The ISA-18.2 and IEC 62682 standards define an alarm as an “audible and/or visible means of indicating to the operator an equipment malfunction, process deviation, or abnormal condition requiring a timely response”. One of the reasons why alarm systems are out of control (alarm overload, nuisance alarms) is because the alarm summary display is used to communicate everything that the operator needs to know, whether it is an alarm or not.
Q. When is an “alarm” not an alarm?
A. When the DCS or SCADA alarm system annunciate a notification that doesn’t meet the criteria of being an alarm (above). So, an “alarm” would not be considered an alarm in the following examples:
- An event is recorded in a database for review / analysis, but is not presented to the operator
- it is NOT intended for the operator but instead for a different role (e.g., maintenance technician, process engineer, network administrator)
- the operator’s action is NOT urgent and/or the consequence of inaction is NOT imminent
- the notification is for information or awareness only (e.g., a step in an automated sequence has completed)
- the system is waiting for an operator action and response to proceed (e.g., entering lab data or a manual additions step in a batch process).
One category of non-alarm notifications is called an alert. In the ISA-18.2 / IEC standards, non-alarm notifications are largely grouped into a category called an “alert”.
Alert: a notification of an abnormal condition that requires assessment or action and which does not meet the criteria for an alarm (ISA-18.2-2016)
Other than the definition, no requirements or guidance was provided on how to handle alerts or other types of notifications, such as prompts or notices (formerly called messages).
Prompt: a notification requiring a timely response and which is part of normal operation (e.g. granting of specific authorization)
Notice: a notification which does not require a timely response
The ISA-18.2 committee has started work on a new Technical Report (ISA-18.2 TR8) on “Alerts and Other Notifications” to address this gap. The scope of TR8 is to “provide guidance on the application of the techniques described in ISA-18.2 to manage alerts and other notifications that do not meet the criteria defined in the standard for an alarm. In ISA-18.2, any notifications that did not meet the definition of an alarm were designated as “alerts” and not discussed further. The 18.2 definition constrained alerts to the operator role. This TR expands that definition of alerts into other types, purposes, and roles.”
Stay tuned for further information and developments. If you would like to participate in the development of TR8, please send me an email and I will connect you with the working group chairs.