Perspectices for annunciator systems

Operators with supervisory control tasks in large Systems, such as chemical process plants or electricity generation plants, are usually supported in their work by an annunciator system. This annunciator system alerts the operator when measured variables exceed their desired limits or when certain discrete events are detected. The functioning of such annunciator Systems is discussed in this paper. The basic principle of conventional annunciator Systems is that the system's state, as determined from the measured data, is compared to a reference state. Unacceptable deviations are signalled as alerts. However this principle of state-based annunciation does not provide support for the operator's task of achieving the system goals. Functional modelling offers the tools to build a new generation of annunciator Systems that can "understand" mode changes in a system, and check and report the achievement of system goals instead of conformance to a reference state. The design of such annunciator system leads to less but that are more meaningful alerts. Filtering of alerts, as is done in many annunciator system, becomes unnecessary.