抵抗線温度計における位相補償系の校正方法の改善

概要

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In this study, the improvement of the calibration method of the thermal-fluid measuring instrument wasinvestigated. The quantitative calibration method of the phase-compensator for the frequency-response of thecold-wire thermometer was devised based on the operating principle of the compensation circuit. Thecold-wire thermometer involved the indispensable frequency response of the first-order lag caused by the heatcapacities of the sensor and its supports. The thermometer was equipped with the phase-compensation circuitto compensate the frequency response based on the model of the heat transfer coefficient of the sensor withrespect to the temperature and the velocity. The decrease of the gain of the thermometer was automaticallycompensated through instantaneously controlling of the cut-off frequencies of the phase-compensator inresponse to the changes of the thermal time-constants of the sensor and its supports. In the present calibrationmethod, the frequency characteristic of the compensator was adjusted according to the control-voltage of theCdS (Cadmium Sulfide) photocouplers contained in the compensator. The realization of the requiredcharacteristics for the high-frequency compensation was confirmed through evaluating the transfer function.The proposed method made it possible to simplify the calibration procedure and to make high-accuracymeasurement of the temperature fluctuation.
2011-01-31