This website does not use cookies. Read Privacy Policy here.
Beville Engineering Logo

Alarm Systems: One size does not fit all


Considerable activity has been expended in the process industries to improve plant alarm systems. An underlying assumption has been that an alarm system could be created that had certain inherent characteristics (i.e., the system is either good or bad). Research by Meyer and Bitan into alarming for intensive care situations shows that such an assumption is likely invalid (Meyer, J. and Bitan, Y. "Why better operators receive worse warnings". Human Factors, Vol 44, No. 3, Fall 2002, P343-353.)

It has been proven that low validity/unreliable alarms (cry-wolf alarms) degrade alarm system effectiveness and operator performance. The work of Meyer and Bitan shows that the capabilities of the operator can and do interact with the alarm system to alter its predictive value. Surprisingly, good operators are more likely to have their performance levels drop, because they can anticipate process changes and thereby expect alarms to occur. As a result, the predictive information provided to the good operator is of less value than that provided to the poor operator. The net effect, unfortunately, is a less valid alarm system (lower predictive value) for the better operators. Other research has shown that as the predictive value of alarms decreases, operators are less likely to respond, respond more slowly, and/or assign less weight to the alarm information.

The authors' primary thrust is that an operator's performance alters the value of the alarm system, but what are the implications for control of hazardous processes? At a minimum, there are two major implications. First, we can no longer judge an alarm system independent of the individuals using it. Second, the variance in board operator performance will need to be minimized such that the alarm system can be configured for a narrower, and higher, level of expertise.

For further information, visit the links below.

| Alarm & Display System Analysis Overview | Alarm Management | Display Design | Alarm & Display Design Seminar | Beville Shape Calculator -Excel download | Alarm Distribution Estimator -Excel download |


Article Published By
Consortium Reports New Findings on Alarm Rates Automation World
How Many Alarms Can An Operator Handle Chemical Processing
Impact of Alarm Rates and Interface Design on Operator Performance Automation World
Operator Interfaces: Moving from Comfortable to Most Effective Automation World
Operator Performance as a Function of Alarm Rate and Interface Design


This year's Fall meeting for the Center for Operator Performance will be October 24-26 in Corpus Christi. For more information, please contact Lisa Via. Guests are always welcome!


Our summer newsletter is now available. Click here!

Take our short survey on operator span of control. Click here (new window)

David Strobhar's book, "Human Factors in Process Plant Operation," is now available in both hardcover and Kindle e-book.

Copyright 1996-2019 Beville Engineering, Inc. All rights reserved. (937)434-1093.