About the author:
Lori Lovely is a freelance writer for Water & Wastes Digest. Lovely can be reaced at [email protected].
Supervisory Control And Data Acquisition (SCADA) systems consisting of hardware and software components allow industrial organizations to control processes locally or remotely and to monitor, collect and analyze data from industrial equipment in real time. They also allow operators to view critical settings and measurements such as temperature, power usage, vibration and more.
SCADA systems have been used since the 1960s as various industries sought fully automated methods of controlling their equipment and monitoring physical processes, such as the generation and transmission of electricity, transmission and distribution of gas and oil in pipelines, and water and wastewater distribution and collection. Even traffic lights, manufacturing plants, food production facilities and mass transit systems use SCADA systems.
Advantages such as reduced costs, greater reliability, increased efficiency, enhanced safety and improved workflow are some of the results of using SCADA systems. The ability to view real-time data and alarms for problems, concerns and glitches via the SCADA screens enables operators to address issues before they reach crisis level, causing extended downtime due to delayed response and restoration.
Seeing Beyond the Screen
To be effective, SCADA screens must be easy to read. Too much color or too many graphics can clutter a SCADA screen, obscuring relevant information and even confusing the operator. Despite the clutter, some data may still be missing. Incomplete information can result from not adding context. For example, a numerical value of how much water is in a tank fails to fully explain whether that number is on the rise or fall due to current usage, let alone if that number is within a typical average range.
“SCADA screens need to convey information in context,” said Brent Studnicka, project manager at Strand Associates Inc., a full-service engineering firm. However, defining “in context” is a challenge because it means different things to different people.
Studnicka said that older operators prefer the traditional graphics because that is what they are used to seeing, and the context they need to make sense of the data is already in their heads. They know the historical trends that fill in the knowledge gap left by just a number.
By comparison, younger operators prefer situational awareness graphics, because the information is presented in a way that puts the information in context — much like they are used to seeing in video games or on modern electronic devices, Studnicka added. Thus, they do not have to remember the context, because it will be there the next time they look at the graphic.
Situational awareness graphics provide the institutional knowledge, such as operational ranges, alarm set points and normal values that experienced operators have memorized. By including this information on the SCADA graphic rather than assuming the operator knows it, the organization gets better results from new operators who do not have institutional knowledge committed to memory.
“Historical information is also presented on the graphic to give the operator a feel for patterns or trends that allow them to quickly identify a problem with the current data,” Studnicka said.
Color my World
In designing SCADA screens, Studnicka turned to the “High Performance HMI Handbook” by Bill Hollifield and principles that have been around since the mid-2000s, but not widely used in the water or wastewater fields. In short, he created a grey background, incorporating color sparingly to draw attention to alarms.
With situational awareness graphics, color raises the alarm precisely because it stands out.
“Using color effectively is done by limiting the use of color to indicate alarms instead of making the graphic look ‘pretty’ with all kinds of color,” Studnicka said.
A combination of colors, shapes and numbers creates a hierarchy of conditions. Red indicates a critical or emergency situation, orange designates a less urgent situation and yellow is cautionary, indicating a condition that needs addressing soon but not immediately.
Studnicka mused that he could add an additional color and shape for maintenance alarms — such as overdue PMs or other routine maintenance tasks that have not been done. They might even be on a different screen. But he expressed concern for cluttering up the screen with too much color again. Sticking to the basic alarms means the screen does not flood the operator with unnecessary information. Besides, he pointed out, “in water, most owners don’t want to spend extra time and effort on graphics.”
When money is available, however, he said there’s a “definite pull both ways as to how graphics should be used.” In fact, one municipal customer requested a hybrid version, with both the traditional graphic style and the situational awareness graphics. The older style is useful because it illustrates how the system is put together by providing an overview schematic — sort of a flow chart. The newer style is helpful because it puts data in context. The combination system is more expensive, due to the supplemental programming, Studnicka noted.
Old vs. New
Most of the time, clients see value in putting data in context, Studnicka said. Knowing a tank is almost full is one thing, but knowing tank level trends and if the water level is going up or down enables operators to make accurate predictions.
Having that information easily accessible on the screen is important because many of the older, more experienced operators who already know those trends are retiring.
“Younger people don’t keep information in their heads,” Studnicka says. However, they are digitally oriented and accustomed to looking at graphs and information on a screen. If the SCADA screen provides that level of detail, the information is not lost.
One of the issues that worries Studnicka is whether the younger generation follows up. He envisions a struggle for younger operators making the connection from what they see onscreen to what is happening at the facility.
“SCADA can’t tell you there’s a bad bearing in a pump; you still need to go to the station and do rounds,” he said.
By physically being in the station when something is wrong, experienced operators can use their senses to pinpoint problems. They may hear a motor not running properly, smell burning bearings, or feel vibrations that indicate something is wrong. These are little clues that cannot always be detected on a SCADA screen.
Technology is great, he continued, but operators still need knowledge.
“We still need to transfer institutional knowledge that you won’t see on screens,” Studnicka said. “SCADA is not an operator replacement; it’s supposed to make the operator better. The risk is to rely too much on technology.”
Room for Improvement
Situational awareness graphics can be configured to provide an array of data. Studnicka said high and low level set points could be shown as part of historical trends, but “we’re not doing that in water yet.”
Historic trending is important. Figuring out ways to use energy efficiently relies on tracking patterns; one example is differentiating weekends and holidays from weekdays by monitoring the energy usage related to pumping times.
Studnicka added that the water and wastewater industries do not do a good job of conveying the value of analyzing these relationships, but he believes situational awareness graphics can help operators make a correlation between time and value trends.
Other things that could be helpful to track include the sources that put water in and take water out, although he says monitoring the level of tower storage is more important. Cumulative trending — daily flow totals — and comparisons of production and process totals could also be useful.
While some of these concepts have been in use in the water industry for years, Studnicka noted that it takes time for concepts to gain widespread acceptance.