Integrating plant systems puts data where you need it, when you need it
No one disputes the notion that desktop computing is changing plant and facility engineering as dramatically as PCs changed accounting. More reliable operating systems, plantwide supervisory control and data acquisition systems (SCADA) and human-machine interface (HMI) software systems, and networking are enabling faster exchange of data with greater depth of information than ever before.
The real challenge now is how to convert that data explosion into useful information. Plant engineers, who once could take the pulse of their facility by walking through it, now get spreadsheets, status reports, and reports of every flavor. Where production managers once tracked efficiency by counting the number of units shipped, they now must have access to detailed information about the status of every work-in-progress. Quality control (QC) used to mean testing samples from a processing tank and comparing the results to specifications. Today’s QC systems monitor every aspect of the process control loop.
Fortunately, the same computers that gather, process, and present all that data can also be used to make sense of the information. Knowing the status of each piece of equipment, every work in progress, and each inventory level is helping plant engineers find out about (and fix) problems before they become crises.
Different jobs, different data
Equipment operators and maintenance personnel have vastly different informational needs than purchasing agents, human resources personnel, and company CEOs. Plant engineers need bits and pieces of data from every area, but too much information is every bit as bad as not enough. The true power of computing is not the gathering of information, but the transformation of that data into useful knowledge (Fig. 1). Tying disparate networks together is giving plant engineers valuable insights into the successes and challenges their facilities face.
Ethernet is the undisputed king of computer networking. It is a rare plant that lacks a local area network (LAN) to link desktop computers throughout the facility. The trick is getting those equipment networks — the ones developed for power management, building automation, and process control — to pass information along to the computers that people use. Doing so holds a huge potential return on investment: more effective management of resources, improved equipment efficiency, and better maintenance management. All of these factors directly affect profitability, reliability, and morale. The impact of computer-based data monitoring, gathering, and analysis on plant operations is best viewed by examining four important areas.
– Power and utility management. Keeping utility costs down is one of the most dramatic examples of the impact that information can have. From remote metering to onsite cogeneration, power management offers opportunities for immediate, bottom-line improvements.
– Network performance. Effectively managing various networks and data flow may be less dramatic than utility management, but it is certainly no less important. Knowing who is using what resources on the network, and identifying trouble spots before they become crises, allow more accurate forecasting for future growth.
– Safety and security systems. Safety and security matters also are critical. Monitoring equipment interlocks, tracking equipment operating parameters, and logging alarms and their causes all help make the plant safer and more efficient.
– Process control. Process control is the workhorse of industrial automation. Monitoring a single programmable logic controller (PLC) or a network of a hundred controllers is easier with an HMI and SCADA system connected through a facility’s network. A single program that tracks all of these systems, and delivers the right information to the right person at the right time, helps plant engineers find and avert crises before anyone knows there’s a problem.
With the deregulation of electric utilities, knowledge truly is power. Monitoring and improving power quality (Fig. 2) improves the reliability and performance of virtually all equipment throughout a plant, whether electricity is purchased on the open market or generated on-site.
At one manufacturing facility’s cogeneration power plant, for example, a sophisticated SCADA software package integrates all plant equipment operating information into one centralized control system. The system monitors equipment status, as well as load conditions and faults. Improved information management allows for more aggressive and timely maintenance, faster response when a fault occurs, and reduced downtime. Operators can often locate, identify, and correct a fault from right within the control room.
A graphical user interface (GUI) with more than 20 screens designed inhouse relays data from more than 4000 analog and digital I/O points and logs the information to a Microsoft SQL database. If a compressor alarm is triggered, operators can immediately see maintenance records for the component, review operating conditions, and pinpoint the cause of the problem. Because control and I/O are distributed, a fault can be isolated, allowing component repair or replacement without shutting down the rest of the system. A single operator can troubleshoot and repair many faults before anyone outside the control room even knows there’s a problem.
More efficient control of the powerhouse has lead to lower costs, as the equipment that draws electricity lasts longer and operates more efficiently. The centralized control architecture also reduces the time it takes operators to complete their tasks, and ongoing diagnostics and preventive maintenance have decreased short and long-term expenses for repairs and replacement parts.
