Measurement and control. Automation. Pt100 resistance thermometers between the standard and the new. Already established technologies find entry to the new version of the DIN en 60751 norm [MSR. Automation. Pt100 zwischen norm und neu. Bereits etablierte technologien finden eingang in neue version der norm DIN en 60751]
Saecker D.,Wika Alexander Wiegand SE and Co. KG
CIT Plus | Year: 2010
Since 1996 much has happened, including in the techniques of making measurements. The time has been ripe for a new edition of the most important standard for the making of industrial temperature measurements, the DIN EN 60751. Some technologies that had already penetrated the practice of temperature measurement had not yet been mentioned in the standard Of 1996. The most important point relates to the use of the thin film resistance. The discussion covers the most significant changes and back-up support for the design of the new standard. The new norm or standard DIN EN 60751 defines new realistic limits of use for all sensor types and their specific accuracy classes, and the so-called "1/3 DIN". Unfortunately the new version loses the necessary clarity in the determination of the resistance to vibration of thermometers, opening unnecessary room for interpretation. Discussion topics include constructions of resistance (wire wound, glass, ceramic, thin film); temperature-resistance relationship; limits of use of resistance thermometers and accuracy classes; class A still only up to 450°C; notes on the 1/3 DIN; liquid nitrogen replaces the impossible; lack of clarity with respect to resistance to vibration; query as to what the new norm expresses in fact; and summary. The accuracy class in the old standard was known as the "1/3 DIN", a third of Class B. The new standard replaces this with Class AA. The written word and actual use of Pt100 resistance thermometers come closer in the new norm. The user is clearly informed concerning the possibilities of use of the new technology and its limits. However, the statements about stability against vibration are somewhat vague, demanding greater attention when comparing the products of the statements of the various manufacturers.