In chemical processes

fault diagnosis is relatively difficult due to the incomplete prior-knowledge and unpredictable production changes. To solve the problem

a case-based extension fault diagnosis (CEFD) method is proposed combining with extension theory

in which the basic-element model is used for the unified and deep fault description

the distance concept is applied to quantify the correlation degree between the new fault and the original fault cases

and the extension transformation is used to expand and obtain the solution of unknown faults. With the application in Tennessee Eastman process

the result indicates that CEFD method has a flexible fault representation

objective fault retrieve performance and good ability for fault study

providing a new way for diagnosing production faults accurately.