Implementing high-performance HMIs
Many companies are looking to Abnormal Situation Management (ASM)-based and other high-performance human-machine interfaces (HMIs) as part of a major control system upgrade. These efforts began primarily in refining and petrochemical applications, but have spread to other verticals and continue to grow.
Many approach the situation by referring to these projects as "ASM graphics," but this misses much of the point. ASM guidelines influence what operator screen graphics look like, but the most important improvement is the visible manifestation of extensive analysis related to situational awareness among operators, including prioritization of the different elements of the process. The objective is to make the things the operators need to see the most visible. The item needing attention will then jump out so there is no question of what the next act needs to be in a problem situation.
Achieving such an objective takes a lot of work, but those who analyze and embrace the ASM concepts find them worth the effort. The analysis necessary to make it work involves two main areas:
First, each operator graphic has to have a purpose-an objective. What is it the operator needs to know when looking at this screen, and what is the best way to show it? Understanding how an operator perceives a situation is critical.
Second, there needs to be a thorough alarm analysis. This may seem counterintuitive, but knowing what occurrences need to have an alarm tells much about what the operators need to know. Any item alarmed should be important and require operator attention.
With these two areas working together, it’s a simple step to determine how the screens should interact. Many procedural elements will come out of the process as well, which will help determine how operators should behave in a variety of circumstances.
The biggest real-world limitation when undertaking this kind of project is usually lack of resources. The stakeholders may have a clear vision of what needs to be accomplished, but there is always a finite amount of time and money available. It’s never possible to go through every conceivable screen graphic, every bit of logic, or every alarm—but it should not deter what can be accomplished. Even if everything is not ideally optimized from the outset, huge improvements can be made if priorities have been set well. The amount of human error is the greatest contributor to upsets and safety incidents and can be reduced dramatically.
Older operators who worked in process plants many years ago can remember the effect of controlling a process while located closer to the actual equipment. When an operator hit the button to start a pump, awareness was high because they heard it kick in along with the movement of fluid in the pipes. Moving operators to a control room environment brought many benefits, but their only means of process awareness now comes through the control system and its HMI, so it’s important to optimize these components.
Ed Watkins is project engineer, Maverick Technologies. Maverick Technologies is a CFE Media content partner. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, email@example.com.
See related stories on distributed control system (DCS) migration linked below.