| 摘要 |
PROBLEM TO BE SOLVED: To provide a valve positioner for controlling a valve by automatically measuring the characteristics of portions to be controlled for automatic tuning. SOLUTION: The valve positioner comprises an input signal for setting the opening of a valve, a position sensor for detecting the opening of the valve, a control arithmetic part for performing control arithmetic operation corresponding to the input signal from a deviation between a valve opening signal obtained by the position sensor and the input signal to generate a control signal, an electropneumatic change mechanism part for generating an air flow rate in accordance with the control signal, and a pressure amplifier for supplying to the valve an air pressure based on the air flow rate generated by the electropneumatic change mechanism part. When portions to be controlled consisting of the electropneumatic change mechanism part, the pressure amplifier, the position sensor and the valve receive automatically setting signal, the characteristics of the portions to be controlled are automatically measured and tuning parameters for generating the control signal for the control arithmetic part are found with arithmetic operation from the characteristics of the portions to be controlled so as to be replaced with present tuning parameters.
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