Research And Implementation Of Remote Calibration System For Resistance Thermometer

Resistance thermometers are contact temperature sensors which arewidely used in industrial environment under300℃. Although the resistanceelements are protected by the case, but theirs performance are too fragile andsensitive to be easily changed after a long time use. So the resistance thermometersmust be calibrated on a regular basis. There are some problems in the traditionalcalibration such as long calibration interval, high uncertainty, long traceabilitychain and difficult management. In order to better solve the above problems, thispaper based on the verification regulation of resistance thermometers and theinternational temperature scale ITS90, research the remote calibration system forresistance thermometer. The main research and implementation is by the followingaspects.1. The theoretical research. The shortcoming analysis of the traditionaltemperature calibration was carried out combining with the temperaturemeasurement theory and the temperature calibration theory. According to a largenumber of domestic and foreign material and literature, this paper summarizes ageneral method and tool used in establishing remote calibration. Aimed at someproblems in remote calibration for temperature, based on the metrologicalcharacteristics for the resistance thermometers, the research content and the paper’stechnology roadmap is proposed.2. The general design and implementation of system. According to demandanalysis, this paper designs remote calibration system wholly, including the generaldesign of the system, the structure design of the network, the design of backstagesupporter’s database and the security design. Following the system functionrequirements, it designs the software for each module. The software design includesMFC program for the PC based on VC6.0and C program for the single-chip basedon Linux. The MFC program implement the customer login, the SQL databaseoperation, the remote calibration, the video monitoring and exporting the report. The C program outputs controlling instructions between the PC and calibrationequipment, completes data acquisition and supports the web server to videomonitoring.3. Uncertainty evaluation. This paper presents the gray method for the type Auncertainty because of small sample tests and the source of uncertainty is complexity.By analyzing and comparing those method and Bessel method, studies show thatassessment method based on gray system theory is feasible. In this paper, we useGUM department assessment method based on gray system theory for industrialresistance thermometers of remote calibration system uncertainty evaluation.