The problem is bigger than you think. The Abnormal Situation Management Consortium (ASM) recorded over 1000 incidents last year alone. Alarms not considered a priority during design phase, and thus too many alarms configured. Many plants are running with high alarm rates and operators are overloaded. Alarm bursts in certain plant conditions and nuisance alarms degrade alarm system’s effectiveness.
Prior to the modern DCS, Annunciator Panels provided alarm indication to the operators. The physical space requirements and hardware costs limited the number of indicators available to the operator. Careful thought and design was put into the overall annunciator content. The advent of the modern DCS eliminated the physical space required by alarm indicators and enabled the viewing of alarms on monitors. The hardware costs, although still present, were reduced by the intelligent programming of controllers and Human Machine Interface nodes. With the cost and space restrictions removed, the designers were provided with an unprecedented degree of freedom in the amount of information that could be provided to the operators. However, as the engineers began to take advantage of this wealth of information, an unanticipated side effect occurred – information overload. The alarm list became flooded with maintenance alarms, control permits, multiple trip indications, mistuned alarm limits, and Smart Device information. Improvements in the filtering of alarms were hindered by shorter project delivery cycles, limited resource availability, and just in time deliveries including equipment vendor selections.
Question 2: How do I know if I have an alarm management problem?
Top 10 signs you may have an alarm management problem:
10) You always need “Page Down” button to scroll your alarm list
9) Your SOP has only one instruction – Acknowledge the alarm
8) You find your finger on the “Silence” button all the time
7) You use “Ack All” feature way too often
6) You run out of disk space for your A&E historian every 3 months
5) You have one value for your H, HH and HHH limits
4) You have never seen an alarm other than ‘High’ priority
3) You get nervous when you don’t see your usual alarms in the list
2) You bet with your buddy on what the next alarm would be!
1) You have an active alarm dated 8-Aug-2009 09:34:00
How to develop an alarm management strategy?
The process of managing this flood of information begins with an effective Alarm Management. The ISA 18.2 standards help with the process of developing an alarm management strategy. The key idea is that every alarm should be useful and relevant to the operator and that there should be no alarm without a predefined operator response. Another key component for operator success entails the rate of alarms. The desired alarm rate during normal operation should be below 1 alarm in 10 minutes.
But how do you generate such a strategy? ISA 18.2 provides a great Life Cycle approach to alarm management. The First Step is defining the Alarm Management Philosophy for the plant. Questions to think about include:
· What are the Key Performance Indicators and how to measure the KPI’s?
· Who will manage and review the state of Alarm Systems and who will provide input?
· What makes an alarm relevant and how to define a priority to the alarm?
· How do I establish Management of Change for alarm configuration?
Once the alarm philosophy is created, the next steps are the identification of alarms, the assignment of alarm properties and alarm response, and the design and implementation of alarms, all then documented and placed into operation. Finally, monitoring and assessment of the alarm implementation is required to determine if the alarm philosophy has been satisfied. If improvements or other modifications are required, then the Management of Change process is utilized to begin the alarm management process steps. A periodic review is scheduled to view the alarm performance versus the alarm philosophy and analyze any performance gaps or organizational discipline. Lastly, it is important to note that the alarm management process is iterative (Benchmark, Plan, Implement, and Review) and requires input from all parties (vendor, engineering firm, operators, and operation management).
How can the quantity of alarms be reduced?
If an alarm philosophy has not been designed, eliminating nuisance alarms, such as alarm settings and hysteresis, creating filters on Alarm list, and removing alarms that do not require an Operator response, reduces the quantity of alarms displayed. ISA 18.2 provides direction for analytical reports to help reduce the amount of alarms viewed by the operator. The low hanging fruit (easiest alarms to rationalize) can be investigated using the alarm and event frequency reports. The Top 10 or 20 alarms during the time period selected often indicate where alarm limits and/or hysteresis adjustments are necessary. Another report to help with alarm limit and hysteresis adjustments is the Alarm Duration Report. For example, alarms that are active for very short time periods (less than 10 seconds) and those that occur frequently in the alarm list are identified in an Alarm Duration Report. The Alarm Duration report helps with Standing alarms, alarms that are active for long periods of time and the alarms do not require operator action to resolve. The standing alarms report indicates which alarms should be filtered for maintenance personnel. Filtering alarms within the ISA 18.2 standards target a distribution of 5% High Priority, 15% medium priority, and 80% of low priority alarms. A quick look at the priority distribution report alarms provides a good indication if operators are sensitive to urgency. The filtering of alarms can be accomplished by the organization of the priority (any maintenance type alarms should be greater than 3 transparent to the operator) and reduced by inhibiting or hiding alarms based on equipment or process status. Inhibiting or hiding alarms can be analyzed by looking for bursts of alarms. A burst may have occurred during the start up or shutdown of a major piece(s) of equipment which may be used as the inhibitor to alarms. The co-occurrence report may also be useful in configuration of alarm inhibits or hiding rules.
The Event Management tools within the ABB Power Generation Information Manager Event Management and Symphony® Plus History systems provide the necessary help for documenting and analyzing the Alarm Management system performance. ABB Power Generation Service group supports customers with their alarm management needs.