Alarm Structures and Hierarchies

Just as with screen displays, there are alarm hierarchies. These hierarchies must be easy to assemble and modify within the control system. Alarm groupings can be arranged by plant areas, by function, by unit processes, or by equipment. Alarm access must be direct without the need to go through process tags, names, or lists, and when getting to the alarm, full information should be available to the operator to make a proper decision. The handling of the alarms should be made easily because the priority setting, annunciation technique, and the act of acknowledging should direct operators to that corrective action. Alarm summary lists are very personal to each process or plant. Traditionally, operator actions were gathered on printers blended with alarm summaries. Once an alarm structure is established, carefully investigate if all the significant alarms are highlighted. A critical aspect of the operator interface is the alarm capability provided by the control system.