Network performance and use monitoring
Power is not the only critical commodity that travels over a plant’s wires and cables. Telecommunications and computer networks were the first to enter most buildings, and as PCs proliferate in the front office and on the shop floor, phone and data networks are still the most widespread.
Most plant engineers would never install a new pipeline for water, fuel, or compressed air without a preventive maintenance program in place to make sure there are no leaks. But this is exactly what happens in many data “pipelines.” A network is installed and the system tested, then forgotten except when it breaks. When the network goes down everyone in the plant knows about it.
If the LAN goes down, the local server might be the culprit. Sometimes, though, the problem is that the network has grown too big for its switches. A 10BASE-T Ethernet LAN designed to handle 10 megabits/sec is ideal for simple file sharing within a department, or even for many control networks. However, put a PC on every desktop, give every employee e-mail and web access, start passing CNC-part programs around, or implement collaborative engineering, and the overloaded LAN will operate painfully slow or crash completely.
This scenario doesn’t have to be the case. New software tools offer better ways to look at networks (Fig. 3). By tracking data flow through the “pipes” of the network, bottlenecks and logjams can be identified and cleared — before they cripple the system. Sophisticated systems track disk use, software installations, and data maintenance actions such as backups through the network. Pinpointing bandwidth hogs and tracking down users who abuse the power of their desktop machines help keep a network humming — or at least help managers identify where the problems lie.
Safety and security systems
Of course, there is more to successful plant operation than preventing mechanical or electronic failures. Safety and security are critical systems, too. Operator safety used to mean padlocks and machinery interlocks to shut down equipment during maintenance and repairs. In today’s high-uptime facilities, however, 24/7 operation is the norm rather than the exception.
With distributed control systems or VME backplane-based PLCs, components can be taken offline in isolation, allowing the rest of the system to continue working. Networking the pieces simplifies data management and control, providing all the information necessary to those who need it.
At a wind tunnel operation, for example, users monitor and control the facility through software that runs under the Windows operating system. The tunnel generates airspeeds of up to 250 mph for aerodynamic testing of buildings, automobiles, high-speed trains, and new aircraft wings. Safety and repeatability functions are built into the system, which relies on more than 400 control system I/O points and an additional 1200 data I/O points.
Three levels of alarms protect people and equipment and alert operators to abnormal operating conditions:
1. Warnings — for conditions out of normal operating ranges or faults that the system self-corrected
2. High alarms — generated when process limits have reached design limitations
3. Critical alarms — which trigger main drive shutdowns in response to safety-critical failures.
Software that serves as the HMI tells operators what caused the alarm, what process or component is out of tolerance, and what needs to be done to correct the problem. In addition, all alarms are automatically logged to a write-once, read-many compact disk drive to provide a permanent record.
Plant engineers can track alarms on any PC using Microsoft software, and can make that information available through an intranet or over the web (Fig. 4). Remote accessibility means that system designers and installers can troubleshoot problems overseas without leaving their cubicles in the United States.
Manufacturing and process control
Remote access pays off for local operators, too. Many plants are spread out over a single campus location. For example, wastewater treatment pumping stations, tanks and ponds, meters, and other processes may be miles apart. HMI and SCADA systems ensure operators have timely access to the information — not just the data — they need.
At one midwestern plant, data collection and process control have cut recording and reporting time, slashing maintenance request response time from weeks to hours (Fig. 5). Operators review operating conditions, monitor alarms, and check water quality from a central control room. They learn about problems as they develop, and have enough information to take corrective action immediately. Management may never know about the day-to-day difficulties that occur. Timely access to useful data means the system works smoothly and virtually eliminates overtime requirements in many cases.
Tying it together
Turning data into useful information may be what takes computing into the next century. Just as spreadsheets led to widespread use of PCs in business offices, integrated systems are giving plant engineers new insights into the workings of their facilities. Faster access to more data leads to more accurate, more timely decisions.
The key is implementing systems that can tie varying networks together. Desktop computers are powerful enough to make sense of data from anywhere in the facility. With the correct HMI, everyone from machine operators to executives can gain access to the data they need in usable form. Getting the right information at the right time helps everyone from equipment operators to engineers find and fix problems before they become apparent — which may be the best incentive yet for integrating plant systems now.
— Edited by Jeanine Katzel, Senior Editor, 630-320-7142, firstname.lastname@example.org