Expanded summary alarm records

For expanded summary alarms, when an alarm occurs, a record is generated in the alarm display object showing that an alarm condition has occurred. The record shows the date and time stamp of the alarm. This record remains visible until an operator acknowledges the alarm and a return-to-normal state has occurred. If the return-to-normal state occurs before the alarm is acknowledged, then two records are shown in the alarm object.

For example, a boiler’s temperature exceeds the high limit state and triggers an alarm. Later, the boiler returns to its normal temperature range before an operator can acknowledge the alarm. The alarm system generates a record that a high limit alarm occurred and an another record indicating the alarm was not acknowledged.