Fault diagnosis-a user´s view

It is explained that the increasing complexity of industrial plants makes the diagnosis of faults more difficult. There is a need for an automated system that detects faults and presents a list of possible causes. The ways in which humans find faults are discussed. Besides its having good fault finding logic, it is also helpful for a plant to be designed for ease of fault finding and of the replacement of faulty parts. The article discusses diagnosis at the PLC level, and computerised systems. Reasons for failure of diagnostic systems are considered. Cost justification is also discussed. The discussion is illustrated by the example of steel plant arc furnaces