Alarm coding of a model-based display

The author discusses and illustrates alarm coding of a model-based display. The model-based display synthesizes the heat engine cycle within a light water reactor. A digital computer uses measured process variables to form an icon of the heat engine cycle. The Rankine cycle serves to structure the data in terms of the temperature and entropy properties of water. The iconic display serves as a visual knowledge base of the plant process for the operator, thereby reducing reducing the operator´s mental workload in evaluating the process. Process data from the loss of feedwater event at the Davis Besse Plant (June 9, 1985) serves to illustrate alarm coding methods. The articulation of the alarms are by the use of color and symbols within the process icon instead of the traditional text on separate alarm windows. The integration of the alarms with the process data facilities the operator´s use of the data.<>