PLANT DIAGNOSTIC SYSTEM

A plant diagnostic system wherein a plant to be diagnosed is expressed as an auto regressive model to calculate correlation function with respect to a difference obtained on the basis of an estimated value based on the auto regressive model and a plant value of the plant to be diagnosed, thus to diagnose the plant, characterized in that there is additionally provided time constant determination means for determining time constant at which a change of one plant value has the greatest influence on the plant value or other plant values by using a coefficient matrix of the auto regressive model, thereby enabling calculation of correlation function in consideration of the time constant of the plant to be diagnosed, thus to conduct identification of abnormality or failure source which is in conformity with the characteristic of the plant to be diagnosed.