The most common use of Alarm Help is for process (and SIS) alarms. However, Alarm Help is also available for alarms based on alerts from control system hardware and intelligent field devices. Though the maintenance organization is often responsible for hardware and device alarms, it may be appropriate to annunciate some hardware and device alarms to operators. The DeltaV system allows separation of alarm lists for operators and maintenance personnel based on the combination of alarm source and priority.
To conform to the ISA-18.2 concept that an alarm always requires an operator action, it is important that operators are never in doubt about expected response to an alarm. Thus the principal use of Alarm Help for system hardware and device alarms for operators will in many cases be to declare the action as either:
Urgent — requiring immediate verification by an outside operator, investigation by maintenance, and so on.
Routine — requiring work order initiation and so on.
A cognitive change — requiring elevated attentiveness to a specified process, instruction to notify the outside operator, and so on.
Authors of Alarm Help should always consider the responsibility of the intended reader.
Hardware and device Alarm Help can also be used to document physical equipment location or cross-reference the equipment to associated control units or modules.