The Console Alarm Analysis Report includes an alarm rationalization analysis aligned with the ANSI/ISA-18.2 standard. This topic explains how stations are classified and how the rationalization metrics are calculated.
Overview
Alarm rationalization is the process of reviewing each alarm to ensure it is necessary, has a defined response, and is set at the correct priority and limit. The report automates the counting phase of rationalization by aggregating alarm tag counts per station and comparing them against configurable ISA-18.2 §4.3 thresholds.
Station Classification
Each station is assigned a status based on its alarm tag counts compared to the configured thresholds:
Status
Condition
Row Color
Manageable
All counts are below their respective thresholds
Green
Marginal
Total count is within 20% of the Total threshold
Amber
Challenging
Any count exceeds its threshold
Red
ISA-18.2 §4.3 Thresholds
The default thresholds are based on ISA-18.2 §4.3 steady-state alarm rate guidance:
Threshold
Default
Guidance Basis
Analog Alarm Threshold
100
ISA-18.2 §4.3 analog alarm guidance
Digital Alarm Threshold
100
ISA-18.2 §4.3 digital alarm guidance
Total Alarm Threshold
150
ISA-18.2 §4.3 steady-state manageable alarm rate
Thresholds can be adjusted in the Station Summary Thresholds section of Report Options. See Report Settings and Options.
Unrationalized Alarm Rows
In the Tag Data worksheet, rows where an alarm parameter carries a priority of NOACTION or NONE are highlighted in amber when the Highlight Unrationalized Rows setting is enabled. These rows identify alarms that have not been reviewed and assigned a meaningful priority.
ISA-18.2 Priority Distribution (§5.3)
The ISA-18.2 KPIs worksheet shows the distribution of alarm priorities across the console scope. ISA-18.2 §5.3 recommends that no more than a defined percentage of alarms should be in the highest priority levels (Critical, Urgent, High). Exceeding this percentage indicates alarm priority inflation.
Note: The ISA-18.2 priority compliance threshold is configurable in Report Settings. The default is 5% for Critical/Urgent/High combined.
