Common misconceptions and pitfalls in alarm management
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The document discusses common misconceptions and pitfalls in alarm management. It emphasizes that the goal of alarm management is quality alarms that clearly indicate abnormal process conditions requiring operator action, rather than just reducing alarm counts. Common issues discussed include making alarm count reduction the sole goal, not considering consequences of ignoring alarms, alarming normal events, unclear alarm messages, and overreliance on metrics. The document stresses the importance of taking a holistic approach to alarm management with focus on the operator's needs.
Common misconceptions and pitfalls in alarm management
- 1. Standards Certification Education & Training Publishing Conferences & Exhibits Common Misconceptions and Pitfalls in Alarm Management By Darwin Logerot, P.E. ProSys, Inc.
- 2. Presentation Overview • Why Alarm Management? – Objective – Definition of an alarm • Common Pitfalls and Misconceptions 2
- 3. Why Alarm Management? With DCS systems, alarms can be configured with a few keystrokes, cheap and easy Proper consideration is seldom given to alarm configuration during initial design Hence, many more alarms configured than needed Information overload, especially during upsets, is the natural result of excess alarm numbers 3
- 4. Why Alarm Management? In a number of industrial incidents, alarm floods were identified as a significant contributing cause to the incident… As found by EEMUA in 1999 and CSB The connection of alarm floods to incidents has been well known for over 12 years with very little progress made in industry 4
- 5. NO! 5 Objective of Alarm Management The objective of alarm management is to reduce the number of alarms annunciated to the operator Agree? Disagree?
- 6. 6 Objective of Alarm Management The objective of alarm management is to reduce the number of alarms annunciated to the operator NO! Although reduction in annunciated alarm count will almost always be a result of a well-conceived and executed AM project, this is NOT the primary objective
- 7. 7 So, What is It About? It’s about the QUALITY of the alarms
- 8. What is a Quality Alarm? • An annunciated abnormal process condition to which the operator can and must take corrective action in order to return the process to normal and safe operation Alarm? 8
- 9. What is a Quality Alarm? Alarm? Every alarm should: • Be clear and relevant to the operator • Indicate an abnormal process condition that has consequences of inaction and defined response • Be unique 9
- 10. What is a Quality Alarm? Alarm? Every alarm should: • Be clear and relevant to the operator • Indicate an abnormal process condition that has consequences of inaction and defined response • Be unique 10
- 11. Misconceptions and Pitfalls Summary • Making alarm count reduction the goal • “Check the Box” mentality • No consequences for an alarm • Alarming normal events or status messages • Multiple alarms for a single event • Alarm messages not clear or relevant 11
- 12. Misconceptions and Pitfalls Summary • Using alarm settings to trigger interlocks or other automatic actions • We only need to rationalize tags with alarms • Only doing bad actors • Ignoring dynamic behavior • Eliminating start-up and shutdown from alarm metrics • Over-reliance on metrics 12
- 13. “Check the Box” Mentality • Too often, alarm management is seen as a top down requirement. • It’s easy to just go through the motions • It’s easy to rush the project • Concentrate on the base goal to provide a reliable and consistent alarm system • Target audience for AM is the operator, not upper management! 13
- 14. No Consequences for an Alarm • Too often, alarms configured for conditions which have no consequences if ignored • Examples – High flow where flow is controlled by cascade from level – Low temperature alarms on heater tube skin – Low level in a sump that is routinely empty 14
- 15. Alarming Normal Events Using Alarms as Status Messages • Normal means planned and expected. Alarming normal events means alerting the operator that “the control system is working just fine!” • Examples – One pump not running where two pumps are installed – Sump pump starting / stopping from level signal – Alarming board operator actions – Change of state alarms – Stack damper open when heater switches to natural draft – Alarming every step of a sequence controller 15
