ABSTRACT
Alarm systems are an essential part of the Supervisory Control and Data Acquisition (SCADA) control room system; they are required to alert the operator to a range of situations and system-state changes. Stanton (1994) pointed out that an alarm system is absolutely necessary in light of the sheer amount of information contained within the system; the operators could be monitoring up to 800 pages of information and up to 20,000 alarms. The design of the alarm system has a significant effect on the performance of the operator. A well-designed alarm system considers the operator’s ability to recognize the situation, diagnose the fault, and develop a suitable course of action. A well-designed alarm system also considers the workload of the operator and the time available for action using this information to prioritize alarms. An alarm can be defined as a plant variable exceeding a setpoint threshold and resulting in some form of explicit communication to the Operations Engineer via the SCADA display. The communication may be auditory or visual and may utilize a text message, flashing icon, annunciator board, or some other means of attracting attention. The definition of the term alarm is often dependent on its purpose; Stanton (1994) offered the following definition: “An unexpected change in system state, a means of signaling state changes, a means of attracting attention, a means of arousing the operator, and a change in the operator’s mental state.”
