Fault Diagnosis Method Using Fault Tree for Diagnosis

The fault diagnosis method using the fault trees for diagnosis is developed, which describe the relationships among the faults, causes and observations. In this method, the causes and their probabilities are estimated by the fault trees for diagnosis and the data of observations. The probabilities of causes are calculated with the failure rate of them, and with Fussell-Vesely importance which is use in the Fault Tree Analysis. So, it is possible to diagnose objectively. This method applied to the draining pump plant fault diagnosis system. In this system, the failed equipment is searched using the fault trees, which is constructed from designer's and maintenance man's knowledge, and the data of observations. To make the human operator understand the results easily, the system presents the estimated causes, the probabilities of the causes, and the process of diagnosis in the picture of display devices. Also, the fault trees, the system block diagrams, and the pictures of the component are shown on the CRT display devices. In the block diagram, the failed parts flicker to show the causes easily for the operator. Moreover, a maintenance guide is shown. In this paper, the diagnosis method and the feature of human interface of the system are described.