Study of generalized delay-timers in alarm configuration

In process plants, alarms are configured to notify operators of any abnormalities or faults. However, in practice a majority of raised alarms are false or nuisance and create problems for operators as they face an increasing number of alarms to handle. Adding delay-timers is a simple technique that can reduce this problem and is widely exercised in industry. In this work we propose a generalized delay-timer framework where instead of consecutive n samples in the conventional case, n1 out of n consecutive samples (n1 ≤ n) are considered to raise an alarm. For the generalized delay-timer, three important performance indices, namely, the false alarm rate (FAR), the missed alarm rate (MAR) and the expected detection delay (EDD), are calculated using Markov processes. Moreover, the performance and sensitivity of generalized delay-timers are compared with conventional delay-timers.

► A generalized delay-timer framework is proposed, where instead of consecutive n samples in the conventional approach, n1 out of n consecutive samples are required to raise or clear an alarm.
► False alarm rates, missed alarm rates and expected detection delays are calculated for the generalized delay-timer.
► Performance of conventional and generalized delay-timers is compared.
► Preliminary sensitivity analysis is presented.