4.1.2-9 Logical Consequences Processing

If a single event invariably leads to subsequent alarmed events that are the direct consequence of this event, only the alarm message associated with the main event may be presented and the other alarm messages suppressed, so long as this does not interfere with the use of alarm information.

Additional Information:
For example, logical consequences processing may be used to suppress alarms that follow as a logical consequence of trip or isolation conditions. When implementing logical consequences processing, the designer should ensure that messages associated with the "consequence" alarm conditions are not needed for other operational tasks, and that operators are aware that the associated "consequence" alarm conditions were generated but not presented. This guideline only suggests suppression of these alarms, not their complete elimination (i.e., filtering).