider having a ratio winding with 11 identical sections. In calibration of the reference divider itself, an auxiliary 11:1 transformer is used.
In accordance with ISO 17025, measuring and test equipment, including gear and spline artefacts must have been traced back to recognized national or international primary standards through an unbroken traceability chain. This is the reason why there have been national gear standards and gear standard measuring equipment in Germany since the sixties, for example for the elements: profile, helix, pitch, radial run-out of gearings and roughness. In contrast to this, no direct link-up to spline artefacts has so far been made at the PTB for splines. If one proceeded in compliance with the DKD...
For a long time the terms calibration and verification and verification have often been used as synonyms. Sometimes the difference of meaning is connected with the application in legal metrology or in industry. Today the international Vocabulary of Basic and General Terms in Metrology (second edition – 1993) doesn’t speak about verification but other standards make its definition clear. In industry what is to be done in the context of Quality assurance implementation? From our point view the user has to choose between ‘calibration” and ”verification” in order to demonstrate the traceability...
Paper presents two classes of unconventional measurement signals with special, designed shapes, in context of their application for the identification measurements. Firstly, measurement idea, choosing proper observables and signal shape design principle are explained. In the next part of the paper mirror signals (power and Poisson) and polynomial signals (Chebyshev, Legendre) are presented. An example illustrating practical applications of polynomial signals is included.