- 16. Multiple Alarms for One Event • Best to only provide one alarm for any given abnormal event • Exception, if there are two transmitters in a critical service • Example – Shutdown systems – High/Low measurement (at shutdown point) – First out alarm – Shutdown alarm – Command to close shutdown valve – Shutdown valve closed 16
- 17. Alarm Messages Not Clear or Relevant to Operator • If the operator does not understand the alarm message, the alarm will be useless 16E20-2 LSR AIR COOLER • This description was used for six different points 16E18 BTMS EXCHANGER BYPASS • Operators in that plant don’t speak the equip number language 17
- 18. Alarm Messages Not Clear or Relevant to Operator HDR PNL 17LP3N-1B-C • Operators have no clue what this means Naptha Stripper (16-V-3) Overhead Pressure PT-3032 18
- 19. Triggering Interlocks from Alarms • Alarms and interlocks exist for different reasons • Not generally a good practice to force both at same setting • This ties the AM Team’s hands • Can’t change the alarm without changing the interlock • Suppressing the alarm can disable the interlock 19
- 20. Only Rationalize Tags with Alarms • Approach sometimes used to minimize the project scope (cost) • Optimum alarm configuration can be masked • Best to include all tags in the control system as candidates for alarming 20
- 21. Only Do Bad Actors • Not Recommended by ISA 18.2 • Alarms considered singularly, not holistically • The process can remove worthwhile process alarms • When does it stop??? • Never really gets anywhere to solve alarm floods 21
- 22. Ignoring Dynamic Behavior Plant operation is not static Alarm configuration shouldn’t be either 22
- 23. Ignoring Dynamic Behavior • Rationalizing only the expected run condition seldom adequately addresses alarm floods • Dynamic or state-based alarming addresses identified operating modes • Modifies alarm configuration accordingly 23
- 24. TI213 AC013 PVHI LI010 PC022 Dynamic Alarming Without Dynamic Alarming – Each alarm is stand alone and does not have knowledge of current plant status – Normal and abnormal conditions alarmed PVHI PVLO PVLO Heater S/D 24
- 25. Dynamic Alarming With Dynamic Alarming – Change of process state is managed – Only abnormal conditions alarmed TI213 AC013 PVHI LI010 PC022 PVHI PVLO PVLO Heater S/D 25
- 26. 26 Ignoring Dynamic Behavior ASM Consortium finding: • Study of 37 consoles / 90 months of data overall • Static Rationalization – “peak alarm rate is not closely correlated with the degree of rationalization” Zapata and Andow – HUG 2008 – Highlights from the ASM Consortium
- 27. Eliminate Startups and Shutdowns from Alarm Metric Calculations • Edits actual data to conceal floods during startup and shutdown • Keeps management in the dark • Eliminates potential investment to fix problem • Doesn’t help the operator 27
- 28. Over-Reliance on Metrics Typical metrics • Average alarm rate • Peak alarm rate • Time in flood (>10 /10 min) • No. of chattering alarms • Number of stale alarms ISA Recommended value < 1 per 10 min < 10 per 10 min < 1% 0 < 5 28
- 29. Over-Reliance on Metrics • Best not go overboard with alarm metrics • Focus on providing a reliable and consistent interface for the operator • Numbers will take care of themselves Effective alarm management is not a numbers game! 29
- 30. Over Reliance on Metrics • Numbers can indicate a problem • Numbers cannot indicate that there is not a problem Metrics do not replace Alarm System Design 30
- 31. Over-Reliance on Metrics • What is the solution to pure numbers? Zero configured alarms 31
- 32. Summary • Remember the Goal - AM is not a numbers game • Operator is the target audience • Do more than check the box • Review all tags • Include dynamic behavior • Don’t go overboard on metrics 32
- 33. Summary Five alarm keywords • Abnormal • Consequences • Actions • Relevant • Unique 33
- 34. Standards Certification Education & Training Publishing Conferences & Exhibits Questions ? 225-291-9591 x225 www.prosys.com Sales @prosys.com