JP2783635B

PURPOSE:To improve the operating reliability of a plant by providing a data preserving device, a statistic-quantity computing device, a statistic-quantity-reference preserving device, a feature extracting device, a diagnostic knowledge preserving device and first and second diagnosing devices. CONSTITUTION:A data preserving device 3 preserves data associated with process signals inputted from a plant (a). A statistic-quantity computing device 4 reads out the data in the device 3, analyzes frequencies and converts the results into various kinds of the statistic quantities. A statistic-quantity-reference preserving device 6 preserves the reference value of the statistic quantity which is learned in the known plant state. A first diagnosing device 5 compares and collates the output of the device 4 and the reference value and diagnoses the plant state. A feature extracting device 8 receives the output of the device 4 and the reference value under the normal state when the output of the device 4 does not agree with the reference value of any statistic quantity as a result of the diagnosis and extracts the change in feature of change from the normal state. A diagnosis-knowledge preserving device 10 preserves the diagnosis knowledge describing the feature of the change from the normal state with respect to various kinds of assumed events. A second diagnosing device 9 compares and collates the output of the device 8 and the diagnosis knowledge and diagnoses the plant state.