Alarm information in fault diagnosis

The presentation of alarm information is not always compatible with the response required by the operator. It was therefore considered necessary to find out what operators do with alarm information. These investigations took the form of interviews, questionnaires and observations. The findings suggest six identifiable stages in alarm handling, namely: observe, accept, analyse, investigate, correct and monitor. Each of these stages have different information requirements, and some of these may be in conflict with each other. It is proposed that better definition of `alarms´ coupled with improved presentation of alarm media could offer substantial benefits to the operator. These benefits should ideally be measurable in terms of: time to diagnosis, mental workload, number of control actions, success of control actions, quality of diagnosis and output performance. This approach is counter to alarm reduction techniques, which have successfully reduced the number of alarms present, but have not always produced corresponding improvements in the operator´s performance. This is because the apparent redundancy of the information may hide its usefulness in keeping the operator abreast of the state of the process and developments therein, as well as aiding the diagnosis task