Alarm Management

June 20, 2010
Visit NASA’s Kennedy Space Center at Cape Canaveral and you can see the Mission Control Center.  A few years ago, we visited and stood in Mission Control as they did a dramatic reenactment of an Apollo launch. Prominent were the very large lighted Annunicator Panels that showed the stages of readiness to launch and any alarms.
These were exactly the old alarm panels that were used at the power plants when I stared as a controls engineer in the early 1980’s. The alarm panels were hardwired to a switch or a relay to create an alarm. Back in those days we didn’t have lots of nuisance alarms. We also didn’t have a way to report on the alarms or the sequence of alarms during an upset either.
I was among those that installed first and second generation Distributed Control Systems (DCS) and Programmable Logic Controllers (PLC). We were given the ability to easily create alarms – and boy we sure did! We created the nuisance alarm by making redundant, low deadband alarms, non-actionable alerts, and unintelligible notifications. We created noise that has hurt the effectiveness of our operations.
Now, we have excellent tools available to analyze our alarms – to remove those not needed and present the information better and more actionable to operations. We can now use the alarms to help us understand and improve the alarms that our operators depend upon and to use the alarm information to help our process engineers and managers understand the process and determine root-cause for problems.
  • Collect alarms from multiple systems into a single plant alarm database.
  • Analyze alarm history to find and correct nuisance alarms
  • Present alarms from many different systems in one view to the right people. (Color coding, audible or silent)
  • Show the sequence of events of process alarms.
  • Automate alarm notification to multiple people and provide automatic escalation.
Automatic Alarm Modification
Dynamic alarming is the automatic modification of alarms based on process state or conditions. These advanced methods are used when basic alarm designs do not achieve the performance goals stated in the alarm philosophy.
State-Based Alarming State-based alarming modifies alarm set point, priority or suppression status based on defined operating states for equipment or processes.
Operating states are often determined by:
  • Status of a logical variable
  • Defined process variable which reaches a specific limit
  • Logic that looks at many variables and indicators
  • Operator selection Management
Modelization Techniques
Building dynamic alarming systems where the system is aware of the state of any equipment and can automatically decide to shelve or unshelve alarms depending on the equipment state.
  • Benefits of Dynamic Alarm Reduction
  • Reduce risk of human injury and incidents.
  • Reduce cognitive load for the operators
  • Avoid plant shutdown, lost product and associated costs
  • Better understanding of current process state
  • Avoid nuisance alarms, improved fault tracing
  • Alarm reduction, reducing operator’s cognitive load
  • Reduce risk of critical alarm miss, or acknowledge by mistake
Kevin
Kevin Totherow is a Business Development Manager of MES for Schneider Electric and a consultant for helping manufacturing clients manage their operations better. Kevin has been a controls engineer, consultant and president of Sylution Incorporated. He can be reached at (864) 252-6819 or by email at kevin.totherow@schneider-electric.com.

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