512-863-3653 sales@tipsweb.com

Analyses Types

Frequency Analysis

A frequency analysis displays the number of times alarms occur. It is essentially a count of alarm records, grouped by the criteria specified in the analysis configuration, and sorted most to least frequent. This Analysis can be used to evaluate alarm loads as specified under ISA 18.2 section 16.4.5.

The Results tab is segmented by tag and/or alarm type depending on the duration analysis configuration. If an Alarm KB is linked to the real-time data the Tag Description (KBT Description) and Alarm Priority (KBA Priority) are also displayed in the results.

Duration Analysis

A duration analysis shows how long events have been in alarm and also includes some problematic categories. There are 5 types of duration alarms:

  • Time in alarm – how long an alarm has been in alarm
  • Time to acknowledge – how long an alarm has been in alarm before it was acknowledged
  • Standing – current outstanding alarms (not cleared)
  • Stale – which alarms were in alarm for a specified number of seconds, minutes, hours, and so forth
  • Fleeting – an alarm that was active for a very short amount of time, 3 or 4 seconds from the time the alarm was active, and its associated clear

Durational analyses are used to discover alarms that are problematic under ISA 18.2 sections 16.4.6 and 16.4.7. According to ISA 18.2, there should be few stale alarms per operator console, with action plans to address them. No alarm should be intentionally designed to become stale and there is no long-term acceptable number of stale alarms.

The Results tab is segmented by tag and/or alarm type depending on the duration analysis configuration. If an Alarm KB is linked to the real-time data the Tag Description (KBT Description) and Alarm Priority (KBA Priority) are also displayed in the results.

Chattering Analysis

A Chattering Analysis quickly informs about alarms that are activating and clearing several times in a specific time interval, such as having the same alarm go into alarm 10 times within 5 minutes.

Chattering analyses are used to discover alarms that are problematic under ISA 18.2 section 16.4.6. According to ISA 18.2, chattering alarms are often high in the listing of the most frequent alarms. Chattering alarm behaviors should be eliminated via rationalization, and there is no long-term acceptable quantity of chattering or fleeting alarms.

The Results tab is segmented by alarm type. If an Alarm KB is linked to the real-time data the Tag Description (KBT Description) and Alarm Priority (KBA Priority) are also shown in the results.

The Count column is the number of Chattering Alarm occurrences that meet the analysis configuration. The Percent column indicates the percentage of chattering alarms relative to the total number of ALL alarms for the period, chattering or not.

Flood Analysis

A flood analysis displays periods of time when alarms were occurring at a high rate. This can be an excellent measure of operator loading, particularly during process upsets, as well as identifying periods where the system is operating outside of industry best practice recommendations for alarm rate.

This analysis helps alignment with ISA 18.2 section 16.4.4. According to that section, alarm floods should be of short duration and low total alarm count, and an alarm system should be in flood for less than one percent of the time.

For each flood period a ‘Start Time’ shows the initial time the alarm rate was exceeded per the analysis configuration. The ‘End Time’ shows the time when the alarm rate fell below the threshold per the analysis configuration. The ‘Count’ column specifies the number of alarm activations during the flood period. The ‘Duration’ column provides the time duration between the Start Time and End Time.

Alarm State Analysis

An alarm state analysis provides statistics on the alarm, clear, and acknowledgment patterns for an alarm or group of alarms. Alarms are grouped by the fields specified in the analysis configuration and sorted most to least frequent. This analysis provides detailed insight into individual alarms and groups of alarms (grouped by area for example).

The ‘Alarms’ column shows the number of alarm activations for the total time range specified in the calendar. The ‘% of Total’ is the percentage of number of alarm activations for a specific tag divided by the total number of alarms during the period.

The ‘Clears’ column is the number of alarm clears (or Return to Normal) for the specific tag or alarm. The ‘Acks’ column is the number of alarm acknowledgments for the specific tag or alarm. The ‘% Ack’ column is the percent of acknowledged alarms over the total number of alarms for the specific tag.

Nuisance Analysis

A nuisance analysis provides a weighted frequency of alarms, grouped by tag, alarm type, and time. The data is rolled up at varying time intervals of Total, Months, Weeks, and Days depending on the length of the time range that the analysis is run for. This quickly highlights alarms that are consistently bothersome over time and also enables the user to quickly zero in on a particular time of activity with the multi-level summary intervals.

The results of the Nuisance Analysis are segmented by the Tag and Alarm Type. The ‘Start Time’ and ‘End Time’ show the initial time and last time the alarm was active during the time range specified. If an Alarm KB is linked to the real-time data, the Tag Description (KBT Description) and Alarm Priority (KBA Priority) are also displayed in the results.

The ‘Count’ column indicates the number of alarm activations over the total time range specified. The ‘Num Days Occurred’ shows the number of days that the alarm occurred between the Start Time and End Time. Keep in mind that there may be days between the Start Time and End Time that the alarm did not meet the specified threshold for alarm activations. The ‘Weight’ value is the product of the ‘Count’ times the ‘Num Days Occurred.’

Data is sorted by the ‘Weight’ column to indicate those alarms that are chronic and have high alarm activations.

Overview Analysis

An Overview Activity Analysis does not generate a graph, unlike the rest of the activity analyses. The Overview Analysis is a list of metrics that provides a user with a general idea of the alarm system’s health.