As in all information presentation, display design requires an understanding of what information needs to be conveyed to the recipient. Adding unnecessary information results in a cumbersome, "noisy" system. Beville utilizes a variety of techniques to identify how the operators use the process information. This is then translated into display design requirements. For example, one plant had an extremely stable process, so the operators had become very sensitive to changes in valve outputs. Ensuring outputs in the display system became a critical requirement for that unit, whereas for a less stable process the output information would simply be distractions or noise.
The information requirements, both variables and how they are to be encoded (color, shape, etc.), need to be combined into an integrated system. Beville can help create an interface structure that allows the operator to quickly access the right information at the right time. In general, the interface should be hierarchical in nature, where (1) different displays are created that match their use and (2) the displays are organized into a structured information environment.
A major flaw with many DCS systems is the inability for the operator to obtain the big picture of plant operation, or situational awareness. This may result in the operator developing "tunnel vision" during problems and upsets. To mitigate this problem, Beville can provide guidance in the creation of a single overview screen for the operator's entire span of control. The overview that is developed will display qualitative status information on the major plant systems, and will be supported by lower hierarchy displays.
Upgrading to DCS should not be a major trauma for the operators and create more problems than it corrects. Proper selection and structuring of information, one of Beville's areas of expertise, is the means to ensure maximum operator performance with a DCS system.
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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.
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