Plant historians became popular in process plants in the 1980s. More recently they are being used broadly throughout industry to improve operations, identify problems, and find opportunities for enhancement. An early forerunner of historians were electromechanical pen-and-paper chart recorders. They produced a graph of one or more measured values over a period of time for analysis and a permanent record of critical information.
Plant historians acquire real-time data from automation and other systems to store time-stamped data at high speed to maintain a chronology of information. This industrial process information is then available to any user for reference and analysis including production status, performance monitoring, quality assurance, troubleshooting, tracking, and genealogy. A major advantage of historians is the ability to research and correlate any data easily to identify trends and relationships.
Initially historians were very expensive, but they have now gained broader use. Lower-cost computers and storage make it possible to record large amounts of plant data from operators, sensors, and processes at a reasonable cost. Compared to keeping paper records, it is much simpler to manage data, analyze it, and archive it electronically.
Before the term “big data” was being used as part of the Internet of Things, plant historians were handling large volumes of time-synchronized data. Consider time sampling and storing a single temperature sensor value every half second (500 milliseconds)—it generates more than 63 million samples per year. Tracking 1,000 temperature sensors in a plant would generate more than 63 billion stored samples per year. For sequential samples where values do not change, data compression techniques are often used to conserve storage. It is also common to filter measurements before sending data to a historian to reduce the significant amount of “noise” in the data. In an automation system, typical items tracked and stored include temperature, flow rate, pressure, level, machine cycles, run time, and overall equipment effectiveness. The recognition that big data can be valuable has put greater emphasis on historians to capture more data in plants than in the past. Fortunately, technology enables the collection and handling of big data at lower costs.
Information increasingly is being put to use by a wide variety of people, including plant management, engineers, operators, accountants, business analysts, scientists, quality control workers, and information technology (IT) specialists. Data alone does not deliver benefits; it is the people who use the information to solve problems and make improvements who deliver benefits. The ISA-95 international standard for the integration of enterprise and control systems data has been widely adopted to organize and communicate historic information. There are several use cases for data captured by historians:
Legal and compliance verifications
In both process and discrete industries, companies need to maintain a genealogy record of production and quality tests for legal and compliance reasons. Historians have detailed data that can be used in defense against litigation and to determine what products must be recalled, if necessary. Requirements in the food and pharmaceutical industries are long standing. Recent quality incidents and recalls in the automotive industry illustrate the need to capture and keep production data. Pharmaceutical application of historians must comply with 21 Code of Federal Regulations (CFR) Part 11, also known as electronic records/electronic signatures. Given the importance of the data, the FDA has strict regulations regarding access, security, and ability to edit such records, as documented in this CFR.
Track and trace serialization
Track and trace (TnT) serialization initiatives to maintain the history of products in the pharmaceutical and food industries are creating a greater need to capture and retain historic production records. The pharmaceutical industry is gearing up to TnT as government agencies and companies take measures to reduce drug counterfeiting and product diversion and increase patient safety. There are a number of motivations including contamination recalls, counterfeit drugs (Viagra is the most counterfeited drug), and drug thefts. The street value of drugs can easily range from $15 to $50 per tablet or in the case of codeine, $200 to $300 per pint. Thefts of pharmaceuticals in transit have ranged from $2 million to $80 million per incident. Countries worldwide are planning to require track and trace, increasing the need for plant history information.
When production issues occur, historic data is fundamental to identifying sources of problems using root-cause analysis. A root cause is a cause that prevents the final undesirable event from recurring when it is removed from the problem fault sequence. For example, common issues in process applications that can be identified include operator error, inadequate cleaning times, poor cleaning solution strengths, device malfunctions, and wrong process temperatures.
Many times, having chronological data is fundamental to pinpointing automation, control, and equipment problems. Chronological data gives troubleshooters deep insight into the behavior of processes at any point in time.
Chronological historic data provides in-depth system performance analysis that companies use when developing methods to optimize processes. This information can be the inputs to simulation software to understand the production process and simulate optimization methods.
At the annual Pharmaceutical Automation Roundtable, a major pharmaceutical company described how it uses historian data for new insights to improve the control methods of biological processes that are complex and difficult to predict. Using historic information and off-the-shelf analytic software, it learned about the interaction between process and equipment data that had not been apparent in the past. This also helps to identify a range of other problems, including maintenance issues.
Power and energy monitoring
Energy has been a blank check in industrial plants. However, by using a historian, along with submetering and power monitoring, plants can allocate energy costs to production steps and products to achieve closer cost accounting, find problems, and identify areas for improvement.
Advanced intelligence capabilities are being applied using data trends and patterns to predict failures and events. These predictive analytics are only possible with historian data.
Justifying the investments to replace and upgrade equipment can be more accurate using actual historic plant data, opposed to estimates. Historic data provides integrity to investment proposals made to management.
I recently asked an automation manager from a major pharmaceutical company about the value of historians, and he commented they are invaluable for providing the data store needed for true process understanding based on analysis, especially for batch processes. He also noted that many managers think of historians as simply a data store to cover a firm for regulatory purposes and do not clearly see the untapped value of information that can be harvested from historians for process improvement, process optimization, or aiding with root-cause analysis.
Bill Lydon is chief editor of InTech magazine. Lydon has been active in manufacturing automation for more than 25 years. He started his career as a designer of computer-based machine tool controls; in other positions, he applied programmable logic controllers and process control technology. In addition to experience at various large companies, he co-founded and was president of a venture-capital-funded industrial automation software company. Lydon believes the success factors in manufacturing are changing, making it imperative to apply automation as a strategic tool to compete.
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