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--- alarm_analysis.reports.stalealarms:stale_alarms [2020/06/08 09:14] – su
+++ alarm_analysis.reports.stalealarms:stale_alarms [2021/01/22 15:14] – [Stale Alarm Detection] su
@@ Line 1: / Line 1: @@
-**Stale alarms** are alarms which are/were on for 24 hours or more and transitioned in the period selected.
+====== Stale Alarms Report ======
+**Definition:** Stale alarms are alarms which are/were on for 24 hours or more.
+{{ :alarm_analysis:stalealarmreport_01.png?direct&800 |}}
+The picture above shows an example Stale Alarm Report.
+By default, the report shows the Top 20 stale alarms (sorted by "Total On Time") for a defined reporting period (e.g. 1 Oct 2020 00:00:00 - 1 Nov 2020 00:00:00).
+The calculated metrics are:
+  * **Count:** Number of Stale Alarms / Total Number of Alarms, for reporting period.
+  * **Total on Time (days):**  The accumulated on-time of stale alarms.
+===== Stale Alarm Detection =====
+Alarm Analysis operates on //Reporting Periods//. That is, Alarm Analysis compiles metrics for a given date-range and will only detect a Stale Alarm if it transitions (annunciates or returns) within the reporting period.
+{{ :alarm_analysis.reports.stalealarms:stale-alarms-vis.png?direct&600 |}}
+{{ :alarm_analysis.reports.stalealarms:stale-alarms-legend.png?direct&200 |}}
+With reference to the above illustration, the Stale Alarm report **includes** alarms that...
-The historical view of standing alarms report will show alarms that
   * were on for 24 hours in the selected period (1).
   * transitioned after 24 hours (or more) in the selected period (2,3)
   * were on for longer than 24h but haven't returned to normal within the selected period (4).
-  * were on for longer than 24h but haven't started inside the selected period boundaries (5).
-This can visualised like so:
+Example 5 has no associated Alarm, therefore no on-time can be estimated and is therefore omitted.
-{{ :alarm_analysis.reports.stalealarms:stale-alarms-vis.png?direct&600 |}}
+Examples 6 and 7 transition outside the reporting period and are therefore **omitted**
-Example 6 is part of **standing alarms** report and does **not** contribute to stale alarm report.