Ask Control Engineering
The Ask Control Engineering blog covers all aspects of automation, including motors, drives, sensors, motion control, machine control and embedded systems. Control Engineering answers questions from readers of Control Engineering's print and online magazines, newsletters and other publications. To comment on any blog posting, click on the post's highlighted question and scroll to the "Post a Comment" box at the bottom. Submit questions as comments to any existing post.
Why can't we have more exciting graphics?
February 18, 2011
Dear Control Engineering: I was reading the article Gray Backgrounds for DCS Operating Displays. Why is operator response so important? Aren’t most problems caused by the equipment?
The Abnormal Situation Management Consortium says that people factors account for 42% of incidents, which is why the group spends so much time on operator training and how individuals interface with the control system. (If you’re curious, equipment factors account for 36% of incidents, and process factors for only 22%.)
If an operator has to look at an HMI screen and ask him or herself what that blinking red thing means, it means that the operator is not adequately trained, or that the HMI graphic is not consistent in its use of color. Any time spent gathering thoughts and interpreting graphics simply slows the response and allows the problem to go on longer, potentially escalating in scale and damage. Worse yet, an operator may take the wrong action if he or she doesn't understand immediately what the display is trying to say. Consistency is critical.
Peter Welander, pwelander(at)cfemedia.com
Monday, 14-03-11 16:53
I think you answer your own question in the text of your comment. Operator intervention is important and in some cases time to respond is critical in preventing a minor disturbance from escalating, even in situations where equipment is the primary source of the disturbance or upset. The use of color in a display can influence the speed and accuracy of an individual's response to solve problems. For example, color and other visual coding techniques can influence whether operators notice all of the areas impacted and hence obtain adequate situation awareness prior to taking action. There are ample examples in history of well-trained individuals who focus on one aspect of a problem and fail to notice all evidence, particularly evidence that is inconsistent with their initial conclusions.