A disturbing trend (not the only one) in distributed control system (DCS) conversions is the proliferation of CRTs. Where at one time three CRTs per operator was common, today it is not unusual to see six or more CRTs per operator. Are all these CRTs necessary?
On straight logic, if three CRTs are adequate with an early generation DCS, why would one need more CRTs with the better display capabilities of the current DCS? Shouldn't you need fewer CRTs?
The counter argument (if you can call it an argument) is, "Why not have the additional CRTs if they're available?" Besides the obvious and practical (why pay for something you don't need), there are potential negative effects on operator and system performance if excess CRTs are present. A two-fold effect is possible: (1) display designers might feel compelled to "spread out" the display system to accommodate all the CRTs (note: information systems should be 'compact') and/or (2) the operators will feel that all the CRTs should be used in solving a problem (a common characteristic of problem solving is assuming all available information is relevant, and people actually do better in processing information from a single source). Another related problem is based in signal detection theory: extra, unnecessary CRTs add noise to the information environment, thereby decreasing the ability of the operators to find the information they need.
Can you have too many CRTs? Yes. Are most new DCSs using too many CRTs? Probably. Should refineries pay more attention to CRT selection? Definitely.
Copyright © 1990 Beville Engineering, Inc. , All Rights Reserved
RELATED EXTERNAL MEDIA
|Operator Interfaces Expand Human Factors||Automation World|
|How to Build a Better Operator - ABB Automation & Power World||Control Design|
|Operators Get More Help||Chemical Processing|
|Impact of Alarm Rates and Interface Design on Operator Performance||Automation World|
|Simple, Strong and Easy-to-Use||Control Global|
|DCS Console Operator Issues in Related Industries||TAPPI|
|Operator Performance as a Function of Alarm Rate and Interface Design||Mesa.org|
|Operator Interfaces: Moving from Comfortable to Most Effective||Automation World|
|User Centered Design at Work||Control Global|
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 © 1996-2018 Beville Engineering, Inc. All rights reserved. (937)434-1093. Beville@Beville.com