Quality vs. quantity of alarm messages - How to measure the performance of an alarm system
Gyula Dörgő, Ferenc Tandari, Tibor Szabó, Ahmet Palazoğlu, János Abonyi
Abstract
Despite significant efforts to measure and assess the performance of alarm systems, to this day, no silver bullet has been found. The majority of the existing standards and guidelines focus on the alarm load of the operators, either during normal or upset plant conditions, and only a small fraction takes into consideration the actions performed by the operators. In this study, an overview of the evolution of alarm system performance metrics is presented and the current data-based approaches are grouped into seven categories based on the goals of and the methodologies associated with each metric. Deriving from our categorical overview, the terminological differences between the academic and industrial approaches of alarm system performance measurement are reflected. Moreover, we highlight how extremely unbalanced the performance measurement of alarm systems is towards quantitative metrics instead of focusing on qualitative assessment, invoking the threat of excessive alarm reductions resulting from such a unilateral approach. The critical aspects of qualitative performance measurement of alarm systems is demonstrated in terms of the comparison of the alarm system of an industrial hydrofluoric acid alkylation unit before and after the alarm rationalization process. The quality of the alarm messages is measured via their informativeness and actionability, in other words, how appropriate the parameter settings are for the everyday work and how actionable they are by the operators of the process.